Overgrazing leads to soil cracking that later triggers the severe degradation of alpine meadows on the Tibetan Plateau

Abstract Soil cracking is an important process and feature of degradation in terrestrial ecosystems. However, the patterns and causes of cracks related to alpine rangeland overgrazing have not been reported. In this study, we used a multiscale approach to investigate the distribution of soil‐cracking areas at a landscape scale (217 survey sites), selected the grazing‐induced parameter that was closely related to the cracks at a small scale (2013–2017), and evaluated the water infiltration due to mosaic cracking at a microscale. The results showed that cracks only formed in the alpine meadow after overstocking. Soil compaction and water content explained 89.0% of the total variance in the crack characteristics, and soil compaction was closely related to cracking. The initial infiltration rate and steady infiltration rate of the healed cracks were significantly higher than those in the raised areas in the centre of the mosaic crack patches ( p < .001). We propose a new model of alpine meadow degradation considering the cracking phenomenon due to overgrazing and provide key and easy‐to‐measure indicators to prevent overgrazing and cracking: a residual biomass greater than 65 g m −2 and a height greater than 6 cm, and the soil compaction should be lower than 1,044.26 ± 188.88 kPa. These safeguard thresholds warn rangeland managers to reduce the stocking rate or improve grazing management. We suggest that the cracking stage of alpine rangelands is the most critical turning point in the process of rangeland degradation and that rangeland managers should pay more attention to crack phenomena to prevent severe degradation.