Carbon sequestration has become a crucial service forests provide for regulation and mitigation of climate change through reduction of greenhouse gas emissions. In Kenya, Cupressus lusitanica, Pinus patula and Eucalyptus saligna are common exotic plantation species grown in high potential areas. They are characteristerised by fast growth resulting to removal of more carbon dioxide from the atmosphere. However, little has been done in estimating aboveground and belowground carbon of these species. Therefore, this study sought to: estimate carbon sequestered by these species across ages and sites; and determine relationship between tree growth parameters and carbon biomass. The study was carried at Kiambu and Nyeri Counties in Central Kenya. A total of 99 plots measuring 20 by 50 m were established in government managed forest plantations of selected species stratified according to age and species in different forest compartments. Diameters at breast height, total height, crown diameter and crown depth were measured. CO2FIX V3.1 modelling framework was used in estimating carbon sequestered and linear mixed model used in the analysis of the data. There were significant differences (p=0.006) in the amount of carbon sequestered among species across sites. Eucalyptus saligna had the highest amount of carbon (247.9 ± 44.4 MgC ha-1) sequestered in Nyeri South followed by Pinus patula (145.6 ± 44.4 MgC ha-1) in Nyeri North and Cupressus lusitanica (98.4 ± 44.4 MgC ha-1) in Kiambu. Significant differences (p<0.01) were evident across ages of three species and sites. Age accounted for 70% of the total variability in the amount of carbon sequestered. Growth parameters, aboveground and belowground biomass among three species across ages and sites were significantly correlated (p<0.01). In conclusion, estimates of carbon sequestered from selected tree species in Central Kenya, demonstrated a significant contribution towards emission reduction of harmful gases, specifically carbon dioxide.
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