Takahashi Koichi, Tanaka Saeka
Department of Biology, Faculty of Science, Shinshu University, Asahi 3-1-1, Matsumoto, Nagano, 390-8621, Japan.
Institute of Mountain Science, Shinshu University, Asahi 3-1-1, Matsumoto, Nagano, 390-8621, Japan.
J Plant Res. 2016 Nov;129(6):1041-1049. doi: 10.1007/s10265-016-0852-x. Epub 2016 Jul 22.
This study examined how habitat filtering and limiting similarity affect species assemblages of alpine and subalpine plant communities along a slope gradient on Mt. Norikura in central Japan. Plant traits (plant height, individual leaf area, specific leaf area (SLA), leaf linearity, leaf nitrogen and chlorophyll concentrations) and abiotic environmental factors (elevation, slope inclination, ground surface texture, soil water, soil pH, soil nutrient concentrations of NH-N and NO-N) were examined. The metrics of variance, range, kurtosis and the standard deviation of neighbor distance divided by the range of traits present (SDNDr) were calculated for each plant trait to measure trait distribution patterns. Limiting similarity was detected only for chlorophyll concentration. By contrast, habitat filtering was detected for individual leaf area, SLA, leaf linearity, chlorophyll concentration. Abiotic environmental factors were summarized by the principal component analysis (PCA). The first PCA axis positively correlated with elevation and soil pH, and negatively correlated with sand cover, soil water, NH-N and NO-N concentrations. High values of the first PCA axis represent the wind-exposed upper slope with lower soil moisture and nutrient availabilities. Plant traits changed along the first PCA axis. Leaf area, SLA and chlorophyll concentration decreased, and leaf linearity increased with the first PCA axis. This study showed that the species assemblage of alpine and subalpine plants was determined mainly by habitat filtering, indicating that abiotic environmental factors are more important for species assemblage than interspecific competition. Therefore, only species adapting to abiotic environments can distribute to these environments.
本研究调查了生境过滤和极限相似性如何影响日本中部乘鞍岳沿坡度梯度的高山和亚高山植物群落的物种组合。研究了植物性状（株高、单叶面积、比叶面积（SLA）、叶线性度、叶氮和叶绿素浓度）和非生物环境因子（海拔、坡度、地表质地、土壤水分、土壤pH值、土壤中NH-N和NO-N的养分浓度）。计算每个植物性状的方差、范围、峰度以及邻居距离的标准差除以现存性状范围（SDNDr）的指标，以衡量性状分布模式。仅在叶绿素浓度方面检测到极限相似性。相比之下，在单叶面积、SLA、叶线性度、叶绿素浓度方面检测到了生境过滤。通过主成分分析（PCA）对非生物环境因子进行了总结。第一主成分轴与海拔和土壤pH值呈正相关，与沙地覆盖、土壤水分、NH-N和NO-N浓度呈负相关。第一主成分轴的高值代表了土壤水分和养分有效性较低的迎风上坡。植物性状沿第一主成分轴发生变化。随着第一主成分轴的变化，叶面积、SLA和叶绿素浓度降低，叶线性度增加。本研究表明，高山和亚高山植物的物种组合主要由生境过滤决定，这表明非生物环境因子对物种组合比种间竞争更重要。因此，只有适应非生物环境的物种才能分布到这些环境中。
