降水及温度对内蒙古克氏针茅草原生态系统稳定性的影响

Effect of precipitation and temperature on the ecosystem stability of Stipa krylovii Roshev.Steppe in Inner Mongolia

草地生态系统中,不同物种和功能群之间的相互补偿作用可以减少草地生态系统生产力的稳定性。近年来,大量学者就草地生态系统补偿性及系统稳定性进行了一系列的研究,但将气象因子,如降水和温度同草地生产力结合起来进行的研究还相对甚少。文中用15年的草地生产力及气象动态监测数据拟合回归分析,主要分析结果如下:1)逐步回归筛选出了和草地生产力最密切的气候因子为1-8月份降雨量,二者的回归模型为:Y=4.18952+0.37672X(R=0.3018,Pr=0.0339);2)多年草地生产力数据表明,无论物种水平还是功能群水平上,其生物量比例相对较大的物种或功能群变异性较小,即受气候变化影响程度较小;3)不同物种和功能群之间存在显著的补偿效应。优势种和亚优势种、优势种和非优势种之间存在明显的负相关关系,而亚优势种和非优势种之间存在一定的正相关关系。从研究结果来看,内蒙古克氏针茅草原生态系统受生长前期和生长季降水的影响,生态系统在外界气候条件变动下存在自我补偿和调节机制。研究结果为内蒙古草地在草地退化管理及生态补偿方面提供了一定的基础和理论依据。

The effects of different species or different functional groups,which generately be called corresponding compensatory may reduce the variability of productivity in some grassland ecosystems.The relative studies were conducted in several different type of grasslands.However,these studies did not combine the precipitation and temperature with the ecosystem stability in a long term period.Here,we did collect the long term grassland productivity（aboveground net primary productivity（ANPP）） and weather data in the typical Steppe biome of Inner Mongolia,China.The results showed that most important factor related to ANPP is the precipitation during Jan to August（PPT）,the regression equation is ANPP = 4.18952 ＋ 0.37672PPT（R = 0.3018,Pr = 0.0339）.The coefficients of variation（CV） in species level and plant functional group（PFGs） level both related to the ANPP.While both CVs for species（CVsp） and PFGs（CVPFG） were lower in the relative high ANPP,there is a minor effect of climate fluctuation on the CVsp and CVPFG that have relative high ANPP.There are significant compensatory effects between different species and different PFGs.There is a negative relationship between dominated species and sub-dominated species,while there is a positive relationship between sub dominated species and other species.Thus,we can conclude that precipitation during pre and during growing season have a most effect on the ecosystem stability,there is a compensatory effect and self-regulate mechanism in the Typical Steppe in Inner Mongolia.The study results were useful to the rangeland management and ecological compensatory in the degraded rangeland of Inner Mongolia.