3.2 Importance of Environmental Variables Affecting T.
sinense Distribution
The influence of 16 environmental factors on distribution was evaluated
through a jackknife test (Fig. 2). Notably, the contribution rates (PC)
of Bio6 (44.60%), T_CACO3 (10.29%), and Bio9 (8.90%) ranked highest,
with a cumulative PC of 63.79%. Similarly, the permutation importance
(PI) of Bio6 (34.18%), Bio4 (25.70%), and elevation (21.18%) were
among the top three, with a cumulative PI of 81.06%. This analysis
revealed that the primary environmental factors shaping the current
geographical distribution of T. sinense include bioclimatic
variables (Bio4 and Bio6), soil variables (T_CACO3), and topography
(Elevation) (Table 3).
Environmental factor response curves further elucidated the relationship
between the probability of T. sinense occurrence and
environmental variables (Fig. 3). Generally, when the probability
exceeded 0.5, corresponding environmental factor values favored T.
sinense growth. Based on these curves, suitable environmental factor
ranges for T. sinense growth were determined as follows: 407.4 to
731.3 (Bio4), -8 to 0.61°C (Bio6), 0% to 0.17% (T_CACO3), and 1355.8
to 3508 m (Elevation).