No abstract

by General George S. Patton, Jr. for the purpose of training tank forces in desert warfare techniques. The DTC encompassed 47,105 km2 (17,500 mi2) of arid lands in California, Nevada, and Arizona, including parts of the Mojave, Great Basin, and Sonoran Deserts (Fig. 1). Training operations were conducted from twelve main base camps, each occupied by as many as 15,000 soldiers at any given time. When the camps were abandoned in 1944 most physical structures such as maintenance sheds, water tanks, etc., were removed, but no apparent measures were taken to rehabilitate the land. Environmental changes caused by the military activities remain evident today at the sites of ten former camps (Fig. 2); two camp sites have been plowed for agricultural use. Our study examines the degree to which soils, surface hydrologic characteristics, and vegetation have recovered by natural processes in the 40 years since the camps were abandoned. Disturbances ranging from vegetation clearing and soil trampling in tent areas to road grading and subsequent heavy vehicle usage were studied to assess the importance of disturbance thresholds in recovery. The remoteness of the camps from urban centers has kept postabandonment human impacts to a minimum except on the most easily accessible roads. The camps studied are on similar terrain, but have somewhat varying soil and vegetative characteristics. Variable response to the same types and intensities of use have important management implications that will be discussed in a future report. Previous Work Previous studies of soil and vegetation recovery of arid lands disturbed by military maneuvers are few in number (Wilshire and Nakata, 1976; Lathrop, 1980; Prose, 1985). Studies of recovery of arid lands in the southwestern U.S. from other similar disturbances are, however, relevant. These include studies of raining townsites abandoned as much as 70 years ago (Webb and Wilshire, 1980; Webb and others, in prep.), and studies of utility corridor disturbances (for example, Johnson and others, 1974; Vasek and others, 1975a, b; Brum and others, 1983; Kay and Graves, 1980a, b). These studies show that natural desert systems can remain significantly disrupted for long periods after even relatively minor levels of impact, and that reclamation of highly disturbed lands is difficult. SETTING The five base-camps are: 1) Camp Ibis, 2) 'old Camp Clipper, 3) 'new' Camp Clipper, 4) Camp Iron Mountain, and 5) Camp Granite. They are all located in the eastern part of the Mojave Desert in California on lands managed by the U.S. Bureau of Land Management (BLM) (Fig. 3). The elevations of the camps range from 427 m at Camp Iron Mountain to 570 m at Camp Clipper. Average yearly rainfall in Needles, Ca., while quite variable, is 10.3 cm. Average January and July temperatures are 12.0 C and 35.2 C, respectively (weather data collected at Needles, Ca. airport from 1940 through 1980). The camps were designed and constructed similarly, and their areas vary from approximately 2500 acres at Camp Iron Mountain to 7000 acres...