LTER: Long-term research on the dynamics of high-elevation ecosystems: A framework for understanding rates of ecological response to climate change

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Mountains provide critical services for human society and important habitats for diverse forms of life. They are also changing rapidly: temperatures are rising, leading to shifts in the timing of snowmelt, the amount of water flowing downstream, and the length of the snow-free growing season. While more than one-sixth of the world’s population lives in river basins fed by snow or glacier melt, we know very little about how changing climate in high mountain areas will affect biodiversity and water resources. One reason for this knowledge gap is that rugged mountain terrain causes the patterns of changing temperature to vary dramatically across the landscape. The Niwot Ridge (NWT) LTER is an interdisciplinary research program that is investigating how complex topography interacts with biological processes to determine how high-elevation mountain ecosystems are changing in response to rising temperature. The project documents long-term patterns of climate change in alpine tundra, subalpine forest, mountain lakes, and alpine streams, as well as the associated responses of organisms, populations, communities, and ecosystem processes. Located in the populous Front Range of the Colorado Rocky Mountains, NWT LTER is uniquely positioned to generate results that will directly impact a large human population while engaging diverse audiences in ecology, conservation, and mountain science.For over four decades, the NWT LTER has documented rapidly rising temperatures amidst highly variable precipitation patterns at the study site. The biological responses to these changes in climate have been highly variable in both speed and magnitude. In NWT LTER VIII, scientists will evaluate the ecological mechanisms that determine the rates at which biota and ecosystem processes respond to rising temperature. Leveraging the topographic complexity of NWT terrain, the proposed research will examine how rates of ecological responses to rising air temperature are mediated by spatial heterogeneity in temperature exposure and other abiotic factors (e.g., precipitation, growing season length, nutrients), and if these responses are accelerated or attenuated by biotic processes that play out across the physical template (e.g., life history strategies, community dynamics, ecosystem legacies). The specific objectives of this research include (1) continuing to characterize how high-elevation mountain systems are responding to climate change, (2) testing hypothesized mechanisms that explain variation in the rate at which ecological responses track rising air temperature, and (3) exploring how the aggregated effects of variable rates of response to warming alter forecasts of ecosystem function across mountain landscapes. This research program provides critical information about the effects of climate change on mountain ecosystems that informs the conservation and management of mountain catchments and the resources they provide to society.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.