4.5 Determinants of plant elevational patterns
In summary, this study showed that the changes in the elevational distribution of plants groups in the Yatsugatake Mountains were different from those predicted with the pertinent hypotheses but were rather directly and indirectly influenced by climate and its effect on plant-plant interactions. Therefore, our results correspond to Hypothesis 4, indicating that the applicability of hypotheses for predicting plant elevational patterns largely depends on the environment in the targeted study site.
Our findings demonstrated that the plant groups responded differently to different elevational gradients. These differences may amplify the effects of climate change in montane ecosystems. In particular, given that the plant diversity on the subalpine-alpine transition zone was based on the balance of plant-plant interactions, this ecotone may be vulnerable to climate change.
Previous studies reported that plant–plant interactions change the alpha diversity of plant groups among elevations (Bruun et al., 2006; Stehn, Webster, Glime, & Jenkins, 2010; Sun et al., 2013); this study went one step further and revealed that these interactions affect the beta diversity and dominance of plant functional types. These results imply the importance of studies on elevational patterns using multi-plant groups and multiple indices of plant diversity (e.g, alpha and beta diversity and functional types) to comprehend the interactions among plant groups. Specifically, given that plant functional types consist of those species with similar characteristics and are applied to other areas with different flora, our results linked to functional types can be useful to understand the mechanisms that shape plant diversity along elevations.
TABLE 1. Relationships between the alpha diversity of different plant groups and climatic factors in the Yatsugatake Mountains in central Japan, obtained using generalised linear models.