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Understanding landowners' willingness to act on climate change is important for effective climate policy. This study investigates the determinants of Finnish non-industrial private forest owners' preferences for alternative climate change mitigation strategies related to forests and wood use. The study tests hypotheses concerning the role of risk perception and political leaning for the support of seven alternative strategies with varying degree of disruption to the current logic of commercial forestry in Finland, which further aligns with the temporal delay in the impact of climate change mitigation strategies that landowners are willing to accept. Based on 887 survey responses from three regions, the study finds that forest owners generally support all but one of the seven strategies: reduced harvest. Results from ordinal logistic regression models further indicate that along with socio-demographic determinants, higher perceived risk and left-wing leaning with a university degree explain support for more disruptive strategies with more immediate mitigation impact (increased conservation, reduced harvest), while lower perceived risk and right-wing leaning without a university degree tend to associate with support for the less disruptive strategies (intensified management, increased harvest), both of which arguably sideline the urgency of climate action. In the highly politicized matter of harvest levels in Finland, the study also finds that right-wing leaning may negate the effect of higher education, which otherwise predicts greater support for more disruptive strategies. Implications for policy at the climate-forest nexus are derived. • Preferences of forest owners for mitigation strategies in forests were investigated. • Ordinal logistic regression with 887 survey responses was used. • Forest owners support all but one of the seven strategies: reduced harvest. • High perceived risk and left-wing leaning explain support for strengthening sinks. • Political leaning influences effect of higher education on support for strategies. [ABSTRACT FROM AUTHOR]

• Integrated multi-objective optimization with wood price uncertainty. • Identified trade-offs and synergies, considering wood price uncertainty. • Optimal management allocations shift with spatial and harvest size constraints. • Spatial restrictions and wood price uncertainty impact NPV and carbon sequestration. • Results inform strategic decisions in forest management. Forest ecosystems deliver multiple services crucial for human wellbeing and welfare, with complex relationships among forest ecosystem services (FESs). Implementing sustainable forest management (SFM) policy requires insights into trade-offs, conflicts and synergies among key FESs, necessitating decision-support tools for multiple objectives. However, uncertainty in key parameters adds complexity. We formulated a tri-objective optimization problem concentrating on three vital ecosystem services in Nordic boreal forests: timber supply, climate change mitigation, and biodiversity conservation. Furthermore, future timber price uncertainty was integrated into the optimization model. Utilizing the TreeSim individual-tree growth and yield simulator, we simulated forest growth and yields, carbon stocks, and biodiversity values. Pareto-optimal solutions were found for four distinct management strategies using the epsilon-constrain method to solve the optimization problem. These management strategies differed in spatial restrictions on harvest location and timing, including considerations like harvest adjacency, green-up and maximum harvest opening area (MOA). The analysis revealed trade-offs among all three objectives, with variations influenced by management intensity. Furthermore, within the Pareto solutions for each strategy, a compromise solution was identified based on the knee-point method. The study demonstrated nuanced impacts of green-up constraints related to harvest practices, showing minor effects on harvesting, carbon sequestration, and biodiversity conservation when MOA was restricted to 35 hectares or less. However, more substantial impacts were observed with a MOA limited to 60 hectares or in a strategy without spatial restrictions. Our results underscore the importance of considering multiple objectives in forest management and policy under uncertain wood prices, preventing undesired effects from a singular or deterministic approach. This work provides insights into trade-offs and synergies, contributing to strategic planning and policy design. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Alpine study sites with a long close-to-nature forestry (CNF) history were studied. • Alternative climate change and CNF management scenarios were simulated. • CNF performs well in ensuring multiple forest ecosystem services and biodiversity. • Climate change requires adaptation of CNF by fostering climate-adapted tree species. • High multifunctionality, including biodiversity, needs diversified management. Close-to-nature forestry (CNF) has a long tradition in European Alpine forest management, playing a crucial role in ensuring the continuous provision of biodiversity and forest ecosystem services, including protection against natural hazards. However, climate change is causing huge uncertainties about the future applicability of CNF in the Alpine region. The question arises as to whether current CNF practices are still suitable for adapting forests to climate change impacts while also meeting the increasing societal demands regarding Alpine forests, including their potential contribution to climate change mitigation. To answer this question, we simulated forest development using the ForClim forest model at two Alpine study sites, together representing a large biogeographic gradient from high-elevation inner Alpine forests (Switzerland) to lower-elevation south-eastern Alpine forests (Slovenia). The simulations considered three climate scenarios (historical climate, SSP2-4.5 and SSP5-8.5) and six alternative management strategies, including both current CNF management practices and climate-adapted versions. Using an indicator based multi-criteria decision analysis framework, we assessed the joint impacts of climate and management on biodiversity and key ecosystem services of the investigated regions, including carbon sequestration (CS) inside and outside the forest ecosystem boundary. The joint effects of climate change and CNF varied, both among and within the study sites along the biogeographical gradient. While CS was more resistant to climate change under current CNF at the south-eastern Alpine site, it was more sensitive at the inner Alpine site, where CS potentials decreased at lower elevations. This adverse effect could be partly mitigated by fostering the use of climate-adapted tree species. However, current CNF and adaptations of it did not meet multiple management objectives equally well: while protection from gravitation hazards and timber production also benefited from this silvicultural practice, biodiversity benefited from CNF variants with low-intensity or no management. In conclusion, CNF has a high potential to continue fulfilling its crucial role in European Alpine forests. A differentiated approach will be needed in the future, however, to identify forest stands where adaptive measures are required, especially at sites particularly vulnerable to climate change. In combination with less intensively managed or unmanaged areas, CNF provides a management portfolio that will help European Alpine forests to meet the demands of future society. [ABSTRACT FROM AUTHOR]

