Data set ID:
**We addressed the question, are microarthropod assemblages present in soils throughout the rhizosphere of a deep-rooted desert plant?
If microarthropods are present, what is the taxonomic and functional structure of that assemblage? The presence of a generalist microarthropod assemblage would suggest functional relationships among deep soil biota similar to the relationships documented in shallow soils. Data set consists of microarthropods and microarthropod numbers found at different soil depths associated with four mesquite ecosystems (playa, coppice dune, arroyo, and grassland).
Field and electronic data sheets
*Undisturbed soil cores from the rooting zone of three trees in each ecosystem were removed using a split steel, continuous sampling tube, 1.56 m long with 6.5 cm i.d. This coring device, mounted on a truck, was modified from Kelley et al. (1947). The split-tube bit fits into an outer, rotating auger bit that served as a continuous casing to prevent cave-in. As the outer bit cut through the soil, the inner, nonrotating bit was pressed into the soil. Cores were collected at the edge of the mesquite canopy. The core retainer and the two halves of the split sampling tube were cleaned of all residual soil. Their interior surface was flame sterilized with 95% ethanol before being put together for sampling. Soil samples were removed from the surface 1 m of soil in 0.5 m increments, and thereafter in 1 m increments. Flame sterilized trowels and spatulas were used to replace each depth increment into a clean plastic bag. These were put into icecooled chests, and transported to the Univ. of California, Riverside, where they were subdivided for analysis. Drilling depth for each core was determined by either the absence of roots in two consecutive 1.56 m sampling tube lengths, or the presence of coarse, dry loose soil that could not be retained in the tube. The number of cores (three per ecosystem per sampling) collected was limited by the expense of obtaining the specialized drilling equipment used in this study. Sampling dates at New Mexico were in January 1986, the midpoint of the dormant season; late May 1986, during peak growth; and early October 1986 following the summer rains. The grassland site was not sampled on the Jan-Feb drillings. **A composite sample for microarthropods was taken from each core, comprising three ~300-g subsamples from the upper, mid, and lower part of the core. The composite samples were placed in plastic bags and store in insulated containers until taken to the laboratory for processing. Microarthropods were extracted from 500-g sub-samples in modified Tullgren funnels (Santos et al. 1981). The samples were also subjected to several flotation techniques which were compared to teh Tullgren funnel techniques (Edwards and Fletcher 1971). However, the flotation techniques were less efficient than the funnel extractions and were not continued.
*Four mesquite ecosystems were studied: playa, coppice dune, arroyo, and grassland. An ecosystem dominated by the non-legume, Larrea tridentata, and lacking mesquite was included as a reference. The arroyo, grassland, Larrea and a playa site were loacated on the NSF Jornada Long Term Ecological Research (LTER) site situated 40 km north of Las Cruces, NM, in the northern Chihuahuan desert. A coppice mesquite dune site was located on the adjacent USDA Jornada Experimental Range about 15 km from the above sites.
Five times (January, February, May, September, October)