Collaborative Research: Consequences of Climate-Induced Range Shifts on Multiple Ecosystem Functions

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The healthy functioning of natural ecosystems depends on the interactive roles of the various species that coexist in them. Different but closely related species replace each other along environmental gradients (e.g., from dry to wet). In some cases the new species function similarly, but in others species replacements have major impacts on the ecosystem and the goods and services provided to humans. Around the planet, species distributions are shifting in response to a changing climate, yet little is known about how the shifts will affect ecosystems. One continuous study over the past 25 years of the animals that live in high elevation ponds in the Rocky Mountains of Colorado shows that species are shifting to higher elevations. And at the same elevation animals are moving to different types of ponds (permanent vs. temporary) as the water regime varies. The goal of this new project is to determine how such shifts impact ecosystem function. Training of undergraduate students is a key component of the project and undergraduates will be involved with all aspects of the research. A cross-institutional research experiment will be developed for them, where they can work together to study the impacts of species range shifts from North Carolina to Maine. One graduate student and a postdoctoral associate will also be trained. Finally, the team will continue public outreach at each home institution, as well as at the Rocky Mountain Biological Laboratory in Colorado where most of the research will be conducted. This project will test how range shifts along environmental gradients in the dominant group of detritivores (caddisfly larvae) will affect multiple ecosystem processes, including the transfer of detrital energy to detritivore secondary production, release of detritus-bound nutrients for algal uptake, bottom-up effects of algae on herbivores, and ecosystem metabolism. Researchers will use models, experiments, and comparative data from whole ponds to investigate the degree to which 1) species replacements along permanence and elevational gradients are functional replacements in terms of detritus processing rates and cascading effects on brown (detrital) and green (algal) trophic paths, 2) the interactive effects of species shifts across the permanence gradient within an elevation and those associated with range shifts across elevations, and 3) how changes in ecosystem processes with community rearrangements scale up to natural ponds. Impacts will be assessed on three components: 1) the amounts of nutrients and energy from dead plant parts that are eaten by animals (detritivory), 2) how much of the consumption is released back into the environment and stimulates the growth of algae, which can then also be eaten, and 3) how new combinations of species affect the overall productivity of the ponds.