Study On Landscape Pattern Dynamics And Driving Forces In Mangrove Wetlands Of Dongzhaigang Harbour, Hainan Province

In this paper, theories and methods of landscape ecology, combined with geo-information technologies, field survey and statistical methods are employed to study mangrove wetland landscape pattern dynamics and its driving mechanism from 1988 to 2007 in Dongzhaigang Harbor. The characteristics of mangrove wetland landscape pattern and its spatio-temporal changes, the impacts of interference factors on mangrove ecosystem structure and function in recent 20 years have been studied. On this basis, the strategy of mangrove wetland ecosystems management in conservation mode was proposed. This would provide a scientific conference and practical guidance for the development and construction of mangrove wetlands in conservation area, it also can provide scientific support and decision-making consult for protection, using and ecological restoration of mangrove wetlands.The results show that:1. Along Dongzhaigang Harbor coast, the mangrove wetlands with zonal distribution is the main style. In addition, arable land, forest, and water aquaculture accounted for a large proportion, other land types mixed inside, and two-lane river runs through mangrove wetlands. In recent 20 years, landscape pattern of mangrove wetlands area become uniform, the difference of area between patches has gradually decreased, the diversity of landscape has increased, the fragmentation of mangrove landscape has gradually increased, and the degree of dispersion of landscape distribution has increased. It told us that the impact on mangrove landscape of human being has become stronger.2. In recent 20 years, with an increasing number of patches, shape index and fractal dimension of mangrove landscape increased, the complexity of patch shape increased. The degree of dispersion between patches increased, while connectivity decreased. This kind of mangrove landscape pattern change is harmful for biodiversity maintenance function of mangrove wetlands.3. From 1988 to 1996, the rate of mangrove wetlands maintained 97.57% in the study area. During these years, about 1.21% mangrove wetlands were converted to water aquaculture, while about 0.99% mangrove wetlands are converted to to the river. About 54.13% land suitable for afforestation and 13.14% two-lane river are converted to mangrove wetlands. From 1996 to 2007, about 94.29% mangrove wetlands were maintained, while about 3.02% of mangrove wetlands were converted to water aquaculture and 1.22% to two-lane river,0.93% to land suitable for afforestation. On the other hand, about 48.22% land suitable for afforestation,19.65% two-lane river and 5.05% water aquaculture were converted to mangrove wetlands. With the convert-in of mangrove wetland, the patch area of mangrove landscape was increased; this is helpful for enhancing ecological function of mangrove wetlands. Meanwhile, with the covert-out of mangrove wetlands, the patch area of mangrove landscape was decreased, and it's harmful for ecological functions of the system.4. During the study period, the movement ranges of mangrove centroid were different in three regions. Mangrove centroid moved slightly in Yanfeng area and Beigang area, while in the Sanjiang area, mangrove centroid moved with a larger range, due to the successful implementation of large-scale artificial silvicultural and natural regeneration of mangroves and so on, making the mangrove wetlands seaward rapidly expanding.5. According to analysis of driving forces of mangrove wetland landscape changes, both natural and human factors affected mangrove wetland landscape changes in Dongzhaigang Harbour, but human factors were dominant for mangrove wetland landscape changes in recent 20 years. Especially, regional economic development and industrial structure change were the main driving forces for the change of mangrove wetland. Among industrial structure, the developing of primary industry, especially aquaculture, and tertiary industry has a great impact on mangrove wetland landscape changes.6. For the problems and the corresponding reasons of mangrove landscape dynamics in Dongzhaigang Harbor, the objectives, principles, management mode, measures and support system of mangrove wetland ecosystem management were given out.