|Data by Research Category|
Dataset: Arthropod Trophic Group Composition Data
*We conducted a field study to test the hypothesis that creosotebush (Larrea tridentata) shrubs growing in naturally nutrient-rich sites had better quality foliage and supported greater populations of foliage arthropods than shrubs growing in nutrient-poor sites. This is data for foliage arthropods sampled from LVAR creosotebush shrubs. Sampling was done in April of 1985 and 1986. Shrubs were sampled from 5 separate sites designated A-E. 10 shrubs of 3 different types, R=random, H=high quality, L=low quality were sampled at each site. Total numbers of taxa and individuals of each major trophic group, herbivores, predators, omnivores, from each of the 30 shrubs/site are listed.
*The plots, approximately 1 ha each and designated A through E, were selected randomly from a 1.0 by 0.5 km area within a creosotbush stand situated on a gradually sloping east-facing alluvial slope below the Dona Ana mountains. Creosotebush was the dominant shrub in the area, associated with less abundant subshrubs and a variety of small annual forbs. (These five plots were randomly located between Whitford's upper storage trailer and old LTWN plots.)
*Thirty shrub were selected for sampling from each of the five plots. To test for differences in foliage characteristics and arthropod densities between nutrient-rich and nutrient-poor shrubs, we selected 10 high nutrient shrubs and 10 low nutrient shrubs in each plot. Shrub nutrient status was determined on the basis of the relative size of leaf litter accumulations on the ground beneath shrub canopies. Ten shrubs were selected at random from each plot prior to selecting different type shrubs, to provide us with measures of natural variablity of shrub characteristics and foliage arthropods. Foliage arthropods were sampled form each of the 150 shrubs on May 2, 1986. Three branches were selected randomly from each shrub and shaken into an insect sweep net. A consistent-sized branch of 50 cm in length was sampled each time to provide a standardized sample from each shrub, regardless of shrub size. The contents of three branch samples per shrub were combined into one zip-lock plastic storage bag and taken to the lab, frozen, and later sorted. Field sampling was done in the morning at sunrise. As in our previous work, we classified arthropods into trophic groups, or guilds of taxa that had simliar morphological feeding mechanisms and fed on similar food resources.
once per year