降水变化对古尔班通古特沙漠优势植物多样性的影响

Effects of Precipitation Change on the Dominant Plant Species Diversity in the Gurbantü nggü t Desert

为探讨气候变化的背景下,了解降水变化对沙漠植物群落优势种的影响对保护和管理沙漠的抗逆植物资源,保护沙漠生态环境有重要意义。本研究通过分析1977-2012年降水数据,发现沙漠5个地理差异较大的地区降水总体呈增加趋势,但各分区降水变化幅度不同。对古尔班通古特沙漠南部43个样地(1000 m2/样带)的植物多样性进行调查,降水量高的区域植物多样性指数(α多样性、均匀度)和优势种物种数高于降水量低的区域。采用空间代替时间的方法,研究了不同样方降水量对主要物种的密度影响。结果显示,发现有4种灌木对降水变化有响应,其中蛇麻黄、白茎绢蒿的密度随降水的增加而增加,而白梭梭、淡枝沙拐枣密度随降水的增加而减少。1种灌木梭梭与降水没有相关性。草本植物中15/24的物种密度均随降水增加而增加,其中10种达到显著水平,仅有小花角茴香的密度随降水的增加会下降。由此可知,在降水增加的背景下,草本植物总体优势增加,而灌木白梭梭和淡枝沙拐枣会下降,需要高度重视。

With the background of global climate change,it is important to protect the desert ecological environment and manage adverse- resistant plant resources by investigating the influence of precipitation change on the dominant plant species.After analyzing the precipitation data of 1977- 2012,we found that precipitation of five regions in the desert increased,with considerable geographical differences.However, the ranges of precipitation varied among five regions differences.We surveyed plant diversity of 43 plots(1000 m2/plot) in the southern Gurbantünggüt Desert.The plant diversity index(α- diversity and evenness)and the number of dominant species in the regions of high rainfall were greater than that in the regions of low rainfall.We found that there were four kinds of shrubs in response to precipitation by 'Space- for- time' substitution analysis.The density of shrub Ephedra distachya and Seriphidium terrae- albae increased with the increasing of precipitation,whereas the density of Haloxylon persicum and Calligonum leucocladum decreased.The density of Haloxylon ammodendron had no correlation with precipitation.The density of 15/24 herbage species increased with the increasing of precipitation,10 of which reached significant levels.Only Hypecoum parviflorum did decrease with the increasing of precipitation.Therefore,if precipitation continues to increase in future,the distribution advantage of herbage will increase.However,Haloxylon persicum and Calligonum leucocladum will decrease with the increasing of precipitation,which should be paid more attention.