The contribution of plateau pika disturbance and erosion on patchy alpine grassland soil on the Qinghai-Tibetan Plateau: Implications for grassland restoration

Patchy alpine grassland with soil excavated by plateau pika (Ochotona curzoniae) and with bald patches is common on the Qinghai-Tibetan Plateau (QTP) where desertification has developed rapidly over the last few decades. This may have significant effects on alpine grassland restoration, by changing soil properties. In this study, the contribution of plateau pika disturbance and erosion on patchy alpine grassland soil, were examined by classifying the surface of the patchy grassland into 4 types vegetation patch, new pika pile, old pika pile and bald patch and comparing (t)he gravel content of the top layer of soil, soil moisture, soil hardness, soil organic carbon (SOC), and soil total nitrogen (TN) among them in the four study areas with different climatic conditions, altitudes, and grassland types on the QTP. We also analyzed the relationship between the amount of soil surface gravel and the Green Fractional Vegetation Cover (GFVC) using aerial photos. The results showed that (1) gravel content was significantly greater in bald patches and pika piles than in vegetation patches (p < 0.05); (2) soil moisture, hardness, SOC and TN were the highest in vegetation patches, and significantly lower in pika piles than in vegetation patches (p < 0.05); (3) GFVC was negatively and linearly correlated with the amount of soil surface gravel, with the amount of soil surface gravel in non-vegetation patches significantly greater than in vegetation patches (p < 0.001). Our results suggested that pika burrowing activity may increase the gravel content of the top layer of soil and decrease soil moisture, hardness, SOC and TN, which can increase soil erosion and hinder vegetation restoration. (C) 2017 Elsevier B.V. All rights reserved.