Analysis of landscape pattern changes in different periods

(a) Landscape pattern changes at the level of landscape types

1. Landscape pattern changes at the level of secondary landscape types

The secondary landscape types were compared from two aspects: area and patch number. After 13 years, the forestland area increased significantly, increasing by 4446.56hm2, while the marshland and sparse forestland area decreased significantly, decreasing by 4802hm2 and 1 199hm2 respectively. The number of patches with woodland increased obviously, and the degree of fragmentation increased. Generally speaking, woodland is the landscape matrix of the study area, which plays a leading role in the overall structure, function and dynamic process of the landscape. The area of marshland has decreased by 4802.06hm2, and the area of sparse forest land has decreased by1199.16 hm2, which will indirectly affect the local climate in this area. Cutting land decreased by 373.23hm2, other land decreased by 308.35hm2, and non-forestry land decreased by 155. 1 1hm2, which is closely related to local closing hillsides to facilitate afforestation and changing forest management measures, reflecting the basic process of forest vegetation restoration and landscape quality improvement in forest areas. See Table 3-9.

Table 3-9 1987 and Analysis Table of Composition Change of Secondary Landscape Types in 2000

2. The landscape pattern has changed at the level of three landscape types.

According to the analysis in Table 3- 10 and Figure 3-5, the proportion of Korean pine forest in the total area increased from 0.402 1 in 1987 to 0.7409 in 2000, and the number of patches increased from 42 in 1987 to/kloc in 2000. The area of spruce-fir forest increased from 293.06hm2 to 65 1.88hm2, and the number of patches also increased from 15 to 80. Larix gmelinii also showed a similar trend, increasing from 33963.83hm2 to 44596.34hm2, and its proportion increased from 15.45% to 25.42%, and the area of mixed coniferous and broadleaved forests. The area of mixed coniferous and broad-leaved forest increased from 13406.50hm2 to 19729.63hm2, and the number of patches increased from 355 to 1059. The area of oak forest decreased from 9634.62hm2 to 7905.80hm2, and the number of patches increased from 393 to 545. The area of broad-leaved mixed forest decreased from 92579.00hm2 to 76097.38hm2, and the number of patches changed little. The proportion of Betula platyphylla forest in the total area increased from1.65,438+0.973 in 987 to 8.7539 in 2000, and the number of patches increased from 1.30 to 1.6544. In Yang Shulin, the proportion decreased from 9.2058 to 2.0072, the number of patches decreased from 836 to 370, and the dominance decreased. Comparatively speaking, from 1987 to 2000, the area of Shuihu forest changed the most, and the area decreased from 1 199 1.42 to 86.555438+0, followed by Yang Shulin, with an area of 20239./kloc. In 2000, the area of landscape types increased the most, including larch forest, coniferous and broadleaved mixed forest and birch forest.

Table 3- 10 1987 Comparison of Three-level Landscape Type Index with 2000

Figure 3-5 Stand Area in Different Years

For fractal index, the order of 1987 is mixed forest > mixed forest > Korean pine forest > birch forest > broad-leaved mixed forest > water Lin Hu > Yang Shulin > oak forest > larch > coniferous forest > spruce-fir forest; In 2000, water Lin Hu > miscellaneous forest > oak forest > birch forest > spruce fir forest > Korean pine forest > broad-leaved mixed forest > Yang Shulin > larch > mixed forest > coniferous forest, 1≤MPFD≤2. The larger the value, the more complex the shape of the patch boundary. It can be seen that the fractal index of patches and landscape types with smaller area changes greatly, and the boundary shape of sub-blocks is more complicated.

For patch density, the order of patch density in 1987 is broad-leaved mixed forest > larch > Yang Shulin > oak forest > coniferous and broad-leaved mixed forest > Lin Hu > coniferous and broad-leaved mixed forest > birch forest > Korean pine forest > miscellaneous forest > spruce-fir forest; In 2000, the order of patch density was broad-leaved mixed forest > larch forest > birch forest > coniferous and broad-leaved mixed forest > oak forest > Yang Shulin > coniferous and broad-leaved mixed forest > miscellaneous forest > Korean pine forest > spruce-fir forest > Lin Hu. Compared with the two periods, the patch density has little change, which shows that the patch density reveals the degree of landscape fragmentation in a certain sense, and the patch density can not fully reflect the spatial structure characteristics.

(B) Landscape pattern changes on the landscape scale

Table 3- 1 1, comparing the different land use conditions in this area, the number of patches increased from 8079 in 1987 to 5670 in 2000, and the maximum patch index (LPI) was greatly reduced. Starting from 0. 1987 in 2486 is 0. In 2000, the patch density decreased from 4. 5798 changes to 7 at 1987. In 2000, it was 24 15, which reflected that the degree of landscape fragmentation in this area increased in 2000. The landscape diversity index (SHDI) ranges from 0. 1987 in 4904 is 0. 4 175, which also reveals the decline of landscape diversity, which is manifested by the obvious increase of woodland area. However, due to the different changes of different tree species, this will be analyzed later. The landscape fractal dimension (MPFD) and evenness index (SHEI) did not change much, but generally decreased in 2000 compared with 1987, indicating that the landscape was more and more dispersed in geographical distribution.

Table 3- 1 1 Comparison of landscape indices of secondary landscape types Table 3-1/comparison of secondary landscape indices 1987 and 2000.

The analysis results in Table 3- 12 show that compared with the landscape conditions of different forest types in this area, the number of patches has increased, from 89 16 in 1987 to184 in 2000, with an increase of 2268 patches. Starting from 0. 1987 in 2492 is 0. 07215 in 2000, the patch density was from 4. 05 in 1987 to 6. 37 in 2000. These indicators all reflect the increase of landscape fragmentation in this area in 2000, which indicates that the landscape has been divided. The evenness index represents the evenness of different landscape types in the landscape. The closer Shannnon evenness index (SHEI) is to 1, the more uniform the distribution of all types in this area. Shannnon evenness index in this area shows a downward trend, indicating that the distribution of types in this area is uneven. The landscape shape index (LSI) reflecting the ratio of patch perimeter to area and the average patch fractal dimension reflecting the complexity of landscape shape all decreased. The landscape diversity index ranges from 1. 79 to 1. 58, reflecting the decline of landscape diversity, showing an increase in the proportion of landscape elements. From the ecological point of view, the improvement of landscape pattern diversity can provide more diverse habitats, thus increasing species diversity; Conversely, it is not conducive to the development of species diversity. Shannon's diversity and evenness index decreased, indicating that the degree of landscape heterogeneity decreased and the landscape types tended to be single or unbalanced.

Table 3- 12 Comparison of Landscape Index of Three Landscape Types