Conference program

The program for the 3rd Conference of the Norwegian Ecological Society has been announced.

3rd Conference of the Norwegian Ecological Society

Welcome to the third biennial conference of the Norwegian Ecological Society. The conference will take place on the 12th and 13th of January 2017 at Blindern Campus, Oslo, organized and hosted by the Centre for Ecological and Evolutionary Synthesis (CEES).

The theme of the conference is Evolutionary Ecology, emphasizing the growing links and merger between the separate traditions of ecology and evolutionary biology.

There are 58 lectures (including 5 keynotes) organized into 10 different sessions and there will be approximately 22 posters presented during the reception on Thursday evening. After the reception we welcome those of you who have opted for the conference dinner to enjoy a meal with colleagues and interesting conversations.

We hope you enjoy the talks, the posters, the conversations and yourselves.

 

The organizing committee: Anders Nielsen, Jostein Starrfelt, Anders Herland, Anne.Brysting, Jo Skeie Hermansen, Olja Toljagic, Nils Chr. Stenseth.

 

 

 

Thursday January 12th

08:30 – 09:25

Coffee and Registration

09:25 – 09:30

Welcome

09:30 – 10:15

“On Evolutionary Ecology and the Red Queen”

Nils Chr. Stenseth

10:15 – 11:00

“Males exist. Does it matter?”

Hanna Kokko

Parallel sessions

Auditorium 1

Auditorium 2

Auditorium 5

 

Assorted Topics

Diversification and Trait Dynamics

Life Histories and Functional Traits

11:05 – 11:25

T. R. Haaland

E. G. Ofstad

L. A. Vøllestad

11:25 – 11:45

B. Star

J. M. I. Barth

R. E. Roos

11:45 – 12:05

E. Sperfeld

S. Einum

K. van Zuijlen

12:05 – 13:00

Lunch

Parallel sessions

Mating and Parental Care

Diversification and Trait Dynamics

Life Histories and Functional Traits

13:00 – 13:20

M. Rowe

F. Eroukhmanoff

K. Rydgren

13:20 – 13:40

Ø. H. Holen

E. I. F. Fossen

S. Hamel

13:40 – 14:00

A. Mennerat

J. A. M. Raeymaekers

E. Bellier

14:00 – 14:20

Coffee

14:20 – 15:05

“Population dynamics: a necessary link between ecology and evolution?”

Bernt-Erik Sæther

Parallel sessions

Climate Change

Societal Perspective

Conservation

15:25 – 15:45

K. A. Bråthen

D. J. Dankel

I. Auestad

15:45 – 16:05

  1. Eycott

K. Kausrud

E. Søvik

16:05 – 16:25

F. Jaroszynska

L. M. Jeno

L. N. Hamre

16:25 – 16:45

Coffee

Parallel Sessions

Climate Change

Population Dynamics and its Drivers

Conservation

16:45 – 17:05

B. B. Hansen

C. C. Cloete

L. Tingstad

17:05 – 17:25

H. Kauserud

E. F. Kleiven

K. Flatlandsmo

17:25 – 17:45

M. A. Mörsdorf

 

L. E. Sundt-Hansen

17:45 – 19:00

Reception and poster session in the lobby

19:00 à

Conference Dinner

 

 

 

 

Friday January 13th

09:00 – 09:45

“A burning issue: Ecological and evolutionary consequences of climate and land-use in a domesticated ecosystem”

Vigdis Vandvik

09:50 – 11:10

Radio show (EKKO with coffee / waffles

Parallel sessions

Auditorium 1

Auditorium 5

 

Forest Ecosystems

Biotic Interactions

11:10 – 11:30

F. Ssali

J. Mellard

11:30 – 11:50

K. M. Mathisen

A. A. Pepi

11:50 – 12:10

H. E. Pilskog

R. L. Malison

12:10 – 13:00

Lunch

13:00 – 13:45

“Of monstrous marmots and garish guppies: the interplay of inter- and intra-specific interactions and how to evolve a new body size and life history”

Tim Coulson

Parallel sessions

Forest Ecosystems

Biotic Interactions

13:50 – 14:10

L. Nybakken

B. A. Hatteland

14:10 – 14:30

P. Krokene

H. K. Lodberg

14:30 – 14:50

T. Birkemoe

E. F. Acanakwo

14:50 – 15:10

Coffee

Parallel sessions

Forest Ecosystems

Biotic Interactions

15:10 – 15:30

A. Vollsnes

A. G. Hertel

15:30 – 15:50

S. L. Olsen

M. S. Ugelvik

15:50 – 16:10

M. Steinert

N. Trandem

16:15 – 17:00

Conference summary, closing remarks, presenting NØF 2019

 

 

 

 

 

Abstracts

S0. Plenary lectures. Auditorium 1. 3

Nils Chr. Stenseth: Evolutionary Ecology and the Red Queen. 3

Hanna Kokko: Males exist. Does it matter?. 4

Bernt-Erik Sæther: Population dynamics: a necessary link between ecology and evolution?. 4

A burning issue: Ecological and evolutionary imprints of climate and land-use in coastal heathlands - Vigdis Vandvik. 4

Tim Coulson: Of monstrous marmots and garish guppies: the interplay of inter- and intra-specific interactions and how to evolve a new body size and life history. 5

S1. Evolutionary Ecology of Assorted Biological Topics – Auditorium 1. 5

Thomas Ray Haaland: Social foraging in a variable environment – A model of the evolution of plasticity and learning in producer-scrounger behavior 5

Bastiaan Star: Ancient DNA reveals an early Viking-Age origin of long-distance stockfish trade. 6

Eric Sperfeld: Bridging frameworks in nutritional ecology: Ecological Stoichiometry and Nutritional Geometry 6

S2: Evolutionary Ecology of Diversification and Trait Dynamics – Auditorium 2. 6

Endre Grüner Ofstad: Home range size of ungulates. 6

Julia M.I. Barth: Tracing differentiation in the face of connectivity and gene flow – a case study from highly mobile marine fish. 7

Sigurd Einum: Smaller when warmer, but how much? A quantitative model for oxygen availability driving the temperature-size rule. 7

Fabrice Eroukhmanoff: Rapid evolution following colonization of a newly restored habitat 7

Erlend I. F. Fossen: Half full or half empty? Genetic variance in optimism in Daphnia. 8

Joost A. M. Raeymaekers: Genomic variation at the tips of adaptive radiations in stickleback, Darwin’s finches and cichlids. 8

S3: Evolutionary Ecology of Life Histories and Functional Traits – Auditorium 5. 8

L. Asbjørn Vøllestad: Population differentiation and life history diversification: rapid and small scale? 8

Ruben Erik Roos: FuncFinse: Primary producer traits across an altitudinal gradient 9

Kristel van Zuijlen: FuncFinse: a common garden experiment on lichen functional traits, microclimate and decomposition. 9

Knut Rydgren: Growth pattern of the moss Hylocomium splendens reveals the timing of a Mesolithic tsunami in the North Atlantic. 9

Sandra Hamel: Compensatory growth dissipates cohort variation with age at the price of late-life survival 10

Edwige Bellier: Relationships among survival, recruitment and species traits in an avian community 10

S4: Evolutionary Ecology of Mating and Parental Care - Auditorium 1. 10

Melissah Rowe: Trade-offs between pre-copulatory and post-copulatory investment generate positive correlations across species. 10

Øistein H. Holen: Avian brood parasitism: Should hosts defend early or wait and see?. 11

Adele Mennnerat: Fewer brood failures in mixed-paternity broods of a socially monogamous bird. 11

S5: Evolutionary Ecology and Climate Change – Auditorium 1. 11

Kari Anne Bråthen: Trajectories of vegetation change under climate warming are modified by allelopathy and herbivory. 12

Amy Eycott: Of seeds and sheep: can poop help plants cope with climate change?. 12

Francesca Jaroszynska: Biotic interactions are important determinants of plant community structure and function. 12

Brage B. Hansen: When extreme weather becomes the normal: less variable ungulate dynamics in a warmer high Arctic. 13

Håvard Kauserud: Fungi show trait-dependent responses to climate change. 13

Martin A. Mörsdorf: How changing winter conditions determine terrestrial nutrient dynamics in the tundra during the growing season. 13

S6: Evolutionary Ecology and the Society Auditorium 2. 14

Dorothy J. Dankel: Transdisciplinary insights into Integrated Ecosystem Assessments: What they are, what they can be, what they should be. 14

Kyrre Kausrud: Anthrax: Ecology in a Landscape of Fear 14

Lucas M. Jeno: The effects on motivation and learning of a mobile application tool for identification of species 14

S7: Evolutionary Ecology and Conservation - Auditorium 2. 15

Inger Auestad: Measuring restoration success using ordination-based successional rates: how to handle bioclimatic variation in the data set 15

Eirik Søvik: Bees, Metal, and Behaviour 15

Liv Norunn Hamre: Paradise lost - the transformation of the gully landscape in SE Norway. 15

Lise Tingstad: How regional perspectives can inform national conservation priorities: a case study of red listed forest species in Fennoscandia. 16

Kåre Flatlandsmo: Some aspects of the economic valuation of a river basin. Examples from Raundalselva, Voss – Norway. 16

S8: Evolutionary Ecology of Population Dynamics and its Drivers – Auditorium 2. 16

Claudine C. Cloete: Environmental dynamics and zoonotic diseases – The case of anthrax in Etosha National Park 16

Eivind F. Kleiven: Temporal transferability of spatial state-space models: predicting lemming outbreak abundances 17

S9: Evolutionary Ecology of Forest Ecosystems – Auditorium 1. 17

Fredrik Ssali: The problem with bracken in tropical Africa. 17

Karen M. Mathisen: Previous browsing increases future browsing - a maladaptive plant response?. 18

Hanne Eik Pilskog: Long-lasting effects of logging on beetles in hollow oaks. 18

Line Nybakken: Facing dangers as you grow up: chemical defence of trees across season and age. 18

Paal Krokene: How bark beetles and their microbiome interact to kill well-defended trees. 19

Tone Birkemoe: The potential of insects to disperse fungi to dead wood. 19

Ane Vollsnes: Reforestation without insecticides. Protecting spruce seedlings against pine weevils on a clear felling. 19

Siri Lie Olsen: Local and landscape effects of stand age on biodiversity in productive boreal forests 20

Mari Steinert: Plant communities in power-line clearings: maintaining open-canopy habitats through frequent clearing could positively affect diversity of pollinating insects. 20

S10: Evolutionary Ecology of Biotic Interactions – Auditorium 5. 20

Jarad Mellard: Combined effects of predation and scavenging in a food web model. 20

Adam A. Pepi: Elevationally biased avian predation as a contributor to the spatial distribution of geometrid moth outbreaks in sub-arctic mountain birch forest 21

Rachel L. Malison: Eurasian beavers have little impact on juvenile Atlantic salmon and trout populations in Midt-Norway. 21

Bjørn A. Hatteland: Tracing trophic interactions using molecular methods. 21

Hanna K. Lodberg-Holm: Bears follow the blue wave through a landscape of risk. 22

Erik F. Acanakwo: Seed removal in an African savanna landscape. 22

Anne G. Hertel: Berry production drives bottom-up effects on life history traits of an omnivore, the brown bear. 22

Mathias S. Ugelvik: Salmon already infected with salmon lice are more susceptible to new infections 23

Nina Trandem: Fatal attraction: male spider mites prefer females killed by fungi to healthy living ones 23

 

 

S0. Plenary lectures - Auditorium 1.

Nils Chr. Stenseth: Evolutionary Ecology and the Red Queen

University of Oslo

Hanna Kokko: Males exist. Does it matter?

University of Zurich. Switzerland.

The evolution of sex, and its subsequent high prevalence in nature, is one of the great mysteries of life. The main reason, the so-called "twofold cost of sex", has something to do with male production: the cost does not exist in the same form in isogamous organisms that lack males and females. Such organisms, however, can still experience e.g. costs of mate-finding. The differences in costs are relevant because sex does not always coincide with there being two sexes in a population: ancient sex was neither obligatory nor did it feature a male-female dimorphism. I will spend some time discussing how this impacts the evolution of sex, and how the rules of sex change once there are males (a specialized morph that finds it more difficult to switch to asexual reproduction than what is possible for females).

 

Bernt-Erik Sæther: Population dynamics: a necessary link between ecology and evolution?

University of Trondheim

Variation in population size caused by density-dependence and fluctuations in the environment may strongly affect which phenotypes that contribute the most to future generations, introducing a link between ecological dynamics and evolutionary processes. Here I will present some recent attempts to include density dependence and environmental stochasticity in analyses of phenotypic selection. I will show evidence for that density dependent selection may be an important selective agent in natural populations. This may even induce r- and K-selection, in which phenotypes favoured at low densities are selected against at high population densities. I will argue that these results may have important implications for our understanding of phenotypic evolution as process in natural populations.

