China doubles mangrove forest area to support coastal biodiversity

Researchers from Ningbo University used 22 years of satellite imagery to track the restoration of mangrove forests across China's coastline.

The team analyzed over 13,000 Landsat images and records from the Global Biodiversity Information Facility to measure how these coastal habitats changed between 1998 and 2020. The study found that the mangrove area expanded by 166 percent during this period, growing from roughly 10,600 hectares to more than 28,000 hectares.

This growth followed the 2000 Wetland Protection Action Plan, which directed resources toward coastal recovery. The most rapid expansion occurred between 2003 and 2008, with the majority of the new growth concentrated in Guangdong, Hong Kong, Macao, and Guangxi. The expansion coincided with a rise in recorded bird diversity, which nearly tripled from 148 to 397 species. Scientists found that while larger forests directly increased species richness, the expansion also changed water chemistry to support phytoplankton.

These microscopic organisms form the base of marine food webs that support fish and the birds that eat them. The researchers noted that some gains were lost to extreme weather, such as when Typhoon Nuri destroyed 80 percent of new seedlings in Guangdong in 2008. They also cautioned that the jump in bird numbers might be partly due to a more active birdwatching community and better monitoring.

Furthermore, the conversion of mudflats into forests can sometimes reduce foraging space for specific migratory shorebirds.