First Assessment of Carbon Stock in the Belowground Biomass of Brazilian Mangroves

ABSTRACT Studies on belowground roots biomass have increasingly reported the importance of the contribution of this compartment in carbon stock maintenance in mangrove forests. To date, there are no estimates of this contribution in Brazilian mangrove forests, although the country has the second largest area of mangroves worldwide. For this study, trenches dug in fringing forests in Guaratiba State Biological Reserve (Rio de Janeiro, Brazil) were used to evaluate the contribution of the different classes of roots and the vertical stratification of carbon stock. The total carbon stock average in belowground roots biomass in these forests was 104.41 ± 20.73 tC.ha−1. From that, an average of 84.13 ± 21.34 tC.ha−1 corresponded to the carbon stock only in fine roots, which have diameters smaller than 5 mm and are responsible for over 80% of the total belowground biomass. Most of the belowground carbon stock is concentrated in the first 40 cm below the surface (about 70%). The root:shoot ratio in this study is 1.14. These estimates demonstrate that the belowground roots biomass significantly contributes, more than 50%, to the carbon stock in mangrove forests. And the mangrove root biomass can be greater than that of other Brazilian ecosystems

Mangrove forest restoration and rehabilitation

We analyzed current best practices and recommendations used in the implementation of mangrove rehabilitation and restoration (R/R) projects in the Atlantic-East Pacific (AEP) and the Indo-West Pacific biogeographic regions during the last 20 years. Comprehensive literature and World Wide Web searches were performed identifying 90 sites around the world where R/R actions have been implemented. For each site, we analyzed the sources of damage/impact and classified the origin as natural (siltation, erosion, the direct and indirect effect of tropical storms or tsunamis) or anthropogenic (pollution, land use policies, overharvesting, aquaculture, altered hydrology and hydroperiod). In most cases, the causes of damage were a complex mixture associated to erosion, hydrological impairment, deforestation, siltation, and land conversion for aquaculture and other land uses. The area extension of mangrove sites undergoing restoration or just afforestation ranged from few square meters to several thousand hectares. Numerous projects were implemented without an underlying science-based approach and were often ill-prepared and unsuccessful. Although there is no “one-size-fits-all” solution to restore or rehabilitate mangrove wetlands, published studies (particularly peer reviewed) provide useful insights into designing R/R projects with clearly defined and prioritized management objectives based on a diagnostic of the source of damage/deterioration. A critical step is to develop a decision tree that serves as a guide to optimize the use of available funding in the development, implementation, and monitoring of R/R protocols to set clear objectives, goals and deadlines. These steps should be part of a robust research agenda based on sound ecological theory and reliable monitoring practices, including the participation of local communities. Any monitoring and reporting program should address spatial and temporal replication that explicitly includes reference sites near the target restoration site. The results of each R/R project, whether successful or not, should be published, as they are critical sources of data and information for further development of mangrove R/R practices and methods within the community of restoration ecology science. We urge the continental level implementation of guidelines to advance international initiatives aimed to protect and conserve one the most productive and threatened coastal ecosystems in the world.SCOPUS: ch.binfo:eu-repo/semantics/publishe