Vigdis Vandvik: A burning issue: Ecological and evolutionary imprints of climate and land-use in coastal heathlands

 

Department of Biology, University of Bergen, Norway Corresponding authors e-mail address: vigdis.vandvik@bio.uib.no

 

50 years after "The silent spring" and as the global temperature is increasing at an alarming rate it is uncontroversial that humans have strong, and often negative, impacts on natural ecosystems. However, the debate is often polarized into a 'people vs. nature' dichotomy, and fails to acknowledge that aspects of nature that we value are also partly shaped by human imprints. The coastal heathlands of north-west Europe is one example of landscapes that have emerged under, and are shaped by, strong anthropogenic forcing. These heathlands have been continuously managed by traditional burning and grazing regimes for up to 6000 years, and support characteristic ecosystems and biodiversity.

 

Understanding the ecology and evolutionary biology of the heathlands requires understanding of how the interplay between natural and anthropogenic forcing has shaped heathland ecosystems and their flora and fauna through history. We combine different methods, such as palaeoecological reconstructions, landscape ecology and germination ecosphysiology, to explore the roles of climate and land-use in shaping heathland ecology and evolutionary biology. In contrast to the often stated 'biotic homogenization' paradigm, we find that the species colonizing heathlands after fire are not widespread generalists, but a characteristic set of relatively narrow-range species representing a characteristic subset of the local and regional flora. The traditional heathland management, such as grazing and management burning, thus contributes significantly to the biodiversity of the heathland landscape across a range of spatial and temporal scales. We also demonstrate that past human manipulation of coastal heathland fire-regimes have triggered evolution of smoke-responsive seed germination in the keystone species Calluna vulgaris. Such evolutionary imprints of (pre)historic anthropogenic impacts are severely under-studied, and research is urgently needed to inform decision-making in conservation science and ecosystem management.

 

Acknowledgments: Liv Guri Velle, Inger Elisabeth Måren, Peter Emil Kaland, Ann Norderhaug, Samson L. Øpstad, Liv S. Nilsen, Matt I. Daws, Joachim Töpper, Einar Heegaard, Sigird S. Bruvoll, Lyngheinettverket, The Norwegian Research Council.

 

 

Tim Coulson: Of monstrous marmots and garish guppies: the interplay of inter- and intra-specific interactions and how to evolve a new body size and life history.

University of Oxford, UK.

The dynamics of alleles, genotypes, phenotypes, demographic rates, populations, communities and ecosystems are all intimately intertwined. Ecology and evolution is concerned with how dynamics at each level influence dynamics at other levels. In this talk I will explain how ecological feedbacks influence the associations between genotype and phenotype, and between phenotype and demographic rates, and how these feedbacks generate micro-evolution (change in allele frequencies) as well as changes in the way that species interact. These changes have consequences for populations, communities and ecosystems. I will illustrate my talk with examples from systems ranging from freshwater fish to mountain mammals.

 

 

S1. Evolutionary Ecology of Assorted Biological Topics – Auditorium 1

 

Thomas Ray Haaland: Social foraging in a variable environment – A model of the evolution of plasticity and learning in producer-scrounger behavior

Thursday at 11:05 in Auditorium 1.

The producer-scrounger model is a frequency-dependent cooperation/conflict game describing social situations where the efforts of certain individuals (producers) are exploited by others (scroungers). In a social foraging context, producers discover patches of food and scroungers join the producers at already discovered patches. Theoretical work has identified which parameters influence the equilibrium frequencies of the two tactics in a group, and many of the results have been confirmed in experimental studies on birds. However, analytical results do not predict whether the ESS is comprised of fixed strategists or mixed strategists playing each tactic with ESS probability, or when we also expect the evolution of conditional strategists that have to gather information about their social environment in order to show adaptive plasticity between producing versus scrounging. We extend existing theoretical treatments with an evolutionary simulation model, where genes for the social reaction norm evolve across generations, and we examine the evolutionary stability of fixed, mixed and conditionally plastic strategies, and how these are affected by environmental or demographic stochasticity. We also investigate whether conditional strategists should best assess their social environment through private or public information, and the value of memory and learning under different patterns of environmental fluctuation.

 

Bastiaan Star: Ancient DNA reveals an early Viking-Age origin of long-distance stockfish trade

Thursday at 11:25 in Auditorium 1.

The first systematic historical records show that dried Atlantic cod (stockfish) dominated the Norwegian export already in the 14th century AD, consisting of 80% of its total value. Nonetheless, the first origin of this trade and its expansion up to that period is unclear. While it has been suggested that the stockfish trade began around AD 1100, archaeological evidence remains inconclusive. Such evidence is based on the analysis of stable isotopes and/or on the lack of skull bones within Atlantic cod bone assemblages. Since fish were typically decapitated before export, bone assemblages without skulls are indicative of long-distance trade. Yet fish from nearby sources could also be similarly processed and stable isotopes only provide a low-resolution guide to source origin. Here, we use whole genome sequencing (WGS) to investigate the origin of Atlantic cod during the Viking Age. We have obtained WGS data from samples between 1250 to 800 years BP, which we compare to an extensive contemporary dataset of 240 specimens from various populations in the North Atlantic region. Identifying the source of early Viking Age trade and it subsequent expansion into Norway’s medieval stockfish export has implications for the timing of anthropogenic impacts on Northern Atlantic cod populations.

 

 

Eric Sperfeld: Bridging frameworks in nutritional ecology: Ecological Stoichiometry and Nutritional Geometry

Sperfeld E., Halvorson H.M., Malishev M., Clissold F.J., Wagner N.D., Raubenheimer D.

Thursday at 11:45 in Auditorium 1.

Within the last two decades, Ecological Stoichiometry (ES) and Nutritional Geometry (NG, also known as Geometric Framework for nutrition) have delivered novel insights into core questions of nutritional ecology. These two nutritionally explicit frameworks differ in the ‘nutrient currency’ used and the focus of their past research. NG originates from behavioural ecology using terrestrial insects as model organisms in tightly controlled feeding experiments, while ES originates from biogeochemistry focusing on the transfer of key elements across trophic levels, mainly in aquatic environments. Despite these differences, both NG and ES have developed in explaining patterns across various scales of biological organization and share common concepts, such as nutrient budgets and homeostasis. I will show how response surface plots, a tool commonly used in NG studies, can be applied to element budget data from an ES study to reveal the interplay between egestion and excretion depending simultaneously on the consumed amount of carbon and phosphorus. I will also present similarities and differences in the conception of homeostasis between the two frameworks and briefly introduce dynamic energy budget (DEB) models as a general tool to address homeostatic regulation at the fundamental level of the organism.

 

 

 

S2: Evolutionary Ecology of Diversification and Trait Dynamics – Auditorium 2

 

Endre Grüner Ofstad: Home range size of ungulates

Thursday at 11:05 in Auditorium 2.

The spatial scale of animal space use, e.g. measured as individual home range size, is a key trait with important implications for ecological and evolutionary processes as well as management and conservation of populations and ecosystems. Explaining variation in home range size has therefore received great attention in ecological research. However, few studies have tested multiple hypotheses simultaneously, which is important given the complex interactions between species characteristics, biology, and behaviour. Here we assess how differences in habitat use and species characteristics affect the body mass-home range size relationship of ungulates, accounting for estimate uncertainty and phylogeny. Habitat type was the main factor explaining interspecific differences in home range size after accounting for species body mass and group size. Our results suggest that the spatial scale of animal movement predominantly is a result of their body mass, group size, and the landscape they inhabit.

 

Julia M.I. Barth: Tracing differentiation in the face of connectivity and gene flow – a case study from highly mobile marine fish.

Thursday at 11:25 in Auditorium 2.

Recent advances in genomic tools offer new exciting opportunities to investigate population divergence under gene flow, the basis of phenotypic traits, and evolutionary signatures of selection. Especially in the marine environment, where the potential for population differentiation has long been dismissed due to the apparent lack of geographical barriers, high dispersal capabilities, and slow genetic drift as a result of large effective population sizes, genomic data have shown to be essential to reveal fine scale population structure and locally adapted populations despite considerable gene flow. However, genomics have not yet been used to their full potential for the management and conservation of the world’s highly overexploited fish stocks, and mechanisms allowing local adaptation despite gene flow in natural populations still remain poorly understood. Here, we use large population genomic datasets of highly mobile, oceanic, predatory, and commercially exploited fish species, to show how genomics can shed light on mechanisms enabling local adaptation in species that experience high connectivity and gene flow, and how such findings can aid to reveal biologically relevant population units for the delineation of

management areas.

 

Sigurd Einum: Smaller when warmer, but how much? A quantitative model for oxygen availability driving the temperature-size rule

Thursday at 11:45 in Auditorium 2.

Ectotherms are commonly smaller at higher temperatures. Oxygen availability and requirements is suggested to explain such a “temperature-size rule“. Due to surface-to-volume allometries and metabolic responses to temperature, larger animals are disproportionally challenged by oxygen limitations with increasing temperatures. This is expected to be particularly pronounced in aquatic environments where oxygen availability is low. Indeed, empirical data does demonstrate a stronger relationship between temperature and body size in aquatic than in terrestrial environments, thus providing support for the oxygen limitation hypothesis. However, no rigorous efforts have been made to predict how much the maximum body size should respond to temperature. When doing this for aquatic organisms I find that published relationships between body size and temperature are much weaker than predicted across a wide range of plausible parameter space. I hypothesize that oxygen is not limiting body size across the whole temperature ranges animals are adapted to. Rather, oxygen availability may constrain body size only in the higher end of the thermal conditions that organisms may experience in their natural environment. I test a prediction from this hypothesis using Daphnia.

 

 

Fabrice Eroukhmanoff: Rapid evolution following colonization of a newly restored habitat

Thursday at 13:00 in Auditorium 2.

Real-time observation of adaptive evolution in the wild is rare and limited to cases of dramatic, often anthropogenic, environmental change. Here, we present the case of a small population of reed warblers (Acrocephalus scirpaceus) undergoing adaptation over a period of only 19 years (1996 – 2014) after colonizing a restored wetland habitat in Malta. Our data show that body mass follows an evolutionary trajectory consistent with a population ascending an adaptive peak, a so-called Ornstein-Uhlenbeck process. We corroborate these findings with genetic and ecological data, revealing that individual survival is correlated with body mass, and more than half of the variation in mean-population fitness is explained by variation in body mass. Despite a small effective population size, an adaptive response has taken place within a decade. A founder event from a large, genetically variable source population to the southern range margin of the reed warbler distribution likely facilitated this process.
 

Erlend I. F. Fossen: Half full or half empty? Genetic variance in optimism in Daphnia

Thursday at 13:20 in Auditorium 2.

Predicting the onset of winter and preparing for it is critical for many populations in temperate climates. In Daphnia populations this involves shifting from reproducing asexually to producing overwintering resting eggs through sexual reproduction. For a particular pattern in seasonality, there should be strong stabilizing selection for an optimal timing of onset of sexual reproduction. However, variation in levels of within-season environmental stochasticity across years is likely to produce fluctuating selection that will maintain genetic variation in such timing along an “optimist-pessimist axis”. Specifically, in years with higher environmental stochasticity, “optimistic” genotypes that require stronger cues to shift to sexual reproduction are favored over “pessimists” because the former will have more clonal copies by the end of the season that in turn can produce more resting eggs. Here we exposed genotypes of Daphnia magna to a range of temperatures and examined the production of asexual offspring and resting eggs. We find consistent genetic differences in resting egg production across temperatures, and particularly at the lowest temperature where a bimodal distribution of “optimists” vs. “pessimists” was observed. This level of genetic variance suggests a strong potential for evolutionary responses to spatio-temporal patterns of within-season environmental stochasticity.

 

Joost A. M. Raeymaekers: Genomic variation at the tips of adaptive radiations in stickleback, Darwin’s finches and cichlids

Thursday at 13:40 in Auditorium 2.

The classic model of adaptive radiation posits a series of key steps. First, populations of an ancestral species colonize multiple geographical locations with distinct environments. Environmental differences then impose divergent selection pressures, causing an initial phase of adaptive divergence between these populations. As adaptive divergence proceeds, reproductive barriers may evolve as a consequence, such that the different populations experience at least partial reproductive isolation when they come into secondary contact. Finally, competitive and reproductive interactions that occur following secondary contact can drive further adaptive divergence (e.g., character displacement) and reproductive isolation (e.g., reinforcement). These key elements of adaptive radiation, which often involves the emergence of multiple species in relatively short periods of time, are now well established in iconic models such as stickleback, cichlid fishes, and Darwin’s finches. For each of these model systems, I will illustrate how genomic studies help us to understand the initial stages of adaptive radiation.

