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.

Bioturbation by subterranean mammalian herbivores and its impact on ecosystems.

Reichman, O.¹, Seabloom, Eric², ¹ UC-Santa Barbara, Santa Barbara, CA, USA² National Center for Ecological Analysis and Synthesis, Santa Barbara, CA, USA

ABSTRACT- North American pocket gophers and their ecological cognates around the world have profound impacts on ecosystems. These subterranean herbivores maintain an energetically expensive life habit in which burrowing through the soil costs 360-3,400 times as much as walking the same distance on the surface. Accordingly, they consume large amounts of vegetation, primarily roots, which significantly impacts plants. Excavation behavior, which involves construction of long burrows by displacing soil into mounds on the surface, generates major impacts on the physical environment. These produce a complex mosaic of nutrients and soil conditions that results in vertical mixing (through burrow collapse and moving deep soil to the surface) and horizontal patchiness (in relation to the hollow burrows, refilled burrows, surrounding soil matrix, and surface mounds). In addition, the excavations accelerate soil processes such as erosion and the downslope movement of soil at both micro- and macrotopographic scales. The burrows of pocket gophers are uniformly distributed while the mounds are highly clumped, producing impacts on both plant communities and the soil that occur in spatially explicit configurations. Through the combination of extensive impacts on vegetation and soil dynamics, fossorial mammals are important ecosystem engineers.

Key words: engineer, disturbance, ecosystems, gopher