Effects of grazing regime on vegetation structure, productivity, soil quality, carbon and nitrogen storage of alpine meadow on the Qinghai-Tibetan Plateau

摘要

Grazing regime has an important effect on grassland ecosystem. however, the mechanisms how alpine meadow vegetation, soil quality responds to this management regime remain unclear. A short term field experiment (4-5 years) was conducted to quantify the impact of different grazing management regimes (fencing (NG), grazing rest in growing stage (RG), traditional grazing (TG) and continued grazing (CG)) on alpine meadow of the Qinghai-Tibet Plateau (QTP) and investigated vegetation structure, soil physicochemical properties, C and N storage regarding grazing regime, during two consecutive years: 2014 and 2015. Our results revealed that the above-, below-ground and litter biomass, plant coverage in NG were significantly higher than those in RG, TG and CG in 2014 and 2015. The NG significantly increased the diversity, evenness and richness indexes when compared to CG, while NG significantly decreased those indexes compared with RG. Meanwhile, litter biomass and plant coverage had no significant difference between RG and TG in 2014 and 2015, and the above- and below-ground biomass had no significant difference between RG and TG in 2014, but RG significantly increased the above- and below-ground biomass compared with TG in 2015. The NG, RG and TG sites all significantly improved the bulk density, soil compaction in 0-30 cm soil depth, available nitrogen and available potassium concentrations in 0-10 cm soil layer compared with CG site. NG, RG and TG all significantly increased the soil water content, total nitrogen, total phosphorus and available phosphorus in 0-30 cm soil depth compared with CG site. The C and N storage in vegetation, 0-40 cm soil depth and whole ecosystem were significantly increased in NG, RG and TG compared with CG in both years. Our results demonstrated that fencing is the most suitable grazing management regime on alpine meadow of the QTP. However, taking into account other factors such as: use and update of grassland resources, economic income stability of herdsmen, the grazing rest in the growing stage enable to promote the efficient use of grassland resources, maintaining alpine ecosystem and preventing it from further degradation or desertification is the best one. (C) 2016 Elsevier B.V. All rights reserved.