The study describes an integrated impact assessment tool for the net carbon dioxide (CO₂) exchange in forest production. The components of the net carbon exchange include the uptake of carbon into biomass, the decomposition of litter and humus, emissions from forest management operations and carbon released from the combustion of biomass and degradation of wood-based products. The tool enables the allocation of the total carbon emissions to the timber and energy biomass and to the energy produced on the basis of biomass. In example computations, ecosystem model simulations were utilized as an input to the tool. We present results for traditional timber production (pulpwood and saw logs) and integrated timber and bioenergy production (logging residues, stumps and roots) for Norway spruce, in boreal conditions in Finland, with two climate scenarios over one rotation period. The results showed that the magnitude of management related emissions on net carbon exchange was smaller when compared with the total ecosystem fluxes; decomposition being the largest emission contributor. In addition, the effects of management and climate were higher on the decomposition of new humus compared with old humus. The results also showed that probable increased biomass growth, obtained under the changing climate (CC), could not compensate for decomposition and biomass combustion related carbon loss in southern Finland. In our examples, the emissions allocated for the energy from biomass in southern Finland were 172 and 188 kg CO₂ MW h⁻¹ in the current climate and in a CC, respectively, and 199 and 157 kg CO₂ MW h⁻¹ in northern Finland. This study concludes that the tool is suitable for estimating the net carbon exchange of forest production. The tool also enables the allocation of direct and indirect carbon emissions, related to forest production over its life cycle, in different environmental conditions and for alternative time periods and land uses. Simulations of forest management regimes together with the CC give new insights into ecologically sustainable forest bioenergy and timber production, as well as climate change mitigation options in boreal forests.

Background: The homestead forests of Bangladesh occupy 0.27 million hectares (10% of the total forested area) and have potential to store carbon (C) and conserve biodiversity. Small scale forestry practices, however, are lacking reliable estimation of C stocks and tree species diversity. This may hinder successful implementation of REDD + and similar mechanisms as they concentrate on large-scale forests. This study aimed to estimate the above- and below-ground carbon stocks in homestead forests of Maheshkhali Island in Bangladesh and how tree species diversity and stand structural variation affect these C stocks. We randomly surveyed a total of 239 homestead forests in the hillside, beachside, and inland in 2019.Results: Tree biomass C stocks were 48–67% greater in the inland and hillside forests than in the beachside due to significantly greater stand density, basal area, tree diameter. In total we found 52 tree species, but most abundant species in the inland and hillside forests,Mangifera indica,Samanea saman, andArtocarpus heterophyllusstored the most C in tree biomass. Greater tree species richness and diversity index in the inland and hillside forests indicated greater above- and below-ground tree biomass C stocks. An increase in tree species richness and diversity index by one unit was found to increase the tree biomass C stock by 22 and 30 Mg C ha⁻¹, respectively. The total soil C stock was also affected by tree species diversity, stand density, and their interaction with soil properties. Total soil C stocks were greatest (51 Mg ha⁻¹) in the inland forests, having also the greatest stand density and tree species richness. C stock in soil surface was greatest in the hillside forests due to the greatest litterfall, but the average share of litterfall from the total biomass C was only 0.1%.Conclusions: Homestead forest ecosystems could store 96 Mg C ha⁻¹in total, which can contribute to climate change mitigation by generating C credits for small-scale homestead forests owners. Above- and below-ground tree biomass C stocks were found to correlate with tree species diversity, which may also contribute to biodiversity conservation in the REDD + in Bangladesh and countries alike.

The impacts of alternative forest management scenarios and harvest intensities on climate change mitigation potential of forest biomass production, utilization and economic profitability of biomass production were studied in three boreal sub-regions in Finland over a 40-year period. Ecosystem modelling and life cycle assessment tools were used to calculate the mitigation potential in substituting fossil materials and energy, expressed as the net CO₂ exchange. Currently recommended management targeting to timber production acted as a baseline management. Alternative management included maintaining 20% higher or lower stocking in forests and final felling made at lower breast height diameter than used in the baseline. In alternative management scenarios, logging residues and logging residues with coarse roots and stumps were harvested in final felling in addition to timber. The net CO₂ exchange in the southern and eastern sub-regions was higher compared to the western one due to higher net ecosystem CO₂ exchange (NEE) over the study period. Maintaining higher stocking with earlier final felling and intensified biomass harvest appeared to be the best option to increase both climate benefits and economic returns. Trade-offs between the highest net CO₂ exchange and economic profitability of biomass production existed. The use of alternative displacement factors largely affected the mitigation potential of forest biomass.

In this work, we studied the potentials offered by managed boreal forests and forestry to mitigate the climate change using forest‐based materials and energy in substituting fossil‐based materials (concrete and plastic) and energy (coal and oil). For this purpose, we calculated the net climate impacts (radiative forcing) of forest biomass production and utilization in the managed Finnish boreal forests (60°–70°N) over a 90‐year period based on integrated use forest ecosystem model simulations (on carbon sequestration and biomass production of forests) and life‐cycle assessment (LCA) tool. When studying the effects of management on the radiative forcing in a system integrating the carbon sink/sources dynamics in both biosystem and technosystem, the current forest management (baseline management) was used a reference management. Our results showed that the use of forest‐based materials and energy in substituting fossil‐based materials and energy would provide an effective option for mitigating climate change. The negative climate impacts could be further decreased by maintaining forest stocking higher over the rotation compared to the baseline management and by harvesting stumps and coarse roots in addition to logging residues in the final felling. However, the climate impacts varied substantially over time depending on the prevailing forest structure and biomass assortment (timber, energy biomass) used in substitution.

The overall aim of this work was to assess the effects of stump and root extraction on the long‐term carbon sequestration and average carbon storage in the integrated production of energy biomass and stemwood (pulpwood and sawlogs) under different thinning options (unthinned, current thinning and 30% increased thinning thresholds from current thresholds). The growth and development of Norway spruce (Picea abiesL. Karst.) stands on a fertile site (Oxalis‐myrtillus) in central Finland (Joensuu region: 62˚39΄N, 29˚37΄E) was simulated for two consecutive rotation periods (80 + 80 years/160 years). Stemwood and energy biomass production, carbon sequestration, and average storage and emission dynamics related to the entire production process of biomass were assessed. The assessment was done by employing a life cycle assessment tool, which combines simulation outputs from an ecosystem model and the related technosystem emissions. It was found that stump and root harvesting constituted 21–36% of the total biomass production (energy biomass and stemwood) depending on the thinning regimes and rotation period. No considerable effect was found in stemwood production when stump and root extraction was compared to the regime in which stumps and roots were left at the site. Stump and root extraction did not affect carbon sequestration on the following rotation and, in fact, an increase in forest growth was found for the unthinned and 30% increased thresholds compared to the first rotation. The results also showed that if current thinning threshold is increased, win‐win situations are possible, especially when climate change mitigation is the main concern. The substitution of coal with energy biomass is possible without reducing carbon storage in the forest ecosystem. The utilization of energy biomass, including stumps and roots, instead of coal could reduce up to 33% of emissions over two rotation periods depending on the thinning regimes. Even if stumps and roots were excluded, a maximum of 19% carbon emissions could be reduced by using only logging residues.