Carbon Storage of Eucalypts Planted on Paddy Bunds in Chachoengsao Province

Abstract

This study investigated the potential to store carbon in the biomass of eucalypt clones planted on paddy bunds in two trials in Chachoengsao province: 1) a clonal trial of four clones; and 2) a spacing trial with five different distances between trees. There were two study sites on farms in each trial. Three years after planting, samples of stems, branches, leaves and roots were taken from six to eight trees in each of the four clones in the clonal trial for an analysis of carbon content. On each study site, the height and diameter at breast height (1.30 m) of all trees were measured. Allometric relationships were used to estimate the biomass of stems, branches, leaves and roots, which then were converted to carbon storage, using the respective carbon content values from the analysis.

Significant differences were observed in the carbon content among tree components (stems, branches, leaves and roots), but not among clones. The difference in carbon content diminished when the tree biomass was converted to carbon storage and as a result, the difference in carbon stored in the biomass was reflected better by the difference in biomass. The carbon stored in the aboveground biomass was significantly different among clones, but not between sites, while the carbon in the total biomass was not significantly different, either among clones or between sites. However, the greatest carbon storage was observed in the clone K58, followed by clone K59, with the values ranging from 6.24 to 6.50 and 4.33 to 6.00 kgC/tree/yr, respectively, depending on the planting site. The result from the spacing trial showed highly significant differences among spacing distances and between sites. K51 planted 2.0 and 2.5 m apart showed the greatest carbon storage per tree, while the 0.5 spacing had the greatest carbon storage per unit area, due to the higher tree density. Overall, the carbon storage potential of eucalypt clones planted on paddy bunds ranged from 11.95 to 51.96 kg CO₂/tree/y or from 8.03 to 38.39 t CO₂/ha/yr depending on the clone, spacing and/or site. The findings suggested that matching clones to the site and/or choosing an appropriate spacing could be a useful practice to increase the tree biomass and carbon storage potential in these eucalypt clones.

Keywords:  eucalypt, clone, spacing, paddy bund, carbon content, carbon storage