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Catchment vegetation and temperature mediating trophic interactions and production in plankton communities.

https://arctichealth.org/en/permalink/ahliterature282411
Source
PLoS One. 2017;12(4):e0174904
Publication Type
Article
Date
2017
Author
Anders G Finstad
Erlend B Nilsen
Ditte K Hendrichsen
Niels Martin Schmidt
Source
PLoS One. 2017;12(4):e0174904
Date
2017
Language
English
Publication Type
Article
Keywords
Animals
Arctic Regions
Bayes Theorem
Climate change
Ecosystem
Fishes - physiology
Food chain
Lakes
Models, Biological
Phytoplankton - growth & development - physiology
Plankton - growth & development - physiology
Temperature
Zooplankton - growth & development - physiology
Abstract
Climatic factors influence the interactions among trophic levels in an ecosystem in multiple ways. However, whereas most studies focus on single factors in isolation, mainly due to interrelation and correlation among drivers complicating interpretation and analyses, there are still only few studies on how multiple ecosystems respond to climate related factors at the same time. Here, we use a hierarchical Bayesian model with a bioenergetic predator-prey framework to study how different climatic factors affect trophic interactions and production in small Arctic lakes. Natural variation in temperature and catchment land-cover was used as a natural experiment to exemplify how interactions between and production of primary producers (phytoplankton) and grazers (zooplankton) are driven by direct (temperature) and indirect (catchment vegetation) factors, as well as the presence or absence of apex predators (fish). The results show that increased vegetation cover increased phytoplankton growth rate by mediating lake nutrient concentration. At the same time, increased temperature also increased grazing rates by zooplankton. Presence of fish increased zooplankton mortality rates, thus reducing grazing. The Arctic is currently experiencing an increase in both temperature and shrub vegetation cover due to climate change, a trend, which is likely to continue. Our results point towards a possible future general weakening of zooplankton grazing on phytoplankton and greening of arctic lakes with increasing temperatures. At the same time, the impact of the presence of an apex predator indicate considerable local variation in the response. This makes direction and strength of global change impacts difficult to forecast.
Notes
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PubMed ID
28414736 View in PubMed
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Circumpolar status of Arctic ptarmigan: Population dynamics and trends.

https://arctichealth.org/en/permalink/ahliterature309515
Source
Ambio. 2020 Mar; 49(3):749-761
Publication Type
Journal Article
Date
Mar-2020
Author
Eva Fuglei
John-André Henden
Chris T Callahan
Olivier Gilg
Jannik Hansen
Rolf A Ims
Arkady P Isaev
Johannes Lang
Carol L McIntyre
Richard A Merizon
Oleg Y Mineev
Yuri N Mineev
Dave Mossop
Olafur K Nielsen
Erlend B Nilsen
Åshild Ønvik Pedersen
Niels Martin Schmidt
Benoît Sittler
Maria Hørnell Willebrand
Kathy Martin
Author Affiliation
Norwegian Polar Institute, Fram Centre, Postbox 6606, Langnes, 9296, Tromsø, Norway. eva.fuglei@npolar.no.
Source
Ambio. 2020 Mar; 49(3):749-761
Date
Mar-2020
Language
English
Publication Type
Journal Article
Keywords
Alaska
Animals
Arctic Regions
Galliformes
Greenland
North America
Population Dynamics
Russia
Svalbard
Sweden
Abstract
Rock ptarmigan (Lagopus muta) and willow ptarmigan (L. lagopus) are Arctic birds with a circumpolar distribution but there is limited knowledge about their status and trends across their circumpolar distribution. Here, we compiled information from 90 ptarmigan study sites from 7 Arctic countries, where almost half of the sites are still monitored. Rock ptarmigan showed an overall negative trend on Iceland and Greenland, while Svalbard and Newfoundland had positive trends, and no significant trends in Alaska. For willow ptarmigan, there was a negative trend in mid-Sweden and eastern Russia, while northern Fennoscandia, North America and Newfoundland had no significant trends. Both species displayed some periods with population cycles (short 3-6 years and long 9-12 years), but cyclicity changed through time for both species. We propose that simple, cost-efficient systematic surveys that capture the main feature of ptarmigan population dynamics can form the basis for citizen science efforts in order to fill knowledge gaps for the many regions that lack systematic ptarmigan monitoring programs.
PubMed ID
31073984 View in PubMed
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Circumpolar status of Arctic ptarmigan: Population dynamics and trends.