 

S3: Evolutionary Ecology of Life Histories and Functional Traits – Auditorium 5

L. Asbjørn Vøllestad: Population differentiation and life history diversification: rapid and small scale?

Thursday at 11:05 in Auditorium 5.

Classically, ecological and evolutionary time was assumed to be orders of magnitude different, indicating that contemporary evolutionary processes were difficult to observe and study. There has, however, been a major shift in the way the time scales of these two processes are viewed, and now it is clear that they can occur at comparable timescales. Freshwater fish populations are often differentiated due to complex landscape leading to reduced connectivity and limited gene flow. This structuring can lead to significant levels of local adaptation. Here, I will present data from a long-term study on lake-living and stream-spawning grayling Thymallus thymallus in Norway. Grayling invaded a small sub-alpine lake in c. 1880, and has since then established numerous subpopulations in tributaries to the lake. These tributaries differ in spring water temperature, leading to large differences in spawning phenology among the sub-populations. Based on population genetic studies over several years we find significant isolation-by-distance genetic structure among sub-populations, but the sub-populations are clearly not in migration-drift equilibrium. Using common-garden experiments coupled with quantitative genetic and proteomic studies we show that several early life-history traits have become significantly differentiated among the sub-populations during the c. 25-30 generations that have elapsed since the populations were established. Using a set of climate and weather models we show that the divergence have developed during periods with very variable environmental conditions producing large temporal variation in the opportunity for gene flow among sub-populations. In order to understand how populations diverge and differentiate a range of methods and approaches are needed. Clearly, ecological and evolutionary change happens at the same time scale, and both ecological and evolutionary processes needs to be studied when trying to understand population dynamics and resilience.

 

Ruben Erik Roos: FuncFinse: Primary producer traits across an altitudinal gradient

Thursday at 11:25 in Auditorium 5.

One of the major challenges for contemporary ecologists is to understand how ecological communities respond to environmental changes. Although classifying species to their taxonomy is useful, it has major limitations when it comes to answering ecological questions. A more functional approach, based on a species set of traits that define its performance within an ecosystem, provides much more insight. Many plant ecologists have now applied such trait-based approaches, but these studies are often limited to vascular plants and do not include other important primary producer groups such as lichens and bryophytes. However, there may be clear differences in what drives changes in community level traits across environmental gradients between producer groups: in vascular plants changes in species community are often most important and intraspecific variation is often also significant, whereas recent studies suggest that in lichens intraspecific variation alone drives changes in community level traits. In this presentation, I will present the layout and first results of a study on the relative importance of species turnover versus intraspecific variation as drivers of community-level traits in different primary producer groups simultaneously across the same environmental gradient in Finse, Southern Norway.

 

Kristel van Zuijlen: FuncFinse: a common garden experiment on lichen functional traits, microclimate and decomposition

Thursday at 11:45 in Auditorium 5.

An organism’s performance in a certain environment is determined by its traits. A way to study the performance of an organism and its impact on ecosystem processes is by studying functional traits. This has been widely acknowledged for vascular plants but only occasionally for other important primary producers such as lichens. The FuncFinse project aims to study functional traits of all primary producers groups (vascular plants, bryophytes and lichens) and their effects on ecosystem processes in alpine ecosystems. This autumn, a common garden experiment with lichens has been set up in the mountains of Finse, South Norway. The aim of this experiment is to measure traits of different transplanted lichen species with contrasting thallus colour and structure and the effect of their traits on the microclimate (soil moisture and temperature). Furthermore, the effect of lichen traits and the microclimate on decomposition rate of coexisting vascular plants will be studied by using litter bags. In this presentation, I will talk about the scientific background, the set-up, methods and hypotheses of this experiment.

 

 

Knut Rydgren: Growth pattern of the moss Hylocomium splendens reveals the timing of a Mesolithic tsunami in the North Atlantic

Thursday at 13:00 in Auditorium 5.

The giant Storegga tsunami, about 8150 years ago, flooded margins of the North Sea and the Norwegian Sea that were occupied by Stone Age humans. The impact on the population might have been devastating, but least in summer and early autumn when people went to the mountains to hunt reindeer. By using the growth pattern of moss stems of Hylocomium splendens that were buried alive in the tsunami deposits we show that the tsunami happened in autumn, probably late October. At that time in the season, people along the North Sea-Norwegian Sea coastline would have been near their seashore settlements. The huge waves that suddenly appeared and swept away people and their belongings must have been terrifying. The loss of stores, infrastructure and tools must have caused serious problems for the Stone Age humans, and many survivors may have succumbed during the first winter.

 

Sandra Hamel: Compensatory growth dissipates cohort variation with age at the price of late-life survival

Thursday at 13:20 in Auditorium 5.

Environmental conditions experienced during early growth and development markedly shape phenotypic traits. Consequently, individuals of the same cohort may show similar life-history tactics throughout life. Conditions experienced later in life, however, could fine-tune these initial differences. For instance, compensatory/catch-up growth can decrease the magnitude of cohort variation with increasing age. Compensatory growth, however, is expected to be traded-off against lifespan. Such long-term costs have not been documented in the wild. Using body mass data from 11 populations of large herbivores spread along the “slow-fast” continuum of life histories, a comparative analysis was performed to quantify cohort variation in individual body size trajectories and to assess whether it resulted in long-term trade-offs in terms of survival. Clear cohort clusters were identified and they showed distinct growth trajectories, highlighting that variation in early size is structured among cohorts and that early size is a fundamental determinant of lifetime growth patterns. Initial cohort variation dissipated throughout life, and lifetime patterns changed both across species with different paces of life and between sexes. After accounting for viability selection, compensatory/catch-up growth in early life explained much of the decrease in cohort variation. Initial body mass had a positive influence on late-life survival, supporting a silver spoon effect, whereas allocation to compensatory growth decreased late-life survival. This comparative analysis illustrates how variability in growth changes over time and provides the strongest empirical support to date that individuals face a trade-off between growth and late-life performance in the wild.

 

Edwige Bellier: Relationships among survival, recruitment and species traits in an avian community

Thursday at 13:40 in Auditorium 5.

Edwige Bellier, Marc Kéry and Michael Schaub

Comparative studies about the relationship between vital rates and functional traits at the community level are lacking because estimating vital rates requires detailed demographic data. From counts of unmarked breeding birds, we study the relationships between avian vital rates and species traits of 53 species of passerines. We use new dynamic N-mixture models that account for intraspecific density, environmental stochasticity and accommodate imperfect detection to estimate vital rates from unmarked individuals. Our results show that the relative importance of recruitment and adult survival as contributors to population growth varied greatly among species, while interspecific differences in vital rates reflected differences in species traits.

 

 

S4: Evolutionary Ecology of Mating and Parental Care - Auditorium 1

 

Melissah Rowe: Trade-offs between pre-copulatory and post-copulatory investment generate positive correlations across species

Thursday at 13:00 in Auditorium 1

Theoretical models predict a trade-off between investment in pre-copulatory and post-copulatory sexually selected traits. Here, using data for 21 species of Old World leaf warblers (Phylloscopidae), we show that pre- and post-copulatory sexual traits (sperm length and song complexity) are positively correlated, which is consistent with several recent empirical studies. We then show theoretically, that whenever trade-offs exist within species, investment into pre- and post-copulatory sexual traits will generally be positively correlated across species, provided there is variation in the total resources males invest into obtaining fertilizations. This applies to all forms of pre-copulatory male competition (i.e. contest and scramble), as well as female choice. In contrast, negative covariance between pre- and post-copulatory investment is expected only under limited conditions, notably when total resource investment is relatively constant and mating system is variable across species. These results imply that assessment of the strength and direction of covariance between pre- and post-copulatory investment would benefit greatly from taking into account variation in resource availability and the total investment males make into obtaining fertilizations.

 

 

Øistein H. Holen: Avian brood parasitism: Should hosts defend early or wait and see?

Thursday at 13:20 in Auditorium 1.

Øistein H. Holen and Rebecca M. Kilner

Most host defences against avian brood parasitism are concentrated at the early stages of the nesting attempt, during egg laying and incubation, reflecting the fact that hosts usually suffer less fitness costs the earlier they get rid of a brood parasite. However, in some host species the defences are concentrated at the nestling stage, and the factors that favour late defence over early defence are not well understood. One possibility is that late-defending hosts make better-informed decisions. To study this, we model optimal timing of nest desertion for hosts gathering cumulative information about the risk of parasitism throughout the nesting attempt. The model considers the best use of the total information gained, and predicts when it can be most usefully acted upon. The host uses information from sightings of adult parasites, eggs, and nestlings to assess the risk of parasitism, and defends before laying, after clutch completion, or immediately after hatching. Factors that increase the ratio of brood rejection to clutch rejection include low cost of delaying desertion from egg to chick stage, better host discrimination at chick than egg stage, and low cost of early desertion (i.e. before onset of egg laying).

 

Adele Mennnerat: Fewer brood failures in mixed-paternity broods of a socially monogamous bird

Thursday at 13:40 in Auditorium 1

Despite a large research effort, there seems to be limited empirical support for genetic (i.e. indirect) benefits of extra-pair copulation (EPC) in birds, while clearcut ecological (i.e. direct) benefits were only found in particular species. However avoidance of brood failure due to predation has scarcely been considered as a potential ecological benefit of EPC, despite the strong selection pressure it represents. A recent ‘nicer neighbourhood’ model shows that EPC can in theory evolve as a female strategy that, by spreading paternity among males in neighbouring nests, selects for increased participation in antipredator defence in the neighbourhood, thereby providing direct benefits to her brood. Here we present patterns from a blue tit (Cyanistes caeruleus) population that do not support the indirect benefits hypothesis, but suggest links between EPC and brood failure consistent with the ‘nicer neighbourhoods’ model. These patterns should motivate further exploration of such potential ecological benefits of EPC.

 

S5: Evolutionary Ecology and Climate Change – Auditorium 1

 

Kari Anne Bråthen: Trajectories of vegetation change under climate warming are modified by allelopathy and herbivory

Thursday at 15:25 in Auditorium 1.

Organisms that modify the environment (niche constructors) are likely candidates to mediate effects of climate warming. Here we assess the mediating effect of the common allelopathic dwarf shrub Empetrum nigrum and the large herbivore Rangifer tarandus on responses of tundra plant communities to increasing temperatures.

We developed a structural equation model based on data from a field-based study of 1450 tundra plant communities, covering a temperature gradient, contrasting Rangifer densities, and a range of Empetrum abundances. We found temperature to be a significant predictor of Empetrum, herbaceous and woody plant abundances. However, in communities with Empetrum present, temperature was significantly reduced as predictor for herbaceous plant abundance and Empetrum presence was the strongest predictor for woody plant abundance. In comparison we found Rangifer density to have marginal or no effect.

Results from this study indicate how the encroachment of Empetrum is likely to drive tundra communities towards slower process rates and lower biodiversity. This is one of a few empirical studies showing, over a large scale, how plant species with niche constructing abilities can mediate the effects of climate warming in tundra ecosystems. Our results substantiate the importance of including niche constructor species in predictive models of climate change.

 

Amy Eycott: Of seeds and sheep: can poop help plants cope with climate change?

Thursday at 15:45 in Auditorium 1.

Ungulates perform an important service as dispersers of seeds and endozoochory may be the only way for many plant species to travel fast enough to keep pace with climate change. We used three approaches to consider which ungulate species are likely to move seeds sufficiently far or upwards. Firstly we analysed data from 50 studies of endozoochorous dispersal by ungulates, finding that the mean number of seeds per dropping varies by five orders of magnitude and is not simply explained by variation in ungulate body mass. The number of species dispersed is largely a function of seed number dispersed, but grazers’ droppings have significantly lower species richness after adjustment for seed number. Secondly we compared plant species’ current maximum elevations with the viable seed content of faecal pellets from sheep and goats collected over an elevational gradient in Flåmsdalen, western Norway. Several species were deposited above their current elevation limit, demonstrating the potential importance of outfield grazing for plant elevational range shifts. Our third approach, resampling in Jotunheimen and Troms, showed that increased grazing actually decreases the rate at which plant species move uphill. It is only under particular circumstances that endozoochorous dispersal is worth the risk.

 

Francesca Jaroszynska: Biotic interactions are important determinants of plant community structure and function.

Thursday at 16:05 in Auditorium 1.

Shifts in these interactions due to global climate change, mediated through disproportional increases of certain species or functional groups, may therefore have strong effects on plant community properties. Still, we lack knowledge of community-level effects of climate-driven alterations of biotic interactions. In this study we examined how a dominant functional group affected community and ecosystem properties of subordinate plant species by experimentally removing graminoids in semi-natural grasslands in southern Norway. To test whether the effect of graminoids varied with climate, the removal experiment was replicated along broad-scale temperature and precipitation gradients. Competition from graminoids predominantly limited species richness of the non-graminoid plant community across the climate gradients. The relative importance of competition also increased with increasing temperature. These findings partly correspond with the results of a previous population-level study, indicating that increased relative importance of competition may be a common response to climate warming across organizational levels of plant communities. Our study suggests that competitive interactions with graminoids may further limit non-graminoid seedling recruitment and species richness in semi-natural grasslands in a warmer future climate, thereby reducing biodiversity of these often highly diverse ecosystems.