Boreal forests are often managed to maximize wood production, but other goals, among which climate change mitigation, are increasingly important. Hence, it is necessary to examine synergies and trade-offs between forest production and its potential for carbon sequestration and climate change mitigation in forest stands. To this aim, we develop a novel mass-balanced process-based compartmental model that allows following the carbon path from its photosynthetic fixation until its return to the atmosphere by autotrophic or heterotrophic respiration, or by being burnt as wood product. Following carbon in the system allows to account for how long forest ecosystems and wood products retain carbon away from the atmosphere (i.e., the carbon transit time). As example, we apply the model to four management scenarios, i.e., mixed-aged pine, even-aged pine, even-aged spruce, and even-aged mixed forest, and contrast metrics of performance relative to wood production, carbon sequestration, and climate change mitigation potential. While at the end of an 80 yr rotation the even-aged forests held up to 31% more carbon than the mixed-aged forest, the mixed-aged forest was superior during almost the entire rotation when factoring in the carbon retention time away from the atmosphere, i.e., in terms of climate change mitigation potential. Importantly, scenarios that maximize production or amount of carbon stored in the ecosystems are not necessarily the most beneficial for carbon retention away from the atmosphere. These results underline the importance of considering carbon transit time when evaluating forest management options for potential climate change mitigation. [Display omitted] • We evaluate wood production and climate change mitigation potential of boreal forests. • We combine an ecophysiological growth model with forest inventory tree allometries. • Higher carbon sequestration does not ensure higher climate change mitigation potential. • Potential climate change mitigation depends on carbon time away from the atmosphere. [ABSTRACT FROM AUTHOR]

Despite the need for climate change mitigation and altered forest management practices, little is known about the impacts of silvicultural practices such as partial-cuts and clear-cuts on forest ecosystem carbon (C) dynamics. Specifically, the effect of these two overstory treatments on C pools other than the aboveground biomass of trees remains poorly understood. Here, C stocks were estimated for a northern temperate mixed forest located in eastern Québec, Canada, five years after clear-cutting and partial-cutting, either with or without a brushing treatment to control the competing vegetation. The biomass of the aboveground vegetation (trees, saplings, understory), litter and woody debris (coarse, small, fine), as well as the roots (diameter ≤ 1.5 cm) was evaluated. Additionally, soil C pools up to a depth of 35 cm of the mineral soil were assessed. Total ecosystem C stocks were influenced by the overstory treatments reflecting harvest intensities. Although the belowground C pools were major contributors to total ecosystem C stocks, silvicultural treatments only influenced forest floor and aboveground C stocks. However, assessments like the one presented here capture contemporary C stocks, which highlights the need for monitoring to build suitable forest ecosystem C models and to understand long-term C dynamics. • Northern temperate mixed forests store large quantities of carbon. • Belowground carbon pools are major contributors to total ecosystem carbon stocks. • Total ecosystem carbon stocks are influenced by silvicultural overstory treatments reflecting harvest intensities. • Silvicultural treatments only influenced forest floor and aboveground carbon stocks. [ABSTRACT FROM AUTHOR]

