Degradation of near surface ice-rich permafrost may release a large amount of water to arctic and subarctic ecosystems, and the degree to which plants will use and transpire the water via new root growth into former permafrost horizons is not known. Determining the role of plants in affecting the fate of water from degrading permafrost is important for constraining estimates of evapotranspiration in models of soil moisture and energy balance. Preliminary data show that plant species vary in their ability to use permafrost-derived water. The objective of this investigation is to quantify new root growth into former permafrost horizons and quantify the use of permafrost-derived water by different plant species by comparing sites with and without permafrost. Hydrogen and oxygen isotopes of water from the active layer, permafrost, and plant stems collected in taiga ecosystems in Alaska will be measured. Bayesian inverse modeling will be applied to determine water sources used by different species and how they vary with seasonal changes in active layer thickness. The study will contribute to understanding the consequences of permafrost degradation and changes in plant water use for subarctic water cycling, energy balance, and potential feedbacks to climate. The proposed work is supported by a Post-doctoral Fellowship that will foster multiple collaborations and will enable the principal investigator (PI) to initiate her first full-scale research program in arctic ecosystem ecology. The PI will be trained in Bayesian statistics, ecology of subarctic ecosystems, permafrost and hydrological science, and science education and outreach. A workshop for high school teachers aimed at integrating sub-Arctic ecology into the curriculum will be held at the Museum of the North, University of Alaska Fairbanks.
