Effects of long-term grazing exclusion on vegetation structure, soil water holding capacity, carbon and nitrogen sequestration capacity in an alpine meadow on the Tibetan Plateau
Vol20 No.3: 779-791
【Title】Effects of long-term grazing exclusion on vegetation structure, soil water holding capacity, carbon and nitrogen sequestration capacity in an alpine meadow on the Tibetan Plateau
【Author】YANG Yong-sheng1,2; ZHANG Fa-wei1,2; XIE Xian-rong3; WANG Jun-bang4*; LI Ying-nian1,2*; HUANG Xiao-tao1,2; LI Hui-ting3; ZHOU Hua-kun1,2
【Addresses】1 Key Laboratory of Adaptation and Evolution of Plateau Biota and Key Laboratory of Restoration Ecology in Cold Region of Qinghai Province, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining 810008, China; 2 Qinghai Haibei National Field Research Station of Alpine Grassland Ecosystem, Xining 810008, China; 3 Xi Ning Municipal Beishan Forestry Farm, Xining 810003, China; 4 Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China
【Corresponding author】WANG Jun-bang; LI Ying-nian
【Citation】Yang YS, Zhang FW, Xie XR, et al. (2023) Effects of long-term grazing exclusion on vegetation structure, soil water holding capacity, carbon and nitrogen sequestration capacity in an alpine meadow on the Tibetan Plateau. Journal of Mountain Science 20(3). https://doi.org/10.1007/s11629-021-7232-2
【DOI】https://doi.org/10.1007/s11629-021-7232-2
【Abstract】Grazing exclusion is one of the primary management practices used to restore degraded grasslands on the Tibetan Plateau. However, to date, the effects of long-term grazing exclusion measures on the process of restoring degraded alpine meadows have not been evaluated. In this study, moderately degraded plots, in which the vegetation coverage was approximately 65% and the dominant plant species was Potentilla anserina L, with grazing exclusion for 2 to 23 years, were selected in alpine meadows of Haibei in Qinghai-Tibet Plateau. Plant coverage, plant height, biomass, soil bulk density, saturated water content, soil organic carbon (SOC) and total nitrogen (TN) were evaluated. The results were as follows: (1) With increased grazing exclusion duration, aboveground biomass and total saturated water content at 0-40 cm depth, the average SOC and TN contents in moderately degraded alpine meadows increased as a power function, and the plant height increased as a log function. (2) The average soil bulk density at 0-40 cm depth first decreased and then increased with increasing grazing exclusion duration, and the minimum value of 0.90 g·cm-3 was reached at 15.23 years. The plant coverage, total belowground biomass at 0-40 cm depth, total aboveground and belowground biomass first increased and then decreased, their maximum values (80.49%, 2452.92 g·m-2, 2891.06 g·m-2) were reached at 9.41, 9.46 and 10.25 years, respectively. Long-term grazing exclusion is apparently harmful for the sustainable restoration of degraded alpine meadows. The optimal duration of grazing exclusion for the restoration of moderately degraded alpine meadows was 10 years. This research suggests that moderate disturbance should be allowed in moderately degraded alpine meadows after 10 years of grazing exclusion.
【Keywords】Long-term grazing exclusion; Soil water holding capacity; Soil carbon and nitrogen sequestration; Biomass; Alpine meadow