长白山区泥炭地现代有壳变形虫环境意义探讨

ENVIRONMENTAL IMPLICATIONS OF THE MODERN TESTATE AMOEBAE IN THE PEATLANDS IN CHANGBAI MOUNTAINS

有壳变形虫(testate amoebae)是一种新的具有潜力的环境变化生物指标。对采集自长白山区哈泥(42°12′50″N,126°31′05″E)、金川(42°20′47″N,126°21′35″E)、赤池(42°03′16″N,128°03′22″E)和圆池(42°01′55″N,128°25′58″E)等4个泥炭地不同生境的75个有壳变形虫样品,采用冗余分析方法(RDA)研究有壳变形虫种类组合变化与7个环境变量的关系,所有采样点均以泥炭藓(Sphagnum)为优势植被。结果表明水位埋深(depth to watertable),pH值和泥炭湿度是影响长白山区泥炭地有壳变形虫种类变化的主要环境因子,显著性检验达到p<0.001的水平。这一结果与国外其他地区的研究结果相一致,这3个环境因子可以作为目标变量进行有壳变形虫-环境因子转换函数的构建。

Testate amoebae are unicellular organisms living in soils, wetlands and aquatic habitats which produce decayresistant shells （tests）. They are especially diverse and abundant in Sphagnum peatlands. In addition, testate amoebae show clear responses to the main environmental gradients in peatlands, such as depth to water table and pH. Many studies on modern ecology of testate amoeba have now been conducted in different regions of the world for their applications in paleoecology. However, most of them were conducted in Europe and North America, and none were in China,despite the presence of numerous peatlands here. In this study, 75 samples were collected along hydrological gradients from 4 peatlands namely Hani （42°12′50″N,126°31′05″E）, Jinchuan （42°20′47″N,126°21′35″E）, Chichi （42°03′16″N,128°03′22″E） and Yuanchi（42°01′55″N,128°25′58″E）, in the Changbai Mountains, North East China. All sampling spots were dominated by Sphagnum and covered different habitats including the hollow, the top, middle and low part of hummock. Depth to water table （DWT）, moisture of peat, pH and conductivity were measured in situ. Latitude, longitude and altitude were recorded with GPS. 33 testate amoebae taxa and 12984 tests were recorded. Detrended correspondence analysis（DCA） shows that 4 peatlands have similar testate amoebae assemblages. Since the length of gradient is short than 3, a linear ordination model, redundancy analysis （RDA） , was used to explore the relationship between testate amoebae assemblages and 7 environmental variables including latitude, longitude, altitude, pH, conductivity, DWT, and moisture of peat. The results show that the 7 environmental variables explain 31.8% of variation in species data. DWT,pH and moisture of peat have greater marginal effects, which are 10%,9% and 8% , respectively. All of these three variables are extremely significantly correlated with axis 1 of ordination. So they are principal factors which determine the assemblage of testate amoebae in peatlands in the Changbai Mountains. Monte Carol significance tests （999 permutation）of DWT, pH and soil moisture are all p 〈0. 001, which proves that they can be target variables in developing transfer functions for quantitative paleoenvironmental reconstruction. The conclusion of this paper is consistent with ecological studies of testate amoeba conducted in other regions in the world. This convinces us that testate amoebae can be an extra method in paleoecological study on peat sediments in the Changbai Mountains. Coupling with other proxies such as pollen, plant macrofossil,humification degree,and isotope composition,we can recover a more integrated picture for the past.