Exotic Laguncularia racemosa drives rapid shifts in pond-to-mangrove restoration communities

The rapid decline of mangrove ecosystems worldwide underscores the urgency of restoring these environments. In China and Southeast Asia, a recently popular method involves converting abandoned aquaculture ponds into secondary mangrove forests (i.e., pond-to-mangrove restoration), which reshapes the landscape to create suitable habitats for mangrove plants. However, an often overlooked issue is how these new habitats may facilitate the spread of exotic species. Our study examined plant communities in a pond-to-mangrove restoration area, comparing the plant community four and eight years after restoration began. We found that the exotic species Laguncularia racemosa expanded rapidly, significantly suppressing native mangrove species and altering the community structure. The relative abundance of L. racemosa increased from 8 % in the fourth year to 57 % by the eighth year, during which time three native species disappeared from the plot. By the eighth year, L. racemosa also dominated in terms of plant height. Given the rapid spread of invasive species and the high connectivity of wetlands, we recommend closely monitoring non-native plants during restoration projects like pond-to-mangrove restoration. Our study highlights the threat biological invasions pose to restoration efforts and the importance of managing ecological niches created by restoration processes.