4.2 Spatial distribution relationship between the SCE and the GFG
intensity
Figure 4a provides the spatial distribution of GFG intensity (the ratio
between the area of cultivated land converted to forest or grassland and
the area of original cultivated land in a region) in Yan’an, which shows
significant spatial agglomeration. The high-intensity areas of GFG are
concentrated in Wuqi, Baota, Zichang, and Luochuan. The low-intensity
areas are mainly distributed in Ansai, Huanglong, Yanchang, and Ganquan.
It can be seen that this agglomeration is controlled by the county
boundaries. This is because, in China, the formulation and
implementation of related measures of the GFG are based on counties, so
there can be significant differences in the intensity of GFG among
counties. Figure 4b shows the SCE produced by GFG in Yan’an. It can be
found that its spatial distribution also has an obvious agglomeration
effect. The areas with obvious SCE are mainly distributed in the east,
south, and Ansai in the north. While counties such as Wuqi, Zhidan, and
Baota have achieved certain results in soil conservation, they are not
as obvious as in other regions.
[Figure 4 near here]
Although the above two indicators have their specific spatial
distribution law, the correlation between them is not significant, and
the correlation coefficient is only −0.12. By comparing Figure 4a and
4b, it can be found that Wuqi, Baota, Zichang and other places with
higher GFG intensity have lower SCE. Yanchuan, Yanchang, and Yichuan,
where the SCE are obvious, have less GFG intensity. This situation
reflects the mismatch between the GFG intensity and the SCE in spatial
distribution. That is, the SCE is not necessarily better in areas with
relatively high GFG investment. Considering that the main purpose of GFG
in this region is soil conservation, it can be considered that the
current GFG does not achieve optimal input allocation.
As mentioned earlier, the optimal allocation of GFG investment should be
concentrated in regions with greater SCP. Therefore, we compared the SCP
before GFG (Figure 4c) with the GFG intensity (Figure 4a). It was found
that the matching degree of SCP and GFG at the spatial level was low,
and the correlation coefficient was only −0.05, which was obviously
inconsistent with the theoretical analysis. Considering that the GFG is
mostly implemented at the county level, the SCP before GFG and the GFG
intensity of all counties in Yan’an were ranked and compared. As shown
in Table 3, the ranking difference of most counties is large, which
further validates their inconsistencies. Taking Wuqi as an example, the
county has the least SCP before GFG. While its GFG intensity ranks the
3rd, indicating that the GFG intensity in Wuqi has far exceeded the
reasonable range of soil conservation. On the contrary, Yanchuan,
Yanchang, and Yichuan in eastern Yan’an, which have the greatest SCP
before the GFG and should have the highest GFG intensity theoretically.
However, the GFG intensity rankings are far from the SCP, which
indicates that the implementation of GFG in these areas needs to be
improved. These results indicate that the previous GFG investment did
not take into account the SCP, not only failed to achieve the optimal
SCE, but also caused a waste of resources. If the GFG investment can be
formulated and adjusted according to the SCP in each region, the
implementation efficiency of GFG can be greatly improved, so as to
achieve better SCE.
[Table 3 near here]
To better illustrate the above point, we calculated the ratio of the GFG
area and the soil erosion reduction (RGS) from 2000 to 2015. Comparing
the GFG areas in several counties under the premise of achieving the
same SCE (Table 4). Obviously, the RGS of Wuqi (1.836) is much higher
than that of Yanchang (0.105), Yichuan (0.196), and Yanchuan (0.307).
That is, under the premise of achieving the same SCE, the GFG investment
in Wuqi needs to be higher. The result indicates that if the focus of
GFG investment can be placed on counties with great SCP, the investment
cost of GFG will be significantly reduced, thereby saving capital and
resources.
[Table 4 near here]