Effect of Removal of Standing Dead Material on Growth of Agropyron spicatum

Abstract

Agropyrorz spicatum (bluebunch wheatgrass), in the ungrazed condition, grows in clumps with a dense accumulation of dead culms and leaves, collectively known as standing dead. Standing dead modifies the environment of young leaves, and to a lesser degree older leaves, by intercepting sunlight and reducing air movement. Reduced light intensity may decrease photosynthetic activity. On the other hand, reduced air movement may favor a reduced vapor pressure deficit at the leaf surface and reduced water stress in plant tissues, compensating perhaps for the reduced light intensity. This report describes the effect on bluebunch wheatgrass of the removal of standing dead without the removal of live material. The results of this research are relevant to ecosystems studies focusing on the effect of standing dead on the growth of bluebunch wheatgrass. Grazing studies have dealt with the effect of removal of both live and dead material from rangeland grasses during the growing season (Rickard et al. 1975; Mueggler 1972, 1975; Wilson et al. 1966; Heady 1950). In contrast, this study addresses the effect of removing dead material early in the season before growth initiation of new leaves.