Statistical estimation the effect of edaphic, topography, DBH,
genetic variation and spatial on MVPS
The relative influence of microhabitat, individual life stage, genetic
variation and spatial attributes on MVPS were determined by using MRM in
R 3.1.0 with the “ecodist” packages (Goslee & Urban, 2007). MRM, an
extension of partial Mantel analysis, can employ non-parametric or
non-linear multiple regression. In this study, independent variables
increasing one by one from single edaphic variables to multiple
variables, such as edaphic, topography, spatial, individual life stage
and genetic variation were used to construct five MRM models. We first
used Spearman correlations to assess the relationships between
environmental distance matrices and the MVPS matrix; then the
significant explanatory variables were identified using a
forward-selection procedure; finally, the significance of MRM models was
tested with 1,000 permutations on the objects of the response distance
matrix. The r2 from MRM analyses was used to assess
MVPS variation explained by these significant environmental variables,
and the significantly correlated variables were excluded within each
group of variables (edaphic, topography, individual life stage, genetic
variation and spatial variables). The relationship between DBH and
methylation level was also analysed with MRM.