Arthropod Response to Fire in a Chihuahuan Desert Grassland in Texas

Abstract

A Chihuahuan Desert grassland winter prescribed burn was studied for its effect on first-year arthropod
abundance, biomass, composition, and recovery at the Elephant Mountain Wildlife Management Area,
Brewster County, Texas. The burn was conducted in early February 1997, resulting in a cool, discontinuous
fire. Arthropods were collected pre- and postburn from January-December on unburned control and burned
treatment sites with suction collection. Insects were identified to the familial level, pooled at the ordinal level;
counted, dried, and weighed, whereas arachnids were grouped, counted, dried, and weighed. Preburn
vegetation was comparable between treatments, and no differences were found for insect and arachnid
abundance and biomass (P ≤ 0.05). Postburn, herbaceous cover was reduced significantly, and abundance
differences were found in arachnids and for nine of 15 insect orders (P ≤ 0.05). Biomass at the ordinal level
differed for the Hymenoptera, Orthoptera, and Psocodea (P ≤ 0.05). The fire did not strongly impact diversity
and evenness of arthropod populations although composition differed. Postburn arthropod abundance and
biomass tracked vegetation changes over the ensuing year and were highest at peak growing season following
monsoonal rains. Arthropod abundance, biomass, and diversity between treatments were comparable at the
end of the first postfire year, and trends indicated that population abundance was approaching pre-burn levels,
although composition remained different.