To quantify species β-diversity in relation to spatial distance,
regional differences, and elevation gradient, the grouped plot-level
β-diversity matrix was calculated and then partitioned into various
independent spatial components that reflect various β-diversity levels
(β-dissimilarity between sampling plots within regions) and δ-diversity
(δ-dissimilarity between regions). We thus calculated insect species
dissimilarity of (1) plots within transects (β1: 40-100
m scale), (2) plots between two neighboring transects within a region
(β2: 200-300 m scale), (3) plots between two transects
covering the highest elevation gradient within a region
(β3: 1-3 km scale), (4) plots between two neighboring
regions (δ1: 250-300 km scale), and (5) plots between
two regions covering the highest spatial distance (δ2:
> 500 km scale). We firstly performed two-way ANOVAs to
test for differences in Horn similarity values between insects and
plants at various spatial scales, and the checking of residuals’
normality and homoscedasticity caused doubt about the robustness of the
anova result, so we choose Nonparametric Kruskal–Wallis ANOVA, followed
by Scheffe’s post hoc tests. The spatial component of turnover in tree
species composition was investigated in an identical fashion. Next,
Wilcoxon paired tests were used to assess whetherβ-diversity was similar
for trees and beetles for each respective separation distance (i.e.,
β1, β2, β3,
δ1andδ2). P-values were adjusted
accordingly (Bonferroni corrections).