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ABSTRACT
Cicada nymphs (Homoptera: Cicadidae) are soil-dwelling insects that form cylindrical back-filled burrows. These unique burrow features persist in soils for thousands of years and are common in soil descriptions in and and semiarid regions of the inland Pacific Northwest (PNW). We examined the burrowing depth of live cicada nymphs and found that burrowing is concentrated in the upper 50 cm of soil. This depth may be used to distinguish between contemporary and relict burrows in soil profiles developed in transported parent materials, and can serve as a means of identifying paleosols from observations of burrows at greater depths. We then searched all official soil series descriptions within the USDA-NRCS State Soil Geographic (STATSGO) data base for cicada-burrowed horizons below the active burrowing depth to identify buried paleosols. We suggest that evidence of cicada nymph activity can be used to assess soil-stratigraphic relationships at broad scales in the inland PNW.
Abbreviations: OSDs, official soil series descriptions; PNW, Pacific Northwest.
SOIL-DWELLING FAUNA perform many important activities such as mounding, mixing, forming voids, backfilling voids, and forming and destroying structural units. These activities influence erosion, nutrient cycling, and the movement of water and air (Hole, 1981). There is widespread evidence of cicada nymph activity in soils of the and and semiarid regions of the inland PNW (Hugie and Passey, 1963; USDA-NRCS Soil Survey Division, 1998; O'Geen and Busacca, 2001). Relatively little work, however, has focused on the pedologic significance of these features and their implications for better understanding of landscape evolution.
A cicada nymph refers to the immature life stage of Homoptera: Cicadidae. In the inland PNW, cicada nymphs develop below ground for 6 to 9 yr, forming unique cylindrical, back-filled krotovinas that are 1 to 2 cm in diameter. These features exhibit a crescentic-- packing pattern in thin section or wind-etched exposures (O'Geen and Busacca, 2001). Cicada burrows were described as cylindrical blocky soil structure in desert soils of the northern Great Basin by Hugie and Passey (1963). Cylindrical blocky structure is seldom used in OSDs in the PNW, even though cicada populations are large (O'Geen, 1998). A variety of other descriptors, however, are used to document cicada activity in OSDs (USDA-NRCS Soil Survey Division, 1998). These include cylindrical nodules, rounded krotovinas, and...