Soil and Plant Recovery After Historic Military Disturbances in the Sonoran Desert,USA

Abstract

Military training exercises in desert areas have resulted in various types of disturbance through time. Camp Laguna, located on the U.S. Army Yuma Proving Ground in southwestern Arizona, served as a military base camp during World War II. The camp exhibits a variety of historic disturbances, including vehicle traffic (motor pool) and foot traffic (tent rows, commons, and footpaths). The extent of soil and plant recovery that has occurred at Camp Laguna in the 56 years since abandonment was assessed by comparing sites with historic disturbance to an apparently undisturbed control site. Vegetative recovery was determined by measuring perennial plant foliar cover and density. Soil was characterized by maximum penetration depth measurements and presence of biological soil crusts. Soil samples were collected and analyzed for inorganic and organic carbon and total nitrogen content. The tent city, disturbed primarily by foot traffic, did not show full recovery of vegetation and biological soil crust to predisturbance conditions. The slow recovery may be attributable to grading that removed topsoil and seed sources when the camp was established. In contrast, most plant species at the motor pool exhibited higher density and greater foliar cover than was found at the control site. This may be the result of a compacted soil layer that enhanced soil-water relations of the upper horizon of the sandy soil and provided fine plant roots with a greater amount of moisture.