Oishi Yoshitaka
Center for Arts and Sciences Fukui Prefectural University Fukui Japan.
Ecol Evol. 2021 Mar 17;11(9):4887-4897. doi: 10.1002/ece3.7397. eCollection 2021 May.
Elevation is involved in determining plant diversity in montane ecosystems. This study examined whether the distribution of plants in the Yatsugatake Mountains, central Japan, substantiated hypotheses associated with an elevational diversity gradient. Species richness of trees, shrubs, herbs, ferns, and bryophytes was investigated in study plots established at 200-m elevational intervals from 1,800 to 2,800 m. The changes in plant diversity (alpha and beta diversities, plant functional types, and elevational ranges) with elevation were analyzed in relation to climatic factors and elevational diversity gradient hypotheses, that is, mass effect, mid-domain effect, and Rapoport's elevational rule. In addition, the elevational patterns of dominance of plant functional types were also analyzed. A comparison of alpha and beta diversities revealed that different plant groups responded variably to elevation; the alpha diversity of trees and ferns decreased, that of herbs increased, whereas the alpha diversity of shrubs and bryophytes showed a U-shaped relationship and a hump-shaped pattern. The beta diversity of shrubs, herbs, and bryophytes increased above the subalpine-alpine ecotone. In accordance with these changes, the dominance of evergreen shrubs and graminoids increased above this ecotone, whereas that of evergreen trees and liverworts decreased. None of the plant groups showed a wide elevational range at higher elevations. These elevational patterns of plant groups were explained by climatic factors, and not by elevational diversity gradient hypotheses. Of note, the changes in the dominance of plant groups with elevation can be attributed to plant-plant interactions via competition for light and the changes in physical habitat. These interactions could alter the elevational diversity gradient shaped by climatic factors.
海拔高度参与决定山地生态系统中的植物多样性。本研究调查了日本中部八岳山的植物分布是否证实了与海拔多样性梯度相关的假说。在海拔1800米至2800米之间以200米的海拔间隔设立的研究样地中，对乔木、灌木、草本植物、蕨类植物和苔藓植物的物种丰富度进行了调查。结合气候因素和海拔多样性梯度假说，即质量效应、中域效应和拉波波特海拔规则，分析了植物多样性（α和β多样性、植物功能类型和海拔范围）随海拔的变化。此外，还分析了植物功能类型优势度的海拔格局。α和β多样性的比较表明，不同植物类群对海拔的响应各不相同；乔木和蕨类植物的α多样性降低，草本植物的α多样性增加，而灌木和苔藓植物的α多样性呈现U形关系和驼峰形模式。灌木、草本植物和苔藓植物的β多样性在亚高山-高山交错带以上增加。随着这些变化，常绿灌木和禾本科植物的优势度在该交错带以上增加，而常绿乔木和叶苔的优势度则降低。在较高海拔地区，没有一个植物类群具有广泛的海拔范围。植物类群的这些海拔格局是由气候因素而非海拔多样性梯度假说所解释的。值得注意的是，植物类群优势度随海拔的变化可归因于通过光照竞争的植物-植物相互作用以及物理栖息地的变化。这些相互作用可能会改变由气候因素塑造的海拔多样性梯度。
