Abstract
The North American semi‐arid sagebrush, Artemisia spp., biome exhibits considerable climatic complexity driving dynamic spatiotemporal shifts in primary productivity. Greater and Gunnison sage‐grouse, Centrocercus urophasianus and C. minimus, are adapted to patterns of resource intermittence and rely on stable adult survival supplemented by occasional recruitment pulses when climatic conditions are favorable. Predictions of intensifying water scarcity raise concerns over new demographic bottlenecks impacting sage‐grouse populations in drought‐sensitive landscapes. We estimate biome‐wide mesic resource productivity from 1984 to 2016 using remote sensing to identify patterns of food availability influencing selective pressures on sage‐grouse. We linked productivity to abiotic factors to examine effects of seasonal drought across time, space, and land tenure, with findings partitioned along gradients of ecosystem water balance within Great Basin, Rocky Mountains and Great Plains regions. Precipitation was the driver of mesic resource abundance explaining ≥70% of variance in drought‐limited vegetative productivity. Spatiotemporal shifts in mesic abundance were apparent given biome‐wide climatic trends that reduced precipitation below three‐quarters of normal in 20% of years. Drought sensitivity structured grouse populations wherein landscapes with the greatest uncertainty in mesic abundance and distribution supported the fewest grouse. Privately owned lands encompassed 40% of sage‐grouse range, but contained a disproportional 68% of mesic resources. Regional drought sensitivity identified herein acted as ecological minimums to influence differences in landscape carrying capacity across sage‐grouse range. Our model depictions likely reflect a new normal in water scarcity that could compound impacts of demographic bottlenecks in Great Basin and Great Plains. We conclude that long‐term population maintenance depends on a diversity of drought resistant mesic resources that offset climate driven variability in vegetative productivity. We recommend a holistic public–private lands approach to mesic restoration to offset a deepening risk of water scarcity.
Highlights
Water input is one of the most dynamic determinants of terrestrial productivity in arid and semi‐arid regions and is fundamental to biological processes responsible for ecosystem function
Annual and intra‐annual variability in precipitation is typical with distinct dry seasons and unpredictable prolonged droughts that lead to frequent periods of water scarcity (Schlesinger et al, 1990)
To better quantify landscape sensitivity to seasonal drought and its influence in structuring mesic resources for sage‐grouse, we leveraged over 15,000 satellite images to produce a spatiotemporal dataset that tracked annual vegetative productivity patterns across the sagebrush biome from 1984 to 2016
Summary
Water input is one of the most dynamic determinants of terrestrial productivity in arid and semi‐arid regions and is fundamental to biological processes responsible for ecosystem function. Efficiencies in arid lands conservation rely on an ability to predict landscape response to offset water scarcity, yet our understanding of drought to structure spatiotemporal intermittence of primary production remains limited (Vicente‐Serrano et al, 2013). Wide‐ranging species like sage‐grouse may experience regional variability in selective pressures associated with nonlinear landscape response to drought as soil moisture is a primary driver of seasonally important food resources associated with mesic sites (e.g., forbs and macro invertebrates, Wenninger & Inouye, 2008). To better quantify landscape sensitivity to seasonal drought and its influence in structuring mesic resources for sage‐grouse, we leveraged over 15,000 satellite images to produce a spatiotemporal dataset that tracked annual vegetative productivity patterns across the sagebrush biome from 1984 to 2016. Study outcomes deliver new insight to support development of regionally specific conservation strategies necessary to offset drought‐induced bottlenecks impacting sage‐grouse and other drought sensitive wildlife in sagebrush ecosystems
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