西藏高原高寒草地群落植物多样性和地上生物量监测方法的比较研究

Comparative Study of Monitoring Methods about Plant Diversity and Aboveground Biomass of Alpine Grasslands in the Tibetan Plateau

以西藏高原高寒草地3种植被类型（高寒草甸、高寒草原和高寒荒漠草原）为研究对象,分别采用样线法、样方法和巢式样方法进行实地调查,记录每条样线上或每个样方内出现的所有物种,并分物种刈割样方内地上部分,通过统计分析比较不同高寒草地群落植物多样性和地上生物量监测方法,以阐明西藏高原高寒草地不同植被类型的最小取样面积和最少样方数或样线长度。结果显示：（1）就物种丰富度而言,400m样线法观测到的高寒草甸、高寒草原和高寒荒漠草原的所有物种数分别占3种方法调查到的总物种数的55%、71%和50%;8m2巢式样方法调查到高寒草甸、高寒草原的总物种数占所有3种方法观测的物种总数的57.5%和57%,而8m2的巢式样方对高寒荒漠草原的调查监测到的物种数最多,其中2m2观测到的物种数就达到所有可能出现物种的83%;20个样方法监测到高寒草甸和高寒草原的物种数最多,占3种方法观测到总物种数的78%和86%,所以对物种丰富度的调查高寒草甸和高寒典型草原至少需要20个样方,高寒荒漠草原需要最小面积不少于2m2的2个样方。（2）就地上生物量而言,由地上生物量与物种数之间的变异关系得出最小样方数为7~11个,而由地上生物量的变异系数可知,在变异系数小于等于5%的前提下,高寒草甸的最小取样面积不小于0.25m2,高寒典型草原和高寒荒漠草原的最小取样面积不少于1m2。研究表明,对于生产力的监测方法而言,高寒草甸采用10个0.5m×0.5m的样方,而高寒草原和高寒荒漠草原采用10个1m×1m的样方为宜;而对于物种丰富度的监测方法而言,高寒草甸以20个0.5m×0.5m的样方和高寒草原20个1m×1m的样方为宜,高寒荒漠草原采用2个不小于2m2样方面积为宜。

With three alpine meadow vegetation types of Tibetan Plateau（alpine meadow,alpine steppe and alpine desert steppe）as research objects,we made a fact-finding through the sample line method,quadrat method and nest quadrat method,respectively.Afterwards,we recorded all species of each transect line or per quadrat and mow the aboveground part of the quadrats.By the comparison of different alpine grassland plant diversity and aboveground biomass monitoring methods via the statistical analysis,we derived the minimum sampling area and the number of quadrats or transect lengths of different vegetation types of the Tibetan Plateau alpine grasslands.The results show that：in terms of species richness,400 m line transects observed the number of species accounts for 55%,71%,50% of all three methods＇ investigation of alpine meadow,alpine steppe and alpine desert steppe,8 m2 nest quadrats observed the number of species accounts for 57.5% and 57% of all the total number of species of the alpine meadow and alpine steppe separately,And 8 m2 nest quadrats monitored the largest number of species of the alpine desert steppe,of which 2 m2 number of observed species reached 83% in all possible species.The 20 sampling methods monitored largest number of species of the alpine meadow and alpine steppe,accounting for 78% and 86% of total number of species observed of three methods.Therefore,investigation of species richness is not less than 20 plots in alpine meadow and alpine steppe,alpine desert steppe required minimum area is not less than 2 m2 of the two plots.Just in terms of aboveground biomass,the minimum number plots is not less than 7~11 derived from the relationship of coefficient of variation between aboveground biomass and the species,but by the coefficient of variation of aboveground biomass shows that the coefficient of variation is less than 5% of such premise.The sampling area of alpine meadow is not less than 0.25 m2;alpine steppe and alpine desert steppe is not less than 1m2.It can be drawn a conclusion that considering monitoring method of productivity,it will show great advantage for the alpine meadow to use 10 quadrates of 0.25 m2（0.5 m×0.5 m）,but for the alpine typical steppe it will be better to choose 10 quadrates of 1m2（1m×1m）.However,for species richness of monitoring method,we obtain that it is convenient for the alpine meadow to chooses 20 quadrates of 0.25 m2（0.5 m×0.5 m）and for the alpine desert steppe the data should be accept 20 quadrates of 1 m2（1m×1m）.Additionally,for alpine desert grassland it is prior to select 2 quadrates of 2 m2.