Topography-dependent Pattern of Tree Species Distribution on Different Spatial Scales in a Subtropical Evergreen Broad-leaved Forest

I evaluated the difference in the topography-dependent pattern of tree species distribution in a subtropical evergreen broad-leaved forest in the northern part of Okinawa Island. The values and spatial patterns of relief and slope changed with the difference in the spatial scale. The slope and relief had significantly positive relationships between the different scales. The rank of median for the slope and relief of the quadrat in which tree species occurred was not so different with the spatial scale. On the other hand, variable topography-dependent patterns of each tree species distribution were detected on different spatial scales. Castanopsis sieboldii trees clumped in a small convex area (5 mx5 m) both on large convex and concave areas (35 mx35 m), though they distributed on more convex slopes on every spatial scale. Schima wallichii trees distributed on steeper and more concave slopes than C. sieboldii on every spatial scale. With an increase in the tree sizes, C. sieboldii trees distributed on gentler and more convex slopes, while S. wallichii did not show such a significant pattern. The topography-dependent patterns of tree species distribution could be from the topographic structure of the study plot, in addition to being from the results of the tree population response to the topography.