Let’s start off by acknowledging that carbon accounting is extremely challenging and accounting for carbon sinks is still an evolving practice!
Our current estimates are based upon averages derived from a cross-section of studies conducted on mangrove ecosystems in equatorial regions focusing on countries in Southeast Asia and Africa, and Acadian ecosystems in Eastern Canada. The following variables are taken into consideration when we estimate carbon sequestration rate: i) species planted (including maturity age of the tree species), ii) forest type, iii) region, and iv) average tree survivability. Based on these variables, carbon sequestration is first calculated at the hectare level and includes above ground carbon (leaves, plant biomass, stumps, etc.), below ground carbon (roots, debris, etc.), and soil carbon (carbon that has been affixed to the soil). Carbon sequestration estimates are then quantified at the per tree level based on forecasted planting densities.
When primary data are not available, as a general rule of thumb, veritree uses a conservative set of secondary data, proxy data or assumptions to ensure that we are not overestimating the carbon sequestration rate resulted from our projects. Moreover, we use data collected at the site-level to validate or adjust our estimations and we will continue to improve our estimation method through building partnership with academics in this space. It is also important to note that veritree currently does not offer carbon credits as part of our service due to uncertainties around carbon credits and accounting of carbon sinks.
While we have referenced credible academic papers to arrive at our best estimate of carbon sequestration resulting from our project portfolio, we acknowledge there are limitations and uncertainties based on our current estimation methodology. As such, we will continue to improve our estimation method through building partnership with academics in this space.
Source: Jones, Trevor G., Harifidy Rakoto Ratsimba, Lalao Ravaoarinorotsihoarana, Garth Cripps, and Adia Bey. "Ecological variability and carbon stock estimates of mangrove ecosystems in northwestern Madagascar." Forests 5, no. 1 (2014): 177-205.
Benson, Lisa, et al. Mangrove Carbon Stocks and Ecosystem Cover Dynamics in Southwest Madagascar and the Implications for Local Management, Multidisciplinary Digital Publishing Institute, 31 May 2017, https://www.mdpi.com/1999-4907/8/6/190/pdf.