The characteristics of Kobresia tibetica marsh meadow communities at the Yellow River source zone

We used quadrat sampling to investigate structure characteristics of the kobresia tibetica marsh meadow communities at different degraded levels in the Yellow River source zone,and the purpose is to provide a scientific basis for the management and conservation of resources. The main results are as follows: 1The kobresia tibetica marsh meadow in the Yellow River source zone consists of 11 families and 32 genera 49 species. The plant community composition and important value vary with degradation degrees greatly. With degradation intensifying,average height of Kobresia tibetica lowered from 26. 2cm to 7. 3cm,cover from 76% to 31%. 2The aboveground biomass decreased with degradation,in the order of non-degraded grassland lightly degraded moderately degraded heavily degraded over degradation. The degradation processes is arid succession,i. e.sedges and grasses dominated to sedges and grasses + forbs to forbs dominated. 3Species diversity index was positively correlated with richness and evenness index,and negatively correlated with dominance index; The highest species richness index is in moderate-degradation stage,and the highest diversity and evenness index in heavy-degradation stage,and evenness is largely affected the diversity of the communities. Discussion results indicated that the most effective measures for sustainable use of the meadow is enclosure for nurture and block rotational grazing.