干旱区生态环境知识资源中心

In 1997 the USDA Agriculture Research Service, Hydrology Laboratory began collecting remotely sensed data on semiarid rangelands of the Sevilleta Long-Term Ecological Research (LTER) site in central New Mexico USA. Ground, aircraft, and satellite data are being used to monitor changes in the vegetative, physical, thermal, and radiometric properties of two ecosystems (grass and shrub) typical of the Sevilleta rangeland. This is a companion project to JORNEX [1] at the USDA ARS Jomada Experimental Range in southern New Mexico where similar measurements have been made since 1995. Remote sensing campaigns have been made at Sevilleta in May/June and September/October of 1997, 1998, 1999 and 2000. Data from the different platforms are used to evaluate landscape properties at a range of scales. Radiance measured at ground and aircraft platforms was 3 to 5% higher at the shrub site when compared with the grass site. Temperatures of the landscape surface were 3 to 5 degreesC higher at the shrub when compared with the grass site by 1 pm local time. These differences could have significant effects on the energy and water balances of the Sevilleta rangelands if shrubs continue to expand at the expense of the grassland.