 

Brage B. Hansen: When extreme weather becomes the normal: less variable ungulate dynamics in a warmer high Arctic

Thursday at 16:45 in Auditorium 1.

Brage B. Hansen, Marlene Gamelon, Steve Albon, Audun Stien, Justin Irvine, Leif Egil Loe, Vebjørn Veiberg, Erik Ropstad, Aline M. Lee, Bernt-Erik Sæther, Vidar Grøtan

Global warming increases the frequency of extreme weather events, which long-term consequences for the population dynamics of long-lived species are generally difficult to predict. Here we use demographic modelling of wild reindeer dynamics to show that in Svalbard, a high Arctic climate change hot-spot, more frequent episodes of heavy winter rain and icing results in slightly reduced average population sizes, yet much less population variability and less frequent and violent crashes. This occurs because the food-limiting effect of icing depends on population density and age structure. At high density, a single icing event will suppress the vital rates and cause a large population decline and long-term changes in population state (i.e. an age structure with a larger proportion of prime-aged), reducing the vulnerability to subsequent events. Thus, accounting for interactions with demography and density-dependence is crucial for predictions of climate change effects in long-lived species.

 

Håvard Kauserud: Fungi show trait-dependent responses to climate change

Thursday at 17:05 in Auditorium 1.

Håvard Kauserud, Carrie Andrew, Einar Heegaard & the ClimFun Team

We have assembled ~7 mill fungal records data from Europe dating back to the 17th century to investigate effects of climate change on fungi’s fruiting patterns, ecology and distributions. The fungal records were paired with climate data and various fungal traits data were obtained. On a European scale, we observe that climate factors have large influences on the assembly of fungal communities and how they change through time. Using advanced statistical analyses we observed trait-dependent temporal shifts in fungi’s altitudinal ranges, where high altitude species apparently respond most dramatically to climate change. In a study from the UK, we observed trait-dependent changes in fungi’s distributions. We have also revealed that changes in fungi’s fruiting phenology and yields are highly context-dependent, showing different trends across Europe. This project exemplifies how historic collection data can be used to reveal effects of climate change and address questions in macroecology.

 

Martin A. Mörsdorf: How changing winter conditions determine terrestrial nutrient dynamics in the tundra during the growing season

Thursday at 17:25 in Auditorium 1.

Martin A. Mörsdorf, Bo Elberling, Nanna Baggesen, Anders Michelsen, Per Lennart Ambus, Philipp R. Semenchuk, Nigel G. Yoccoz, Elisabeth J. Cooper

Climatic changes in the Arctic are likely to cause changes in snow fall, depth and length of lie. Due to insolation effects, deeper snow during winter increases subnivean temperatures, which leads to higher microbial activity and nutrient mineralization rates within soils. However, whether those nutrients are available to tundra plants during the growing season is questionable, because nutrient leaching and nutrient competition between microbes and plants are common in the Arctic as well.

Here we used a nine years snow fence experiment in Svalbard to address this question. Snow fences accumulate snow and increase snow depth during wintertime and the lasting of snow cover. The experiment thereby yields three different snow regimes: controlled – medium – and deepened snow. In addition, we combined those snow regimes with open top chambers during the growing season, to simulate warmer summer temperatures. We sampled soil and plant nutrient data within the different experimental treatments weekly throughout the growing season 2015. Data analyses are currently underway and will address the soil and plant related nutrient dynamics in different treatments throughout the growing season.

Results will give us important insights into the mechanisms and consequences of climatically induced changes in the Arctic terrestrial nutrient cycle.

 

S6: Evolutionary Ecology and the Societal Perspective Auditorium 2

Dorothy J. Dankel: Transdisciplinary insights into Integrated Ecosystem Assessments: What they are, what they can be, what they should be

Thursday 15:25 in Auditorium 2.

Integrated Ecosystem Assessments are scientific frameworks that synthesize data to inform policy decisions. Today many science institutions develop and conduct Integrated Ecosystem Assessments as the integral tool of ecosystem-based management. However, the scholarship on the role of Integrated Ecosystem Assessments in policy and how these assessments can or cannot spur political actions remains at best fragmented, and the actual use of Integrated Ecosystem Assessments in policy processes is not fit for purpose.

The state-of-the-art of Integrated Ecosystem Assessments is pointing strongly in the direction of a push towards a “technological lock-in” where quantitative modelling is the method of choice. Experiences show that once a technology process is locked-in, any efforts to reform will be an uphill battle (i.e. the use of gas-powered automobiles for personal transport). If Integrated Ecosystem Assessments are to be designed for high credibility, legitimacy and societal saliency, a combination of quantitative and non-quantitative disciplines needs to be integrated early-on in the process. Since a common framework for Integrated Ecosystem Assessments in Europe is still lacking, there is an urgency to define how they should work to reach the transdisciplinary potential with an impact on sustainable actions. How can procedures for Integrated Ecosystem Assessments, the core tool linking the implementation of policy objectives and knowledge for marine ecosystem-based management, be designed to be credible, legitimate and salient?

 

Kyrre Kausrud: Anthrax: Ecology in a Landscape of Fear

Thursday at 15:45 in Auditorium 2.

Anthrax, Bacillus anthracis, is a disease mostly known to the public as a bioweapon with terrorism potential. Unfortunately, the public fear may be highly counterproductive as it paradoxically makes spreading anthrax more effective and attractive as a terror strategy, while at the same time hampering research into countermeasures and, more importantly, researching the real threat of anthrax which is primarily damaging wildlife and domestic animals.

Contrary to its image, anthrax is a naturally occurring disease with a complex ecology, a disease which is mostly treatable and manageable as long as control efforts can be directed at the weakest links in the transmission chain. However, the surprising sparsity of ecological knowledge partially caused by the difficulties of studying the bacteria leads to a lot of basic ecological questions remaining unanswered for this important disease.

This talk will give an overview of anthrax in socio-economic context as a perceived and realized threat, before outlining its ecology as seen in a natural unmanaged setting in Etosha National Park, Namibia. Current knowledge in anthrax transmission and epidemiology will presented together with preliminary results of our efforts to determine some of the main as yet unknown mechanisms.

 

Lucas M. Jeno: The effects on motivation and learning of a mobile application tool for identification of species

Thursday at 16:05 in Auditorium 2.

Electronic learning has increased the possibilities to support students´ motivation and learning. Across all age groups, more than 86 percent have access to some sort of ICT (Information Communication Technology). In Norway, more than 96 percent of the students between 19-25 years have a smartphone (OECD, 2015; Slettemeås & Kjørstad, 2016). Including these technologies in biology education increases the possibilities for active learning. In Biology, when students identify species, they have traditionally employed a textbook called Lids Flora (Lid & Lid, 2005). bioCEED – Centre of Excellence in Biology Education (UiB), along with The Norwegian Biodiversity Information Centre, and The Centre of Science Education (UiB), have developed a mobile application tool for identification of species (sedges). The mobile application tool, compared to the textbook, provides the students with more choices and volition in the identification process. Furthermore, it provides the students with feedback and optimal challenges. Across two experimental and randomized studies, we have found that the mobile application had a significant effect on students´ intrinsic motivation, perceived competence, and achievement. Furthermore, we found that the textbook significantly decreased students positive affect and increased negative affect from pre-test and post-test measures. The results are interpreted within the most empirical supported motivation theory Self-Determination Theory (Deci & Ryan, 1985).

 

S7: Evolutionary Ecology and Conservation - Auditorium 2

Inger Auestad: Measuring restoration success using ordination-based successional rates: how to handle bioclimatic variation in the data set

Thursday at 15:25 in Auditorium 5

Renewable energy development is a part of the Green Shift, and as such warmly welcomed by the environment-friendly opinion. However, nature degradation is an unavoidable side effect, for instance in hydropower projects, that leads to establishment of spoil heaps in vulnerable nature types. Restoration can mitigate these problems, but is costly. Therefore, it is important to identify successful and cost-effective restoration methods. Ordination-based calculation of successional rates and estimates of time to recovery stands out as promising tools, as has been demonstrated in spoil heaps in alpine areas. However, we know little about the suitability of this method in other bioclimatic regions. We recorded lichens, mosses and vascular plant species in ten spoil heaps in a bioclimatic gradient from southern boreal to mid alpine zone in early 1990ies and around 2010, and compared to vegetation in the undisturbed surroundings. Preliminary results show that successional rates and time to recovery differed somewhat in the total data set compared to the alpine and boreal subsets. We discuss the potential and limitations of the evaluation methods in restoration projects.

 

Eirik Søvik: Bees, Metal, and Behaviour

Thursday at 15:45 in Auditorium 5.

Many metals play an essential role for life on earth, as necessary co-factors involved in many biochemical processes. In an evolutionary context, some of these metals have been rare, so biological organisms have evolved sophisticated machinery for readily absorbing the most minute of amounts from their environment. However, anthropogenic pollution has ensured that metals, previously only available at trace levels, can now be found in large quantities in nature. While the effects of metal pollution on humans, and the animals we eat, is well studied, not much is known about the effects of these metals on pollinators. Here, I map the extent to which honey bees (and other bees) are exposed to different metals, and demonstrate the effects of some of these metals on bee behaviour.

Liv Norunn Hamre: Paradise lost - the transformation of the gully landscape in SE Norway

Thursday at 16:05 in Auditorium 5.

The gully landscape on marine clays, formed by the last glaciation(s), only exist in a few areas in the world, and is threatened by several factors. In the last years, in Norway, there have been increased focus on the value of the gully landscape. However, we lack knowledge on the rate of change, total area change and the drivers responsible for the changes. We have investigated the gully landscape in five municipalities in the county of Akershus. The study is based on aerial photos from three different points of time from 1955 -2013 (midpoint is 1985-90) elaborated and interpreted in ArcGIS. Our results showed that 74.8% of the gullies still exist, while 20.2% is transformed to agricultural land, 2.3 % to industrial areas and 2.2% to residential areas. The largest decline took place in the first period (23.2%). A 6.2% decline in the second period show that the valuable gully landscape still diminish, but at a slower rate. A national protection plan is needed to save this special landscape, which is only brought back by the return of an ice age followed by deglaciation and postglacial upheaval of former sea beds.

 

Lise Tingstad: How regional perspectives can inform national conservation priorities: a case study of red listed forest species in Fennoscandia

Thursday at 16:45 in Auditorium 5.

Lise Tingstad, Gjerde, I., Grytnes, J.A and Dahlberg, A.

National red lists are considered among the most widely used tools for species conservation worldwide, but few have studied national red-lists in regional perspective. Up-scaling from national to regional perspective could give beneficial input to conservation priorities at national levels as extinction risk is perceived differently at various scales.

Using red listed forest-dwelling species from Norway, Sweden and Finland, we collocated a regional red list and compared species composition and their habitat affiliation for the two spatial levels. Furthermore, European distribution patterns were compared for red-listed and non-red-listed species within four organism groups to investigate how broad-scale geographic gradients impact national red list patterns.

The results showed that approximately 50 % of nationally red-listed species did not qualify for the regional red list because of viable populations in other countries in the region. However, the upscaling did not lead to many proportional changes in the composition of organism groups or habitat affiliations. Regarding the distribution patterns, we found that red-listed species had clearly more restricted distribution patterns in Europe than non-red-listed species, indicating that nationally red-listed species are more often boundary populations than other species.

Being able to narrow down and focus prioritizations is a major benefit from applying a regional approach along with national red lists, and taking the wider distribution patterns into account gives a more relevant picture for overall conservation and management of threatened species. We believe the results to be of interest for management and conservation in many regions where national red lists build up part of the knowledge base for biodiversity conservation.

 

Kåre Flatlandsmo: Some aspects of the economic valuation of a river basin. Examples from Raundalselva, Voss – Norway.

Thursday at 17:05 in Auditorium 5.

Ecosystem services and their contribution to human welfare is a challenging topic. By the turn of the century several studies on this issue were completed, the more significant ones were Millennium ecosystem Assessment (MA) and The Economics of Ecosystems and Biodiversity (TEEB).

The importance of visualizing the economic cost of human action on nature is discussed, as well as the challenging task of introducing this view into the political decision making process at a local level. The importance of The Norwegian Biodiversity Act is discussed and how this legal act may prove to be useful in support of this effort.

The concept of pricing ecosystem services is gradually being accepted by a number of biologists as a tool supporting efforts to maintain the diversity of nature in order to obtain durable ecosystem services.