• The nexus between forest-based climate mitigation and health is poorly researched. • This scoping review identified exposure pathways and health co-benefits from forests. • There is potential for synergies between forest management and health benefits. • Interdisciplinary efforts are required for advancement of research and understanding. Climate change is a pressing global challenge with profound implications for human health. Forest-based climate change mitigation strategies, such as afforestation, reforestation, and sustainable forest management, offer promising solutions to mitigate climate change and simultaneously yield substantial co-benefits for human health. The objective of this scoping review was to examine research trends related to the interdisciplinary nexus between forests as carbon sinks and human health co-benefits. We developed a conceptual framework model, supporting the inclusion of exposure pathways, such as recreational opportunities or aesthetic experiences, in the co-benefit context. We used a scoping review methodology to identify the proportion of European research on forest-based mitigation strategies that acknowledge the interconnection between mitigation strategies and human impacts. We also aimed to assess whether synergies and trade-offs between forest-based carbon sink capacity and human co-benefits has been analysed and quantified. From the initial 4,062 records retrieved, 349 reports analysed European forest management principles and factors related to climate change mitigation capacity. Of those, 97 studies acknowledged human co-benefits and 13 studies quantified the impacts on exposure pathways or health co-benefits and were included for full review. Our analysis demonstrates that there is potential for synergies related to optimising carbon sink capacity together with human co-benefits, but there is currently a lack of holistic research approaches assessing these interrelationships. We suggest enhanced interdisciplinary efforts, using for example multideterminant modelling approaches, to advance evidence and understanding of the forest and health nexus in the context of climate change mitigation. [ABSTRACT FROM AUTHOR]

• Substitution factors for forest products for the Canadian context were developed. • Substitution factors ranging from 0.51 to 0.91 tC/tC were found. • They will lead to more accurate assessments of the forest GHG mitigation potential. • These factors will help governments to manage forest and fight climate change. Evaluating the climate change mitigation potential of the forest sector requires a holistic approach based on forest carbon (C) sequestration, C storage in harvested wood products (HWP) and substitution on markets. High uncertainty is associated with substitution factors, that express avoided fossil greenhouse gas (GHG) emissions from the use of forest-based products in replacement of GHG-intensive materials and fossil fuels. Few studies have focused on the development of substitution factors in Canada, resulting in the use of unrepresentative generic data. Here, we provide a framework to reduce uncertainties related to substitution factors for primary wood products in a Canadian context. A life cycle assessment framework is used to quantify fossil GHG emissions for a baseline and a wood-intensive scenario. For solid product substitution, we focused on the construction sector and analyzed a range of innovative wood buildings with steel and reinforced concrete as alternative materials. We found non-weighted averages of 0.80 tC/tC for sawnwood and 0.81 tC/tC for panels. For energy substitution, we analyzed cases with different specifications on biomass product, facility type and alternative fossil fuel source in non-residential heat production and biofuel transportation sectors. We found a non-weighted average of 0.80 tC/tC for non-residential heat production and 0.51 tC/tC for biofuel transportation, that can be interpreted as 0.91 tC/tC for heavy fuel oil, 0.69 tC/tC for light fuel oil and 0.68 tC/tC for natural gas substitution. These results provide a benchmark for substitution factors in Canada, to help guide forest management strategies for climate change mitigation. [ABSTRACT FROM AUTHOR]

