Estimation of aboveground and belowground carbon stocks in urban freshwater wetlands of Sri Lanka

Abstract

Background: The occurrence of climate change at an unprecedented scale has resulted in alterations of ecosystems around the world. Numerous studies have reported on the potential to slow down climate change through the sequestration of carbon in soil and trees. Freshwater wetlands hold significant potential for climate change mitigation owing to their large capacity to sequester atmospheric carbon dioxide (CO 2). Wetlands among all terrestrial ecosystems have the highest carbon density and are found to store up to three to five times more carbon than terrestrial forests. The current study was undertaken to quantify carbon stocks of two carbon pools: aboveground biomass (AGB) and belowground biomass (BGB). Chosen study sites; Kolonnawa wetland and Thalawathugoda wetland park are distributed within the Colombo wetland complex. Colombo was recognized as one of the 18 global Ramsar wetland cities in 2018. A combination of field measurements and allometric tree biomass regression models was used in the study. Stratification of the project area was performed using the normalized difference vegetation index (NDVI). Results: The AGB carbon stock, across strata, is estimated to be in the range of 13.79 ± 3.65-66.49 ± 6.70 tC/ha and 8.13 ± 2.42-52.63 ± 10.00 tC/ha at Kolonnawa wetland and Thalawathugoda wetland park, respectively. The BGB carbon stock is estimated to be in the range of 2.47 ± 0.61-10.12 ± 0.89 tC/ha and 1.56 ± 0.41-8.17 ± 1.39 tC/ha at Kolonnawa wetland and Thalawathugoda wetland park, respectively. The total AGB carbon stock of Kolonnawa wetland was estimated at 19,803 ± 1566 tCO 2 eq and that of Thalawathugoda wetland park was estimated at 4180 ± 729 tCO 2 eq. Conclusions: In conclusion, the study reveals that tropical freshwater wetlands contain considerable potential as carbon reservoirs. The study suggests the use of tropical freshwater wetlands in carbon sequestration enhancement plans in the tropics. The study also shows that Annona glabra, an invasive alien species (IAS), has the potential to enhance the net sink of AGB carbon in these non-mangrove wetlands. However, further studies are essential to confirm if enhanced carbon sequestration by Annona glabra is among the unexplored and unreported benefits of the species.

Responses of Above- and Belowground Carbon Stocks to Degraded and Recovering Wetlands in the Yellow River Delta

“…The aboveground C stocks are originated from plant C content and aboveground biomass (Dayathilake et al, 2020). In this study, aboveground C stocks were tightly related with aboveground biomass and slightly associated with the plant C content, suggesting aboveground biomass was the predominant factor driving aboveground C stocks in degraded and recovering wetlands (Sharma et al, 2020).…”

The Economic Value of Wetlands in Urban Areas: The Benefits in a Developing Country

“…Therefore, the ESVD is defined as a reliable source for benefit transfer applied to this research. In addition, we have taken into account the study of Dayathilake et al [23] to refine our valuation of the carbon sequestration service. Last, we differentiate the value per hectare of urban and peri-urban (rural) wetlands, following the study of Chaikumbung et al [24], who state that urban wetlands are more valuable than rural wetlands.…”

“…Those corresponding to inland wetlands with local study scale located in developing countries were also selected. Moreover, aboveground and belowground carbon stock indicators from Dayathilake et al [23] were taken and valued. Finally, considering that the coefficient on urban wetlands of meta-regression proposed by Chaikumbung et al [24] is positive and statistically significant, we have taken into account this coefficient to differentiate the value of urban and peri-urban wetlands in Cali.…”

Impact of Land Use Conversion On Carbon Stocks And Selected Peat Physico-Chemical Properties In The Leyte Sab-A Basin Peatland, Philippines

“…The use of allometric relationships is the most practical and cost-effective alternative to estimate belowground root biomass/carbon stocks (Dayathilake et al 2020). The belowground biomass for trees was estimated using the allometric equation developed by Cairns et al (1997).…”