The environmental costs of a hydropower project is quantified based on surveys of individual preferences. As these preferences are related to adjacent and similar projects, value transfer techniques are used to estimate the damage cost of a potential hydropower project in Raundalselva as a possible flood preventing measure.

 

 

 

Line E. Sundt-Hansen : Ecological impacts and performance of native salmonid invaders

Thursday at 17:25 in Auditorium 5

Line Elisabeth Sundt-Hansen1*, Julien Cucherousset2 and Kjetil Hindar1

For decades, native invading salmonids have regularly been introduced into the wild, either intentionally by stocking or non-intentionally by escapes from aquaculture. Native invaders are of the same species as the native species, but has a different phenotype or genotype (i.e. farmed salmon or genetically modified salmon). Breeding programs for many salmonids have focused on developing more extreme phenotypes (e.g. faster growth rate, increased disease resistance, and/or larger size at reproduction), which may disproportionally impact native salmonids once they are released into recipient biota. Such invasions may not only threaten native fish species, but also impact different components of the native biodiversity. Traditionally, invasion biologists have primarily focused their investigations on between species interactions, however there is a gap of knowledge on the ecological impacts of conspecific native salmonids invaders at higher levels of biological organisation. This is despite the fact that non-native invaders induce important community and ecosystem impacts and that there is an increased risk of farmed and genetically modified salmonids to be introduced in the wild.

The aim of the study was to quantify experimentally the performances and ecological impacts of invading native salmonids. Growth hormone implanted juvenile Atlantic salmons were used as model for an growth enhanced invading native species. We tested performance (survival and growth) and impacts of native invading salmonids on the community-and ecosystem levels (i.e. prey community composition and primary production) in semi-natural streams with a range of ecological complexity. Results from this experimental study will be presented.

 

 

S8: Evolutionary Ecology of Population Dynamics and its Drivers – Auditorium 2

Claudine C. Cloete: Environmental dynamics and zoonotic diseases – The case of anthrax in Etosha National Park

Thursday at 16:45 in Auditorium 2

Fluctuations in climatic conditions may cause changes in the ecology of zoonotic diseases. This can be observed in changes in disease transmission, host or vector density, and host susceptibility. These changes can cause the epidemiology of zoonoses to be altered. Bacillus anthracis, the causative agent of anthrax, forms endospores that are resistant to a variety of environmental factors enabling them to survive in the environment for many years. This hardy bacterium causes infections in both humans and animals, with herbivorous mammals being most susceptible. In order for B. anthracis to survive as a species, it needs to maintain its sporulation-germination cycle. This cycle is thought to be dependent on climatic conditions. Anthrax deaths are a common occurrence in the Etosha National Park (ENP) where a definite seasonal difference in mortalities among elephants and plains ungulates is observed. Anthrax is not managed in ENP making it the ideal natural laboratory in which to study the disease and its causative pathogen.

In order to better understand the ecology of anthrax, we have to investigate the interactions between biotic and abiotic factors. Therefore, we aim to determine the impact of anthrax on host populations as well as to assess the effects of climate on anthrax outbreaks in ENP.

 

 

 

Eivind F. Kleiven: Temporal transferability of spatial state-space models: predicting lemming outbreak abundances

Thursday at 17:05 in Auditorium 2.

  1. Worries about the consequences of global environmental change have sparked calls for making ecology a more predictive science by increasing ecological models transferability in time and space. Here, we tested the temporal transferability of spatial state-space models developed to estimate season-dependent biotic and climatic predictors of outbreak abundance of the Norwegian lemming. We validated spring and autumn models (reflecting winter and summer processes respectively) parametrized by spatial trapping data from one cyclic outbreak with data from a subsequent outbreak. There was a distinct difference in model transferability between seasons. The model for the summer dynamics (i.e. predicting lemming autumn abundances) had good temporal transferability, whereas the winter model (i.e. predicting lemming spring abundances) performed poorly. The poor performance of the winter model is likely due to a temporal inconsistency in the ability of the climate predictor to reflect the winter conditions impacting lemmings both directly and indirectly. This shows that there is an urgent need for data and models that better predict the effect of winter processes, in particular in face of the expected rapid climate change in the Arctic.

 

 

S9: Evolutionary Ecology of Forest Ecosystems – Auditorium 1

Fredrik Ssali: The problem with bracken in tropical Africa

Friday at 11:10 in Auditorium 1.

Large areas dominated by bracken Pteridium aquilinum occur on every continent except Antarctica. In the East African Highlands bracken covers hundreds of square kilometres of previously forested habitat. This is a management concern in conservation areas where persistent bracken replaces other more valuable forest habitat. Given that droughts and fire, a major cause of bracken dominated vegetation, are predicted to increase in the next decades, such vegetation is likely to spread. In the Bwindi Impenetrable National Park and a world heritage site, bracken thickets are locally abundant and persistent. They retard forest recovery and reduce its biodiversity and carbon value. Temperate studies show that bracken interferes with the re-establishment of woody species. However, various interference mechanisms have been documented and it is unclear which are involved in tropical Africa.

Our study examines how bracken slows forest recovery. We conducted a series of experiments and surveys to explore why bracken establishes in some places and not others and how the forest can be assisted to grow and establish itself. We ask: Does bracken inhibit germination? Does bracken influence growth or survival of seedlings? Is bracken truly persistent or is it slowly being replaced by forest? Which mechanisms explain why bracken does not allow more rapid re-colonisation by forest? And how can we help forest recovery? A pilot study was carried out to select study sites and pre-test the methods.

Results from ongoing analyses show that the density of woody species decreases rapidly with increasing bracken density along the forest-edge-bracken gradient. Further analysis will clarify the mechanisms that explain how bracken slows forest regrowth. Such knowledge can help guide the development of conservation and restoration strategies that counter bracken-mediated tree regeneration failure after forest disturbance.

 

Karen M. Mathisen: Previous browsing increases future browsing - a maladaptive plant response?

Friday at 11:30 in Auditorium 1.

Mathisen, K. M., Milner, J. M. and Skarpe, C.

Sessile plants have evolved a diverse set of responses to defend themselves against or to tolerate predation from herbivores. Plant responses to herbivory are context dependent, and may be limited by resource availability or modified by dominance of certain meristems. Trees previously browsed by moose (Alces alces) in boreal forest, often show increases in shoot size, increase in nutrient concentration and sometimes a decrease in defense compounds, all traits that increase the probability of future browsing. This leads to a positive feedback loop between plant responses and browsing probability. The object of this study was to investigate if an index of accumulated browsing, which describes the tree’s architectural response to previous browsing, could predict current winter browsing by moose in young Scots pine forest stands in south-eastern Norway. We found that preference for individual trees as well as number of bites per tree increased with accumulated browsing for all tree species. Preference for browsed trees may be linked to increased availability of shoots in browsing height and higher palatability of shoots. This indicates that trees respond to browsing in a way that increases the risk of future browsing, which may be maladaptive under high herbivore densities.

 

Hanne Eik Pilskog: Long-lasting effects of logging on beetles in hollow oaks

Friday at 11:50 in Auditorium 1.

Habitat loss is one of the largest threats to biodiversity worldwide, but an increasing number of studies show that accounting for past habitat loss is essential to understanding current distributional patterns. Hollow oaks (Quercus spp.) are important habitats for species that depend on deadwood. We sampled beetles in hollow oaks along a gradient spanning 40 km from the coast to inland areas reflecting historical logging intensity through 500 years in Southern Norway. We expected higher species richness inland due to later large-scale logging and we also expected oak specialists to respond more markedly. Higher species richness and total abundance inland indicate that historical logging has affected the beetle communities, but the oak specialists did not respond. The beetles also responded to scale-specific environmental variables at the tree, local and landscape scale. Whereas population sizes of the oak specialization groups were controlled by local conditions of the tree and the close surroundings, species richness responded to habitat on a landscape scale, indicating that larger areas are necessary to maintain species richness through time. The beetles’ response to historical logging suggest that current management of old oaks is likely to affect the species not only today, but also far into the future.

 

Line Nybakken: Facing dangers as you grow up: chemical defence of trees across season and age

Friday at 13:50 in Auditorium 1.

Plant defence against environmental stressors often changes dramatically as plant develop. The composition of secondary compounds (PSM) in the vegetation of a landscape has extensive influence on ecosystem functioning. It is therefore crucial that we understand how various temporal factors affect plant content of PSMs, particularly those indirectly induced and controlled by human activity. One illustrative PSM group of major ecological interest is phenolics, which serve needs as diverse as herbivory defence, pathogen resistance, allelopathy or symbioses signalling, frost and drought hardiness, and photodamage protection. I will present results from our ongoing studies of defensive chemistry of European beech (Fagus sylvatica) and birch (Betula spp) across seasons and ages, and discuss the results in relation to ecological theories and functionality of plant chemical defence.

 

Paal Krokene: How bark beetles and their microbiome interact to kill well-defended trees

Friday at 14:10 in Auditorium 1.

Bark beetles and associated microorganisms can be enormously destructive to forests, but are also fascinating biological subjects. Bark beetles are small, tree-colonizing insect herbivores in the family Curculionidae that include the most devastating tree-killers in boreal and temperate forests worldwide. These insects are also spec­tacular profiteers of global climate change, as warming temperatures have contributed to historically unprece­dented beetle outbreaks over the last 15 years, decimating hundreds of millions of conifer trees. Despite their huge economic and ecological importance, the exact mechanisms by which these small insects, no bigger than a grain of rice, can overwhelm the defenses of huge conifer trees are still largely unknown. However, cooperation is likely essential to successful tree colonization. This includes intraspecific cooperation, as the beetles attack trees in coordinated mass-attacks that may involve thousands of beetles, and interspecific cooperation, through interactions with phytopathogenic fungi carried on the outer surface of the beetles and bacteria in the beetle gut. Here I will describe how the European spruce bark beetle Ips typographus and its associated microorganisms work together to successfully colonize and kill well-defended Norway spruce trees that are up to 200 million times the beetles’ own size.

 

 

Tone Birkemoe: The potential of insects to disperse fungi to dead wood

Friday at 14:30 in Auditorium 1.

Rannveig Jacobsen, Tone Birkemoe, Anne Sverdrup-Thygeson and Håvard Kauserud

Insects and fungi are the main decomposers of dead wood, and they form an exceptionally species rich community in boreal and temperate forests. The decomposition process can be influenced by interactions between insects and wood-decay fungi, such as fungivory or dispersal of fungi by insects. While it is well-known that the symbiotic fungi of ambrosia beetles and wood wasps rely on dispersal by insects, it is unknown whether insect-vectored dispersal is important to other species of fungi such as Basidiomycete polypores. In an ongoing project we are investigating the potential of insects to act as vectors of fungi to newly dead aspen wood at two sites in close proximity to Oslo. In order to reveal these interactions, we use three approaches: 1) correlation between beetle occurrence in newly dead wood and later occurrence of sporocarps, 2) analysis of fungal DNA in beetles landing on newly dead wood and 3) analysis of fungal DNA from wood samples of logs with and without experimental exclusion of insects. We have found indications that insects visiting newly dead wood do influence which sporocarps we find several years later on the same dead wood. Also, the beetles landing on the wood do indeed carry saprophytic fungi. The exclusion experiment remains to be analyzed.

 

Ane Vollsnes: Reforestation without insecticides. Protecting spruce seedlings against pine weevils on a clear felling.

Friday at 15:10 in Auditorium 1.

Norwegian forest owners must assure that a new forest will grow in the area after a clear felling. For spruce (Picea abies) forests, this is normally done by planting young seedlings from a forest nursery. Pine weevils (Hylobius abietis) are attracted to the smell of stubs and fly into clear fellings to mate and lay eggs near the roots under the stubs. At the same time, they eat the bark off the newly planted seedlings, causing great losses unless the plants are protected by an insecticide. There is a drive all over Europe to avoid these insecticide treatments for environmental and worker health reasons. One solution is to cover the lower parts of the stems with a layer of wax. Thus, the seedlings are mechanically protected instead of chemically protected. In the talk, I will describe the biology of the plants and insects and show how we are working to make this environmentally friendly method applicable to the forest nurseries and the forest owners. In an effort to improve the method further, we are now doing choice experiments with the weevils, mixing repellents into the wax.

 

Siri Lie Olsen: Local and landscape effects of stand age on biodiversity in productive boreal forests

Friday at 15:30 in Auditorium 1.

