Genetic Variation and Herbivory in Aspen: Consequences for Ecosystem Processes

University Of Wisconsin-Madison, Madison WI

Investigators

Abstract

Scientists have long known that genetic variation exists within plant populations, but the importance of this source of biological diversity for basic ecosystem processes (e.g., carbon and nitrogen cycling) is poorly understood. Another poorly recognized aspect of ecosystem science is how forest herbivores, such as insect pests, influence nutrient cycles. As insect herbivores feed, they induce chemical changes in plants and alter inputs of organic matter to the soil. These impacts in turn are likely to influence basic ecological properties that influence forest health, and the capacity of forests to take up carbon from the atmosphere. This proposal integrates two major themes - the ecosystem consequences of both genetic variation and herbivory - through the shared common denominator of plant chemistry. The purpose of this research is to investigate the independent and interactive effects of within-species genetic variation and herbivory on basic ecosystem processes (decomposition and nutrient cycling). We will use trembling aspen as a model system because of its expansive geographic range and ecological importance, and because aspen expresses striking genetic variation in plant chemistry and is subject to dramatic defoliation events. Our methods will span the range from short-term chamber experiments with soil, microorganisms, and purified chemical extracts, to long-term multi-year experiments that investigate nutrient cycling in natural aspen stands. This research will provide fundamental new insights into the importance of biodiversity to forest ecosystem function, and thereby inform policies of state and federal agencies involved in management of forest lands. Moreover, this work will contribute to the scientific and technical training of undergraduate and postdoctoral students.