Temporary carbon storage and substitution benefits of harvested wood products (HWPs) aid in mitigating global warming. However, the extent of this effect remains unclear. Current studies typically rely on a simple summation of the annual carbon sink. This method overlooks the fact that, due to radiative forcing delay, each ton of carbon sequestered has an impact on global warming, which dynamically changes year by year. Such an oversight could lead to an underestimation of HWPs' contribution to global warming mitigation. This study focused on a forestry resource-based city in Northeast China and utilized the Carbon Budget Model for the Canadian Forest Sector (CBM-CFS3) and dynamic life cycle assessment (DLCA) to quantify the dynamic global warming impact (DGWI) of forestry biogenic carbon. The results indicate that: 1) From 2020 to 2120, the maximum DGWI could reach −42.70 Mt CO 2 e. Enhancing the collection and utilization of harvesting residues and promoting products with longer lifespans and higher substitution potential can further increase these benefits. 2) The DLCA method, integrating substitution effects, offers a more precise evaluation of forestry's climate mitigation benefits. Across all scenarios and periods in this study, HWPs' contribution to mitigating global warming, as calculated by the DLCA method, exceeds that estimated by the simple carbon sink summation method by 7.70 %–560.72 %. These findings help to delve deeper into the role of forests in emission reduction and carbon sequestration, providing important references for achieving sustainable forestry management. • Developing and strategically using HWPs positively impacts global warming mitigation. • Method of simply summing up carbon sinks undervalues HWPs' cumulative climate impact. • DLCA method helps assess dynamic global warming impact of forestry biogenic carbon. • Forest management should balance wood production and climate mitigation. [ABSTRACT FROM AUTHOR]

• Most of the NbS of Tropical drylands of India are not follow the IUCN standard criteria. • The Identified NbS are baised towards environmental services than addressing social needs of the people. • Improved NbS interventions requires intensive enagement of stakeholders for addressing social causes. Nature-based Solutions (NbS) is a flexible, adaptable, and multi-functional strategies employed to address climate change. However, all the claimed NbS are actually do not adhere the criteria of being NbS. Therefore, present study analysed 87 articles to appraise adherence of potential NbS as per the IUCN Global Standard, along with evaluation of flow of associated ecosystem services (ES). The review identified 39 interventions, out of which only twelve interventions adhered the criteria of NbS. Among the classified NbS, two interventions, namely, sustainable forest management (SFM) (80.83%) and haveli rejuvenation (75.61%) strongly adhered to the IUCN Standard. Lack of adherence in the non-classified NbS interventions was mainly attributed to absence of information on inclusive governance, monitoring and associated trade-offs. The identified 39 interventions were also observed to be enhancing a total of 37 ES, evaluated through 37 distinct indicators i.e. different and enhanced flow of ES were observed by the different NbS. However, the majority of classified NbS were biased towards flow of environmental services than social services. Present study results that all claimed NbS cannot fulfilled the intended objectives of NbS and thus cannot be classified under the NbS as per global standard. Moreover, assessing the flow of associated ES may be an additional support to broaden the scope of NbS implementation. Therefore, present study also highlights to integrate the flow of ES along with the adherence criteria of NbS. Moreover, the review also facilitate to understand constraints associated with the implementation of potential NbS interventions and thus, suggests considering wider aspects in the future researches for assessing the implementation of NbS. [ABSTRACT FROM AUTHOR]

