Abstract
AbstractEcological patterns and processes can vary with scale, causing uncertainty when applying small‐scale or single‐scale studies to regional or global management decisions. Conducting research at large extents and across multiple scales can require additional time and effort, but may prove necessary if it uncovers novel patterns or processes. Knowing the degree to which patterns vary between spatial extents and grains can provide insight into the importance of considering scale, particularly in applied research. Across multiple spatial scales, we evaluated variation in the strength and direction of large mammal responses to human footprint, a measure of human infrastructure (e.g., roads, buildings) and landscape change (e.g., agriculture, forestry). We focused on the response of five boreal mammals: gray wolf (Canis lupus), Canada lynx (Lynx canadensis), coyote (Canis latrans), white‐tailed deer (Odocoileus virginianus), and moose (Alces alces). Firstly, we asked how responses measured at the regional extent of the boreal forest of Alberta (approximately 400,000 km2) compared to those measured at a nested subregional extent (40,000 km2) and to those reported in previous studies conducted at smaller spatial extents (median 2400 km2, mean 46,993 km2). Secondly, we tested whether responses differed across three spatial grains of measurement (250 m, 1500 m, or 5000 m radii) at the regional extent. Using the Alberta Biodiversity Monitoring Institute's snowtrack survey data (2001–2013) and human footprint map, we created a set of generalized linear mixed‐effects models for each species, which related relative abundance to individual and cumulative effects of human footprint and compared these using an information theoretic approach. We found variation across spatial extents in both direction and strength of estimated mammal responses to human footprint, suggesting that some patterns are scale‐dependent. This reinforces the need for regional studies to complement those conducted at smaller extents in order to fully understand, and thus manage for, the impacts of human footprint on mammalian biodiversity. By contrast, we found little variation in direction and strength of responses across spatial grains, indicating that analyses across multiple grain sizes may be of less importance than those conducted across multiple spatial extents.
Highlights
Scale in ecology and management It is increasingly recognized that patterns and processes of species and ecosystems can vary with spatial scale (Levin 1992, Wheatley and Johnson 2009)
The remaining ones either did not provide sufficient information to have a precise or estimated study area, or are sources which compiled multiple studies. Of those for which we had study extent data, we found that the majority were completed at small extents, with very few at regional scales (Fig. 2; Appendix S6)
There was wide variation in terms of which footprint features best explained relative abundance when comparing between extents in our analyses of Alberta Biodiversity Monitoring Institute (ABMI) snowtrack data (400,000 km2 and 40,000 km2), and between our analyses and expectations based on previous studies
Summary
Scale in ecology and management It is increasingly recognized that patterns and processes of species and ecosystems can vary with spatial scale (Levin 1992, Wheatley and Johnson 2009). Variations in patterns across spatial scales can partly be explained by habitat heterogeneity Species respond differently to their environment at varying scales due to differences in each species’ perception of the landscape (Wiens 1989), such as through hierarchical habitat selection (Johnson 1980) which often varies with body size and dispersal ability (Holling 1992, Fisher et al 2011). Species respond to different patterns in the heterogeneity of ecosystems and landscapes, which may emerge due to unique structuring processes operating at different scales (Holling 1992, Levin 1992, Allen and Holling 2002). Differences in responses across scales can be due to interacting and accumulating processes (Ewers and Didham 2006) and variation in the relative importance of different processes between scales (Gotelli et al 2010, McGill 2010)
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