EFFECT OF FENCING, ARTIFICIAL SEEDING AND ABANDONMENT ON VEGETATION COMPOSITION AND DYNAMICS OF 'BLACK SOIL LAND' IN THE HEADWATERS OF THE YANGTZE AND THE YELLOW RIVERS OF THE QINGHAI-TIBETAN PLATEAU

Rangeland management can affect plant diversity and plant functional groups of native grassland communities. To improve pasture for livestock grazing, from the existing poisonous and ruderal vegetation in the 'black soil land' grassland in the headwaters of the Yangtze and the Yellow Rivers (HAYYR) of the Qinghai-Tibetan Plateau, three treatments (fencing-FT, artificial seeding with local grasses-ST and abandomnent-AT) were applied during a 5-year period (2000-2005). Plant diversity and groups (sedges, grasses and dwarf shrubs) in the treated plots were compared with non-treated control plots. Results showed that M FT promoted an increase in forbs species. but there was no chance in the other plant functional groups: (2) with ST, species richness of forbs decreased but grass species increased indicating that sowing local grasses could chance plant composition of black soil land in the short-term. and increase the proportion of grasses and, thus. forage for grazing and (3) AT, after plowing, was similar to CK plots, with forbs being the dominant plant functional group for the 5 years. In conclusion, the goal to alter black soil land cover from poisonous and ruderal plants to more useful plants for livestock grazing by either fencing. artificial seeding or abandonment was not successful in the long term. Copyright (c) 2008 John Wiley & Sons, Ltd.