Effects of seasonal grazing, drought, fire, and carbon enrichment on soil microarthropods in a desert grassland

This study was designed to test hypotheses about the combined effects of short-term, seasonal grazing with seasonal drought, fire, and carbon enrichment on soil microarthropod communities in a Chihuahuan Desert grassland. The study was conducted in eighteen 0.5 ha plots following three consecutive years of treatment: six plots intensively grazed in summer, six in winter, and six not grazed. There was no difference in perennial grass cover on the summer-grazed and winter-grazed plots. Intensive seasonal grazing had no effect on the abundance and community composition of soil microarthropods. Within each plot there were six subplots: summer rain-out, winter rain-out, burned, glucose amendment, rain-out control and burn-glucose control. Fire and carbon enrichment had no significant effect on soil microarthropod abundance or community composition. The average number of microarthropods ranged from 8915 ± 1422 m ^-2 in the ungrazed, unburned plots to 7175 ± 1232 m ^-2 in the winter-grazed, unburned plots. Microarthropod densities in the glucose-amended plots were 8917 ± 4902 m ^-2 in the winter-grazed plots and 10,731 ± 863 m ^-2 in the glucose-amended, summer-grazed subplots. The prostigamatid mite, Tydeus sp., was the most abundant microarthropod taxon in all treatment plots.