Inter- and intraspecific variation in mangrove carbon fraction and wood specific gravity in Gazi Bay, Kenya

© 2018 The Authors. The tropical mangrove ecosystem harbors great potential for carbon offsetting schemes because of their exceptionally high carbon sequestration potential. These cannot only generate an income for local communities by financially compensating for the non-exploitation of protected or replanted stands, but also simultaneously reduce emissions due to forest degradation and deforestation, thereby helping to counteract the global threat on these forests. As carbon is directly monetized through offsetting carbon emissions, accurate species-specific estimation of carbon content in trees is essential and reduces the propagation of errors generated by accounting uncertainties. Accordingly, this study assessed variation in both carbon fraction and wood specific gravity among and within the 10 mangrove species occurring in Gazi Bay, Kenya. Significant interspecific differences were found with values ranging from 45.8% (Avicennia marina) to 49.8% (Ceriops tagal) for carbon fraction and from 0.58 (Sonneratia alba) to 0.93 (Pemphis acidula) for wood specific gravity. The influence of environmental factors (soil salinity, stand density, and elevation a.s.l. as a proxy for multiple interrelated conditions) was investigated, but only elevation a.s.l. appeared to have a species-specific though moderate influence only on carbon fraction. Significant differences in carbon fraction and wood specific gravity were found between stem, aerial roots, and branches of Rhizophora mucronata. In contrast, no significant differences in carbon fraction were found among different stem tissues of A. marina, C. tagal and R. mucronata, the Bay's most abundant species. These results provide insight in carbon content variation, confirming the importance of considering species-specific or even site-specific values of carbon fraction and wood specific gravity, thereby rendering future carbon accounting more accurate.

Jaar van publicatie:2018