Spatial-Temporal Dynamics of Dongzhaigang Mangrove Forests on Hainan Island, China: Evidence from Landsat Observations (1988–2019)
摘要
The goal of this study was to determine the spatiotemporal characteristics of mangrove distribution and fragmentation patterns from 1988 through 2019 in Dongzhaigang. Land cover datasets were generated for Dongzhaigang for multiple years via a decision tree method based on a classification and regression tree (CART) algorithm using Landsat time series images. Spatiotemporal transform and fragmentation patterns of mangrove distribution were separately assessed with a transfer matrix of land cover types and a landscape pattern index. The classification method combined with multi-band images showed good accuracy, with overall accuracy higher than 90%. Mangrove areas in 1988, 1999, 2009, and 2019 were 2050, 1875, 1818, and 1750 ha, respectively, with decreases mainly due to conversion to aquaculture ponds and farmland. A mangrove growth index (MGI) was proposed, reflecting the water-mangrove relationship, showing positive mangrove growth from 1988–2009 and negative growth from 2009–2019. Study results indicated anthropogenic factors play a leading role in the extent and scale of mangrove effects over the past 30 years. According to the analysis results, corresponding management and protection measures are proposed to provide reference for the sustainable development of Dongzhaigang Mangrove Wetland ecosystem.