川西平原农田啮齿动物群落的试验操作: 去除优势种(英文)

EXPERIMENTAL MANIPULATIONS OF A CROPLAND RODENT COMMUNITY IN THE WESTERN SICHUAN PLAIN: DOMINANT SPECIES REMOVAL

１９９３～１９９５年我们在川西平原面积为２ｈｍ２的试验样地进行了试验，内容是去除啮齿动物优势种大足鼠（Ｒａｔｕｓｎｉｔｉｄｕｓ），同时在相同生境中设置了１．５ｈｍ２的对照样地。试验估计了优势物种在多大程度上影响其他啮齿动物种群。用捕鼠笼活捕进行监测后试验样地和对照样地间差异的成对数据ｔ检验显示，移除大足鼠后：（１）褐家鼠和黄胸鼠的种群密度、社鼠的生物量在某一年或整个研究期增加；（２）１９９５年及整个研究期的物种数和物种多样性Ｓｈａｎｎｏｎ指数显著增加；（３）结合密度、生物量和物种均匀性无明显改变。这些结果说明，优势种的存在对农田啮齿群落物种数和组织有重要作用，它与其它种群围绕资源的竞争限制了群落的物种数。

During 1993 ～ 1995 we conducted an experiment in which we removed the dominant species of rodent, Rattus nitidus , from a 2 hm 2 plot in the Western Sichuan Plain and set a 1 5 hm 2 control plot in the same habitat. The experiment evaluates the extent to which the dominant species influences other rodent populations. Monitoring with live traps and statistical analyzing with paired t testing of difference between the experimental and control plots revealed that: the removal of R. nitidus (1) resulted in increases of population density (R. nevigicus and R. flevipectus) and biomass (R. confucians) during a certain year or overall study period; (2) induced significant increases in the number of species and Shannon indexes of species diversity during 1995 and overall study period; (3) resulted in no significant changes in joint population density, biomass, evenness of species. These results indicate that occurrence of the dominant species plays a major role in regulating the number of species and determining the organization of cropland rodent communities. Competition between the dominant species and other rodent populations for resources was limiting the number of species in the community. But we have not identified which components in resources were working in limiting the species number and species diversity by our relative simple experimental manipulations.