Effects Of Warming On The Main Plant Phenology And Community Characteristics Of Alpine Meadow In Different Degraded Gradients In Northern

Tibetan Plateau of alpine meadow ecosystem is distributed largest and most types of ecosystems, and has a close relationship with global climate change process. In recent years, due to climate change and overgrazing, leading to serious degradation of the grassland ecosystem, to study effects of temperature enhancement on different degraded of major plant phenology and community characteristics of alpine meadow in northern Tibet, helping to understand the environment in the context of global warming, response of different degraded main plants growth cycle of alpine meadow in northern Tibet. In this paper, through the Open Top Chamber simulated warming method, comparative studying of different degraded(non-degraded, moderately degraded meadow of Kobresia pygmaea and severe degraded meadow of Heteropappus hispidus) of plant phenology and community characteristics in response to short-term warming of alpine meadow in Nagqu. The studying found:(1)OTC simulated by warming after one growing season, compared with the control group, the warming significantly delayed non-degraded and moderately degraded plant communities of turning green stage, squaring stage, seed-setting stage; the warming significantly delayed severe degraded plants communities of flowering stage and seed-setting stage; and the warming did not have a significant effects on the community of squaring stage, post-fruiting stage and withering stage.(2)While on non-degraded condition, warming significantly delayed Kobresia pygmaea of turning green stage, squaring stage, flowering stage and seed-setting stage, and the warming did not have a significant effects on severe degraded Kobresia pygmaea of phenology; has a little effect on the non-degraded and severe degraded Potentilla multifida of phenology; under severe degradation conditions, warming make Heteropappus hispidus in advance of turning green stage, withering stage significantly delayed, extending its growing period, warming make Chenopodium glaucum are turning green stage delayed, withering stage ahead, but all did not have a significant impact, shorten its growth period.(3)Non-degraded of community coverage> moderately degraded> severe degraded and severe degraded significantly lower than non-degraded and moderately degraded, and warming for the different degradation gradient of communities cover has no significant impact; moderately degraded communities of height> non-degraded> severe degraded, warming increases the communities height of the three different degradation gradient, but the effect was not significant; community species diversity index of moderately is the largest, followed by severe degradation and non-degraded, while moderately degraded and non-degraded are significant differences between severe degradation, warming not has a significant impact on the community species diversity index; regardless of whether warming and different degradation gradient, the community aboveground biomass of severe degradation is the lowest, and Warming make communities has increased aboveground biomass, but did not reach significant levels.