Introduction and Background of the study
Tropical forests have the largest capacity to mitigate climate change amongst the other forest types through conservation of existing carbon pools and expansion of carbon sinks (Brown et al., 1996, Brown et al., 2002). Biomass change represents the capacity for carbon emissions to the atmosphere through deforestation and biomass burning. On the contrary, growth results in increase of biomass which represents carbon sequestration in the terrestrial biosphere (Cairns et al., 2003). Mangrove forests are highly productive ecosystems and are sites of intense carbon processing with a potentially significant impact to the global carbon budget (Borges et al., 2003, Dittmar et al., 2006, Alongi, 2007).
Among the least studied ecosystem services provided by mangroves is their importance as global carbon stock. The carbon stored within mangrove forest ecosystem has started to take significant economic value as seen with the emergence of carbon markets. Its economic value arises from the knowledge that CO2, a major greenhouse gas, is sequestered by forest ecosystems including mangrove forests, thus reducing the effects of global climate change (Barbier et al., 2011; Alongi, 2008; Bouillon et al., 2008).
Mangroves trap and fix atmospheric carbon dioxide into organic compounds in their biomass through the process of primary production (Bouillon et al., 2008). Many studies have shown that mangrove ecosystem is a vital carbon sink (Bouillon et al., 2009). The comparatively high aboveground biomass carbon together with carbon-rich soils resulted in the presence of large ecosystem carbon stocks compared to other tropical forests (Kauffman et al., 2011).
Komiyama et al., (2008) reported mangrove aboveground biomass carbon ranges from 20 to 230 Mg ha-1 in the Pacific region while Kauffman et al., (2011) reported that in Palau the estimated aboveground biomass carbon was 257 Mg ha-1. Siikkamki et al., (2012) disclosed that the global estimated aboveground biomass carbon is 147 Mg ha-1 in mangrove forest. Study in Soloman Islands also revealed that the aboveground component of mangrove contained the range of 190 - 430 Mg C ha-1 (Albert et al., 2012). These data represented higher carbon storage capacity than most of the other hardwood forests which have estimated aboveground biomass carbon in the range of 38 – 90 Mg ha-1 (Brown, 2002).
The net carbon sink of the terrestrial ecosystem is controlled by the net effect of land-use practices (agriculture, deforestation and degradation), the indirect effects of human activities and the effects of the changing climate, climatic variation and disturbances (Brown, 2002). Mangroves are estimated to store more than 4.0 gigatons (Gt) of carbon in both above and below tree components including sediments (Ong, 1993; Twilley et al., 1992). Clearly, the estimated aboveground biomass carbon varies based on environmental conditions (McLeod and Salam, 2006).
Amidst the significant ecological services and prevention of coastal erosion mangroves are depleting at an alarming rate around the world. Approximately 35% of mangrove forest have been degraded or lost over the last few decades (Barbier et al., 2008, Alongi, 2002). Guyana has lost about 68, 368 ha or 75 % of mangrove forest between 1990 and 2011(GFC, 2011). The rapid deforestation was mainly due to anthropogenic activities and increasing sea level which resulted in tidal energy increase thus leading to soil erosion. Guyana is one of the very few countries in the tropics that are implementing REDD+ readiness proposal (LCDS 2013). With the bilateral REDD+ payment agreement, Guyana adopted Low Carbon Economic Development trajectory while promoting conservation of natural resources and enhancing carbon stocks. Of late, a number of carbon Monitoring, Reporting and Verification (MRV) efforts are taking place, most of which are relates to terrestrial ecosystem. Ironically, to date, no mangroves carbon stock measurement studies are conducted. This research is a very first of its kind in Guyana pursuing to quantify mangrove carbon stocks in six coastal regions and three major riverine ecosystems, namely Berbice, Essequibo and Demerara rivers. The overarching objective of the research is to provide an estimate of above-ground mangroves carbon in order to spearhead and strengthen conservation practices in the ever receding coastal mangroves in Guyana. The outcome will also provide an impetus to REDD+ and Monitoring, Reporting and Verification strategies to the policy makers. Two most dominant mangrove species, Avicennia germinans (Black mangrove) and Rhizophora mangle (Red mangrove), were selected to draw a conclusion for the following research question and hypothesis as below:
Research question: Do carbon stock of red and black mangroves in Guyana varies by region?
