Influence of Selected Soil Properties on Soil Organic Carbon (SOC) Levels in Mangrove Soil: A Study from Rekawa Lagoon, Southern Sri Lanka

Abstract

Carbon that is stored and sequestered in marine coastal ecosystems, such as mangroves, salt marshes and seagrass meadows is termed as Blue Carbon, which plays an important role in the global carbon cycle and climate change mitigation. It has long been known that mangroves which are confined to tropical and subtropical latitudes, have higher rates of net primary production and carbon sequestration capacity. This study, therefore evaluated the influence of some selected soil physicochemical properties on the soil organic carbon (SOC) content in mangrove soil, in Rekawa mangrove forest in Southern coast of Sri Lanka. The effects of pH, soil salinity, conductivity, soil moisture content (%), soil bulk density, soil porosity, phosphate content and nitrate content on soil organic carbon were examined along selected six transects covering periphery, middle and water edge zonation and the influence was quantified as correlations. Results indicate that soil organic carbon content was positively correlated with soil salinity, conductivity, soil moisture content, and soil porosity, (Spearman rank correlations; P<0.001) while it was negatively correlated with soil bulk density and nitrate content (Spearman rank correlations; P<0.05). Among the measured properties, pH and phosphate content showed no significant correlation with SOC. Final Generalized Linear Model (GLM; AIC = 142.04), improved by stepwise elimination, significantly explained the SOC as a function of soil porosity, soil salinity and soil bulk density (P<0.05). Furthermore, it is recommended to investigate the influence of other soil physicochemical factors which were not discussed in this study on SOC content and stability in future studies and the outcome/s will be highly beneficial in future to challenge the environmental crisis conditions such as global warming and climate change.

Full text

19th Academic Sessions - 2022
University of Ruhuna, Matara, Sri Lanka ISSN 2362-0412
91
Influence of Selected Soil Properties on Soil Organic
Carbon (SOC) Levels in Mangrove Soil: A Study from
Rekawa Lagoon, Southern Sri Lanka
G.G.N.K. Wijeratnea, D.P.D. Ranawakaa, N.V.K. Chamikaa, D.U.V. Gunathilakaa,
W.M.I.C. Wijesundaraa, N.K. Abeysinghea, N.D.S.D. Thilakarathnaa,
A.J.D. Pereraa, N.P. Dissanayakea, N.R. Kankanamgeb, L.P. Jayatissaa,
J. Andrieuc, K.A.S. Kodikara a*
aDepartment of Botany, Faculty of Science, University of Ruhuna, Matara, Sri Lanka
bRyan Institute, School of Natural Sciences, National University of Ireland, Galway
cGEOSpatial Monitoring & amp; Information Technology (GeoSMIT) department,
French Institute of Pondicherry (IFP), Pondicherry, India
*Corresponding author: sunandaruh@gmail.com
ABSTRACT
Carbon that is stored and sequestered in marine coastal ecosystems, such as mangroves, salt
marshes and
seagrass meadows is termed as Blue Carbon, which plays an important role in the
global carbon cycle and climate change mitigation. It has long been known that mangroves which
are confined to tropical and subtropical latitudes, have higher rates of net prim
ary production
and carbon sequestration capacity. This study, therefore evaluated the influence of some selected
soil physicochemical properties on the soil organic carbon (SOC) content in mangrove soil, in
Rekawa mangrove forest in Southern coast of Sri L
anka. The effects of pH, soil salinity,
conductivity, soil moisture content (%), soil bulk density, soil porosity, phosphate content and
nitrate content on soil organic carbon were examined along selected six transects covering
periphery, middle and water
edge zonation and the influence was quantified as correlations.
Results indicate that soil organic carbon content was positively correlated with soil salinity,
conductivity, soil moisture content, and soil porosity, (Spearman rank correlations; P<0.001)
wh
ile it was negatively correlated with soil bulk density and nitrate content (Spearman rank
correlations; P<0.05). Among the measured properties, pH and phosphate content showed no
significant correlation with SOC. Final Generalized Linear Model (GLM; AIC =
142.04),
improved by stepwise elimination, significantly explained the SOC as a function of soil porosity,
soil salinity and soil bulk density (P<0.05). Furthermore, it is recommended to investigate the
influence of other soil physicochemical factors whic
h were not discussed in this study on SOC
content and stability in future studies and the outcome/s will be highly beneficial in future to
challenge the environmental crisis conditions such as global warming and climate change.
Acknowledgement: FSPI-SEDRIC project provided the financial assistance for the research.
Keywords: Blue carbon, Mangroves, Physico-chemical, Rekawa, SOC