Effects Of Warming And Precipitation Regime On Plant Phenology And Productivity In An Alpine Meadow, Northwestern Sichuan, China

Greenhouse gases are being concentrated in the atmosphere because of theinsensitive human activities, which lead to global warming. In the context ofglobal warming, the increased temperature must be accompanied by changes inprecipitation.Temperature and rainfall are fundamental factors controlling theprocess of plant growth, which variations may result in the changes of plant fromindividual to community level. Therefore, impacts of warming and precipitationchange on terrestrial ecosystem have become one of the key issues in globalchange ecology. Grassland is an important component of the terrestrial ecosystem.Researches on the response of grassland ecosystem to warming and rainfallchanges are contributed to understanding of terrestrial ecosystem response toclimate change.Alpine meadow in the northwestern Sichuan province, which located in thejunction of the Qinghai-Tibetan Plateau and the Sichuan Basin, was the typicalecotone. The ecological environment in this region is fragile and sensitive toclimate change. Therefore, it is an ideal place to study the response of terrestrialecosystems to climate change. Researches on the impact of climate change on thealpine meadow ecosystem will not only facilitate to understand the relationshipbetween global climate change and terrestrial ecosystem, but also to provide thenecessary theoretical support for biological conservation and ecosystemmanagement in this region.Alpine meadow ecosystem in northwestern Sichuan was chosen to study theeffects of climate change (artifical warming and precipitation changes) on grassland. The phenology of the dominant species (such as Saussurea,Gentianopsis, Ranunculus) and net primary productivity of the alpine meadowwere examined during the experimental period. The main results are shown asfollows.1) Experimental warming resulted in5～8days in advance in thereproductive phonologies of Saussurea and Gentianopsis, and no significantchanges in phenological phases of the Ranunculus. However, elevatedtemperature significantly decreased the amount of Ranunculus’flowers. Inaddition, the impacts of changes in precipitation on the reproductive phenologiesof all dominant species were not found in the current study;2) Net primary productivity is sensitive to the stimulated climate change,the artifical warming decreased productivity significantly (F=38.222,P<0.01), inwhich precipitation: Reduce180mm, natural and increased180mm processingthe NPP reduced38.71g/m~2,37.2g/m~2and51.46g/m~2; the shifted precipitationshift productivity (F=4.904,P=0.014), Being compared with the precipitationdecreased, increased precipitation increase the biomass32.58g/m~2in the naturaltemperature, while in the case of warming,19.83g/m~2.3) Community structure changed, the artificial warming declines thepercentage of weeds and sedges in occupancy of community’s biomass, which theweeds dropped by an average power of3.5%, sedges decreased by2.3%. On thecontrary, grass biomass percentage rise, the biomass percentage improved by9.6%,5.6%and3.3%.In the precipitation: decrease, in the case of natural andincreased.