Long-term variation in soil temperature of the Mojave Desert, southwestern USA

Soil temperature, an important climatic variable, regulates ecosystem processes, especially those occurring below ground, and is an indicator on how changing global climate affects regional ecosystems. We examined the correlation between the mean annual soil temperature (MAST) and climatic factors in the Mojave Desert and built an empirical model to predict changes of MAST from mean annual air temperature (MAAT) and annual precipitation (P), such that MAST (degrees C) = 6.84 + 0.925 x MAAT (degrees C) - 0.0031 x P (mm yr(-1)). Based on climate records from 1904 to 2008, the mean annual air temperature in the Mojave Desert has risen by approximately 2 degrees C. The annual precipitation pattern showed distinctive wet and dry cycles. However, the outcomes of linear regression showed that the annual precipitation did not significantly change over the time. We back-casted the mean annual soil temperature of the past century, which showed regional warming at a rate of 0.204 degrees C every 10 yr.