公主岭市土地利用变化的生态效应研究

The Ecological Effect of Land Use Change in Gongzhuling County

不同的景观结构组成和空间配置具有不同的生态效应，因此土地利用，土地覆被变化会影响生物多样性和生态系统功能的发挥。本文选取1975年Landsat／MSS影像数据和1986年、1996年和2000年Landsat／TM标准假彩色合成影像作为基本信息源，借助GIS空间分析和地统计分析功能，从景观生态学角度提出了景观生态指数来反映LUCC变化所带来的生态效应。研究发现，近30年来公主岭市土地利用，土地覆被变化显著。1975年～1986年间各类土地利用类型的变化尤为明显，到1996年-2000年间土地利用变化的速度明显减慢。从土地资源分布重心可以看出，土地利用分布空间变化主要是由耕地的变化引起的。景观生态指数计算结果表明，公主岭市1975年～1986年间由于土地利用，土地覆被变化造成的生态风险不断增加，随后逐渐减小，这种变化与该地区土地利用类型的变化，特别是耕地、林地和草地的变化趋势呈高度相关，说明该地区土地利用／土地覆被变化对生物多样性及生态安全具有重要影响。

Different landscape patterns have different ecological effects. Thus, the changes of land use/cover will influence biodiversity and the function of ecosystem. Using the Landsat/MSS data in 1975 and the Landsat/TM data in 1986, 1996 and 2000, this paper obtains the land-use map in 1975, 1986, 1996 and 2000 and the dynamic data from 1975 to 2000. The research shows that the land use/cover has changed greatly in Gong Zhuling County during the last 30 years, especially from 1975 to 1986. During that period, some kinds of land use area have increased, including dry land, shrubbery land, town and construction land, residential land and the reservoir. The velocity of land use change has decreased evidently from 1996 to 2000 and the area of paddy field and shrubbery land has increased. Spatial change of distribution of land use was mainly caused by the cultivated land changes. Supported by GIS analysis and geological statistical analysis, this paper proposes the landscape ecological index and selects the fragmentation index, the isolation and the dominance index reflecting the ecological effect of LUCC change. The three indices reflect the ecological effect of landscape pattern from different aspects. This paper adds them up in order to reflect the integral effect. The results show that the landscape ecological index has changed distinctly from 1975 to 2000. It shows rising trend from 1975 to 1986. It is related to the area decrease of woodland and grassland and the rapid increase of dry land. Due to the policy of converting cropland to forest and grassland, the ecological risk of this region has decreased from 1986 to 1996 and the ecosystem function has tended to be Optimized. This trend remained in 2000. From the spatial distribution, we can see that the landscape ecological index of different regions has great difference during the research period. The high value lied in the southeast and northeast of Gong Zhuling County in 1975. Then it moved to the south in 1986 and it transferred to the southwest in1996 and 2000. This change is consistent with the change of land use, especially the change of farmland, forestland and grassland. It shows that the land use/cover change has important effect on the biodiversity and ecological safety.