Landscape Pattern Changes For A Decade And GAP Analysis Of Mangrove Ecosystems In China's Five Provinces

Mangroves are important ecosystem types,usually growing on the tidal flats of tropical and subtropical coasts and providing important ecosystem services,including bank protection from erosion,air purification,and pollutant degradation.It is also the most threatened type of all coastal wetlands.It is of significance to recognize the conservation status of mangroves and strengthen their protection and management,according to the threat status assessment of mangrove ecosystems in China.In our study,using mainly GIS analysis techniques,we analyzed the status,changes,and driving forces for mangrove spatial distribution by combining the map data from the China Academy of Sciences'Remote Sensing Investigation with the field investigation,to ultimately propose protection strategy and recommendation.The main conclusions can be summarized as follows:(1)In 2010,the total area of mangroves was 264.1km~2 on China's coasts,and mainly distributed in the Guangxi,Guangdong,and Hainan provinces.These areas accounted for 45.5%,34.1%,and 16.7%of the total mangrove area in China,respectively,with only 2.7%in Zhejiang and Fujian provinces.(2)From 2000 to 2010,China lost 58.0km~2 of mangrove area,but restored96.1km~2.Although the total area increased by 36.1km~2,the trend of landscape fragmentation still exists.On the regional level,the only province with a decrease in mangrove area is the Guangdong province mangrove,with an 8.7%decrease from 2000to 2010.(3)Human activity is one of the main driving factors in the decline and fragmentation of the mangrove wetland area.For example,aquaculture expansion,tidal flat reclamation,and the aquaculture account for 68.4%of the mangrove area loss.At the same time,artificial mangrove cultivation is the main reason for the increase in mangrove area from 2000 to 2010.(4)The mangrove ecosystem's determination as endangered,based on the results of the assessment of the spatial limitation,degree of the decline in distribution area and water environment status,indicating that the current situation of the mangrove ecosystem is serious in China.(5)Currently 61%of mangrove forests are covered by nature reserves in China.Among the major distribution provinces,Hainan has a small area but a high coverage proportion for reserves,while Guangxi and Guangdong have large areas but low coverage proportions.Among the three mangrove types,Rhizophora apiculata–Xylocarpus granatum and Rhizophora stylosa–Bruguiera gymnorrhiza have a high coverage proportion(>90%)by reserves despite covering a relatively small area.On contrast,Kandelia candel–Aegiceras corniculalatum–Avicennia marina had a relatively low coverage(around 40%)in reserves although it covers a large area.Priority areas outside the reserves were identified and the way of ecological redlining was proposed for further protection of this ecosystem.The following protection suggestions are intended to counteract the many existing problems in mangrove protection.The first is to enhance the construction of protected areas,through the expansion of natural reserves and the establishment of ecological protection red lines,thereby incorporating more mangroves in the reserve system.The second is to strengthen the supervision of mangrove ecosystems and reduce the damage and disturbance of these areas.The third is to study the establishment of a diversified ecological compensation mechanism,so that we can promote the development of a regional economy and raise the livelihood for local community residents in the process of mangrove forest distribution.