The field team in Krabi, Thailand taking the quickest route back to the boat after a day’s worth of sampling.

TRI Field Notes: Predicting Carbon Stocks for Mangroves in Southeast Asia

by Jacob Bukoski, 2015 TRI Fellow in Thailand and Vietnam

Calf-deep in mud and supporting a two-meter long steel soil auger across my shoulders, I pause to watch Bang Ream – a member of my field team – stoop down and rake the mud with an old, L-shaped metal pipe. After three or four swipes, he reaches down and picks up a muddy ball approximately the size of my fist. He turns and vigorously shakes the mudball around in the salty water quickly seeping into one of my ankle deep footprints in the mud. Looking up at me with a big grin on his face, he holds up his prize and says “hoy” with a tonal up-swing, which means clam in Thai.

Whether it’s the shellfish, mushrooms, fish mangrove, poles for building their homes, or coastal protection from coastal-based storms, the value of forests to the local communities living within them is immense. As mangroves are heavily impacted by both natural (sea-level rise impacting natural hydrology and drowning entire stands) and anthropogenic (often-times clear-cutting forests for shrimp farms) threats, international forestry and development circles are now seeking means to empower local communities in conserving their mangroves.

As a TRI fellow, I am contributing to a joint UN-FAO/USAID/IUCN project entitled “Income for coastal communities for mangrove protection.” The project seeks to identify and promote means of generating income for mangrove conservation-related activities within local communities. One component of the project, and my current research under TRI, is to develop a low-cost mechanism for valuing mangrove forests within carbon markets.

Although following the same basic premise as the UN Reducing Emissions from Deforestation and forest Degradation program (REDD+), my research differs in that it seeks to create a carbon accounting methodology that requires little-to-no field work. One of the criticisms of REDD+ is that the intensive carbon monitoring, reporting and verification (MRV) activities that are required to obtain verified carbon credits are simply too expensive and too logistically demanding to make carbon forestry mechanisms profitable.

Due to deep soil depths, anoxic conditions that limit microbial decomposition of carbon, and sedimentation of organic matter during tidal in-flows, mangrove soils are believed to be among the most carbon-dense of all tropical forest types.

Due to deep soil depths, anoxic conditions that limit microbial decomposition of carbon, and sedimentation of organic matter during tidal in-flows, mangrove soils are believed to be among the most carbon-dense of all tropical forest types.

Mangroves, in particular, require intensive field work as soft soils, dense stilt roots that create aptly named jungle-gym like conditions, and limited accessibility make data collection both difficult and expensive. Additionally, the vast majority of carbon stocks are believed to be found in the deep, anoxic soils of mangroves – which require time-intensive field sampling and expensive laboratory analysis to gather empirical measurements. Thus, my research seeks to fill the gap of feasibly estimating carbon stocks in mangroves through the development of a predictive model.

As a Tropical Resources Institute fellow, I am currently validating the model to see how well it predicts ecosystem carbon stocks. I am visiting mangroves forests in both Thailand and Vietnam – two sites in each country – to obtain empirical measurements of carbon stocks. Upon measuring the quantities of carbon in each forest, I can subsequently use the predictive model to generate stock estimates for each site and compare the two values. Through the comparison, my colleagues and I will gain a strong understanding of where the model succeeds, and where the model fails.

Upon validation of the model, it is hoped that rapid appraisals of carbon stocks in mangroves can be obtained and entire forests can be valued via carbon markets. While only one mechanism of the larger UN FAO-USAID-IUCN project, the model will help mobilize carbon funds to local communities in support of mangrove conservation activities.

“TRI Field Notes” share the stories of TRI Fellows as they conduct independent summer research throughout the tropics.  The Tropical Resources Institute (TRI) is a center at the Yale School of Forestry and Environmental Studies.  For more information on research and fellowships visit http://environment.yale.edu/tri/