https://arctichealth.org/en/permalink/ahliterature299777
Source
Ambio. 2019 May 09; :
Publication Type
Journal Article
Date
May-09-2019
Author
Eva Fuglei
John-André Henden
Chris T Callahan
Olivier Gilg
Jannik Hansen
Rolf A Ims
Arkady P Isaev
Johannes Lang
Carol L McIntyre
Richard A Merizon
Oleg Y Mineev
Yuri N Mineev
Dave Mossop
Olafur K Nielsen
Erlend B Nilsen
Åshild Ønvik Pedersen
Niels Martin Schmidt
Benoît Sittler
Maria Hørnell Willebrand
Kathy Martin
Author Affiliation
Norwegian Polar Institute, Fram Centre, Postbox 6606, Langnes, 9296, Tromsø, Norway. eva.fuglei@npolar.no.
Source
Ambio. 2019 May 09; :
Date
May-09-2019
Language
English
Publication Type
Journal Article
Abstract
Rock ptarmigan (Lagopus muta) and willow ptarmigan (L. lagopus) are Arctic birds with a circumpolar distribution but there is limited knowledge about their status and trends across their circumpolar distribution. Here, we compiled information from 90 ptarmigan study sites from 7 Arctic countries, where almost half of the sites are still monitored. Rock ptarmigan showed an overall negative trend on Iceland and Greenland, while Svalbard and Newfoundland had positive trends, and no significant trends in Alaska. For willow ptarmigan, there was a negative trend in mid-Sweden and eastern Russia, while northern Fennoscandia, North America and Newfoundland had no significant trends. Both species displayed some periods with population cycles (short 3-6 years and long 9-12 years), but cyclicity changed through time for both species. We propose that simple, cost-efficient systematic surveys that capture the main feature of ptarmigan population dynamics can form the basis for citizen science efforts in order to fill knowledge gaps for the many regions that lack systematic ptarmigan monitoring programs.
PubMed ID
31073984 View in PubMed
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The cost of maturing early in a solitary carnivore.

https://arctichealth.org/en/permalink/ahliterature96456
Source
Oecologia. 2010 Jul 6;
Publication Type
Article
Date
Jul-6-2010
Author
Erlend B Nilsen
Henrik Brøseth
John Odden
John D C Linnell
Author Affiliation
Norwegian Institute for Nature Research, 7485, Trondheim, Norway, erlend.nilsen@nina.no.
Source
Oecologia. 2010 Jul 6;
Date
Jul-6-2010
Language
English
Publication Type
Article
Abstract
Central to the theory of life history evolution is the existence of trade-offs between different traits, such as the trade-off between early maturity and an extended period of body growth. Based on analysis of the reproductive tracts of harvested Eurasian lynx (Lynx lynx) females in Norway, we find that females that mature early are generally heavier than those that postpone maturation. A higher proportion of 1.5-year-old females showed signs of ovulation in areas with high prey density, where they were also heavier. Further, we show that female Eurasian lynx that mature early have the same number of placental scars (an index of breeding investment and litter size) as older females, suggesting that they have a relatively high investment in their first litter. This induces a cost in terms of body weight development, as those females that had matured at the age of 1.5 years were substantially lighter by the age of 2.5 years than those that postponed breeding. This effect tended to be more pronounced in areas with low prey density. We discuss to what extent this might affect their future fitness prospects, and suggest that such costs of maturing early in terms of body weight development might be high in terrestrial large carnivores due to a prolonged period of postnatal care.
PubMed ID
20607292 View in PubMed
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Guild composition and habitat use of voles in 2 forest landscapes in south-eastern Norway.