Siri Lie Olsen, Olav Skarpaas, Anne Sverdrup-Thygeson, Egil Bendiksen, Björn Nordén, Odd Stabbetorp, Annika Hofgaard, Aksel Granhus

Deforestation and habitat degradation is affecting much of the world’s forests. In areas dominated by forestry, such as the Fennoscandian boreal forest, biodiversity-rich natural forests are replaced by younger, less diverse stands of varying management intensity. Formerly selectively logged, near-natural forests have partly compensated for the loss of the natural forest. However, increased harvest due to rising demands for biomass may reduce the area of old, near-natural forest, resulting in managed forest landscapes with a higher proportion of young, intensively managed stands. We combine biodiversity data collected at Norwegian National Forest Inventory plots with remote sensing data on stand age, to examine the relationship between diversity and abundance of different organism groups (vascular plants, epiphytic lichens and polypores) and stand age at various spatial scales in a managed forest landscape in southeast Norway. Preliminary results show that whereas the effect of stand age on generalist species varied between organism groups, specialist forest species were generally positively related to stand age, both locally and at larger spatial scales. Our findings, providing a quantitative basis for assessing effects of forestry on biodiversity, suggest that retaining a sufficient proportion of old, near-natural forest is crucial for specialized forest species in managed forest landscapes.

 

 

Mari Steinert: Plant communities in power-line clearings: maintaining open-canopy habitats through frequent clearing could positively affect diversity of pollinating insects

Friday at 15:50 in Auditorium 1.

Mari Steinert, Markus A.K. Sydenham, Ørjan Totland, Katrine Eldegard, Stein R. Moe

Linear habitats, such as power-line clearings, have been thought to affect biodiversity negatively. However, during the last decade several studies have highlighted the potential value of power-line clearings as habitats for several taxonomic groups, like bees and butterflies. The vegetation below power-lines is continuously reset to earlier successional stages, which provides suitable habitats for several native plant species hosting diverse assemblages of pollinating species. With proper management, power-line clearings could be important for conservation of species associated with open-canopy habitats. We conducted a large-scale field experiment in 19 power-line clearings in southeast Norway and tested how different management practices affected species and functional composition of vascular plants known to be important for pollinators. At each site, we established three plots with treatments; 1) Cut: woody vegetation cut and left to decay, 2) CutRemove: woody vegetation cut and removed, 3) Uncut. The following three years we surveyed understory plant communities in each treatment and sampled habitat characteristics and environmental conditions. We investigated both the iconic diversity measures and functional diversities to estimate the response of the plant community. Using a field-experiment, we were able to identify important environmental factors that together with treatments are favorable for forbs, dwarf shrubs and shrubs, which provides improved foraging resources for pollinating insects. We conclude that areas suited for implementation of treatment practices in power line clearings are sites with intermediate to high productivity, both at higher and lower elevations, with available source habitat areas and with lower average precipitation and higher temperatures in growth season.

 

 

S10: Evolutionary Ecology of Biotic Interactions – Auditorium 5

Jarad Mellard: Combined effects of predation and scavenging in a food web model.

Friday at 11:10 in Auditorium 5

Despite numerous calls to link predation and scavenging in models of food webs, few models have done so. Here, we include scavenging and predation in food web modules by explicitly modeling detrital pool biomass and scavenging. Our dynamic model includes multiple predators and scavengers and multiple detrital pools. We examine the effect of key parameters on equilibria and show dynamical consequences of including scavenging in the model. We explore predation versus scavenging strategies in this context. We discuss ramifications of scavenging for food webs linked to the semi-domesticated reindeer as well as other food webs.

 

Adam A. Pepi: Elevationally biased avian predation as a contributor to the spatial distribution of geometrid moth outbreaks in sub-arctic mountain birch forest

Friday at 11:30 in Auditorium 5

Population dynamics and interactions that vary over a species range are of particular importance in the context of latitudinal clines in biological diversity, and due to alterations induced by climate change. Winter moth (Operophtera brumata) and autumnal moth (Epirrita autumnata) are two species of eruptive geometrids that vary widely in outbreak tendency over their range from south to north and by altitude. The effect of predation on larvae and pupae over an elevational gradient is tested, along with bird occupancy of monitoring nest boxes and larval density. Exclusion treatments set up with larvae at 20 replicate stations over four elevations from 50-240 m above sea level showed an effect from bird predation at three lower elevations, but not at the highest elevation, matching with historical outbreak trends. Predation rates on pupae showed no consistent trend in predation by elevation. These results suggest together that elevational variation in avian predation pressure on larvae may help drive elevational differences in outbreak tendency, and that birds may play a more important role in geometrid population dynamics in contrast to the focus on invertebrate and soil predators of previous work.

 

Rachel L. Malison: Eurasian beavers have little impact on juvenile Atlantic salmon and trout populations in Midt-Norway

Friday at 11:50 in Auditorium 5.

Expanding populations of Eurasian beavers (Castor fiber) may negatively impact Atlantic salmon (Salmo salar) and sea trout (Salmo trutta) populations if beaver dams limit the distribution and movement of juvenile salmon and trout. In 2014 I studied six tributaries in two watersheds of the Trøndelag region of Norway: three with beaver and three controls without beaver. I minnow trapped beaver ponds and electrofished free-flowing stream sections to measure fish distributions and densities. I tagged juvenile fish with PIT tags to measure growth and movement rates and tracked fish movements with PIT tag antennae. Juvenile fish reared in stream sections below and above beaver ponds, but were not captured in beaver ponds. Juvenile fish grew at similar rates above and below beaver ponds (0.38 ± 0.04 vs. 0.39 ± 0.18 % daily mass). Similar proportions of juvenile fish were able to move both upstream and downstream in beaver sites and control sites, but the presence of dams limited the amount of repeated movements compared to control sites. In 2015 I studied two beaver sites to determine how much time juvenile fish spent in beaver ponds. Overall, beavers have a low potential to negatively impact fish populations in Midt-Norway.

 

 

Bjørn A. Hatteland: Tracing trophic interactions using molecular methods

Friday at 13:50 in Auditorium 5.

Trophic interactions are an essential part of any ecosystem and form an important part of the provision of many ecosystem services. However, studying these interactions is not always straight forward, especially if the focal species are small like insects or studies need to be carried out in a non-intrusive way. Major advances in the use of molecular methods during the last decade have made it possible to explore, identify and quantify links between trophic levels. This study aim at summarizing the various molecular tools used in studies of trophic interactions, which encompasses the use of antibodies, allozymes and DNA-based studies involving standard PCR, qPCR and next generation sequencing. The different methods will be presented using case studies related to predator-prey, host-parasite and herbivore-plant dynamics. These studies have implications to a range of fields within in ecology such as pest management, invasive species, and conservation ecology.

 

 

 

Hanna K. Lodberg-Holm: Bears follow the blue wave through a landscape of risk

Friday at 14:10 in Auditorium 5.

Hanna Kavli Lodberg-Holm, Henriette Wathne Gelink, Anne Gabriela Hertel, Jon E. Swenson, and Sam M.J.G. Steyaert

Animals adapt foraging behavior to changes in quantity of food resources and varying predation risk. In Sweden, brown bears (Ursus arctos) depend on a near continuous intake of bilberries (Vaccinium myrtillus) during hyperphagia, which overlaps with the bear hunting season. We explore how bears spatially select good berry habitats during hyperphagia, and whether this is impacted by human hunting. We sampled bilberries in South-Central Sweden during summer 2014, to predict the probability of good berry foraging locations. We then extracted bear foraging positions from 35 collared bears during 2012-2015, and matched these with random positions. We contrasted probability of being a good berry foraging location, and the risk of human induced mortality for the foraging and random positions using GAMM. Resource selection functions (GLMM) was applied to explore foraging behavior of shot and surviving bears 10 days before the hunting season. Foraging positions had a higher probability of representing good berry foraging locations, but only at low risk levels. Surviving bears avoided risky areas, while shot bears did not actively avoid these areas and selected stronger for bilberries. We conclude that bears trace good berry foraging plots according to fruiting phenology, while responding to a landscape of risk.

 

 

Erik F. Acanakwo: Seed removal in an African savanna landscape

Friday at 14:30 in Auditorium 5.

Post dispersal seed removal is important in structuring plant population. In the African savanna ecosystem, circumstances under which removal rates are variable are not clear due to limited studies. Termites and large herbivores are both important modifiers of the African savanna landscape that affect vegetation patterns, distribution and abundance of small mammals. We studied the effects of termites and large mammalian herbivores on removal rates of native tree seeds in Lake Mburo National Park in Uganda. We recorded removal of native tree seeds from seed cages that regulated animal access to seeds (Open cages allowed access to all animal guilds, roofed cages allowed access to small mammals and invertebrates, while closed cages allowed access to only invertebrates) on mound and savanna habitats (with and without large mammalian herbivores). In the presence of large herbivores, seed removal rates were significantly higher on mound than savanna habitats. Exclusion of large herbivores resulted in an increase in seed removal rates in the fenced savanna and a significant reduction in the fenced mound habitats. Seed removal rates were highest in the open cages and lowest in the closed cages. Seeds of Scutia myrtina had the highest removal rates from open and roofed cages from savanna and mound habitats with and without large mammals, while Rhus natalensis and Acacia hockii had the highest removal rates in the closed cages. The difference in overall seed removal rates from active and inactive mounds was not significant, but on active mounds, seed removal rates were highest from the open cage (30.9±3.4%) and lowest in the closed cage (6.1±1.0%). When mounds were inactive, seed removal rates reduced in the open cages (26.7±2) and increased in closed cages (11.6±1.3%). The study suggests that variations in seed removal rates in the African savanna are characterized by a complex interaction of termites, large mammalian herbivores, seed removal agents and native seed species.

 

 

Anne G. Hertel: Berry production drives bottom-up effects on life history traits of an omnivore, the brown bear.

Friday at 15:10 in Auditorium 5.

Anne G. Hertel, Atle Mysterud, Jonas Kindberg, Ola Langval, Jon E., Swenson, Andreas Zedrosser

Obligate herbivores dominate studies of the effects of climate change on mammals but there is limited empirical evidence for how omnivores might be affected by changes in the abundance of plant foods. We used a 10-year time series of bilberry production (Vaccinium myrtillus), recorded at permanent plots, to develop an annual index of berry abundance. Using daily temperature and precipitation data, we tested a set of competing hypotheses explaining variation in berry abundance with weather covariates during crucial stages of plant phenology. We found that cold temperatures during flowering, but not winter variability, negatively affected berry production.

Female brown bear (Ursus arctos) body mass in autumn increased with increasing bilberry abundance. Spring body condition modulated the effect of autumn food abundance on female reproductive success. Specifically, when food abundance was low, females that entered hyperphagia in poorer body condition were less likely to reproduce than females that entered hyperphagia in good condition. If food abundance was high however, light-weight females were able to increase their probability to reproduce to the same level as females in good condition, probably due to compensatory feeding.

These findings highlight that carry-over effects from one season to the next may modulate individual’s responses to resource abundance. Testing effects of climate-driven food variation on life histories carried out on the population level only, may fail to detect effects on groups of individuals that contribute importantly to long-term population recruitment.

 

 

Mathias S. Ugelvik: Salmon already infected with salmon lice are more susceptible to new infections

Friday at 15:30 in Auditorium 5.

Aggregation is common amongst macroparasites and might negatively affect fitness related traits such as parasite fecundity and survival. However, for dioecious parasites aggregation might also increase the probability of finding individuals of the opposite sex. We therefore tested if previous experience with salmon lice affected susceptibility to later exposure to the same parasite species. We found that currently infected fish got higher intensities of new lice than naive fish. This positive density dependence might be adaptive, as it might ensure successful reproduction when lice densities are low

 

Nina Trandem: Fatal attraction: male spider mites prefer females killed by fungi to healthy living ones

Friday at 15:50 in Auditorium 5.

Nina Trandem, Upendra Raj Bhattarai, Dirce M. Santos e Silva, Karin Westrum, Geir Kjølberg Knudsen, Ingeborg Klingen

Exploring prospective mates can be risky. Males of the spider mite Tetranychus urticae approach and guard quiescent female nymphs to increase their chances of fathering offspring. We investigated the behaviour of male T. urticae towards adult females killed by either a specialist (Neozygites floridana) or generalist (Beauveria bassiana) fungal pathogen. Males chose between two adjacent leaf discs, one with a cadaver and one with a healthy quiescent female. Choice of leaf disc and occurrence of touching or guarding the females were recorded. For both fungal species, males significantly preferred the cadaver disc, and even guarded the cadaver at least as often as the healthy female. Two types of control experiments were also run: 1) males choosing between two N. floridana-killed cadavers, one of each sex (males preferred the female cadaver), and 2) between a healthy quiescent female and a freeze-killed adult female (no male preference for leaf disc, but healthy was more touched and guarded). Our results indicate that T. urticae males are more attracted to females killed by fungal pathogens than to healthy ones. Possible mechanisms and consequences of this phenomenon will be discussed.

 

Poster abstracts.

