长白山不同海拔梯度裸肉足虫群落分布特征

Distribution of gymnamoebae communities along an elevational gradient in Changbai Mountains

裸肉足虫作为联结微生物和大中型土壤动物的重要环节,在土壤生态系统物质循环和能量流动过程中起着重要作用。为探明裸肉足虫群落沿海拔梯度的分布特征及其主要驱动因子,作者在长白山北坡选择不同海拔梯度(700 m、1,000 m、1,300 m、1,600 m、1,900 m和2,200 m),采用最大可能数法对裸肉足虫进行了培养计数,并采用平板培养、标记、分离再培养的方法进行了分类鉴定,分析比较了不同海拔梯度裸肉足虫的群落组成和结构特征。结果表明:长白山北坡裸肉足虫物种丰富,不同海拔梯度裸肉足虫丰富度指数存在显著差异,且与土壤酸碱度呈极显著正相关关系。其中林分较为单一的岳桦(Betula ermanii)林带(1,900 m)裸肉足虫丰富度最低,位于植被交错带的针阔混交林带(1,000 m)裸肉足虫丰富度最大,Shannon-Wiener多样性指数和Pielou均匀度指数在不同海拔梯度间不存在显著性差异,但变化趋势与丰富度一致。聚类分析结果显示,1,300 m、1,600 m和1,900 m海拔带以及700 m和2,200 m海拔带裸肉足虫群落组成较为相似。典范对应分析(canonical correspondence analysis,CCA)显示,裸肉足虫群落组成和结构主要受土壤酸碱度、铵态氮以及碳氮比的影响,而海拔和土壤含水量对其没有显著影响。综上,裸肉足虫群落多样性随海拔梯度的增加并未呈现递减或单峰的变化趋势,土壤的基本理化性质是驱动裸肉足虫群落分布的主要因素;此外,地上植被也可能通过凋落物和根系分泌物间接影响裸肉足虫的群落组成和多样性。

As an important component of soil food web, gymnamoebae play a significant role in nutrient cycling and energy flows of terrestrial ecosystems by linking soil microorganisms and macro- and meso-fauna. Along an elevational gradient （700 m, 1,000 m, 1,300 m, 1,600 m, 1,900 m, 2,200 m） in Changbai Mountains, the community composition and structure of gymnamoebae were compared using most probable number （MPN） method and plate cultivation technique. The result suggested that gymnameobae richness differed significantly among the various elevational levels and was positively correlated with soil pH. The lowest richness was observed in an Betula ermanii forest with monospecies dominance （1,900 m）, while the highest richness was observed in the 1,000 m ecotone. Shannon-Wiener diversity index and Pielou envenness index performed similar patterns with richness, with no significant differences observed among different elevational levels. The community composition of gymnamoebae was more similar among 1,300 m, 1,600 m and 1,900 m and between 2,200 m and 700 m elevations. Canonical correspondence analysis showed that gymnamoebae community structure was correlated with soil pH, ammonium nitrogen and C/N ratio.However, gymnamoebae communities were not influenced by altitude and soil water content. In conclusion, unlike macroorganisms （e.g. trees and animals）, the richness and diversity of gymnamoebae did not show monotonically decreasing or hump-shaped patterns along the elevational gradient, and soil physicochemical characteristics were the main factors that influencing their distribution. In addition, gymnamoebae community composition and structure might be also indirectly regulated by vegetation type through litter and root exudates.