家畜放牧和鼢鼠干扰对亚高寒草甸植物群落结构的影响

Effects of Livestock Grazing and Zokor Disturbance on Plant Community Structure in Subalpine Meadow

为探究不同干扰方式及不同干扰强度对亚高寒草甸植物群落结构产生的影响,本研究以甘肃省武威市天祝县亚高寒草甸为实验点,选取不同强度家畜放牧和鼢鼠干扰形成的不同龄鼠丘为研究对象,采用野外调查记录、室内数据处理与分析相结合的方式,初步探讨了不同干扰方式、不同干扰强度下植物群落结构的变化。结果表明:(1)不同放牧强度和不同鼢鼠干扰时间的斑块,植物群落结构在空间上发生了变化。(2)对同一植物的生态位宽度而言,在鼢鼠扰动下比在放牧干扰下宽。(3)鼢鼠扰动下,植物群落中生态位宽的物种,生态位重叠值也大,但在放牧干扰条件下,与之相反。(4)在中度放牧与重度放牧下,物种丰富度和Shannon-Weiner指数差异性显著(P<0.05);在鼢鼠扰动下,一年龄鼠丘与三年龄鼠丘植物群落物种丰富度、Shannon-Weiner指数、Simpson多样性指数及总盖度差异性均显著(P<0.05)。(5)不同干扰下,植物群落内生活史组成结构发生了变化,植物功能群重要性有不同程度的提高和降低;随着放牧强度增加,禾本科植物重要性增加,莎草科植物重要性减少;鼢鼠扰动下杂草类植物为优势种,豆科植物随丘龄增加重要性逐渐降低,莎草科植物逐渐出现。

To explore the effects of different disturbance methods and different disturbance intensities on the plant community structure of subalpine meadows,this study site is based on an subalpine meadow in Tianzhu County,Wuwei City,Gansu Province,selected zokormounds with different agesin the experiment blockgrazed by livestock indifferent intensities.The changes of plant community structure under different disturbance modes and different disturbance intensities were preliminarily discussed by a combinationmode of field investigation records,indoor processing data and analysis.The results showed that:(1)For patches with different grazing intensities and different zokor disturbance times,the plant community structure changed in space.(2)The niche width of the same plant was wider under zokor disturbance than under grazing disturbance.(3)Under the disturbance of zokor,species with wide niches in the plant community have a large niche overlap value,but it was opposite under grazing disturbance conditions.(4)There were significant differences in species richness and Shannon-Weiner index between moderate and heavy grazing(P<0.05).There were significant differences in species richness,Shannon-Weiner index,Simpson diversity index and total coverage between one-and three-year-old mounds(P<0.05).(5)Under different disturbances,the life history composition of plant communities changed,and the important value of plant functional groups increased and decreased to different degrees;With the increase of grazing intensity,the important value of grasses increased and the important value of sedges decreased.On the zokor mound,forbs were the dominant species,the important value of legumes gradually decreased with the increase of mound age,and sedge plants gradually appeared.