ABSTRACT
Armadillidium vulgare is the only isopod in the riparian forest (or 'bosque') at the Rio Grande Nature Center in Albuquerque, New Mexico. The forest there is dominated by native cottonwood, Populus fremontii var. wislizeni, and Russian olive, Eleagnus angustifolia. We tested whether leaf litter of these two tree species influences the isopod's microhabitat selection in this relatively simple setting by pitfall trapping during the warm season over a period of 4 years. We evaluated the quality of leaf litter as food by studying growth and survival of Armadillidium fed cottonwood and/or Russian olive leaf litter. ANOVAs of field results indicated that tree species did not influence the distribution of isopods beneath the canopies of four pairs of trees of each species. However, significantly larger catches occurred under trees, regardless of their species, located in clay loam soils than under trees located in sandy loam soils. ANOVAs of laboratory feeding tests showed that Armadillidium grew and survived significantly better on Russian olive and mixed species leaf litter than it did on cottonwood leaf litter. We conclude that the distribution of leaf litter under the two tree species at the Nature Center does not influence microhabitat selection by Armadillidium.
