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The amount of carbon stocked and carbon dioxide sequestered by eight-year old Alnus trees were estimated using a destructive sampling method. The carbon contents were computed using the published average values for tropical trees which is 45 – 50 percent of dry matter and the CO2 sequestered was computed based on the published CO2 to C ratio which is 3.6663. The research was conducted in May 2012 at an Alnus stand at the BSUCollege of Forestry, La Trinidad, Benguet.
The average above-ground biomass (AGB) and below-ground biomass (BGB) of the Alnus trees was 140.99 kg per tree, and their average oven-dry weight was 70.91kg per tree. The AGB was 71.56%, and the BGB was 28.44% of the total biomass. The computed biomass of the Alnus trees using a published formula is much lower;their average AGB is 24.665%, their BGB is 12.58%, and their total computed biomass is 21.18% of the actual biomass.
Based on the oven-dried weight data, the computed average carbon contents of the Alnus trees was 31.91kg per tree, and the average carbon dioxide they sequestered was 116.999 kg per tree in eight-years, or an average of 14.63 kg per tree per year.
Based on the findings, Alnus trees can approximate or exceed the published average CO2 sequestration rate for mature trees which is 48 lb per year. Further, a hectare Alnus plantation with an average of 2m x 2m spacing cansequester about 292.6 tons of CO2 in eight years, or an average of 36.575 tons of CO2 per year which is equivalent to the CO2 emissions of about 16 persons.