Featured Research Project (November - December 2002)

Ecosystem Response to elevated Tropospheric Carbon Dioxide (CO2) and Ozone (03) is Regulated by Plant-Microbe Interactions in Soil

Dr. Donald Zak, Professor of Natural Resources 

Overview

A major uncertainty in our ability to predict ecosystem response to a changing climate is the extent to which increases in plant and ecosystem productivity will be sustained as CO2 continues to accumulates in the Earth's atmosphere. Much of this uncertainty stems from potential interactions between rising atmospheric CO2 and other environmental factors, like troposphere O3, which could diminish plant growth response to elevated CO2. We do not understand the specific ways in which higher levels of O3 will interact with rising CO2 to alter plant growth and net primary productivity (NPP), nor do we understanding how changes in NPP will cascade through terrestrial ecosystems to impact higher trophic levels (i.e., decomposer communities in soil), which further control the flow of energy and nutrients in forest ecosystems.

Goals and Objectives

This research is investigating the underlying mechanisms controlling ecosystem response to elevated CO2 and O3, and it is based on the premise that plant-microbe interactions in soil mediate key feedback mechanisms controlling ecosystem response (e.g., NPP and NEP) to climate change. Investigators propose that understanding how changing resource availability influences the allocation of photosynthate to growth, storage and defense in plants with contrasting life-history traits (early vs. late-successional tree species), coupled with an understanding of microbial bioenergetics, holds promise for providing a conceptual framework that will enable us to predict ecosystem feedback and long-term patterns of ecosystem C and N cycling as CO2 and O3 accumulate in the Earth's atmosphere.

Methods

This research is based on a conceptual model and a coordinated series of hypotheses linking biochemical changes in leaf and fine root litter to physiological changes in microbial communities that influence the cycling and storage of C and N in soil. Each hypotheses will be tested at the FACTS II FACE experiment in Rhinelander, Wisconsin, the only free-air release experiment in the world capable of addressing how CO2 and O3 will interact to alter the structure and function of forest ecosystems.

Project Background

The principle invesitgator of this project, Dr. Donald Zak, received $977,758 in funding from the Department of Energy (DOE) over two years to conduct these experients.

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