3.5 Distribution and change of land use pattern in
climate-stable areas of T. chinense in China
Kappa coefficient was used to verify the simulation accuracy between the
simulation results in 2015 and the actual land use data in 2015. The
results showed that the overall accuracy of the simulation results of
land use change in 2015 was 0.992 and Kappa=0.990, indicating that the
PLUS model was reliable and could predict future land use distribution.
The contribution degree of driving factors of each land use type change
was shown in Table S7. The largest contribution of driving factor of
grassland areas change was distance from water, followed by annual
precipitation (Figure. 7B).
Under different climate scenarios, the total area of climate-stable
areas of T. chinense in China is about 480.01 * 104 km2 (Figure
7A). According to the expansion and contraction trends of land use in
2010 and 2015, the distribution pattern of land use in 2050, 2070 and
2090 within the climate-stable areas is predicted (Figure S4). Among
them, the cultivated land, grassland, and unused land in the
climate-stable areas show a downward trend. And by 2090, they will
decrease by 1.63%, 13.84%, and 10.67%, respectively, compared with
2015 (Figure 7C). In the future, the land use types transferred to
grassland types mainly are forest, unused land, and construction land.
From 2050 to 2070, the areas will transfer from forest, unused land, and
construction land to grassland is about 1.83 * 104 km2, 0.90 * 104 km2,
and 0.70 * 104 km2. With the increase of the years, the transferred
areas gradually increase, and it is estimated that the transferred areas
from 2070 to 2090 are about 3.00 * 104 km2, 0.97 * 104 km2, and 1.08 *
104 km2. In the future, grassland will mainly transfer to forest and
construction land, and the transferred areas will increase from 4.65 *
104 km2 and 1.98 * 104 km2 in 2050 and 2070 to 5.80 * 104 km2 and 2.26 *
104 km2 in 2070 to 2090 (Figure 7C and Table S8). In the future, the
area of forest, waters, and construction land in this region will show
an increasing trend, especially the construction land. By 2090, the area
of forest and water will increase by 5.51% and 1.49%, respectively.
Construction land will increase to 25.71 * 104 km2, expanded by about
46.94%.