Department of Environmental Sciences
University of Virginia
Effect of shrub encroachment on local climate
Shrub encroachment is a global ecological phenomenon that involves a decrease in grass cover along with an increase in density and coverage of woody species in grassland. In Southwestern U.S. deserts, such a dramatic vegetation transition has been occurring since the mid-19th century and has resulted in loss of ecosystem services. This shift in vegetation cover affects the mass and energy exchange between the land surface and the atmosphere and can therefore impact local climate. In particular, nighttime warming (> 2 degrees Celsius on average) has been observed in the shrub dominated landscapes near the encroaching front in grassland in winter months, which is equivalent to a change in regional climate over century scale in central New Mexico. This nighttime warming favors the successful establishment and survival of the shrub species, Larrea tridentata, and therefore is possible to facilitate further shrub encroachment. Using field observations and numerical modelings, we investigated the structure, the evolution, and the underlying mechanism of the shrub encroachment-induced nighttime warming as well as its application.