Assessment of Mangrove Restoration Potential in the North Western Province of Sri Lanka for Climate Change Mitigation

Abstract

Over the geological time, the planet's climate has been changing constantly, with large variations in
global average temperatures. Millions of people are already suffering as a result of natural disasters
worsened by climate change. The Paris Agreement is an international climate change treaty, and
countries will present their climate action plans, referred to as Nationally Determined Contributions
(NDCs). In response to the Paris Agreement, Sri Lanka presented NDCs in 2016. In which the coastal
and marine sector has a restoration target of 10,000 ha of mangroves as a coastal greenbelt with
mitigation co-benefits. However, identification of potential lands for such restoration of mangroves
has not been done. Therefore, identification of potential areas for mangrove restoration is most
important because mangroves cannot be restored where they were not previously existed. The main
objective of this research therefore was to identify potential areas for mangrove restoration within the
North-Western Province. Identification of potential lands in North-Western Province were done by
using Google Earth Pro and ArcGIS 10.2.2. Most important physicochemical parameters such as
salinity, pH, soil organic matter content, soil water holding capacity were analyzed under laboratory
conditions, samples were obtained by different sites of mangrove habitats. Soil salinity, pH were
measured by using calibrated multiparameter. The loss of ignition method for soil organic matter
content and a customized method for soil water holding capacity were used. All parameters were
subjected to two-way ANOVA in MINITAB 14 after following Anderson Darling Normality test.
The mean of soil salinity, pH, soil organic matter content, and soil water holding capacity were ranged
respectively; 4.26% to 5.93%, 6.07 to 8.62, 3.40% to 9.31%, and 30.39% to 46.38%. The potential
lands for restoring mangroves in North-Western Province were identified in Chilaw, Kalpitiya,
Mundel, Panirendawa, Puttalam, Vanathawilluwa and Vennappuwa Divisional Secretariant
Divisions. Among them, availability for historical images in Google Earth Pro there were specially
chosen areas to restore the mangroves. There is no any significant difference of physicochemical
parameters among mangrove habitats and an abandoned shrimp farm where there were previously
mangrove plants existed. Hence, abandoned shrimp farms and salterns can be used to restore the
mangrove plants and the assisted natural regeneration of mangroves in suitable abandoned shrimp
farms by way of facilitating hydrology to be explored as the best option for mangrove restoration.

Keywords: Mangrove restoration, Nationally Determined Contributions (NDCs), Assisted natural regeneration, Areas suitable for mangrove restoration