Assessing mangrove conservation in China by integrating mangrove ecosystem into ecological footprint accounting

Abstract

Mangrove conservation effort have been undertaken in China, but there is still a lack of quantitative assessment of its eco-environmental benefits. The ecological footprint (EF) is an important indicator of the sustainability of ecosystems, with carbon footprint (CF) and biocapacity (BC) being key indicators of forest ecosystems. Despite the high carbon sequestration capacity of mangrove ecosystems, they have not yet been included in EF. This study introduces mangrove ecosystems into EF accounting and assesses the eco-environmental benefits of mangrove conservation in China. To achieve this, the net ecosystem exchange (NEE) of mangrove forests was estimated based on the gross primary production and respiration rates. Average forest carbon sequestration (AFCS) and yield factor, key parameters of CF and BC, were calculated from NEE for the first time. The CF and BC of mangrove ecosystems were then refined using newly defined AFCS and yield factor. The proposed framework was applied to the whole mangrove forests in China to assess mangrove conservation efforts. The results showed that the average CF of mangrove forests is about 1000 M ha, which is lower than that of terrestrial forests, while the BC of mangroves is not as high as expected due to the limited area of mangroves. CF and BC vary along the coastline, whereby CF tends to decrease with decreasing latitude while BC remains high at low latitudes owing to the large mangrove area. There is no significant decreasing trend in CF, but BC increases with increasing mangrove area. The newly introduced ecological footprint accounting of mangrove ecosystems suggests that mangrove conservation in China should focus on ecosystem health and expand the area of forestable land. These findings will benefit future management of mangrove ecosystems in China and other countries.