PARENT SESSION
OOS 4: Organisms as Ecosystem Engineers: Conceptual Progress, Limits and Challenges.
Organized by: JP Wright and CG Jones
Monday, August 2, 8:00 AM to 11:30 AM, Meeting Room E 146.

Linking population dynamics of ecosystem engineers, patch dynamics, and patterns of diversity at the landscape scale.

Wright, Justin^{*,1, 2}, ¹ Department of Ecology, Evolution, and Environmental Biology, New York, NY² Department of Biology, Durham, NC

ABSTRACT- The population dynamics of organisms that modify the physical environment, ecosystem engineers, can have strong impacts on the dynamics of the patches that they create. In turn, the patch dynamics of an ecosystem can exert controls on the number of species found at large spatial scales. Thus, the potential exists to explicitly link the population dynamics of an ecosystem engineer to patterns of species richness at the landscape scale. Here we link models that we have developed to explore the relationship between ecosystem engineer population dynamics and patch dynamics to models that relate the distribution of different patch types in a landscape to the total number of species present in that landscape. We parameterized these models using data collected on the population dynamics of beaver, a model species of ecosystem engineer, patch dynamics of wetlands created via beaver engineering, and plant community structure in beaver-created wetlands and unmodified riparian zones from the central Adirondack Mountains, NY, USA. Currently beaver-created wetlands cover 26.7% of the riparian zone on a per unit length basis, and are responsible for approximately 25% of the total herbaceous plant species present in the riparian zone. Our models suggest that small changes in the number of dispersing beaver or the rate at which beaver abandon sites could lead to significant changes in the total number of plant species found in the landscape. The degree to which changes in the population dynamics of beaver affect species richness at the landscape scale is dependent on assumptions about the proportion of the landscape that is potentially transformable by beaver. Nevertheless, this work clearly demonstrates links between the population dynamics of a single species and species richness at a large scale via the mechanism of ecosystem engineering.

Key words: beaver, landscapes, ecosystem engineer, diversity