Soil Properties Drive Changes in Water Use efficiency Across a Climatic Gradient

Abstract:

This research uses a series of physiological models and empirical measurements to evaluate biogeochemical controls over coupled carbon-water cycles in forest systems from the individual plant to the ecosystem scale. Cellulosic biomarkers, and bulk tissue of leaf, litter, and soil organic matter have been analyzed for specific stable isotope ratios of oxygen and carbon to examine causal links between plant to ecosystem scale productivity and water balance. A series of latitudinal and altitudinal transects established across the California Sierra Nevada was used to study the effects of climatic and edaphic gradients on the formation and preservation of these plant isotopic signals. Changes in plant-soil-atmosphere relations are related to productivity and water use efficiency in an attempt to elucidate how plant material reflects ecosystem scale processes in response to variation in climate and soil properties. The use of a dual isotopic approach constrains the role of environmental variables on stable isotope values, allowing for nutritive vs hydrologic limitations over water use efficiency to be assessed. The result of this work is to promote a framework for tracing plant-soil water relations across scales to better understand and more precisely predict the impacts of climate change on forest ecosystems.