H0 # 1: Above-ground carbon stock of red and black mangroves in Guyana do not vary by regions.
H0 # 2: Above-ground carbon stock does not differ in black and red mangroves in Guyana.
Among the least studied ecosystem services provided by mangroves is their importance as global carbon stock. The carbon stored within mangrove forest ecosystem has started to take significant economic value as seen with the emergence of carbon markets. Its economic value arises from the knowledge that CO2, a major greenhouse gas, is sequestered by forest ecosystems including mangrove forests, thus reducing the effects of global climate change (Barbier et al., 2011; Alongi, 2008; Bouillon et al., 2008).
Mangroves trap and fix atmospheric carbon dioxide into organic compounds in their biomass through the process of primary production (Bouillon et al., 2008). Many studies have shown that mangrove ecosystem is a vital carbon sink (Bouillon et al., 2009). The comparatively high aboveground biomass carbon together with carbon-rich soils resulted in the presence of large ecosystem carbon stocks compared to other tropical forests (Kauffman et al., 2011).
Komiyama et al., (2008) reported mangrove aboveground biomass carbon ranges from 20 to 230 Mg ha-1 in the Pacific region while Kauffman et al., (2011) reported that in Palau the estimated aboveground biomass carbon was 257 Mg ha-1. Siikkamki et al., (2012) disclosed that the global estimated aboveground biomass carbon is 147 Mg ha-1 in mangrove forest. Study in Soloman Islands also revealed that the aboveground component of mangrove contained the range of 190 - 430 Mg C ha-1 (Albert et al., 2012). These data represented higher carbon storage capacity than most of the other hardwood forests which have estimated aboveground biomass carbon in the range of 38 – 90 Mg ha-1 (Brown, 2002).
The net carbon sink of the terrestrial ecosystem is controlled by the net effect of land-use practices (agriculture, deforestation and degradation), the indirect effects of human activities and the effects of the changing climate, climatic variation and disturbances (Brown, 2002). Mangroves are estimated to store more than 4.0 gigatons (Gt) of carbon in both above and below tree components including sediments (Ong, 1993; Twilley et al., 1992). Clearly, the estimated aboveground biomass carbon varies based on environmental conditions (McLeod and Salam, 2006).
Amidst the significant ecological services and prevention of coastal erosion mangroves are depleting at an alarming rate around the world. Approximately 35% of mangrove forest have been degraded or lost over the last few decades (Barbier et al., 2008, Alongi, 2002). Guyana has lost about 68, 368 ha or 75 % of mangrove forest between 1990 and 2011(GFC, 2011). The rapid deforestation was mainly due to anthropogenic activities and increasing sea level which resulted in tidal energy increase thus leading to soil erosion. Guyana is one of the very few countries in the tropics that are implementing REDD+ readiness proposal (LCDS 2013). With the bilateral REDD+ payment agreement, Guyana adopted Low Carbon Economic Development trajectory while promoting conservation of natural resources and enhancing carbon stocks. Of late, a number of carbon Monitoring, Reporting and Verification (MRV) efforts are taking place, most of which are relates to terrestrial ecosystem. Ironically, to date, no mangroves carbon stock measurement studies are conducted. This research is a very first of its kind in Guyana pursuing to quantify mangrove carbon stocks in six coastal regions and three major riverine ecosystems, namely Berbice, Essequibo and Demerara rivers. The overarching objective of the research is to provide an estimate of above-ground mangroves carbon in order to spearhead and strengthen conservation practices in the ever receding coastal mangroves in Guyana. The outcome will also provide an impetus to REDD+ and Monitoring, Reporting and Verification strategies to the policy makers. Two most dominant mangrove species, Avicennia germinans (Black mangrove) and Rhizophora mangle (Red mangrove), were selected to draw a conclusion for the following research question and hypothesis as below:
Research question: Do carbon stock of red and black mangroves in Guyana varies by region?
H0 # 1: Above-ground carbon stock of red and black mangroves in Guyana do not vary by regions.
H0 # 2: Above-ground carbon stock does not differ in black and red mangroves in Guyana.