Geography Reference
In-Depth Information
to reclaim in this study. We also assumed no change in GCAM model. Besides,
according to the accuracy analysis in Table
3.4
, the total average error is about
8.67 %. The good accuracy of simulation indicates that the model is suitable to
simulate land use change trends of China.
3.1.4.2 Simulation of Land Use Change Under Three Scenarios
Land Use Change Under BAU Scenario
Under BAU scenario, we use GCAM model to simulate the trends of land use
changes that drove by inertial socio-economic growth (Fig.
3.2
).
As shown in Fig.
3.2
, under BAU scenario, cultivated land increases first and
then decreases. The total forestry area is relatively stable, while the managed
forestry area shows a downward trend during 1990-2005, then increases gradually
after 2005, and stabilizes in 2080. The unexplored forestry area reduces before
2080, and then steps into a stage of steady increase. Due to expansion of the range
of human activities, the managed grassland goes up until 2065, and then is in a
steady stage during 2065-2095. As for the unexplored grassland, it declines from
1990 to 2050, and tend to be stable after then. The total grassland also decreases
first and then in a stable condition. Urban area under BAU scenario has no sig-
nificant expansion, but it will still increase steadily, and the extent is relative small.
Because of the current rapid development, more food demand requires more
cultivated land, thus cultivated land increases rapidly, and it will reach the max-
imum before the middle of twenty-first century. With the technological develop-
ment, agricultural productivity increases gradually, and the decreasing dependence
on cultivated land needs less cultivated land, so that cultivated land decreases all
the way since the middle of twenty-first century, and the rate of declining will
gradually increase first and then gradually decrease.
Land Use Change Under REG Scenario
In REG scenario, under the drive of socio-economic and simulation results with
GCAM model, we obtained the land use change trends (Fig.
3.3
).
The simulation results of land use under REG scenario show that the obvious
land use characteristics is that urban area increased significantly due to rapid
urbanization. Cultivated land still increases first during 2010-2035 and then
decreases after then. Accelerated economic development promotes the rising
demand for timber, As shown in Fig.
3.3
, the total forestry area decreases sig-
nificantly, and the explored forestry area increases all the way. Rapid economic
development accelerates the scarcity of resources; moreover, the demand gap will
be widened under REG scenario. The total area of grassland is in a downward
trend, and the unexplored grassland reduces all the way, while the explored
