放牧和模拟降水对短花针茅荒漠草原植物功能群多样性的影响

摘要： 为探究放牧和降水变化对植物功能群的影响，本文以内蒙古短花针茅（Stipa breviflora）荒漠草原为研究对象，开展了野外控制试验。试验设置围封和适度放牧，分别进行模拟降水处理（减少降水量50%、自然降水、增加降水量50%、增加降水量100%），并在每年8月观测植物群落组成。结果表明：减水会降低植物功能群多样性、生物量和物种数量，增水有利于植物功能群多样性的提高。多年生丛生禾草多样性随降水量的增加而升高。同时，对降水梯度和功能群多样性进行拟合分析发现，降水量低于年降水量16%则不利于除灌木、半灌木外其他功能群植物的生长。围封草地增水67%~79%时，功能群的Simpson指数、Shannon-Wiener指数、Pielou指数值均较高，功能群多样性较高；由于放牧提高了植物的水分利用效率，放牧地各指数在增水26%~50%时较高，功能群多样性较高。综上，适度的放牧及水分补充有利于提高植物功能群多样性。

关键词: 荒漠草原, 模拟降水, 围封, 放牧, 植物功能群多样性

Abstract: To examine the effects of grazing and precipitation changes on the functional groups of Stipa breviflora desert steppe in Inner Mongolia Autonomous Region, a controlled field experiment was carried out. The grazing experiment including a fenced enclosure (zero grazing) and a moderate grazing was conducted, along with simulated precipitations (reduced precipitation by 50%, natural precipitation, increased precipitation by 50%, and increased precipitation by 100%) applying to those two grazing intensities. The plant community composition was observed in August every year. The results showed that the reduction of precipitation reduced functional group diversity, as well as their biomass and number of species, whereas the increment of precipitation increased functional group diversity, as well as the diversity of perennial grasses. Results of fitting analysis between precipitation gradient and functional group diversity showed that precipitation below 16% of annual precipitation was detrimental to the growth of functional groups other than shrub and half shrub. The Simpson diversity index, Shannon-Wiener diversity index, and Pielou evenness index of functional groups were higher in the fenced enclosure with a precipitation increased by 67%~79%, and the functional group diversity was higher. Furthermore, the values of all individual indexes were higher when the precipitation was increased by 26%~50% because the moderate grazing increased the water use efficiency of plants. Therefore, moderate grazing and water supplement are beneficial to improve the diversity of plant functional groups of the desert steppe.

Key words: Desert steppe, Simulated precipitation, Fenced enclosure, Grazing, Plant functional group diversity

中图分类号: 

S812.5

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