Pitfall traps are used to collect and identify ground-dwelling arthropods at each of the 15 plant NPP sites established in 1989 during LTER II. Objectives. Desertification is hypothesized to have altered the spatial and temporal availability of resources required by the biota. Results of desertification on the Jornada include changes to shrub dominated communities and major soil changes.
We hypothesize that these shifts in vegetation have changed resources temporally for many of the consumers. If grassland systems respond to rainfall without significant lags, but shrub systems do not, then consumer species should reflect these differences. In addition, shifts from grassland to shrubland results in greater structural heterogeneity of the habitats. We have hypothesized that consumer populations, diversity, and densities of some consumers will be higher in grasslands than in shrublands. Diversity and/or densities are hypothesized to be related to the NPP of the sites. Data will be collected for the duration of the LTER program in order to provide data to test these hypotheses.