ARTHROPODS, PLANTS AND TRANSMISSION-LINES IN ARIZONA - COMMUNITY DYNAMICS DURING SECONDARY SUCCESSION IN A PINYON-JUNIPER CHAPARRAL HABITAT

In a pinyon-juniper chaparral habitat in north central Arizona arthropod numbers were reduced for only .apprx. 2 yr after disturbance caused by the construction of high voltage powerlines. Arthropod densities increased to a level equal to or surpassing the control area. Significant reduction occurred in the Acarina, Melyridae and Coccoidea. The number of taxa occurring on the study plot was variable and minimally affected by construction. Arthropod community similarity appears to be related to total plant cover and not exclusively to the presence of a particular plant species. Ecological similarity of new plant colonizers to former inhabitants may also play a important role in the recovery of arthropods. Construction caused a great reduction in perennial grasses, a delayed reduction in perennial herbs and in general an increase in annual herbs. Shrub live oak, a colonizer of disturbed areas, was important in the reestablishment of arthropods on the disturbed plot because it provided a vertical vegetational component and a greater amount of cover. Little site preparation and thus little disturbance was necessary for construction of a transmission tower at this locality, which probably aided in rapid recolonization of plants and arthropods. Greater numbers of arthropod-plant correlations may be the result of reduced foodweb complexity on the disturbed area, with a disruption of the ability of secondary, tertiary and possibly quaternary arthropod consumers to regulate arthropod primary consumer populations.