B060-0008
Global Winter Habitat Indices (WHIs) versus terrestrial biodiversity patterns

Friday, 11 December 2020
Poster
David Gudex-Cross, University of Wisconsin Madison, Madison, WI, United States, Likai Zhu, Linyi University, College of Resources and Environment, Linyi, China, Benjamin Zuckerberg, University of Wisconsin-Madison, Department of Forest and Wildlife Ecology, Madison, WI, United States and Volker Radeloff, University of Wisconsin Madison, Department of Forest and Wildlife Ecology, Madison, WI, United States
Abstract:
Cold temperatures and prolonged snow cover during winter limit the distributions of many species, while others have developed unique adaptations and life history strategies for overwintering. Here, we show that global species richness patterns for several taxa and different life history strategies are closely associated with patterns of frozen ground and snow cover. To characterize global snow and frozen ground patterns, we analyzed satellite data and calculated three global winter habitat indices (WHIs), i.e., duration of frozen ground, duration of frozen ground without snow, and snow cover variability, which we compared to species richness derived from IUCN range maps.

We found that species richness generally decreased with frozen ground duration (winter length) for amphibians (Spearman’s ρ = -0.55, Adj. r2 = 0.23), resident birds (ρ = -0.65, Adj. r2 = 0.34), and mammals (ρ = -0.26, Adj. r2 = 0.13). Conversely, we found higher migratory bird richness with increasing winter length up to a peak around 5-6 months of winter, after which it steadily declined (ρ = 0.57, Adj. r2 = 0.62). The proportion of birds that migrate relationship was similar, but with an extended peak in richness at ~5-8 months of winter, where 70-90% of all bird species were migratory (ρ = 0.79, Adj. r2 = 0.77). Endotherm richness generally increased with winter length (ρ = 0.32, Adj. r2 = 0.16). In regions that regularly experience snow cover, we found that models containing multiple WHIs explained approximately 30-50% of the variation in species richness across taxa and life history strategies. After controlling for winter length, species richness for winter resident taxa (amphibians, mammals, and resident birds) often peaked at moderate levels of frozen ground without snow or snow cover variability and decreased at both low and high levels. Thus some variability may be optimal for winter biodiversity, while too much is limiting. Our results identify key winter habitat conditions for global biodiversity, which is important as climate change rapidly alters global snow and frozen ground dynamics.

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