Direct and indirect effects of regional and local climatic factors on trophic interactions in the Arctic tundra

Volatile organic compounds (VOCs) are released from biogenic sources in a temperature-dependent manner. Consequently, Arctic ecosystems are expected to greatly increase their VOC emissions with ongoing climate warming, which is proceeding at twice the rate of global temperature rise. Here, we show that ongoing warming has strong, increasing effects on Arctic VOC emissions. Using a combination of statistical modeling on data from several warming experiments in the Arctic tundra and dynamic ecosystem modeling, we separate the impacts of temperature and soil moisture into direct effects and indirect effects through vegetation composition and biomass alterations. The indirect effects of warming on VOC emissions were significant but smaller than the direct effects, during the 14-y model simulation period. Furthermore, vegetation changes also cause shifts in the chemical speciation of emissions. Both direct and indirect effects result in large geographic differences in VOC emission responses in the warming Arctic, depending on the local vegetation cover and the climate dynamics. Our results outline complex links between local climate, vegetation, and ecosystem–atmosphere interactions, with likely local-to-regional impacts on the atmospheric composition.

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Trophic interactions and abiotic factors drive functional and phylogenetic structure of vertebrate herbivore communities across the Arctic tundra biome

Ecography ◽

10.1111/ecog.04347 ◽

2019 ◽

Vol 42 (6) ◽

pp. 1152-1163 ◽

Cited By ~ 3

Author(s):

James D. M. Speed ◽

Ina Åsnes Skjelbred ◽

Isabel C. Barrio ◽

Michael D. Martin ◽

Dominique Berteaux ◽

...

Keyword(s):

Trophic Interactions ◽

Abiotic Factors ◽

Arctic Tundra ◽

The Arctic ◽

Phylogenetic Structure ◽

Herbivore Communities

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Disentangling direct and indirect effects of local temperature on abundance of mountain birds and implications for understanding global change impacts

PeerJ ◽

10.7717/peerj.12560 ◽

2021 ◽

Vol 9 ◽

pp. e12560

Author(s):

Francesco Ceresa ◽

Petra Kranebitter ◽

Juan S. Monrós ◽

Franco Rizzolli ◽

Mattia Brambilla

Keyword(s):

Land Cover ◽

Species Distribution ◽

Indirect Effects ◽

Climatic Factors ◽

Local Temperature ◽

Suitable Habitat ◽

European Alps ◽

Direct And Indirect Effects ◽

Bird Abundance ◽

Ecological Requirements

Unravelling the environmental factors driving species distribution and abundance is crucial in ecology and conservation. Both climatic and land cover factors are often used to describe species distribution/abundance, but their interrelations have been scarcely investigated. Climatic factors may indeed affect species both directly and indirectly, e.g., by influencing vegetation structure and composition. We aimed to disentangle the direct and indirect effects (via vegetation) of local temperature on bird abundance across a wide elevational gradient in the European Alps, ranging from montane forests to high-elevation open areas. In 2018, we surveyed birds by using point counts and collected fine-scale land cover and temperature data from 109 sampling points. We used structural equation modelling to estimate direct and indirect effects of local climate on bird abundance. We obtained a sufficient sample for 15 species, characterized by a broad variety of ecological requirements. For all species we found a significant indirect effect of local temperatures via vegetation on bird abundance. Direct effects of temperature were less common and were observed in seven woodland/shrubland species, including only mountain generalists; in these cases, local temperatures showed a positive effect, suggesting that on average our study area is likely colder than the thermal optimum of those species. The generalized occurrence of indirect temperature effects within our species set demonstrates the importance of considering both climate and land cover changes to obtain more reliable predictions of future species distribution/abundance. In fact, many species may be largely tracking suitable habitat rather than thermal niches, especially among homeotherm organisms like birds.

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Circumpolar spatio-temporal patterns and contributing climatic factors of wildfire activity in the Arctic tundra from 2001–2015

Environmental Research Letters ◽

10.1088/1748-9326/aa9a76 ◽

2018 ◽

Vol 13 (1) ◽

pp. 014019 ◽

Cited By ~ 9

Author(s):

Arif Masrur ◽

Andrey N Petrov ◽

John DeGroote

Keyword(s):

Climatic Factors ◽

Temporal Patterns ◽

Arctic Tundra ◽

The Arctic ◽

Spatio Temporal

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Multi-species mechanistic model of functional response provides new insights into predator-mediated interactions in a vertebrate community

10.1101/2021.10.22.464289 ◽

2021 ◽

Author(s):

Andréanne Beardsell ◽

Dominique Gravel ◽

Jeanne Clermont ◽

Dominique Berteaux ◽

Gilles Gauthier ◽

...

Keyword(s):

Functional Response ◽

Foraging Behavior ◽

Indirect Effects ◽

Interaction Strength ◽

Arctic Tundra ◽

The Arctic ◽

Short Term ◽

Density Dependent ◽

Predator Foraging ◽

Prey Handling

Prey handling processes are considered a key driver of short-term positive indirect effects between prey sharing the same predator. However, a growing body of research indicates that predators are rarely limited by such processes in the wild. Density-dependent changes in predator foraging behavior can also generate positive indirect effects but they are rarely included as explicit functions of prey densities in functional response models. With the aim of untangling proximate drivers of species interactions in natural communities and improve our ability to quantify interaction strength, we extended the Holling multi-species model by including density-dependent changes in predator foraging behavior. Our model, based on species traits and behavior, was inspired by the vertebrate community of the arctic tundra, where the main predator (the arctic fox) is an active forager feeding primarily on cyclic small rodent (lemming) populations and eggs of various tundra-nesting bird species. Short-term positive indirect effects of lemmings on birds have been documented over the circumpolar Arctic but the underlying proximate mechanisms remain poorly known. We used a unique data set, containing high-frequency GPS tracking, accelerometer, behavioral, and experimental data to parameterize the multi-species model, and a 15-year time series of prey densities and bird nesting success to evaluate interaction strength between species. Our results showed that: (i) prey handling processes play a minor role in our system and (ii) density-dependent changes in predator foraging behavior can be the proximate drivers of a predominant predator-mediated interaction observed in the arctic tundra. Mechanisms outlined in our study have been little studied and may play a significant role in natural systems. We hope that our study will provide a useful starting point to build mechanistic models of predation, and we think that our approach could conceivably be applied to a broad range of food webs.

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