4.1 Environmental Factors Affecting T. sinense
Distribution
Results from the jackknife test and analysis of the main parameter table
underscore that the potential distribution of T. sinense is
influenced by four key environmental factors: Bio4, Bio6, T_CACO3, and
Elevation. Elevation plays a significant role in species distribution by
indirectly affecting temperature and precipitation (Clark et al., 2007;
Ma et al., 2021). While topsoil calcium carbonate does impose some
restriction on plant distribution, its impact appears less pronounced
(Wang et al., 2023). Therefore, temperature emerges as the primary
factor shaping the geographical distribution of T. sinense , a
finding corroborated by previous studies. Li (2021), for instance,
employed the concept of space-time substitution to investigate the
influence of altitude on the reproductive characteristics of T.
sinense , proposing that temperature variations impact species fitness
and could prompt migration to higher altitudes with rising temperatures.
Similarly, Chen et al. (2023) through correlation analysis of
chronological and meteorological factors, identified air temperature
during specific periods as a key influencer during T. sinense growth stages.
The permutation importance (PI) and jackknife tests further highlight
the critical role of the minimum temperature of the coldest month (bio6)
in shaping the potential geographical distribution of T. sinense .
This finding aligns with observations in other species such asQuercus mongolica (Yin et al., 2013) , Santalum album (Hu et
al., 2014) , Gymnocarpos przewalskii (Zhao et al.,2020) , andThuja sutchuenensis (Ma et al., 2021) . Chen’s research also
revealed a significant negative correlation between T. sinense growth and the lowest temperatures in November. Consequently, the
minimum temperature during the coldest month emerges as a pivotal factor
constraining northward expansion of T. sinense . Low temperatures
not only hinder seed germination and morphological development but also
pose challenges to the species’ cold resistance, ultimately impeding its
normal growth and development in northern China.