Prediction of the joint impacts of sea level rise and land development on distribution patterns of mangrove communities

Abstract

Mangrove distribution along shorelines shows distinct zonation patterns; thus, different communities may face various influences from sea level rise (SLR) and land use. However, long-term change predictions are usually based only on the total extent of mangroves. Few studies have revealed how SLR and land development such as agriculture, aquaculture, and urbanization jointly affect different intertidal mangrove communities. This study proposed a novel framework combining SLAMM (Sea Level Affecting Marshes Model) and the CLUE-S (Conversion of Land Use and its Effect at Small regional extent) model to assess the potential impacts on upper and lower intertidal mangrove communities. Maoweihai in Guangxi, China, was selected as the study area and the potential impacts from the squeeze effect and mangrove expansion potential were evaluated. We established three scenarios combining SLR and land use patterns to predict mangrove coverage projections by 2070. The results showed that, under a single SLR driver, the upper intertidal mangroves would be more adaptive to rapid SLR than the lower intertidal mangroves. However, under the combined influence of the two drivers, the upper intertidal mangroves would experience larger squeeze effects than the lower intertidal mangroves, with up to 80.5% of suitable habitat lost. Moreover, the expansion potential of upper intertidal mangroves would be considerably more limited than that of lower intertidal mangroves. The length of the expandable habitat patch boundary of upper intertidal mangroves only reached 1.4–1.8 ​km, while that of the lower intertidal mangroves reached up to 99.2–111.2 ​km. Further, we found that aquaculture ponds and cropland are the top two land development types that could occupy suitable habitat and restrict the mangrove expansion potential. Our results highlight that timely improvement of land use policies to create available landward accommodation space for mangrove migration is essential to maintain the coverage and diversity of mangrove communities under SLR. The proposed method can be a helpful tool for adaptive mangrove conservation and management under climate change.