ISSN 1556-6757








Volume 2, Issue 2, 2008


The Impacts of Pasture Degradation on Soil Nutrients and Plant Compositions in Alpine Grassland, China   Ronggui Wu, Holm Tiessen, Zhi Chen

This study investigated the effects of grassland degradation on plant community composition and soil erosion in the alpine grassland soil of China. Grasslands were grouped as three categories: lightly (LDP), moderately (MDP), and heavily degraded pasture (HDP). Soil samples were collected from 18 sites at seven locations in Chernozemic soils between elevations of 2600 to 3200 m. Once pasture was heavily degraded, soil 137Cs activity dropped by 22%. Soil total organic carbon (TOC), total nitrogen (TN), and effective cation exchangeable capacity (ECEC) reduced significantly when pasture was heavily degraded. Soil TOC and ECEC in grass-dominated pasture were slightly higher than those in the forb-dominated pasture. Achnatherum inebrians dominated pasture resulted in significantly lower levels of soil TOC and TN. On heavily degraded pasture, changes in plant species composition were found. More grass and grass-like plants were observed in LDP, whereas HDP had more forbs and shrubs. Plant palatability index (PI) decreased from 205 in LDP to 173 in MDP, and then to 151 in HDP, implying that the abundance of more palatable plants have decreased with pasture degradation, while plants with lower forage value tended to increase.
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