Arthropod Response to Fire in a Chihuahuan Desert Grassland in Texas

Abstract

A winter prescribed burn in a Chihuahuan Desert grassland was studied for its effect on arthropod abundance and first-year recovery at the Elephant Mountain Wildlife Management Area, Brewster County, Texas.  The fire was initiated in early February 1997, resulting in a cool, discontinuous burn.  Arthropods were collected pre- and postburn from January-December on unburned control and burned treatment sites using a D-vac suction machine.  Insects were identified primarily to the order level, counted, dried, and weighed, whereas arachnids were grouped, counted, dried, and weighed.  Preburn vegetation was comparable between treatments, and no differences were detected for insect and arachnid counts and biomass (P ≤ 0.05).  Postburn, herbaceous cover was reduced significantly, and count differences were found in arachnids and for nine of 15 insect orders (P ≤ 0.05).  Biomass differed (P ≤ 0.05) for the Hymenoptera, Orthoptera, and Psocodea.  The fire did not appear to impact diversity and evenness of arthropod populations.  Postburn arachnid and insect populations tracked vegetation changes and were highest at peak growing season following seasonal rains.  Arthropod abundance and biomass were equal at the end of the first postfire season, and trends indicated that populations would recover within two to three years.