IMPACTS OF LAND DEGRADATION ON HISTORICAL TEMPERATURE RECORDS FROM THE SONORAN DESERT

dPrevious research revealed that severe overgrazing and resultant land degradation in the semiarid areas of northern Mexico created signific antly higher temperatures in the border area. In this investigation, t he temperature and precipitation records from ten 'homogeneous' statio ns are identified in the arid and hyperarid areas of northwest Sonora and are compared with the records from ten stations in southwestern Ar izona. Our data show that the Mexican stations are again consistently warmer than the Arizona stations when statistical controls are applied to correct for the linear or nonlinear effects of latitude and/or ele vation. The stations in Sonora warm at a statistically significantly f aster pace than the stations in Arizona during the study period. Furth ermore, and consistent with other dryland areas undergoing land degrad ation, the stations in Sonora reveal a significant increase in the diu rnal temperature range during the summer season. Local precipitation r educes the temperature differential between nations on the time scale of days, but enhances the differential on the time scale of months and seasons. Among other findings, the results show how land degradation in dryland areas appears to influence local historical temperature rec ords.