Study on the Change Trend of Ecosystem Pattern and Stability of Nature Reserves in Shanxi Province
2018, 33 (2):
Knowing the ecosystem pattern of nature reserves is of great significance to the understanding of the status of the ecological environment, the valuation of the protection effect, and the proposal of protective measures. In this paper, the transition trend of ecosystem pattern of nature reserves in Shanxi during 2000-2010 was analyzed with ecosystem transfer matrix and the Positive and Negative Transformation Index (PNTI) model, and the stability of ecosystem was analyzed with Shannon-Wiener diversity index and Net Primary Productivity (NPP) grading standard. The results showed that: 1) Forest ecosystem was the main ecosystem in the nature reserves in Shanxi, followed by grassland ecosystem and farmland ecosystem. From 2000 to 2010, the area of forest ecosystem increased, while the area of grassland ecosystem and farmland ecosystem decreased. 2) During the ten years, the grassland ecosystem had the largest area that transformed into forest ecosystem, which was 1 117.21 km2. It was the result of the natural forest protection project, Taihang Mountain greening project and plain greening project in Shanxi. In addition, 49.1 km2 farmland ecosystem transformed into forest ecosystem, which indicated that the vegetation was restored and the ecological environment was improved during the ten years. However, due to human disturbance, 466.72 km2 forest ecosystem degenerated into grassland, 3.63 km2 forest ecosystem and 5.92 km2 grassland ecosystem transformed into farmland ecosystem, and 4.18 km2 grassland ecosystem became construction land, which indicated that the management and rehabilitation of relevant nature reserves need to be strengthened. 3) The positive conversion rate of nature reserves was higher than the reverse conversion rate, and the ecological system pattern was developing in a favorable direction. The net conversion rate of the grassland meadow reserves, forest ecosystem reserves and wild plant reserves was 29.47%, 8% and 4.04%-7.32%, respectively. However, the net conversion rate of wildlife reserves was less than 1.1%, and the protective effect in wildlife reserves was weak. 4) The diversity index of nature reserves showed an increasing trend, and the stability of ecosystems enhanced. The total amount of NPP in the nature reserves increased from 2.51×107 g C to 2.59×107 g C. In general, the vegetation growth status of the nature reserves improved during the ten years. The average NPP of nature reserves was between 50-100 g C·m-2·a-1, belonging to the third-class vegetation NPP according to the NPP classification standard of China, which indicated that the ecosystem restoration stability of the nature reserves was strong. However, the NPP of the wildlife reserves, the wild plant reserves and the grassland meadow reserves decreased, and the stability of restoration in these areas became weak. In summary, the ecosystem structure of the nature reserves in Shanxi Province was developing in a favorable direction, the impedance stability and the restoration stability of the ecosystem were increasing, and the growth of vegetation was improved. The protection of forest ecosystem reserves was the most prominent, while the ecosystem stability of other reserves was weak, especially wildlife reserves, such as Lingqiu Black Stork Nature Reserve and Zezhou Monkey Nature Reserve, where there exited degradation phenomenon of forest and grassland. The management and reparation of wildlife reserves need to be strenghened.
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