海口市生态用地变化与安全格局构建

城市化过程中,城市生态用地变化与安全格局构建对于城市生态系统健康、城市居民生活质量和城市可持续发展有着重要意义,生态用地的变化直接影响生态安全格局变化,生态用地安全格局又对生态用地的规划有指导作用。基于GIS技术,对海口市1991年至2016年生态用地的时空变化过程进行研究,进而分析生态用地演变。选取高度、坡度、水资源安全作为生态安全影响单因子,并分级赋值,构建综合生态用地分布格局。以底线型生态用地为源,基于最小累计阻力模型(MCR),以阻力阈值作为分级边界,划分不同安全水平的生态用地区域,进而确定源间生态廊道、辐射道与战略点,构建生态用地安全格局。分析结果表明:1991年至2016年,海口市三类生态用地变化最大,其中林地减少13.33%,园地增加9.136%,坑塘水面增加3.71%。南渡江以西生态用地从以林地为主转为园地与建设用地为主,其余地区变化较少。生态用地安全变化区域集中在海口市西部与东部,其中西部高安全水平区减少,整体安全水平急剧恶化,东部高安全水平区略有提升。故需要制定和实施合理的生态用地保护政策,对生态用地格局进行优化调整,以期构建区域内生态环境协调发展的可行方案。

Ecological land use change and construction of ecological land security pattern in Haikou city

In the process of urbanization, the change of urban ecological land use and the construction of a safety pattern are of great significance for the urban ecosystem health, the quality of life of urban residents, and the sustainable development of cities. Ecological land use change affects the ecological security pattern directly. The ecological land security pattern has a guiding role for the planning of ecological land. Based on the GIS technology, the temporal and spatial changes of ecological land in Haikou from 1991 to 2016 and the evolution of ecological land were studied. Selected height, slope and water resource security as single factor of ecological safety impact, give them graded amounts to build a comprehensive ecological land distribution pattern. Based on the minimum cumulative resistance (MCR) model, the resistance threshold was used as the hierarchical boundary, the ecological land area of different safety levels was divided, and then the ecological corridors, radiators, and strategic points were established to build a security pattern of the ecological land. The results showed that from 1991 to 2016, the three types of ecological land areas in Haikou City had the biggest changes, with the forest land decreasing by 13.33%, the garden area increasing by 9.136%, and the pond water surface increasing by 3.71%. The ecological land to the west of Nandu River mainly changed from forest land to garden land and construction land, and the rest of the area changed less. The high safety level area in 1991 was much larger than in 2016, but the low safety area was lower than in 2016. The overall trend gradually deteriorated. Over two years, the western and southern areas of the two "source" as the center, the high security area, the safety area, and the low security area formed a circular arrangement, while the Nandu River was the "source", with high, medium, and low areas localized along the river. In 2016, the corridors were arranged in three rings, distributed evenly throughout the city, but the relationship between the sources was weakened. The radiation path was still irregularly distributed, while the number of strategic points decreased significantly compared with those in 1991, indicating that the ecological impact and imbalance of each part become more and more serious, the stability of ecological safety in the region has been destroyed. The area where ecological land use change occurred is concentrated to the west and east of Haikou City, while the high safety area to the west of Haikou was reduced and the overall safety level deteriorated rapidly. The high safety level area to the east slightly improved. Therefore, it is necessary to formulate and implement a reasonable ecological protection policy and land use pattern to optimize the adjustment, with a view of building a coordinated environment for coordinated development of the ecological environment within the region.