Remote sensing documentation of historic rangeland remediation treatments in southern New Mexico

The Jornada Experimental Range and the New Mexico State University Chihuahuan Desert Rangeland Research Center are fruitful areas to study the long-term effects of rangeland remediation treatments which started in the 1930s. A number of diverse manipulations were completed under the direction of federal agency and university scientists, and abundant remote sensing imagery is available to assist in relocating the treatments and evaluating their success. This is particularly important because few of the treatments were maintained following the loss of scientific personnel coinciding with the start of World War II, and most records of Civilian Conservation Corps scientific work were lost with the disbanding of the agency in 1942. Aerial photography, which was systematically used to image the United States beginning in the 1930s, can be used to identify types of treatments, measure areal coverage, estimate longevity, and help plan locations for new experiments. No long-lasting vegetation response could be determined for contour terraces, brush water spreaders, strips grubbed free of shrubs (despite the fact that these strips have remained visible for 65 years), and mechanical rootplowing and seeding. Distinct positive, long-term vegetation responses could be seen in aerial photos for water retention dikes, certain fenced exclosures, and some boundaries where different land management practices meet. It appears from both aerial photos and existing conventional records that experimental manipulation of rangelands has often been ineffective on the landscape scale because treatments are not performed over large enough contiguous areas and hydrological and ecological processes overwhelm the treatments. In addition, treatments are not maintained over time, treatment evaluation periods are sometimes too short, multi-purpose treatments are not used to maximize effects, and treatments are often not located in appropriate sites.