|Whitford, Walt - NEW MEXICO STATE UNIV|
Submitted to: Biology and Fertility of Soils
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 1, 1997
Publication Date: April 1, 1999
Citation: Whitford, W.G., Sobhy, H.M. Effects of repeated drought on soil microarthropod communities in the northern Chihuahuan Desert. Biology and Fertility of Soils. 1999. v. 28(2). p. 117-120. Interpretive Summary: The dominance of shrubs in the Chihuahuan Desert has resulted in the redistribution of soil water and nutrients to small resource islands under shrub canopies. Soil microarthropods have been shown to be most abundant in these below-canopy soils. In order to test the effects of drought on soil microarthropods, study plots were established centered around creosote bushes and on mesquite coppice dunes. Nine plots were covered by greenhouse plastic roofing during the rainy season and received no natural rainfall. An additional nine plots were left uncovered and did receive natural rainfall. Soil samples collected from each plot over a 2-year period showed that drought affects both the abundance and types of microarthropods found under shrub canopies. However, the magnitude of the effect is related to several other factors, such as differences in the stability of the soil surface, litter accumulation, and microclimate associated with the shrubs.
Technical Abstract: Soil microarthropods were sampled in plots centered on creosotebushes (Larrea tridentata) and in plots centered on mesquite (Prosopis glandulosa) coppice dunes. Nine plots in each area were covered by rain-out shelters with greenhouse plastic roofs which excluded natural rainfall and nine plots received natural rainfall. There were differences in the abundance of several mite taxa in soils from the mesquite coppice dune plots. Some taxa (Stigmaeidae, Nanorchestidae and Entomobryidae) occurred in significantly lower numbers in the soils of the drought plots. Other taxa (Tarsonemidae and Cunaxidae) were more abundant in the drought plots in the mesquite coppice dunes. There were no significant differences in the abundance of any of the dominant taxa of soil microarthropods in the drought and control plots centered on creosotebush. In the creosotebush habitat, there were significantly fewer Prostigmata in the plots exposed to drought. In an area with both creosotebush and mesquire, there were no significant differences in microarthropod population responses to drought and in recovery from drought. The differences in responses of soil microarthropods to drought in creosotebush and mesquite habitats are attributed to the differences in soil stability, litter accumulations, and microclimate associated with the shrubs.