Divergent successions increase soil water recharge capacity accompanied by higher evapotranspiration in alpine meadow

Alpine meadow ecosystem are undergoing the divergent successions under the influence of global climate warming and overgrazing by herbivores, which may profoundly impact the ecohydrology function of alpine meadow ecosystem. However, few studies reported the effects of the divergent successions on ecohydrological process of alpine meadow. Here, we report an in situ experiment to examine the effects of the divergent successions on soil pore structure, infiltration rate and evapotranspiration of the two types of divergent-succession meadows (the shrub-encroached meadow and the severely degraded meadow), compared to the normal alpine meadow. Results showed that both the shrub-encroached meadow and the severely degraded meadow significantly reduced the dominant Kobresia spp. (Cyperaceae family) coverage, soil compactness, and belowground biomass, but significantly increased soil non-capillary porosity (P < 0.05) compared to the normal alpine meadow. Soil infiltration rate was significantly negatively correlated with Kobresia spp. coverage, soil compactness and belowground biomass, while significantly positively correlated with soil non-capillary porosity (P < 0.05). Therefore, the shrub-encroached meadow and the severely degraded meadow increased soil infiltration rates not only by reducing the dominated Kobresia spp. (Cyperaceae family) coverage and belowground biomass, but also by increasing soil non-capillary porosity. Compared with the normal alpine meadow, the cumulative infiltration and evapotranspiration increased by 245.25% and 45.19% in the shrub-encroached meadows, and increased by 208.23% and 29.95% in the severely degraded meadow. However, short-term grazing exclusion presented little effect on soil infiltration rate in alpine meadows. Overall, the divergent successions of alpine meadows had a greater impact on soil water replenishment and evapotranspiration than the short-term grazing exclusion. These findings can help to better understand the impacts of the divergent community succession on the ecohydrological process in alpine grassland ecosystem.