Regional characteristics of the alpine meadow degradation succession on the Qinghai-Tibetan Plateau

The degradation succession characteristics of alpine meadow on Qinghai-Tibetan Plateau were studied comprehensively from 2005 to 2012.The results indicated that the typical zonal vegetation on Qinghai-Tibaten Plateau was Gramineae and Kobresia humilis community.The degraded grassland in Guoluo of Qinghai Province was characterized with large-scale erosion of mattic epipedon in Kobresia pygmaea community and forbs-black soil.It was at the stage of succession from K.humilis to K.pygmaea community in Yushu of Qinghai Province.The alpine meadow successes from K.humilis to K.pygmaea community,or it remains the normal K.pygmaea community in the north part of Tibetan Plateau.The reduced excellent edible forage of Gramineae and Cyperaceae,and the increased forbs coverage were the main characteristic of alpine meadow degradation.Meanwhile,this degradation caused the increased soil compaction and the topsoil was more sensitive.The bulk densities of different layers in 0 to 10 cm,10 to 20 cm and 20 to 40 cm were increased by(0.50±0.08) g/m3,(0.16±0.07) g/m3 and(0.04±0.03) g/m3 respectively.Meanwhile,The soil organic matter content was greatly reduced by 19.3% to 53.2% and the reduction slowed down with the soil depth.