Hormone profiles as basis for decision-making in a fish growth model" part 1 and part 2– Camilla H. Jensen & Jacqueline Weidner 2

Consequences of climate change for disrupted plant-pollinator interaction - Linn Vassvik. 2

A population Analysis of the Red Listed Musk Orchid (Herminium monorchis) in Hvaler - Silje Skjelnes Vågen, Kari Klanderud, Marianne Evju and Liv Ingrid Kravdal. 3

Establishment, survival and dispersal limitations of pioneer plants in a Norwegian glacier foreland as revealed by seed sowing, transplantation and seed bank experiments - Anne-Sofie Strømme. 3

LandPress – how does the combination of land use change and climate change affect the Norwegian coastal heathlands? - Siri Haugum.. 4

Effect of climate and disturbance on the resilience of Empetrum nigrum alpine heaths-Victoria Gonzalez 5

Numerical responses of saproxylic beetles to dead wood left by moth outbreak in northern Scandinavia - Petter Carlsen. 5

Dynamics of an age-structured population of barnacle geese in the high Arctic - Kate Layton-Matthews1 6

Massive genome-wide changes accompany rapid adaptation in a natural population - Anurag Chaturvedi1, Joost A. M. Raeymaekers2,3, Till Czypionka1, Luisa Orsini4, Craig E. Jackson5, Katina I. Spanier1, Joseph R. Shaw5, John K. Colbourne4 and Luc De Meester1 7

Genetic diversity and structure of wild Svalbard reindeer populations shaped by landscape and human - Bart Peeters 1*, Knut H. Røed 2, Mathilde Le Moullec 1, Åshild Ø. Pedersen 3, Joost Raeymaekers 1, Bernt-Erik Sæther 1, Brage B. Hansen 1 8

SUSTHERB: Towards Sustainable Herbivore management - Gunnar Austrheim, Victoria Berger, Marc Daverdin, Winta Berhie Gebreyohanis, Anders Kolstad, James Speed, Aurel Marian Venete, Stein Joar Hegland, Erling Meisingset, Atle Mysterud, Erling J. Solberg. 9

Abiotic and biotic conditions of an N-limited grassland present differential impacts at an ecosystem compared to plant community scale -Furey, George N.1, Tilman, David1,2 9

Leaf traits in a temperature and precipitation gradient in Western Norway-Ragnhild Gya. 10

Effects of stand density and other stand and site characteristics on bilberry cover in Norway-Janneke Scholten 10

Nest cameras reveal the secrets of the Eleonora’s falcon-Ronny Steen. 11

Does Arctic shrub growth rings represent past primary production available for the ecosystem- Mathilde Le Moullec 11

Spatial phylogenetics of the Norwegian vascular plant flora- Ida M. Mienna. 12

Impacts of land use intensity on biodiversity in Norway - Case study of butterflies- Eveliina Kallioniemi 12

Herbivores modify the palatability of Silica–rich grasses- Katarina Inga. 13

 

 

 

 

Hormone profiles as basis for decision-making in a fish growth model" part 1 and part 2– Camilla H. Jensen & Jacqueline Weidner

 

"Animal behaviour is affected by stimuli both regarding the internal state of the organism and the environment. Hormones controlling metabolism and growth have the possibility to both directly and indirectly affect how a growing individual trade the cost of predation against foraging. Hormone levels influence activity and overall energy use and regulate feeding behavior and allocation to storage, reproduction, and growth. We present a dynamic optimization model for juvenile fish where growth- and thyroid hormone levels determine energy allocation and growth to maturation. The fish must find food and avoid predation, and we study which hormone profile that best solve the trade-off between risk and energy intake in different environments. The model can be used to study hormonal adaptations in environments differing according to other factors like food availability, predation pressure and seasonality.

 

An introduction to the model's background (hormones and their interaction) will be given by a poster by Camilla H. Jensen and a poster with the preliminary results will be given by Jacqueline Weidner."

 

Consequences of climate change for disrupted plant-pollinator interaction - Linn Vassvik

 

Backround for my thesis: Pollinators provide an important ecosystem service and it is therefore crucial to understand their response to a climate change. Many pollinators dependent on temporal synchrony with their host plants and therefore asynchrony in shifts in phenology of both plants and insects could disrupt such interactions. Recent climate warming is associated with phenologcial advances in plant and animal species and there is now growing evidence that temporal mismatches between plants and animals occur. An important question therefore is what the consequences for disrupted plant-pollinator interactions are? Will an increase in mismatch between plants and their pollinators decrease reproductive output and affect population viability?

The project will assess the effect of disruption in plant-pollinator interactions on the reproductive output of Ranunculus acris. And a field experiment will be carried out along a snowmelt gradient (did fieldwork this summer, but will continue doing fieldwork summer 2017 as well), where plants and insects will vary in the degree of synchrony of pollinator and host plant and therefore cause a “natural mismatch gradient”. Phenology and visiting pollinators will be monitored thorough out the season and reproductive output will be assessed. Half of the plants will be hand pollinated to assess the effect of pollen limitation.

The study will be carried out on Finse Alpine Research Centre, located on the Hardangervidda mountain plateau.

 

A population Analysis of the Red Listed Musk Orchid (Herminium monorchis) in Hvaler - Silje Skjelnes Vågen, Kari Klanderud, Marianne Evju and Liv Ingrid Kravdal.

 

The musk orchid Herminium monorchis is one of Norway's rarest vascular plants, listed as Critically Endangered in the Red-list for species. Since 2011 the species has also been listed as a Priority Species under the Norwegian Nature Diversity Act. Its distribution in Norway is restricted to three populations at Asmaløy, Hvaler municipality, Østfold county. In 2014 we established 80 permanent plots to monitor the populations, and to increase our understanding of important population processes. The three localities differed widely, one being a rich fen, one a salt meadow and the third a dry, short-statured meadow. Flowering was strongly correlated with plant size, and plant size varied among the three localities. The monitoring has now been done for three years , and a long-term monitoring of individual ramets will provide a better understanding of the key processes affecting population viability, so that management actions can be better targeted.

 

Establishment, survival and dispersal limitations of pioneer plants in a Norwegian glacier foreland as revealed by seed sowing, transplantation and seed bank experiments - Anne-Sofie Strømme

 

Glaciers are melting and retreating on a global scale due to climate change. Rapid glacier retreat leave behind large areas of barren ground, in which primary succession and plant establishments can start. However, a typical feature in glaciers forelands is that vascular plants are lacking in a distinct area close to the front of melting glaciers. To explain the absence of plants in this unpopulated area, I have conducted seed sowing, transplantation, and soil seed bank experiments to explore the establishment and survival success in eight pioneer species (i.e. Saxifraga stellaris, Poa alpina, Poa arctica, Oxyria digyna, Arabis alpina, Cerastium cerastoides, Arabis petraea and Beckwithia glacialis) along a chronosequence in the glacier foreland of Hellstugubreen in Jotunheimen, central Norway. Interestingly, my results from the field experiments showed that the study species generally had significantly higher germination success, survival, vitality and better performance in the unpopulated area nearest to the glacier as compared to in the positions furthest away from the glacier. Moreover, the soil seed bank experiment revealed that there was no seed bank in the unpopulated area closest to the glacier front. From these results, I draw the main conclusion that dispersal limitation, and not germination- and survival limitations, explained the absence of plants in the unpopulated area in front of the Hellstugubreen glacier. In addition, to understand what environmental factors that limits the growth of the important pioneer species, i.e. A. alpina, I conducted a growth experiment under four controlled combinations of temperature and light conditions. Here, my results showed that A. alpina grew better under cold and high light conditions, and that the proportion of fertile individuals were significantly reduced with increased temperatures.

 

LandPress – how does the combination of land use change and climate change affect the Norwegian coastal heathlands? - Siri Haugum

 

  1. use change in form of abandonment and reduced land use intensity represents a major threat to semi-natural ecosystems, such as Atlantic heathlands. Today, this ecosystem is classified as greatly endangered in Norway and Europe. Recently, a new concern has emerged; the effects of land use change in combination with climate change including extreme climatic events, such as drought.
  2. Norway, extreme winter drought along the coastline from Stadt to Lofoten during winter 2014, caused a massive Calluna damage and die-back, as well as severe landscape fires. This forms the background for a new project: LandPress (2016-2020). LandPress we aim to quantify the extent and variation in Calluna dieback along the Norwegian coast in relation to land use, local climate, environments and vegetation types. We want to understand the underlying mechanisms of ecosystem responses to drought a long a biogeographical gradient, and to study the effects of prescribed burning on ecosystem resilience along this gradient. Finally, we will assess ecosystem services of coastal heathlands, including the value of a reduced risk of uncontrolled fires as a result of continued management.

 

Effect of climate and disturbance on the resilience of Empetrum nigrum alpine heaths-Victoria Gonzalez

 

Empetrum nigrum is a circumpolar evergreen dwarf shrub, which dominates extensive ecosystems in northern Scandinavia. It gains dominance in alpine vegetation by suppressing the establishment of other plant species through allelopathy and dense clonal growth. The predicted increase in natural disturbance in arctic and alpine environments triggered by climate change makes it urgent to study the resilience of Empetrum dominated ecosystems.

The aim of our study was to apply simple yet controllable experiments out in the field, which coarsely imitate natural disturbances at a sufficient level as to assess their interactive effects in light of ecosystem resilience.

Preliminary results show Empetrum dominated heaths in the higher latitudes of northern Scandinavia to be ecosystems with a low resilience capacity. The regeneration capacity of these ecosystems was found to be very poor, even eight years since the disturbance took place. Furthermore the low biodiversity and persistence of shrubs in the disturbed areas is likely to constrain the successional trajectory back to slower process rates.

 

Numerical responses of saproxylic beetles to dead wood left by moth outbreak in northern Scandinavia - Petter Carlsen.

 

Saproxylic insects are important for the decomposition of dead wood, and therefore crucial for maintaining healthy forest ecosystems. There is however little knowledge about their ability to respond to massive pulses of dead wood resources caused by outbreaks of defoliating insects. This study investigates the numerical response of saproxylic beetles to increased availability of dead wood caused by outbreaks of geometrid moths in the mountain birch forest of Finnmark, Northern Norway. Beetles were sampled with window (flight interception) traps in 2011, 2012, 2015 and 2016 along two 20 km long transects. Both transects started in forest that was damaged by outbreaks during the period 2001-2009 (high dead wood abundance) and ran towards healthy, undamaged forest (normal dead wood abundance). We assess the numerical responses of saproxylic beetles to the dead wood left by the outbreaks by comparing beetle catches between damaged and undamaged forest. Previous studies, using the same methods, have found that saproxylic beetles as of 2012 had shown a weak positive numerical response, driven by a few common obligate saproxylic species associated with early successional stages of wood decay. The present study investigates the degree to which this response has been sustained over a longer period of time, and whether later successional saproxylic species have now started to respond to the outbreak.

 

Dynamics of an age-structured population of barnacle geese in the high Arctic - Kate Layton-Matthews1

 

Supervisors: Vidar Grøtan1, Brage Bremset-Hansen1 & Maarten Loonen2

1Centre for Biodiversity Dynamics, Norwegian University of Science and Technology, Trondheim NO-7491, Norway

2University of Groningen, Arctic Centre, P.O. Box 716, 9700 AS, Groningen, The Netherlands

Population declines in response to climate change are particularly extreme in the high Arctic, where the ecosystem is changing most rapidly. This research is an investigation into the dynamics of an age-structured population of barnacle geese (Branta leucopsis) migrating to the high Arctic each summer. More specifically, to determine how the effects of climate, density dependence and trophic interactions interact to drive their dynamics. 25 years of individual-based, mark-recapture data and an annual population census are used to develop an age-structured, integrated population model, combining multiple data sources to model vital rates and total population size over time.

This population of barnacle geese settled in western Svalbard in the early 1980s and rapidly expanded until reaching carrying capacity around 2000. This study system thus provides a unique opportunity to disentangle the complex relationship between density dependence and external environmental effects. Our analysis so far shows clear differences between age classes and considerable inter-annual variation in survival and reproductive success, related to arctic fox (Vulpes lagopus) predation and food resource quality in addition to density dependence.

