Enhancing the carbon sequestration of high-elevation Eucalyptus plantations in Sri Lanka for future carbon market activities

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.

KEYWORDS:

• Eucalyptus
• higher elevation
• species
• above ground carbon
• rotation length

Acknowledgments

The authors wish to thank the ‎State Timber Corporation of Sri Lanka and the Forest Department of Sri Lanka for their support during the data collection stage. Special thanks are also conveyed to Mrs. Pavithra Rangani Wijenayake, Ms. Ayumi Kitazawa, Mr. Toshio Tatsumi, Mr. Geeth Hettiarachchi, Mrs. Gishani Nisansala Batugampala and Mr. Asela Mawanella for their assistance with the field inventory. We also appreciate the comments from the anonymous reviewers.

Disclosure of potential conflicts of interest

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This research was funded through a master scholarship from the Asian Development Bank–Japan Scholarship Program and the Department of Natural Environment Studies, Graduate School of Frontier Sciences, University of Tokyo. This work was also supported by JSPS KAKENHI Grant Number 19K06106.