https://arctichealth.org/en/permalink/ahliterature261005
Source
Integr Zool. 2011 Dec;6(4):299-310
Publication Type
Article
Date
Dec-2011
Author
Lucrezia Gorini
John D C Linnell
Luigi Boitani
Ulrike Hauptmann
Morten Odden
Per Wegge
Erlend B Nilsen
Source
Integr Zool. 2011 Dec;6(4):299-310
Date
Dec-2011
Language
English
Publication Type
Article
Keywords
Analysis of Variance
Animals
Arvicolinae - physiology
Ecosystem
Food chain
Forests
Norway
Population Dynamics
Species Specificity
Specimen Handling
Abstract
It is widely believed that intensive forestry has influenced small mammal population dynamics, and thereby the entire mammalian community in Fennoscandian boreal forests. The nature of these impacts on the different species is subject to debate. We live-trapped voles between 2006 and 2009 in 2 commercially harvested forests in south-eastern Norway. We investigated the variation in vole abundance among habitat types (e.g. mature forest and clear-cut) and the hypothesis that graminivorous species such as field voles (Microtus agrestis L.) benefit from clear-cuts at the expense of forest dwellers (i.e. the bank vole, Myodes glareolus Schreb.), using fine-scale descriptors of the ground vegetation. We could not find support for the hypothesis that field voles show a preference for clear-cuts, and their overall abundance was low, while bank voles were the dominant species in all habitat types, including clear-cuts in the peak and pre-peak years. We found a positive association between bank vole abundance and bilberry (Vaccinium myrtillus L.) availability rather than a specific habitat type. Low field vole density in clear-cuts might be due to variation in local productivity and ground vegetation as well as to large variation in the species temporal dynamics. The latter is particularly associated with the widespread decline of field voles in Scandinavia. Logging has the potential to negatively affect bank vole population dynamics because of the negative effect on bilberry development.
PubMed ID
22182322 View in PubMed
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Harvest models of small populations of a large carnivore using Bayesian forecasting.

https://arctichealth.org/en/permalink/ahliterature307552
Source
Ecol Appl. 2020 04; 30(3):e02063
Publication Type
Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.
Date
04-2020
Author
Henrik Andrén
N Thompson Hobbs
Malin Aronsson
Henrik Brøseth
Guillaume Chapron
John D C Linnell
John Odden
Jens Persson
Erlend B Nilsen
Author Affiliation
Grimsö Wildlife Research Station, Department of Ecology, Swedish University of Agricultural Sciences, SE-730 91, Riddarhyttan, Sweden.
Source
Ecol Appl. 2020 04; 30(3):e02063
Date
04-2020
Language
English
Publication Type
Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.
Keywords
Animals
Bayes Theorem
Conservation of Natural Resources
Norway
Scandinavian and Nordic Countries
Sweden
Abstract
Harvesting large carnivores can be a management tool for meeting politically set goals for their desired abundance. However, harvesting carnivores creates its own set of conflicts in both society and among conservation professionals, where one consequence is a need to demonstrate that management is sustainable, evidence-based, and guided by science. Furthermore, because large carnivores often also have high degrees of legal protection, harvest quotas have to be carefully justified and constantly adjusted to avoid damaging their conservation status. We developed a Bayesian state-space model to support adaptive management of Eurasian lynx harvesting in Scandinavia. The model uses data from the annual monitoring of lynx abundance and results from long-term field research on lynx biology, which has provided detailed estimates of key demographic parameters. We used the model to predict the probability that the forecasted population size will be below or above the management objectives when subjected to different harvest quotas. The model presented here informs decision makers about the policy risks of alternative harvest levels. Earlier versions of the model have been available for wildlife managers in both Sweden and Norway to guide lynx harvest quotas and the model predictions showed good agreement with observations. We combined monitoring data with data on vital rates and were able to estimate unobserved additional mortality rates, which are most probably due to poaching. In both countries, the past quota setting strategy suggests that there has been a de facto threshold strategy with increasing proportion, which means that there is no harvest below a certain population size, but above this threshold there is an increasing proportion of the population harvested as the population size increases. The annual assessment of the monitoring results, the use of forecasting models, and a threshold harvest approach to quota setting will all reduce the risk of lynx population sizes moving outside the desired goals. The approach we illustrate could be adapted to other populations of mammals worldwide.
PubMed ID
31868951 View in PubMed
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Impacts of predator-mediated interactions along a climatic gradient on the population dynamics of an alpine bird.

