Effects of Patchiness on Soil Properties and Degradation of Alpine Meadow on the Qinghai-Tibetan Plateau

Patchiness is known to affect soil water and soil temperature, and may trigger or accelerate alpine meadow degradation. However, there is a lack of direct evidence concerning the role of the size and type of patches on soil conditions. Here, we estimated the effects of typical patch types on the critical factors of soil water and soil temperature through an in situ survey and then analyzed the potential impacts of patchiness on alpine meadow degradation. The results showed that (1) the soil water storage (SWS) of typical patch types was remarkably different, and vegetation patches had higher SWS than bare patches; (2) with abundant precipitation, the isolated vegetation patch (IV) had higher SWS than the original vegetation patch (OV), accompanied by a decrease in the SWS of the surrounding medium bare patch (MP); (3) patchiness significantly altered the surface soil temperature, with the IV having the highest soil temperature (ST), followed by the OV and bare patches; and (4) the maximum mean value of evapotranspiration was observed in IV (3.85 mm/day), about 12.78% and 46.66% higher than in the bare patches and OV. Our findings indicated that patchiness intensified the heterogeneity of soil water and soil temperature. The IV could absorb soil water from surrounding MP for excessive evapotranspiration through constant high ST, potentially inducing or aggravating degradation. Increasing the connectivity of IV and preventing the transition of OV to IV is important for the stability and restoration of alpine meadow.