Mammal responses to human footprint vary with spatial extent but not with spatial grain




Toews, Mary
Juanes, Francis
Burton, A. Cole

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Ecological 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 (Cams lupus), Canada lynx (Lynx canadensis), coyote (Cams 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 km(2)) compared to those measured at a nested subregional extent (40,000 km(2)) and to those reported in previous studies conducted at smaller spatial extents (median 2400 km(2), mean 46,993 km(2)). 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.



boreal forest, human footprint, landscape management, large mammals, relative abundance, spatial extent, spatial grain, spatial scale


Toews, M.; Juanes, F.; & Burton, A.C. (2017). Mammal responses to human footprint vary with spatial extent but not with spatial grain. Ecosphere, 8(3), article e01735.