[Display omitted] • Stand spatial structure plays an important role in the fragile natural secondary forest. • Species diversity have a negative impact in changing restored woodlands, thereby reducing productivity. • Stand spatial structure has a stronger impact on forest carbon sink than species diversity. • Stand spatial structure is a prioritized indicator in the regulation of fragile forest ecosystems. Increasing attention for adjusting forest structural and species diversity has been paid to enhance carbon storage. However, the relative importance of stand spatial structural diversity and species diversity to restored stand carbon stocks remains unclear. To address this issue, we conducted a sample plot setup in the Loess Plateau with the aim of exploring the effects of stand spatial structural diversity and species diversity on forest carbon stocks. Therefore, we determined index parameters for species diversity (Simpson, Shannon-Wiener, and Pielou) and spatial structural diversity (Angular scale, Mingling, Aggregation, and Competition) within the oak forest ecosystem. We examined carbon storage in all vegetation organs and different soil layers. Additionally, we employed a structural equation model to develop a model that illustrates the effects of stand spatial structure and species diversity on ecosystem carbon storage. The results reveal that stand spatial structure and species diversity influence the ecosystem carbon storage through biomass (trees and litter) and soil carbon (0–100 cm). Stand spatial structure exhibits positive direct effects (path coefficients: 0.764 and 0.890), while species diversity shows negative direct effects (−0.320 and −0.206) on biomass and soil carbon, respectively. Finally, the total effect of spatial structure diversity on forest carbon storage surpasses that of species diversity. Therefore, stand spatial structure should be adjusted preferentially during forest management in fragile ecological environment. Our results provide important insights into the climate change mitigation potential associated with the structure-based management of forests. [ABSTRACT FROM AUTHOR]

• Four design principles would inform a forest carbon market-based mechanism in India. • Robust governance and accounting emerge as key technical considerations. • Local community involvement and flexible spatio-temporal criteria would encourage participation. • Land tenure, implementation challenges and design flaws may inhibit effectiveness. Forest carbon markets (FCMs) have emerged as a significant means to direct resources toward urgent climate action that can mobilize a large set of actors and catalyze funding toward reducing deforestation and promoting sustainable forest management. Here, we conduct a critical qualitative review of global academic and investigative literature to identify ten major sets of design principles that provide a platform for the functioning of carbon markets worldwide. From these, we pinpoint four design principles which may be relevant to future market-based mechanisms in India We propose that clarity over market-quality standards, comprehensive regulatory framework, minimization of transaction costs and upfront financing options, and flexibility in time-bound and spatial commitments would be fundamental to ensure that market-based mechanisms in India accrue sustainable and long-term benefits to climate action and human well-being. A successful market-based mechanism in India's forestry sector would have to overcome challenges around land property rights, local implementation capacities and knowledge gaps, and incentive structures to ensure that it likely caters to the needs of all stakeholders while delivering socio-ecological benefits. [ABSTRACT FROM AUTHOR]

• Forest residues, a renewable energy, have great potential to substitute fossil fuels to reduce enormous pressures of energy shortages in mitigating climate change. However, it is a challenge to quantify forest residues at a fine spatial scale due to large spatial variations of forest species and lacking of suitable research methods. In addition, the natural decomposition of forest residue is often ignored in future greenhouse emission prediction, • We estimated the total forest residues in China reached 152.13 million t in 2018. The forest residues had faster decomposition rate (annual natural decomposition value of carbon from forest residues) in the first ten years, and then gradually decreased. In the first 14 years, the half forest residues was decomposed. The national contribution to climate change (CCC) from forest residues over one-hundred-year reached 49.27 million t CO 2 eq. The peak values of the provincial annual CCC were reached within 15 years and we found that the highest annual CCC occurred in the second year since the natural decomposition. • There are two major contents. First, a method is put forward to downscale the reserve of forest residue to county-level administrative unit. Prior to this, the resolution of the estimations was generally at provincial level. Obviously, more refined data was conducive to encourage the utilization of biomass by providing references for policymakers and investors. Second, a new index was implemented to assess the contribution of the natural decomposition of unused forest residues to climate change. • We estimated that CCC caused by their natural decomposition reaches 4.927 million t CO 2 eq, which was 0.96%−6.5% of other carbon emission sources (i.e. staple crops, inland water) in China. From a global perspective, such carbon emission was 0.015% of global wetland carbon emissions and 1.59% of global peat land carbon emissions. • Our study provides new data to support future climate mitigation, reducing the significant uncertainty in related research, and will make researchers, policymakers, and investors recognize the great potential of forest residues as an energy source and the significant contribution of their natural decomposition to climate change and promote carbon neutrality transition. Under the energy shortage and emerging climate change caused by fossil energy, forest residues were encouraged to be used as an energy resource. However, it is a challenge to quantify the forest residue at the fine spatial scale due to the available data and suitable research methods. We aimed to quantify the available forest residues in China at the county scale and clarify their potential contribution to climate change (CCC). The availability of forest residues reached 152.13 million t in 2018 in China. The CCC accumulated by natural decomposition of forest residues over one-hundred-year had reached 49.27 million tCO 2 eq. The peak values of provincial annual CCC were reached in the first 3 years in the southern region. The top four counties of CCC were all from Yunnan Province. The energy utilization of forest residues is of great significance to the management of forest resources. [Display omitted] [ABSTRACT FROM AUTHOR]

