Response of soil water content and temperature to rangeland desertification in an alpine region with seasonally frozen soil and plateau pika (Ochotona curzoniae) burrows

Abstract

Variations in soil temperature and water content are important indicators of land desertification, and play a significant role in ecological environments in desert regions, thus could help in establishing effective measures to combat desertification. In this study, the changing characteristics of plateau pika (Ochotona curzoniae) burrows, soil water content, and temperature under three levels of desertification (slight, medium, and severe) were assessed. The number of pika burrows was investigated in quadrats with areas of 400 m2. The areas of pika burrow mounds were obtained by taking pictures vertically and measured by AutoCAD, 2007. Soil temperature and water content were monitored by soil temperature and moisture smart sensors installed at depths of 5, 10, 20, and 50 cm. Data were recorded at 10-min intervals by Hobo Data Loggers. The greatest number of pika burrows and the greatest area of pika burrow mounds were found in the medium desertified site, followed by the slightly desertified site, and no pika burrows were found in the severely desertified site. With increasing desertification degree, vegetation coverage and soil water content decreased. The onset dates of soil freeze and thaw in the severely desertified site were both earlier, and the duration of freezing days was shorter, than those in the slightly desertified site at each soil depth. The medium desertified site showed the earliest onset of soil freeze, latest onset of soil thaw, and longest duration of soil freezing days. The annual mean soil temperature was highest in the severely desertified site within 50-cm soil depth of the ground surface due to the loss of vegetation coverage and soil water content, and lowest in the medium desertified site within 20-cm soil depth due to the cooling effects of pika burrows. Desertification resulted in the loss of vegetation cover and reduced soil water content, leading to higher soil temperatures. However, the cooling effects of pika burrows could reduce soil temperatures. These findings provide insights into the impacts of rangeland desertification on soil environments, thereby helping in establishing effective measures to combat desertification.