1. Department of Earth System Science, Ministry of Education Key Laboratory for Earth System Modeling,Tsinghua University, Beijing 100084, China 2. Division of Ocean Science and Technology, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, China 3. Bureau of Zhanjiang National Mangrove Nature Reserve, Zhanjiang 524000, China
Mapping the distribution pattern of mangrove species in regional scales with remote sensing technology is of great significance in the investigation, utilization and protection of mangrove resources. In this study, the authors mapped and analyzed the mangrove species distribution based on the spectrum characteristics of mangroves,vegetation index, texture information and shape parameters calculated from ZY-3 high-resolution multispectral images, in conjunction with the mangrove species sample points, which were collected by the unmanned aerial vehicle (UAV). The authors used object-oriented classification method,decision tree and support vector machine (SVM). The total area of mangrove forests in Leizhou Peninsula in 2014 was estimated at 5 949.3 hm 2, much less than the area reported in most previous studies. For each of the districts in Leizhou Peninsula, mangrove forests covered 1 556.0 hm 2 in Lianjiang City, 1 466.1 hm 2 in Leizhou City, 1 168.0 hm 2 in Zhanjiang Municipal City, 734.7 hm 2 in Suixi County, 479.8 hm 2 in Xuwen County and 544.7 hm 2 in Wuchuan City, respectively. Zonal distribution of native mangrove species is significant from sea to land, with Avicennia marina dominated in the low tide level, followed by Aegiceras corniculatum, Kandelia obovata, Rhizophora stylosa and Brugueria gymnorrhiza dominated from middle to high tide level; the exotic mangrove species Sonneratia apetala is mainly distributed on the land side of Avicennia marina in its introduction area. The proportions of each dominate species are Avicennia marina (41.9%),Sonneratia apetala (23.4%), Aegiceras corniculatum (20.9%),Kandelia obovata(5.4%),Rhizophora stylosa(4.8%) and Brugueria gymnorrhiza (3.6%), respectively. The results show that Sonneratia apetala planting in Leizhou City and Zhanjiang Municipal City has achieved remarkable success in the past several years; however, the risk of its invasive and distribution expansion should also be taken into consideration.
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