ABSTRACT

Eucalyptus plantations at higher elevations in Sri Lanka are being confronted by a conflict between their industrial need maintenance and ecological need conservation. Increasing carbon sequestration can offer income through carbon markets to minimize profit reductions. Changing the main species and extending the rotation length (ERL) can increase carbon sequestration; thus, this study aimed to compare the carbon sequestration of Eucalyptus grandis (EG) and Eucalyptus microcorys (EM) and their economic benefits. As a chronosequence approach, EG and EM monocultures were selected for data collection and the above-ground carbon (AGC) was calculated. The AGC of EG at 25 years of age was considered as the baseline (BL) and a linear model with log-transformed explanation variable was used to predict AGC growth with ERL. The economic viability of increased AGC was determined based on the net present value (NPV) and compared with the replanting cost. The BL stock was 175.91 t ha⁻¹, while there is no significant effect of changing the main species to increase carbon sequestration. ERL by 20%, 40% and 60% can increase carbon sequestration by 13.7%, 25.2% and 35.2%, respectively. The NPVs of carbon offsets of ERL indicate that all studied ERLs are profitable; however, NPV is decreasing with the ERL, ERL by 20% recorded the highest NPV.

摘要

斯里兰卡较高海拔的桉树人工林面临着其工业需求维护与生态需求保护之间的冲突。固碳量的增加可以通过碳市场提供收入，以最大程度地减少利润减少。改变主要种类并延长旋转长度（ERL）可以增加碳固存；因此，本研究旨在比较桉树（Eucalyptus grandis，EG）和桉树微树皮（Eucalyptus microcorys）的固碳能力。（EM）及其经济利益。作为时间序列方法，选择了EG和EM单培养进行数据收集，并计算了地上碳（AGC）。将25岁以下的EG的AGC视为基线（BL），并使用具有对数转换的解释变量的线性模型预测ERL的AGC增长。根据净现值（NPV）确定增加的AGC的经济可行性，并将其与补植成本进行比较。BL储量为175.91 t ha ^-1，而改变主要物种以增加碳固存并没有显着影响。ERL增加20％，40％和60％可使碳固存分别增加13.7％，25.2％和35.2％。ERL碳抵消的NPV表示所有研究的ERL都是有利可图的；但是，随着ERL，NPV下降，ERL下降了20％，创下了最高NPV。