The Effect of Clipping and Phytophagous Nematodes on Net Primary Production of Blue Grama, Bouteloua gracilis

Abstract

Pots of non-mycorrhizal blue grama in an environmental chamber were subjected to three levels of both above ground (0, moderate and heavy clipping) and below ground (0, 50 or 500 phytophagous nematodes per pot) herbivory. Net primary production (NPP), including shoots and crowns, decreased significantly with clipping and nematode infection. Roots also declined with clipping, but moderate nematode infection (50) on unclipped plants significantly increased root weight although NPP was still less. Phytophagous nematode densities decreased with heavy clipping but increased with moderate clipping to over three times the control (unclipped) level. Bacterial feeding nematode densities were depressed both by heavy clipping and by moderate clipping combined with high phytophagous nematode numbers.