Microclimate response of soil to plateau pika's disturbance in the northeast Qinghai-Tibet Plateau

The plateau pika (Ochotona curzoniae) is one of the main native soil faunas on the Qinghai-Tibet Plateau and plays a key role in the terrestrial ecosystem there. To understand how and why the soil microclimate changes after the plateau pika's disturbance, this study measured soil, vegetation, hydrologic and thermal properties and investigated soil moisture and soil temperature dynamics from 2014 to 2015 at the plot scale of four types of land surface: original grassland, new mound, old mound and bald patch. Our results showed that the average coefficients of surface runoff of original grassland, new mound, old mound and bald patch were 0.6, 3.0, 4.3 and 10.0%, respectively (P<0.05). Evapotranspiration was largest for original grassland, especially under wet conditions, and was similar among the other three types of land surface during the growing season (P<0.01). During varying precipitation events, the soil moisture content of new mound increased first, followed by old mound, original grassland and bald patch. Meanwhile, the increasing magnitude of soil moisture content had the same order. At the seasonal timescale, soil moisture content at 5-cm depth was largest for old mound and smallest for bald patch (P<0.01). The mean daily soil temperature at 5-cm depth of new mound was approximately 0.8 degrees C higher than that of old mound (P<0.01) because of the smaller land surface reflectance of the former. The daily range of soil temperature at 5-cm depth of original grassland and bald patch was about 2.7 and 4.7 degrees C higher than the average value of new and old mounds, respectively, because of the larger soil thermal conductivity of the former two. A conceptual framework is suggested in this study to synthesize the evolution of soil microclimate under disturbance by the plateau pika. Overall, results indicated that new and old mounds accelerate soil hydrologic processes and have a better soil temperature buffer.