Early-successional plants regulate grassland productivity and species composition: a removal experiment

Authors

H. Wayne Polley, USDAFollow
Brian J. Wilsey, Iowa State University
Justin D. Derner, USDA-ARSFollow
Hyrum B. Johnson, US Department of Agriculture
Joaquin Sanabria, Texas Agricultural Experiment Station

Document Type

Article

Date of this Version

2006

Comments

Published in Oikos 113: 287-295.

Abstract

Grime’s (1998) ‘‘mass-ratio’’ hypothesis holds that ecosystem processes depend in the short term on functional properties of dominant plants and in the longer term on how resident species influence the recruitment of dominants. The latter of these effects may be especially important among early-successional species in disturbed ecosystems, but experimental tests are few. We removed two groups of early-successional species, an annual forb Gutierrezia dracunculoides (DC.) S. F. Blake and annual species (mostly grasses) that complete growth early in the growing season [early-season (ES) species], from a heavily-grazed grassland in central Texas, USA dominated by a C₄ perennial grass. We sought to determine effects of annuals on grassland functioning [productivity, water balance, soil and plant nitrogen (N)] and composition.