https://arctichealth.org/en/permalink/ahliterature303859
Source
Proc Biol Sci. 2020 12 23; 287(1941):20202653
Publication Type
Journal Article
Research Support, Non-U.S. Gov't
Date
12-23-2020
Author
Diana E Bowler
Mikkel A J Kvasnes
Hans C Pedersen
Brett K Sandercock
Erlend B Nilsen
Author Affiliation
Department of Ecosystem Services, German Centre for Integrative Biodiversity Research (iDiv), Putschstr. 4, 04103 Leipzig, Germany.
Source
Proc Biol Sci. 2020 12 23; 287(1941):20202653
Date
12-23-2020
Language
English
Publication Type
Journal Article
Research Support, Non-U.S. Gov't
Keywords
Animals
Arvicolinae
Bayes Theorem
Birds
Climate
Ecosystem
Food chain
Norway
Population Dynamics
Predatory Behavior
Rodentia
Abstract
According to classic theory, species' population dynamics and distributions are less influenced by species interactions under harsh climatic conditions compared to under more benign climatic conditions. In alpine and boreal ecosystems in Fennoscandia, the cyclic dynamics of rodents strongly affect many other species, including ground-nesting birds such as ptarmigan. According to the 'alternative prey hypothesis' (APH), the densities of ground-nesting birds and rodents are positively associated due to predator-prey dynamics and prey-switching. However, it remains unclear how the strength of these predator-mediated interactions change along a climatic harshness gradient in comparison with the effects of climatic variation. We built a hierarchical Bayesian model to estimate the sensitivity of ptarmigan populations to interannual variation in climate and rodent occurrence across Norway during 2007-2017. Ptarmigan abundance was positively linked with rodent occurrence, consistent with the APH. Moreover, we found that the link between ptarmigan abundance and rodent dynamics was strongest in colder regions. Our study highlights how species interactions play an important role in population dynamics of species at high latitudes and suggests that they can become even more important in the most climatically harsh regions.
PubMed ID
33352076 View in PubMed
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Integrating data from multiple sources for insights into demographic processes: Simulation studies and proof of concept for hierarchical change-in-ratio models.

https://arctichealth.org/en/permalink/ahliterature292672
Source
PLoS One. 2018; 13(3):e0194566
Publication Type
Journal Article
Research Support, Non-U.S. Gov't
Date
2018
Author
Erlend B Nilsen
Olav Strand
Author Affiliation
Norwegian Institute for Nature Research, Torgarden, Trondheim, Norway.
Source
PLoS One. 2018; 13(3):e0194566
Date
2018
Language
English
Publication Type
Journal Article
Research Support, Non-U.S. Gov't
Keywords
Age Distribution
Animal Distribution
Animals
Bayes Theorem
Computer simulation
Ecological Parameter Monitoring - methods
Female
Male
Models, Statistical
Norway
Population Density
Population Dynamics
Proof of Concept Study
Reindeer
Seasons
Sex Distribution
Abstract
We developed a model for estimating demographic rates and population abundance based on multiple data sets revealing information about population age- and sex structure. Such models have previously been described in the literature as change-in-ratio models, but we extend the applicability of the models by i) using time series data allowing the full temporal dynamics to be modelled, by ii) casting the model in an explicit hierarchical modelling framework, and by iii) estimating parameters based on Bayesian inference. Based on sensitivity analyses we conclude that the approach developed here is able to obtain estimates of demographic rate with high precision whenever unbiased data of population structure are available. Our simulations revealed that this was true also when data on population abundance are not available or not included in the modelling framework. Nevertheless, when data on population structure are biased due to different observability of different age- and sex categories this will affect estimates of all demographic rates. Estimates of population size is particularly sensitive to such biases, whereas demographic rates can be relatively precisely estimated even with biased observation data as long as the bias is not severe. We then use the models to estimate demographic rates and population abundance for two Norwegian reindeer (Rangifer tarandus) populations where age-sex data were available for all harvested animals, and where population structure surveys were carried out in early summer (after calving) and late fall (after hunting season), and population size is counted in winter. We found that demographic rates were similar regardless whether we include population count data in the modelling, but that the estimated population size is affected by this decision. This suggest that monitoring programs that focus on population age- and sex structure will benefit from collecting additional data that allow estimation of observability for different age- and sex classes. In addition, our sensitivity analysis suggests that focusing monitoring towards changes in demographic rates might be more feasible than monitoring abundance in many situations where data on population age- and sex structure can be collected.
Notes
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PubMed ID
29596430 View in PubMed
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8 records – page 1 of 1.