Have you ever heard about “Blue Forest” before? Well it might sound a bit unfamiliar, but pretty sure you’ve heard about mangrove. So what’s the correlation between the two?

"Blue forests" are coastal and marine ecosystems, including mangrove forests, seagrass meadows, rockweed, kelp, and tidal salt marshes (Himes et al., 2018). They are considered to be some of the most valuable and productive coastal ecosystems on the planet. They play an important role in protecting marine biodiversity and supporting the livelihoods of coastal and island communities by providing habitats for fisheries, filtering water, guarding shorelines and creating opportunities for tourism and recreation (unep.org).

Figure 1. Mangrove forests, seagrass meadows and tidal salt marshes as a component of “Blue Forest”

The ecosystem services provided by blue forests can be categorized as supporting (i.e., nutrient cycling and maintaining ecosystem functions), provisioning (i.e., providing food and resources), regulating (i.e., purifying water, storing carbon, and protecting coastlines), and cultural (i.e., aesthetics, recreation, and education). 

Many marine species are dependent upon blue forests, because it provides key nursery habitats as well as feeding grounds for marine species from fish to crab; also bird etc. “Blue forests” also  have economic value through tourism and other applications such as edible products for humans and animals, medicines, and thickening agents for cosmetics and foods.

Based on the National Mangrove Map officially released by the Ministry of Environment and Forestry in 2021, it is known that the total area of Indonesian mangroves covers an area of 3,364,076 Ha. Of the 3,364,076 ha of Indonesian mangroves, there are 3 (three) classifications of mangrove conditions categories according to the percentage of canopy cover, namely dense mangroves, medium mangroves, and rare mangroves. The widest distribution of mangroves in Indonesia is in the Province of Papua.

One of the most talked about blue forest ecosystem services has been carbon sequestration/storage due to the growing recognition of the effectiveness of these habitats in climate regulation through pulling carbon out of the atmosphere (Pendleton et al., 2012). The ability of coastal vegetation to sequester carbon is called “blue carbon.” 

Figure 2. Carbon sequestration illustration of mangrove forests (left), salt marshes and seagrass (Source Howard et al., 2014)

Mangroves forest extract up to five times more carbon from the atmosphere than forests on land (unep.org). Mangroves account for only approximately 1% (13.5 Gt year -1) of carbon sequestration by the world’s forests, but as coastal habitats they account for 14% of carbon sequestration by the global ocean (Alongi, 2018). 

While blue forests have a crucial role in mitigating climate change, blue forests ecosystems are significantly threatened worldwide. Using mangrove to enhance coastal communities’ resilience to the increasingly here-and-now impacts of climate change is as important.  It is estimated that up to 67% of the historical global mangrove range, 35% of tidal salt marshes, and 29% of seagrasses have been lost. If these trends continue at current rates, a further 30–40% of tidal marshes and seagrasses and nearly all unprotected mangroves could be lost in the next 100 years (Pendleton et al. 2012).

When vegetation is removed and the land is either drained or dredged for economic development, (e.g., mangrove forest clearing for shrimp ponds, draining of tidal marshes for agriculture, and dredging in seagrass beds—all common activities in the coastal zones of the world), the sediments become exposed to the atmosphere or water column resulting in the carbon stored in the sediment bonding with the oxygen in the air to form CO₂ and other GHG that get released into the atmosphere and ocean (Yu & Chmura 2009; Loomis & Craft 2010; Donato et al. 2011; Kauffman et al. 2011; Lovelock et al. 2011; Ray et al. 2011; Callaway et al. 2012; Fourqurean et al. 2012). Not only do these activities result in CO₂ emissions but they also result in losses of biodiversity and critical ecosystem services.

2022
Azizah Kholifatul Nisa

References

Alongi, D. M. (2018). Mangrove forests. In Blue Carbon (pp. 23-36). Springer, Cham.

Callaway, J. C., Borde, A. B., Diefenderfer, H. L., Parker, V. T., Rybczyk, J. M., & Thom, R. M. (2012). Pacific Coast tidal wetlands. Wetland habitats of North America: ecology and conservation concerns, 103-116.

Donato, D. C., Kauffman, J. B., Murdiyarso, D., Kurnianto, S., Stidham, M., & Kanninen, M. (2011). Mangroves among the most carbon-rich forests in the tropics. Nature geoscience, 4(5), 293-297.

Fourqurean, J. W., Duarte, C. M., Kennedy, H., Marbà, N., Holmer, M., Mateo, M. A., ... & Serrano, O. (2012). Seagrass ecosystems as a globally significant carbon stock. Nature geoscience, 5(7), 505-509.

Himes-Cornell, A., Grose, S. O., & Pendleton, L. (2018). Mangrove ecosystem service values and methodological approaches to valuation: where do we stand?. Frontiers in Marine Science, 5, 376.

Howard, J., Hoyt, S., Isensee, K., Telszewski, M., & Pidgeon, E. (2014). Coastal blue carbon: methods for assessing carbon stocks and emissions factors in mangroves, tidal salt marshes, and seagrasses.

Kauffman, J. B., Heider, C., Cole, T. G., Dwire, K. A., & Donato, D. C. (2011). Ecosystem carbon stocks of Micronesian mangrove forests. Wetlands, 31(2), 343-352.

Loomis, M. J., & Craft, C. B. (2010). Carbon sequestration and nutrient (nitrogen, phosphorus) accumulation in river‐dominated tidal marshes, Georgia, USA. Soil Science Society of America Journal, 74(3), 1028-1036.

Lovelock, C. E., Ruess, R. W., & Feller, I. C. (2011). CO2 efflux from cleared mangrove peat. PloS one, 6(6), e21279.

Pendleton, L., Donato, D. C., Murray, B. C., Crooks, S., Jenkins, W. A., Sifleet, S., ... & Baldera, A. (2012). Estimating global “blue carbon” emissions from conversion and degradation of vegetated coastal ecosystems.

Ray, R., Ganguly, D., Chowdhury, C., Dey, M., Das, S., Dutta, M. K., ... & Jana, T. K. (2011). Carbon sequestration and annual increase of carbon stock in a mangrove forest. Atmospheric Environment, 45(28), 5016-5024.

Yu, O. T., & Chmura, G. L. (2009). Soil carbon may be maintained under grazing in a St Lawrence Estuary tidal marsh. Environmental Conservation, 36(4), 312-320.