What shapes the elevational patterns of plant diversity on Mount
Yatsugatake, Japan?
Abstract
Aim: This study examined whether the hypotheses associated with species
distribution could substantiate the elevational patterns of plants.
Location: Mount Yatsugatake in central Japan. Taxon: Embryophyte
Methods: The species richness of plant groups (trees, shrubs, herbs,
ferns, and bryophytes) was investigated within study plots established
at 200-m elevational intervals from 1800 m to 2800 m. The changes in
species richness (alpha diversity) with elevation were analysed in
relation to climatic factors and the hypotheses pertaining to the
elevational distribution of plants, i.e., mass effect, mid-domain
effect, and Rapoport’s elevational rule. The elevational patterns of
beta diversity, plant functional types, and elevational ranges of plant
groups were examined. Results: The comparison of alpha and beta
diversity revealed that the different plant groups variably responded to
elevation; the alpha diversity of trees and ferns decreased, that of
herbs increased, whereas that of shrubs and bryophytes showed a positive
and negative quadratic curve, respectively. The beta diversity of
shrubs, herbs, and moss abruptly increased above the subalpine-alpine
transition zone. In accordance with these changes, the dominance of
evergreen shrubs and graminoids increased, whereas that of liverworts
decreased at the elevation zone. Regarding the elevational ranges, no
plant group showed a wider elevational range at higher elevations. Main
conclusions: The elevational patterns of the plant groups were
determined by the climatic factors and their effects on plant-plant
interactions. Notably, these interactions were presented based on the
changes in plant functional types, supporting the elevational patterns
of plant diversity. Our finding indicates the importance of studies on
elevational patterns using multi-plant groups and multiple indices of
plant diversity.