快速城市化地区城市森林景观破碎化的动态演变分析

【目的】综合分析城市森林景观破碎化的动态演变趋势,为快速城市化地区的城市总体规划、绿地系统规划、森林城市建设、城市可持续发展提供科学依据。【方法】基于广东省惠州市1990、2000、2010年Landsat TM/ETM+卫星影像,采用景观格局数量分析和转移矩阵从中心区、近郊区和远郊区3个梯度分析城市森林景观破碎化动态特征及演变。【结果】惠州市城市中心区斑块密度由1990年的0.08个·hm~(-2)增加到2010年的0.25个·hm~(-2),平均斑块面积由11.81 hm~2下降到3.92 hm~2;近郊区的斑块密度和平均斑块面积也呈相似的变化趋势,但2000—2010年间的变化相对较小,说明破碎化斑块逐步缩小;在远郊区,景观破碎化趋势较为缓慢,斑块密度由0.18个·hm~(-2)增加到0.30个·hm~(-2),再降至0.11个·hm~(-2),平均斑块面积由9.12 hm~2减小至3.51 hm~2。在1990—2000年期间,城市无序和快速的扩张,城市绿地的斑块数量增多,面积减小;但在2000—2010年期间,通过城市公园、人工荒山绿化、生态修复等人工绿地的有序建设,城市绿地斑块面积逐渐增大,斑块整合逐渐加强,景观破碎化程度逐步降低,表现出典型的逆破碎化趋势。【结论】人为有序和有规划的生态修复和重建可以有效地改善城市森林景观状态,提高城市森林覆盖率。

Analysis on dynamic development of landscape fragmentation for urban forest in fast-urbanization regions

[Objective] The purpose of this study was to analyze dynamic development of landscape frag-mentation for urban forest in fast-urbanization regions, and provide scientific basis for master urban plan, urban green space system plan, urban forest construction and sustainable development in fast-urbanization regions. [Method]Based on the Landsat TM/ETM+ satellite images taken in 1990, 2000 and 2010, the dynamic trends of landscape fragmentation for urban forest in Huizhou, Guangdong were analyzed by landscape pattern indices analysis and transition matrixes along three gradients including the central area, suburban area, and outer suburban area.[Result]The patch density of the central area increased from 0. 08 to 0. 25 per hm2 during 1990—2010. Meanwhile, the mean patch area decreased from 11. 81 to 3. 92 hm2 . Similar changes in patch density and patch area happened to the suburban area, but the change scale reduced from 2000 to 2010 suggesting that the fragmented patches gradually narrowed in the central and suburban area. The landscape fragmentation process was relatively slow in the outer suburban area. The patch density of the outer suburban area first increased from 0. 18 to 0. 30 per hm2 , and then decreased to 0. 11 per hm2 , and the mean patch area decreased from 9. 12 to 3. 51 hm2. In 1990—2000, rapid and out-of-order urbanization led to the increased number and decreased area of urban green pat-ches. However, during 2000—2010 the area of urban green patches gradually increased, the patch inte-gration enhanced, and the landscape fragmentation decreased through construction of urban parks, affor-estation in barren hills, and ecological restoration. A typical defragmentation trend was observed. [Con-clusion]Ecological restoration and reconstruction in an organized process can effectively improve the land-scape condition of urban forest and increase urban forest coverage.