3.1 Ecological niche modelling
Evaluation of model performance based on both training and test sample
data indicated that the models had high predictive power (AUC = 0.9976
and 0.9966, respectively). Results yielded a continuous geographical
distribution of C. chuniana across several mountain ranges in
southern China during the LIG (Figure 2a). In contrast, during the LGM
the geographical distribution contracted into three fragmented areas
(Figure 2b). We compared these data to a vegetation map of the LGM
(http://intarch.ac.uk/journal/issue11/2/map/download_page_js.htm),
based on which the three fragmented distribution areas were located
mainly inside forest steppe (number 7) and partially in semi-arid
temperate woodland or scrub (number 3) (Ray & Adams, 2001). The
geographical distribution of C. chuniana was inferred to have
expanded widely during the MH, occupying most of the Chinese subtropical
region. No changes in the geographical distribution were evident between
MH and current. Precipitation in April, May and June was revealed to be
the most influential climate factor for suitable distribution range ofC. chuniana (Table S1).