Responses of Root Hydraulic Conductivity to Elevated CO2: Patterns and Mechanisms

University Of Illinois At Chicago, Chicago IL

Investigators

Abstract

Rising atmospheric CO2 concentration could have serious consequences for terrestrial ecosystems. These effects are often examined in terms of direct influences on carbon uptake and losses by plants. However, elevated levels of CO2 may result in significant changes in performances of native and crop ecosystems via indirect effects involving uptake and usage of other resources such as water and nutrients. In most native ecosystems, water is the most limiting resource. Therefore, any impact of rising CO2 level on water uptake and usage by vegetation will affect plant and ecosystem productivity as well as affecting the hydrologic biosphere-atmosphere feedbacks. To date, there is some evidence that elevated CO2 may reduce foliage resistance to water loss but considerably less is known about potential changes in other components of water flow within the soil, through the plant and to the atmosphere. The proposed study will examine the effects of projected rise in atmospheric CO2 on a number of forest and crop species. More specifically, effects on root hydraulic conductivity which often constitutes a major barrier to water flow will be examined. Preliminary results along with theoretical considerations indicate that high CO2 may result in a significant change in root uptake and transport capacity of water. The proposed study will also examine the mechanism(s) that may best explain why CO2 would affect root water transport properties. The results will have significant utility for models of plant and ecosystem growth responses to future climates. The study is also designed to determine potential differences in species responses thus providing a mechanistic understanding of CO2 affect on the larger scale ecological processes of biodiversity and population dynamics. Finally, the study will engage K-12 as well as undergraduate students in conceptual and experimental aspects of this research.