4.2 Spatial transformation characteristics of T. chinenseunder climate change scenarios
In this study, Biomod2 was used to predict the distribution of T.
chinense in Asia, and the results were not completely consistent with
the regional niche results predicted by Tang et al. and Gao et al. using
the MAXENT model (P. Gao et al., 2023; Tang et al., 2021). It is
speculated that there are four reasons for this result. The first point
is the choice of modeling scope. In the existing studies, the methods of
constructing species distribution models are divided into complete and
regional niche models. Complete niche models are more reliable models
for describing the climatic niche of species because they can calibrate
the presence and capture a wider range of occupied environmental
conditions (Pearson et al., 2004). However, if unoccupied but
environmentally suitable areas for the species are considered for model
training, then the capacity to predict the species’ potential
distribution will be reduced (Acevedo et al., 2012). Barve et al. argued
that the appropriate geographical background for model training,
validation, and comparison should comprise the set of localities that a
species has over its history (Barve et al., 2011). In this study, the
geographical distribution of T. chinense was reviewed, and the
region with the highest accessibility (Asia) was selected as the study
area. In addition, the use of ensemble species distribution model can
reduce the instability of a single model (Goldsmit et al., 2020; Araújo
& New, 2007), and can more accurately predict the range of suitable
areas of T. chinense . Secondly, there is a serious bias in the
geographical distribution of the occurrence data used by Tang and Gao et
al. in constructing the model (P. Gao et al., 2023; Tang et al., 2021).
Through our field investigation, we found T. chinense populations
also distribute in the high-latitude areas in the northern of China.
However, in the studies of Tang et al and Gao et al., there are few or
even no occurrence data of T. chinense in high latitude areas,
relatively concentrated data in low latitude in the southern of China,
which is biased from the real occurrence data of T. chinense .
This biased regional data cannot objectively identify the niche of
species (El‐Gabbas & Dormann, 2018). In addition to the above factors,
we speculate that the choice of factors is also one of the reasons for
the different results. As a semi-parasitic plant, vegetation (host) is
the premise for the good growth of T. chinense , so biological
factors play a certain role in the distribution modeling of the species.
At present, the inclusion of interspecific interactions is considered to
be the main challenge for species distribution modeling (Y. Wang et al.,
2022). Considering that there are many host species of T.
chinense , mainly Asteraceae, Fabaceae, and Poaceae, and the host
distribution is extensive (Guo & Luo, 2011), we included NDVI data
reflecting vegetation growth in the species distribution model. Although
NDVI data can not describe the specific conditions of vegetation
classification groups in the land acquisition table, we believe that the
inclusion of NDVI data may make the modeling results closer to its real
niche for T. chinense .
Compared with the current, the suitable areas of T. chinense show
an increasing trend under the combination of future climate scenarios.
Spatially, consistently with the migration direction of most plant
species (B. Chen, Zou, et al., 2022; W. Li et al., 2019; Yin et al.,
2022; L. Zhang et al., 2022), the overall distribution areas gradually
move to the northwest of the current suitable areas (high latitude and
high altitude areas). In the future, the suitable areas of T.
chinense in China will mainly expand to Tibet. The expansion area is
currently located in the semi-arid area, and its soil moisture content
can meet the needs of the growth of T. chinense . However, due to
the high altitude, its temperature is lower than other semi-arid areas
suitable for the growth of T. chinense . Therefore, this area is
not suitable for the growth of T. chinense in the current
climate. In the future, the plateau temperate zone in the southern of
China will expand northward, gradually replacing the plateau sub-cold
zone in western China, and gradually increasing the temperature in this
region (S. Wu et al., 2010). Therefore, the climate conditions in this
area may be similar to those in the current suitable areas of T.
chinense in the future, which may be one of the reasons for the
expansion of the suitable areas in this area. In the future, the
disappearing areas of suitable areas of T. chinense are mainly
located in the southern of China, which will change from the subtropical
zone to the tropical zone with climate warming in the future (S. Wu et
al., 2010). At the same time, the increasing temperature will reduce the
moisture of the surface soil, increase evaporation, reduce the Climate
Moisture Index, and is not conducive to the absorption of soil fertility
(Michaelian et al., 2011; Peng et al., 2011). This will make the areas
no longer suitable for the growth of T. chinense .