4.2 Changes in the Potential Geographical Distribution of
T. sinense
Our investigation revealed fluctuations in the total suitable area ofT. sinense , which decreased from 758,258 km2 to
731,469.3 km2 from the last interglacial period to the
last glacial maximum. During this period, suitable habitat contracted,
primarily concentrating in the central part of southwest China. The
mountainous terrain in this region acted as a barrier against cold air,
mitigating extreme climate fluctuations and providing stable conditions
conducive to species survival (Stewart et al., 2010; Li, 2017).
Furthermore, the absence of geographical barriers facilitated migration
to this area, establishing Southwest China as a critical refuge for the
Tertiary relict T. sinense (Chen et al., 2011; Liang, 2020) .
Subsequently, from the last glacial maximum to the mid-Holocene, the
total suitable area expanded to 750,132.8 km2, with
suitable habitat extending outward from the Sichuan Basin and
Yunnan-Guizhou Plateau. This expansion correlates with the warmer and
wetter global climate during the mid-Holocene, aligning with the
hydrothermal conditions favorable for T. sinense growth.
Consequently, the population of T. sinense exhibited significant
glacial contraction and post-glacial expansion, consistent with findings
for other species such as Thuja sutchuenensis (Qin et al., 2017) ,Davidia involucrate (Ye et al., 2021) , and Ulmus elongate
(Zhang et al., 2021) .
In the future, global climate warming is anticipated to substantially
impact suitable habitats for T. sinense , resulting in a
significant distribution shift. The extent of this shift varies
depending on emission scenarios, with the largest loss area observed in
the SSPs8.5 scenario and the smallest in the SSPs2.6 scenario. This
disparity is attributed to temperature surpassing the threshold required
for optimal T. sinense growth in the SSPs8.5 scenario.
Consequently, temperature increase emerges as a primary driver of future
reductions in suitable distribution areas. Extensive research
underscores the transformative effect of climate change on species
distribution, often leading to migration towards higher latitudes
(Thuiller, 2003; Chen et al., 2011). Consistent with this trend, our
study forecasts a shift in T. sinense ’s suitable habitats to
higher latitudes under future climate scenarios. These observations
suggest that previously unsuitable high-latitude regions may become
conducive to T. sinense survival as global temperatures rise,
making them preferred areas for ex situ conservation efforts. Overall,
the dynamic response of T. sinense ’s geographical distribution to
climate fluctuations underscores its adaptive capacity to climate
change, highlighting the necessity for strategic conservation measures.