 

Massive genome-wide changes accompany rapid adaptation in a natural population - Anurag Chaturvedi1, Joost A. M. Raeymaekers2,3, Till Czypionka1, Luisa Orsini4, Craig E. Jackson5, Katina I. Spanier1, Joseph R. Shaw5, John K. Colbourne4 and Luc De Meester1

 

1 Laboratory of Aquatic Ecology, Evolution and Conservation, KU Leuven, Ch. de Bériotstraat 32, 3000 Leuven, Belgium.

2 Laboratory of Biodiversity and Evolutionary Genomics, KU Leuven, Ch. de Bériotstraat 32, 3000 Leuven, Belgium.

3 Centre for Biodiversity Dynamics, Department of Biology, Norwegian University of Science and Technology, N-7491 Trondheim, Norway

4 Environmental Genomics Group, School of Biosciences, University of Birmingham, Birmingham B15 2TT, UK

5 School of Public and Environmental Affairs, Indiana University, Bloomington, Indiana 47405, USA

There is increasing evidence for rapid adaptive trait evolution in natural populations in response to environmental change. Yet, while many responses to major environmental changes are complex and likely involve many genes, we lack insight in the genome-wide responses of natural populations exposed to strong selection through time, especially when the selective force is subsequently relaxed. Here we apply full genome sequencing in a resurrection ecology context, where dormant eggs were hatched from pond sediments to document the genome-wide changes accompanying 16 years of rapid evolution in a natural population of the water flea Daphnia magna. We find that adaptive evolution in response to a strong increase in fish predation pressure across a period of six years (i.e. six generations) involved more than 3,000 genes and was organized in thousands of small to moderate length genomic islands of divergence along the genome. A substantial portion (15.7 %) of the responsive polymorphic sites showed a partial reversal in allele frequency upon subsequent relaxation of predation pressure. The adaptive responses were nearly entirely rooted in standing genetic variation, as almost 90 % of the targeted sites already exhibited allelic polymorphism in the oldest subpopulation. Even single individuals already accounted for 16 to 64 % of these adaptive polymorphisms. The episode of strong selection did not result in genetic erosion for polymorphisms that could fuel adaptive responses to a new episode of strong predation pressure, given that the most recent population harbored > 99 % of the genetic variants that fueled rapid responses to the first transition to high predation pressure. Our results highlight the drastic, highly dynamic, and reversible nature of adaptive genomic evolution in natural populations, and point to the key importance of standing genetic variation fueling rapid adaptive evolution in large populations.

 

Genetic diversity and structure of wild Svalbard reindeer populations shaped by landscape and human - Bart Peeters 1*, Knut H. Røed 2, Mathilde Le Moullec 1, Åshild Ø. Pedersen 3, Joost Raeymaekers 1, Bernt-Erik Sæther 1, Brage B. Hansen 1

 

1 Centre for Biodiversity Dynamics, Department of Biology, Norwegian University of Science and Technology, Trondheim, Norway

2 Department of Basic Sciences and Aquatic Medicine, Norwegian University of Life Sciences, Oslo, Norway

3 Norwegian Polar Institute, The Fram Centre, Tromsø, Norway

* bart.peeters@ntnu.no

A detailed understanding of population connectivity and the effects of anthropogenic stressors on genetic diversity and structure are important for the conservation and management of wild populations. The wild Svalbard reindeer (Rangifer tarandus platyrhynchus) is an island sub-species with particularly low genetic variation. Nevertheless, studies indicate genetic differentiation over short distances, possibly due to sedentary behaviour and landscape barriers (i.e. glaciers, mountains, sea). In addition, major human impact can be expected through historical overharvest, local extinctions and re-introduction programs, as well as climate change (e.g. sea-ice loss). In this study, we use a large panel of populations to evaluate this impact by quantifying genetic diversity and structure, and the connectivity among populations, applying landscape genetics approaches. In the initial round of analysis, we used 152 individuals from eight populations genotyped at 21 polymorphic microsatellite loci. Our results indicate overall low genetic diversity which decreased with distance from central Spitsbergen, where high connectivity and large population sizes may restrict genetic drift. Pairwise genetic differentiation increased strongly with distance and was generally lower for re-introduced populations from a common source population. Accordingly, clustering analysis suggested five genetically distinct groups. More samples will be analysed in order to quantify the effects of landscape barriers (such as open sea) on population connectivity across Svalbard, effective population sizes and genetic drift based on population size estimates, and bottlenecks induced by past overharvest.

 

SUSTHERB: Towards Sustainable Herbivore management - Gunnar Austrheim, Victoria Berger, Marc Daverdin, Winta Berhie Gebreyohanis, Anders Kolstad, James Speed, Aurel Marian Venete, Stein Joar Hegland, Erling Meisingset, Atle Mysterud, Erling J. Solberg

 

Forests provide a range of goods and services of vital importance for human society. The dramatic increase in forest ungulate populations, notably moose (Alces alces) and red deer (Cervus elaphus) in Norway, over the last decades has been a key driver for changes in forest socio-ecosystems. While forests are associated with timber and other provisioning forestry services (biofuel, game meat) regulating (carbon) and cultural services (e.g. outdoor life, hunting), overbrowsing may negatively affect biodiversity and other important services provided by the forest ecosystem. In this project we examine environmental and societal aspects of forest ungulate browsing in boreal ecosystems within an ecosystem services framework to underpin an ecosystem approach to sustain forest resources. This poster gives an introduction to the experimental design and study sites used in the SUSTHERB project and future plans for our research network.

 

Abiotic and biotic conditions of an N-limited grassland present differential impacts at an ecosystem compared to plant community scale -Furey, George N.1, Tilman, David1,2

 

1. Department of Ecology, Evolution, and Behavior, University of Minnesota Twin Cities, Saint Paul, MN 55108, USA
2. Bren School of Environmental Science and Management, University of California Santa Barbara, California 93106, USA.

A long term N addition (NAdd) experiment in a temperate grassland shows that neighborhood effects (plant species richness (SR) in adjacent plots), climate (temperature and precipitation), and deer Odocoileus virginianus presence/absence (fenced exclosure) have strong effects on plant SR, total plant productivity and community composition in addition to known NAdd effects. Neighborhood SR had a large significant effect size increasing within plot SR greater than all other variables except NAdd. Wet, hot growing seasons strongly and significantly increased productivity, whereas only a severe drought in 1988 noticeably decreased SR. Deer presence had negligible effects on productivity and plant SR with no detectable interaction with NAdd. Deer presence did not reduce previously reported invasion and emergent dominance of Elymus repens (C3) outcompeting native C4 grasses with NAdd, rather it slightly increased Elymus biomass. Deer presence instead decreased abundance of forbs and legumes susceptible to removal of floral tissue or florivory. Our analysis demonstrates that neighborhood effects and florivory can be important in shaping species diversity and community composition in addition to the known importance of climate and NAdd.

 

Leaf traits in a temperature and precipitation gradient in Western Norway-Ragnhild Gya

 

Photosynthesis and primary production are important aspects of terrestrial ecosystem function. Leaf traits that reflect these ecosystem properties were chosen to further investigate some of the aspects of photosynthesis and primary production in grasslands.

The traits measured were specific leaf area (SLA), leaf dry matter content (LDMC), leaf thickness (Lth), leaf area (LA) and plant vegetative height (HV). All of which relates to one or several of the processes associated with photosynthesis and primary production.

The traits were measured for a total of 2869 leaves from 89 different species. The leaves were collected over a temperature and precipitation gradient with three temperature levels, and four levels of precipitation. These twelve sites are alpine or subalpine grasslands located in western Norway.

Although the nature of the trait variation over gradients have been studied previously, this study will form the basis of further analyses of productivity, carbon flux and climate change in alpine and subalpine ecosystems.

The poster will present the community weighted means of the different traits and their trends along precipitation and temperature gradients.

 

Effects of stand density and other stand and site characteristics on bilberry cover in Norway-Janneke Scholten

 

The ericaceous shrub bilberry (Vaccinium myrtillus) is a keystone species of the Eurasian boreal forest. Bilberry tolerates shade, and partial shading provides the most optimal conditions for the plant. Thus, an increase in stand density due to e.g. a more intensive forest management or changes in the age structure of forest landscapes might affect bilberry cover. Using Norwegian National Forest Inventory data, we developed a general linear mixed model to predict how bilberry cover is affected by stand density, measured as basal area, and other stand and site characteristics. The effect of stand density was most apparent at sites with low site index and in pine dominated forest, where bilberry cover increased with increasing stand density throughout the age distribution range in our data. However, the opposite was found for spruce dominated forest close to maturity. In conclusion, we show that not only stand density but also tree species composition, age and site index should be taken into account to predict the effect on bilberry resulting from different forest management alternatives.

 

Nest cameras reveal the secrets of the Eleonora’s falcon-Ronny Steen

 

Abstract: The timing of breeding in raptorial birds is adapted to when food is plentiful, to the extreme we find our study species, namely the Eleonora’s falcon (Falco eleonorae). The Eleonora’s falcons breed during autumn and feed their nestlings almost exclusively on migrating passerines migrating from Europe to Africa during August and September. Prey are mainly hunted over open water and near the shores, further they also hunts right above the colonies on small offshore islets. It breeds colonially on sea cliffs and islets in the Mediterranean ocean and approximately 80% of the world population is in Greece. Observations of prey delivery in raptors in general, and in the Eleonora’s falcon in particular, are few and have been based on direct observations from a hide in combination with analyses of prey remnants and regurgitated pellets. Nevertheless, camera technology has enabled temporally high resolution observations of prey delivered to the nestlings during breeding in raptors. In September 2013-2015, we camera monitored parental effort and prey deliveries in the Eleonora’s falcon. The aim of the project is to monitor diet composition and parental effort in terms of food provided to the nestlings. Further, the around–the–clock monitoring have given us some unexpected observations such as conspecific infanticide and ingestion of plastic debris. For more information see project video: https://vimeo.com/animalbehaviour/migratoryprey <https://vimeo.com/animalbehaviour/migratoryprey>

 

Does Arctic shrub growth rings represent past primary production available for the ecosystem- Mathilde Le Moullec

 

Work in progress..

 

Spatial phylogenetics of the Norwegian vascular plant flora- Ida M. Mienna

 

Authors

Ida M. Mienna1, Andrew H. Thornhill2, Brent D. Mishler2, Mika Bendiksby1, James D. M. Speed1, Michael D. Martin1

1The Department of Natural History, University Museum, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway. 2University and Jepson Herbaria, and Department of Integrative Biology, University of California, Berkeley, California 94720-2465, USA.

Biodiversity is commonly measured and compared as the local abundance of discrete species. Recently developed methods for spatial phylogenetics combine large species occurrence datasets with molecular phylogenetic data to recover detailed information about the spatial distribution of biodiversity across landscapes. Here we apply these methods to explore spatial biodiversity in the vascular plant flora of Norway, which contains about 2880 species. About 46% of these are native (not introduced by humans), of which approximately 85% have gene sequences represented in GenBank, with the loci ITS, rbcL and matK particularly well represented. By completing a three-locus sequence alignment and combining this with spatial data from the GBIF database, it is possible to perform a spatial phylogenetic analysis of all Norwegian vascular plants. For species not represented in public databases, we will generate data from borrowed specimens on loan from various herbaria. We will extract genomic DNA and sequence missing loci using commercial kits modified for degraded DNA. We will analyse the complete and aligned dataset phylogenetically using Maximum Likelihood based tools. By using the software Biodiverse, we will investigate the spatial distribution of the vascular plant diversity. Biodiversity hotspots, centres of endemism and phytogeographic regions can also be identified applying this software. As of December 2016, we have extracted DNA from the first bulk of loaned specimens.

 

Impacts of land use intensity on biodiversity in Norway - Case study of butterflies- Eveliina Kallioniemi

Work in progress..

 

Herbivores modify the palatability of Silica–rich grasses- Katarina Inga

 

Silica–rich grasses are often abundant in pastures. The silica content causes these grasses to have low palatability, yet to what extent herbivores themselves modify the silica-content and the nutrient content of these grasses is uncertain.

Here we ask to what extent small rodents and reindeer can modify Silicon (Si), Nitrogen (N) and Phosphorous (P) contents in Si–rich grasses over a summer season in the sub–arctic tundra. We established an exclosure experiment, excluding mainly reindeer, in meadow habitats clearly impacted by small rodents winter activity and in meadow habitats with no visible impacts of small rodents. Within this experimental setup, we studied impacts of small rodents or reindeer or the combined effect of the two different sized herbivores on the nutrient responses in Si–rich grasses in meadow habitats. Leaves of three common Si–rich grasses, Nardus stricta, Calamagrostis spp. and Deschampsia cespitosa, were sampled every second week, from late June to mid September in 2015, after which samples were analysed for their Si, N and P content.

The small rodents winter activity significantly improved the N and P content in the Si–rich grasses and had no effect on the Si content, whereas reindeer summer grazing significantly decreased the Si content late in the season, but with no effect on N and P content. However, the combined effect of small rodents winter activity and summer reindeer activity showed the opposite pattern, with lower N and P leaf content and a higher Si content in the Si–rich grasses.

Results from this study indicates the effect of one herbivore alone improves the palatability of Si-rich grasses, whereas the combined effect of two herbivores, possibly through their combined prolonged activity in the meadow habitats over winter and summer, causes a reduction in Si-rich grass palatability. Consequently, herbivores create a mosaic of forage with different quality depending on if either one or both herbivores are active in the habitat.

Keywords: Silicon, Nitrogen, Phosphorous, herbivore–plant interaction, sub–arctic, reindeer, small rodent, Silica–rich grasses, NIRS

 

Published Dec. 7, 2016 11:32 AM - Last modified Dec. 16, 2016 10:51 AM