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 fragmentation 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 patches. However, during 2000—2010 the area of urban green patches gradually increased, the patch integration enhanced, and the landscape fragmentation decreased through construction of urban parks, afforestation in barren hills, and ecological restoration. A typical defragmentation trend was observed.

Conclusion Ecological restoration and reconstruction in an organized process can effectively improve the landscape condition of urban forest and increase urban forest coverage.