English
norskBlar i forfatter "Hansen, Brage Bremset"
Viser treff 1-10 av 10
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Climate Events Synchronize the Dynamics of a Resident Vertebrate Community in the High Arctic
(Peer reviewed; Research report; Forskningsrapport, 2013-01-18)Recently accumulated evidence has documented a climate impact on the demography and dynamics of single species, yet the impact at the community level is poorly understood. Here, we show that in Svalbard in the high Arctic, extreme weather events synchronize population fluctuations across an entire community of resident vertebrate herbivores and cause lagged correlations with the secondary consumer, ... -
Developing common protocols to measure tundra herbivory across spatial scales
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-03-12)Understanding and predicting large-scale ecological responses to global environmental change requires comparative studies across geographic scales with coordinated efforts and standardized methodologies. We designed, applied, and assessed standardized protocols to measure tundra herbivory at three spatial scales: plot, site (habitat), and study area (landscape). The plot- and site-level protocols ... -
Don't go chasing the ghosts of the past: habitat selection and site fidelity during calving in an Arctic ungulate
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-04-01)Predator avoidance and food availability are both factors known to influence habitat selection and site fidelity around calving in caribou and reindeer. Here, we assess habitat selection and site fidelity during the calving period in the solitary, Arctic Svalbard reindeer Rangifer tarandus platyrhynchus, which is subject to limited predation risk and human disturbance. In this largely predator-free ... -
Environmental effects on spatial population dynamics and synchrony – lessons from northern ecosystems
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-01-13)Environmental variation in time and space generates complex patterns in the spatial structure of temporally covarying populations. Accounting for spatial population structure is important for sustainable management and harvest, but there is a need for a better understanding of the many mechanisms affecting the spatial structure of populations. In the large-scale research project SUSTAIN, detailed ... -
Five decades of terrestrial and freshwater research at Ny-Ålesund, Svalbard
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-04-19)For more than five decades, research has been conducted at Ny-Ålesund, in Svalbard, Norway, to understand the structure and functioning of High-Arctic ecosystems and the profound impacts on them of environmental change. Terrestrial, freshwater, glacial and marine ecosystems are accessible year-round from Ny-Ålesund, providing unique opportunities for interdisciplinary observational and experimental ... -
Growth rings show limited evidence for ungulates’ potential to suppress shrubs across the Arctic
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-02-22)Global warming has pronounced effects on tundra vegetation, and rising mean temperatures increase plant growth potential across the Arctic biome. Herbivores may counteract the warming impacts by reducing plant growth, but the strength of this effect may depend on prevailing regional climatic conditions. To study how ungulates interact with temperature to influence growth of tundra shrubs across ... -
High seasonal overlap in habitat suitability in a nonmigratory High Arctic ungulate
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-05-26)Understanding drivers of space use and habitat selection is essential for management and conservation, especially under rapid environmental change. Here, we develop summer and winter habitat suitability models for the endemic wild Svalbard reindeer (Rangifer tarandus platyrhynchus). The High Arctic Svalbard tundra is currently subject to the fastest temperature increases on Earth, and reindeer ... -
Long-term herbivore removal experiments reveal how geese and reindeer shape vegetation and ecosystem CO2-fluxes in high-Arctic tundra
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-09-23)1. Given the current rates of climate change, with associated shifts in herbivore population densities, understanding the role of different herbivores in ecosystem functioning is critical for predicting ecosystem responses. Here, we examined how migratory geese and resident, non-migratory reindeer—two dominating yet functionally contrasting herbivores—control vegetation and ecosystem processes in ... -
The neglected season: Warmer autumns counteract harsher winters and promote population growth in Arctic reindeer
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-11-24)Arctic ungulates are experiencing the most rapid climate warming on Earth. While concerns have been raised that more frequent icing events may cause die‐offs, and earlier springs may generate a trophic mismatch in phenology, the effects of warming autumns have been largely neglected. We used 25 years of individual‐based data from a growing population of wild Svalbard reindeer, to test how warmer ... -
Ungulate population monitoring in an open tundra landscape: distance sampling versus total counts
(Journal article; Tidsskriftartikkel; Peer reviewed, 2017-07-27)Researchers and wildlife managers strive for low bias and high precision (i.e. high accuracy) when estimating animal population sizes. Distance sampling is currently one of the most widely used monitoring methods. However, it relies on strict sampling designs and modeling assumptions that can be difficult to meet in the field. Here, we use data from two sub-populations of non-migratory wild Svalbard ...
