甘肃酒泉荒漠戈壁灌木群落优势物种生态位特征

Niche of dominant shrub species in desert gobi in Jiuquan,Gansu,China

了解物种利用资源和占据生态空间的能力,对维持完善和科学保育荒漠戈壁植物群落的多样性具有重要意义。在综合反映各生态因子作用的群落类型和海拔梯度组合而成的两条资源轴上,测度分析了甘肃酒泉荒漠戈壁灌木群落主要优势种的生态位特征。结果表明:(1)在群落类型和海拔梯度两条资源轴上,红砂(Reaumuria songarica)、泡泡刺(Nitraria sphaerocarpa)和合头草(Sympegma regelii)的重要值和生态位宽度均较大,说明这些物种适应能力强,能够较好地利用环境资源,分布范围大,作为荒漠戈壁灌木群落中的广域种具有重要的生态地位和作用。(2)荒漠戈壁优势物种间的生态位重叠值多数较小,在群落类型和海拔梯度资源轴上生态位重叠值小于0.5的分别占总种对的62.63%和77.89%。生态位宽度大的物种之间一般生态位重叠值较高,物种利用资源能力强且存在竞争关系;然而,生态位宽度较小的物种与其他物种之间的生态位重叠程度较低,不同物种在环境资源的需求上产生互补,可以和谐共存;生态位宽度小的物种之间生态位重叠值仍较高,物种分布呈斑块现象;因此,生态位重叠与生态位宽度之间无显著相关性。(3)荒漠戈壁优势物种间总体表现为不显著的正关联,表明该植被群落结构及其物种之间处于稳定共存的状态。

The two resource axes are composed by community types and stand altitude,which can reflect various ecological factors. The paper deals with the niche measurement of the dominant species of desert gobi shrub community in Jiuquan,Gansu province. The ability in utilizing resources and occupying ecological spaces by different species is important for maintaining,self-improvement,scientific conservation and managing the diversity of desert gobi shrub communities. The results showed that:(1)Across the community types and altitude gradient,important values and niche breadth were major in Reaumuria songarica,Nitraria sphaerocarpa and Sympegma regelii. Thus,these species had high adaptability,broad habitats,and inclined to be generalist species which played an important role in the communities due to strong ecological adaptability in desert gobi shrub communities.(2)Most shrub species’ niche overlap values were minor,of which 62. 63% and 77. 89% shrub species were lower than 0. 5 across the two resource axes. The species with higher niche breadth had relatively larger niche overlap,due to species had strong ability to utilize resources and were competitive in shrub communities. However,the species with higher niche breadth or species with lower niche breadth had relatively small niche overlap,due to different species complement each other in their environmental resource needs and can coexist in harmony. The species with lower niche breadth had larger niche overlap,because of the habitat patch of species distribution. It suggested that there was no signi ? cant correlation between niche overlap and niche breadth.(3)Macro-association was significantly positively correlated among 20 dominant species,this result indicated that the plant community was in a relatively stable status.