Reliable data on CO₂ quantification is increasingly important to quantify the climate benefits of forest landscape restoration and international commitments, such as the Warsaw REDD+ Framework and Nationally Determined Contributions under the Paris Agreement. Calophyllum inophyllum L. (nyamplung as a local name or tamanu tree for the commercial name) is an increasingly popular tree species in forest landscape restoration and bioenergy production for a variety of reasons. In this paper, we present allometric equations for aboveground biomass (AGB), belowground biomass (BGB), and total above- and belowground biomass (TABGB) predictions of C. inophyllum L. Data collection was carried out twice (2017 and 2021) from 40 trees in Java, Indonesia. Allometric equations using the natural logarithm of diameter at breast height (lnDBH) and ln height (lnH) for biomass prediction qualified the model’s fit with statistical significance at 95% of the confidence interval for AGB, BGB, and TABGB predictions. The results showed that the linear models using both lnDBH and lnH were well fit and accurate. However, the model with lnDBH is more precise than the model using lnH. Using lnDBH as a predictor, the R² values were 0.923, 0.945, and 0.932, and MAPE were 24.7, 37.0, and 25.8 for AGB, BGB, and TABGB, respectively. Using lnH as a predictor, the R² values were 0.887, 0.918, and 0.898 and MAPE were 37.4, 49.0, and 39.8 for AGB, BGB, and TABGB, respectively. Consequently, the driven allometric equations can help accurate biomass quantification for carbon-trading schemes of C. inophyllum L.

Bioenergy production from degraded land provides an opportunity to secure a new renewable energy source to meet the rapid growth of energy demand in Indonesia while turning degraded land into productive landscape. However, bioenergy production would not be feasible without landowner participation. This study investigates factors affecting landowners’ preferences for bioenergy production by analyzing 150 landowners with fire experience in Buntoi village in Central Kalimantan using Firth’s logistic regression model. Results indicated that 76% of landowners preferred well-known species that have a readily available market such as sengon (Albizia chinensis (Osb.) Merr.) and rubber tree (Hevea brasiliensis Müll.Arg.) for restoration on degraded land. Only 8% of preferred nyamplung (Calophyllum inophyllum L.) for bioenergy production; these particular landowners revealed a capacity to handle the uncertainty of the bioenergy market because they had additional jobs and income, had migrated from Java where nyamplung is prevalent, and preferred agricultural extension to improve their technical capacity. These results contribute to identifying key conditions for a bottom-up approach to bioenergy production from degraded land in Indonesia: a stable bioenergy market for landowners, application of familiar bioenergy species, and agricultural extension support for capacity building.

Papua Province has a natural production forest reaching 13.541 million ha, with log production achieving an average of 8.78% of the total national log production of 5.835 million m3/year. The logs were obtained from selective logging activities using reduced-impact logging techniques. This paper...

Felling and skidding are essential in the timber extraction process. But on the other hand, residual stand damage can’t be avoided. This study aimed to analyze the impact of conventional and improved felling and skidding techniques on residual stands in natural forests. Three observation plots were developed to identify the types, numbers, and criteria of residual stand damage due to both techniques. The criteria were categorized as a) minor damage (<25%), b) moderate damage (25–50%), and c) major damage (>50%). It showed that the conventional felling and skidding technique caused damages of 14.92% dominated by tree crown damage and 16.70% dominated by stem wounds, respectively. The residual stand damage due to conventional felling and skidding technique was 31.62% categorized as medium damage. Meanwhile, improved felling and skidding techniques caused damage of 9.89% dominated by broken trees, and 10.27% dominated by stem wounds, respectively. The residual stand damage due to improved felling and skidding technique was 20.16% categorized as minor damage. The improvement techniques can minimize residual stand damage by 36.24%. Therefore, a good understanding of forest concessionaires regarding RIL principles is necessary for achieving sustainable timber harvesting