Abstract: Based on land cover data of 2005, 2011, 2015 and 2017 from Google Earth, we established the health assessment index system of mangrove swamp ecosystem in Zhangjiang Estuary. Combining with pressure stateresponse (PSR) model and ecosystem health index, temporal and spatial differentiation of ecosystem health and driving factors of health level for mangrove swamp were analyzed. The results showed that: (1) From 2005 to 2017, the health status of mangrove swamp gradually deteriorated from sub-health to general health. The health status of pressure and response decreased dramatically, while the state health status improved slightly. (2) From 2005 to 2017, there were significant differences in health status among sub-regions. In the first stage (i.e. from 2005 to 2011), the health index from large to small was in order of the west region, the middle region, the east region, the north region and the south region. In the second stage (i.e. from 2015 to 2017), the health index from large to small was in order of the east region, the middle region, the west region, the north region, and the south region. (3) The increases of sea level, Spartina alterniflora invasion, aquaculture expansion, and seawall construction were the major driving factors for the deterioration of mangrove swamp ecosystem health. Meanwhile, nature reserve establishment and conservation measure implementation played positive roles in maintaining mangrove swamp ecosystem health.

Key words: global radiation, diffuse radiation, clearness index, diffuse fraction, midsubtropical area, seasonal drought.