Mattic epipedon fragmentation strengthened the soil infiltration capacity of a hillside alpine meadow on the Qinghai-Tibetan Plateau

Degradation of hillside alpine meadow ecosystems is a widespread problem that usually results in the fragmentation of the mattic epipedon (ME). The mattic epipedon plays a well-known role in the hydrological cycle of alpine ecosystems due to its high water-holding capacity. However, little is known about how ME fragmentation alters soil infiltrability-a key soil property that influences runoff and erosion processes as well as soil moisture dynamics. To address this issue, we contrasted the infiltration rates and soil and plant characteristics of preserved meadow patches (with full ME) and patches at two stages of ME fragmentation, namely, half ME and without ME. Our results showed that mattic epipedon fragmentation reduced aboveground plant biomass (mainly of sedges) by 58.6-65.6 g m(-2) and root biomass by 5,643-10,054 g m(-2). Soil compressive strength (11.6 kg cm(-2)) and total soil porosity (52%) of fragmented meadow patches without ME were significantly lower than in those with half (17.9 cm(-2) and 62%, respectively) or full ME (31.7 cm(-2) and 62.5%, respectively). In contrast, non-capillary porosity and aggregate stability slightly increased with fragmentation and were highest at patches without ME. Importantly, soil infiltration rates in hillside alpine meadows greatly increased as a result of mattic epipedon fragmentation. Initial infiltration rates were approximately 10 and 20 times higher at patches with half ME and without ME (177 mm h(-1) and 326 mm h(-1), respectively) than at patches with the full ME (17 mm h(-1)). Moreover, steady-state infiltration rates were approximately 6 and 9 times higher at patches with half ME and without ME (60 mm h(-1) and 88 mm h(-1), respectively) than at patches with the full ME (17 mm h(-1)). Overall, mattic epipedon fragmentation improved soil infiltrability by changing the soil and plant characteristics. These findings suggest that mattic epipedon fragmentation will lower runoff maintenance and have drastic effects on the water provisioning function of hillside alpine meadows on the Qinghai-Tibetan Plateau.

Automated summary

Degradation of hillside alpine meadow ecosystems leads to fragmentation of the mattic epipedon (ME) and alters soil infiltrability. ME fragmentation reduces plant biomass and root biomass, and decreases soil compressive strength and total soil porosity. However, non-capillary porosity and aggregate stability slightly increase with fragmentation. Importantly, soil infiltration rates greatly increase as a result of ME fragmentation. Overall, ME fragmentation improves soil infiltrability and has drastic effects on water provisioning function in hillside alpine meadows.