利用随机样法构建种-面积曲线,对每一取样面积下的物种数进行999次随机抽样后计算均值,得到不同取样面积下的植物物种数,由此绘制实际种-面积曲线,并采用8种曲线模型拟合桂林岩溶石山常绿落叶阔叶混交林的种-面积关系,结合赤池信息量准...利用随机样法构建种-面积曲线,对每一取样面积下的物种数进行999次随机抽样后计算均值,得到不同取样面积下的植物物种数,由此绘制实际种-面积曲线,并采用8种曲线模型拟合桂林岩溶石山常绿落叶阔叶混交林的种-面积关系,结合赤池信息量准则AIC值及生物学意义确定最优拟合模型,通过对比群落总种数比例法、二阶导数法与实际种-面积曲线结果,最终确定桂林岩溶石山常绿落叶阔叶混交林的最小面积。结果表明,桂林岩溶石山常绿落叶阔叶混交林种-面积关系的最优拟合模型为累积韦伯分布模型(cumulative Weibull),拟合方程为S=73.8017(1-exp(-0.0138A ^(0.6685)))。二阶导数法比群落总种数比例法更具科学性和准确性,最终确定桂林岩溶石山常绿落叶阔叶混交林的最小面积为2500 m ^(2)。所以,最小面积的确定应根据实际区域的物种特征来确定。展开更多
Species richness and abundance are two important species diversity variables that have attracted particular attention because of their significance in determining present and future species composition conditions. Thi...Species richness and abundance are two important species diversity variables that have attracted particular attention because of their significance in determining present and future species composition conditions. This paper aims to explain the qualitative and quantitative relationships between species diversity pattern and grain size （i.e. size of the sampling unit）, and species diversity pattern and sampling area, and to analyze species diversity variability on active sand dunes in the Horqin Sandy Land, northeastern Inner Mongolia, China. A 50 mx50 m sampling plot was selected on the windward slope, where the dominant species was annual herb Agriophyllum squarrosum. Species composition and abundance at five grain sizes were recorded, and the species-area curves were produced for thirteen grain sizes. The range of values for species abundance tended to increase with in- creasing grain size in the study area, whereas, generally, species richness did not follow this rule because of poor species richness on the windward slope of active sand dunes. However, the homogeneity of species richness in- creased significantly. With the increase in sampling area, species abundance increased linearly, but richness in- creased logarithmically. Furthermore, variograms showed that species diversity on the windward slope of active sand dunes was weakly anisotropic and the distribution pattern was random, according to the Moran Coefficient. The results also showed that species richness was low, with a random distribution pattern. This conflicts with the results of previous studies that showed spatial aggregation in lower richness in a sampling area within a community and inferred that the physical processes play a more important role in species diversity than distribution pattern on active sand dunes. Further research into different diversity patterns and mechanisms between active sand dunes and interdune lowlands should be conducted to better understand biodiversity conservation in sand dune fields.展开更多
文摘利用随机样法构建种-面积曲线,对每一取样面积下的物种数进行999次随机抽样后计算均值,得到不同取样面积下的植物物种数,由此绘制实际种-面积曲线,并采用8种曲线模型拟合桂林岩溶石山常绿落叶阔叶混交林的种-面积关系,结合赤池信息量准则AIC值及生物学意义确定最优拟合模型,通过对比群落总种数比例法、二阶导数法与实际种-面积曲线结果,最终确定桂林岩溶石山常绿落叶阔叶混交林的最小面积。结果表明,桂林岩溶石山常绿落叶阔叶混交林种-面积关系的最优拟合模型为累积韦伯分布模型(cumulative Weibull),拟合方程为S=73.8017(1-exp(-0.0138A ^(0.6685)))。二阶导数法比群落总种数比例法更具科学性和准确性,最终确定桂林岩溶石山常绿落叶阔叶混交林的最小面积为2500 m ^(2)。所以,最小面积的确定应根据实际区域的物种特征来确定。
基金funded by the National Natural Science Foundation of China (41071187)the State Forestry Administration Industry Special Project (201004023)
文摘Species richness and abundance are two important species diversity variables that have attracted particular attention because of their significance in determining present and future species composition conditions. This paper aims to explain the qualitative and quantitative relationships between species diversity pattern and grain size （i.e. size of the sampling unit）, and species diversity pattern and sampling area, and to analyze species diversity variability on active sand dunes in the Horqin Sandy Land, northeastern Inner Mongolia, China. A 50 mx50 m sampling plot was selected on the windward slope, where the dominant species was annual herb Agriophyllum squarrosum. Species composition and abundance at five grain sizes were recorded, and the species-area curves were produced for thirteen grain sizes. The range of values for species abundance tended to increase with in- creasing grain size in the study area, whereas, generally, species richness did not follow this rule because of poor species richness on the windward slope of active sand dunes. However, the homogeneity of species richness in- creased significantly. With the increase in sampling area, species abundance increased linearly, but richness in- creased logarithmically. Furthermore, variograms showed that species diversity on the windward slope of active sand dunes was weakly anisotropic and the distribution pattern was random, according to the Moran Coefficient. The results also showed that species richness was low, with a random distribution pattern. This conflicts with the results of previous studies that showed spatial aggregation in lower richness in a sampling area within a community and inferred that the physical processes play a more important role in species diversity than distribution pattern on active sand dunes. Further research into different diversity patterns and mechanisms between active sand dunes and interdune lowlands should be conducted to better understand biodiversity conservation in sand dune fields.
