Research in climate change examines how environmental factors such as climatic warming can affect plant productivity and nutrient cycling. We also are interested how individual plant species may respond to climate change factors. We currently have two projects associated with climate change, one an ecosystem project in the Greenland arctic and the other a physiological ecology study examining species responses to shifts in temperature

Greenland Project:

Large-herbivore Mediation of Vegetation Productivity Response to Climate Change in the Arctic. PIs. Eric Post, David Eissenstat, Yiqi Luo and Mads Forchhammer

Arctic ecosystems have been a major focus of climate change studies because they have the potential for substantial feedback on climate through changes in plant species composition and carbon balance that might influence atmospheric CO2 concentration. Ecologists have long asserted that vertebrate herbivores exert considerable influence on plant biomass, productivity, soil nutrient dynamics, and species composition of the plant communities in which they forage. Alone or in combination, these influences may mediate vegetation productivity response to climatic warming, especially in arctic and sub-arctic ecosystems, where vegetation productivity is characteristically nutrient limited.

We are conducting controlled experiments involving temperature manipulations inside and outside of caribou- and muskox-proof exclosures in an arctic field site in West Greenland, where we are quantifying the influences of natural herbivory and artificial warming on vegetation productivity above- and belowground and species composition.



Respiration Project:

Using Phylogenetically Independent Contrasts to Examine Temperature Acclimation of Root and Mycorrhizal Fungal Respiration Among Organisms from Broad Latitudinal Gradients. PIs. David Eissenstat, Roger Koide.

Greenhouse gases are leading to warming temperatures. The Intergovernmental Panel on Climate Change predicts a 1.4-5.8 C increase in global surface temperature by 2100, using atmospheric models that assume increases in atmospheric CO2 will lead to increases in ambient temperature, which increases soil respiration, causing a positive feedback. Mycorrhizal root respiration represents the dominant source of soil respiration in many soils. If mycorrhizal roots acclimate to increases in temperature, than predicted increases in surface temperatures may be overestimated. Moreover, most physiological measurements are based on leaf responses to changes in air temperature. Warming of the soil may cause substantially different responses as the roots of arctic plants have adapted to a much narrower range in temperature compared to that of the leaves.

We have collected plants and mycorrhizal fungi of a wide range of families from Alaska, Pennsylvania and Florida and measured the physiological responses to temperature under controlled temperature conditions. Latitudinal contrast are made of species in the same genera. We have found strong evolutionary convergence where the roots of arctic species have consistently exhibited low thermal tolerance to temperatures of only 20C.