Vertical Distribution of Soil-Inhabiting Microarthropods in an Agricultural Habitat in California 1

Abstract

Vertical distribution patterns of soil-inhabiting microarthropods in an agricultural region of the San Joaquin Valley, CA, are described. Eight samples, each 122 cm deep and with surface areas of 426.5 cm 2 , yielded 7727 specimens with 33% from the upper 15.2 cm of the profile and 24% from the 15.2–30.5 cm depth. About 30% were collected from below 46 cm. An additional 16 samples, 4 extending to depths of ca. 250 cm and 12 to ca. 311 cm, and each encompassing a surface area of 426.5 cm 2 , yielded 5904 specimens. Of these, 51% was collected from the upper 15.2 cm and 21.5% from the 15.2–30.5 cm depth. About 20% of the fauna was collected from below 55 cm, and 1.8% or 109 specimens were obtained from depths below 200 cm. Distribution data are presented for the total microarthropod fauna as well as for major component taxa including Acarina, Collembola, Psocoptera, Pauropoda, Protura, Symphyla, larvae of Coleoptera and Diptera, and Japygidae (Diplura). Results are discussed in relation to sampling requirements.