• Interactions of climate, soil, diversity, and competition notably affected tree slenderness. • Interactive effects of indicators were greatest in small-sized trees. • Effect direction of one indicator varied with the gradients of other indicators. • Negative effects of climate and soil on stability can be improved by adjusting density and diversity. The tree slenderness coefficient (TSC) serves as a simplified measure of tree stability, which is subject to the complex influences of climate, soil, diversity, and competition. Quantifying and exploiting the risks affecting the TSC facilitates the development of forest stability restoration measures. In the current climate change and multiple risk coexistence scenario, the interactions of risks are expected to have non-negligible effects on the TSC. However, past efforts have been limited to independent effects without interactive effects, which is detrimental to a proper understanding of ecology. For example, the inconsistent effect direction of the same indicator on TSC in past studies may be due to the neglect of the interactive effects of the indicators. Natural secondary forests are effective mitigation tools for climate change that urgently need to be managed appropriately to maximize their stability and provide a wide range of benefits. Therefore, we conducted the first comprehensive investigation of both independent and interactive effects of climate, soil, diversity, and competition on TSC, utilizing data from 13,874 trees of three principal tree species distributed in Chinese boreal natural secondary forests. Further, simulation examples were provided to present actionable management measures using the improved insight. The results showed that short-wave solar radiation (Srad), cation exchange capacity (CEC), Pielou evenness index (Pielou), and basal area (BA) exerted positive independent influences on TSC, while mean annual precipitation (MAP) did the opposite. The significant interaction terms were BA × Pielou, BA × Srad, Pielou × CEC, and Srad × CEC, all of which showed positive effects on TSC. In addition, the interactions produced non-negligible forces on the TSC, especially for small-sized trees, as the relative importance was quite large. Importantly, the effect directions of the indicators on the TSC were inconstant and changed with the gradients of other indicators due to the presence of interactions. Finally, the simulation results showed that tree stability in 97.1% of the plots was negatively affected by Srad or CEC, which could be transformed into positive effects by adjusting BA or Pielou above the critical points. This research offers a novel insight into the importance of interactions in credible TSC modeling and indicator analysis, which may hopefully serve as a beginning to guide forest management based on tree stability while faced with environmental change. [ABSTRACT FROM AUTHOR]

The forestlands of the Pacific Northwest store a significant amount of carbon, provide wildlife habitat, generate revenue for forestland owners, and provide for sustainable generation of forest products. Promoting forest carbon storage is increasingly recognized as a key management objective to mitigate climate change. We developed an agent-based model to examine the effectiveness of current land management practices in sustaining forest carbon storage and revenue flows, and the utility of market-based carbon payments in improving carbon storage while also improving revenue generation in the Pacific Northwest. We find that while market-based incentives can improve both forest carbon storage and revenue, they are limited in their benefit to small forest owners. Our results highlight the crucial need for additional policy interventions to reduce barriers to market access for small private owners and ensure sustainable forest management in this region. We further show that a forest owners' cooperative, which aggregates small owners to reduce the costs of participating in a carbon market, can help overcome these barriers and result in both greater carbon storage and a more equitable benefit from carbon payments. • Forest carbon management is crucial for climate mitigation; forest owners' management practices play a vital role. • We developed an agent-based model of forest owners' management and their adaptations to carbon-focused policies. • We analyze policy effectiveness for landscape-level and forest owner-level carbon sequestration and revenue generation. • We show policy efficacy for carbon storage and revenue generation, and inequitable economic outcomes across owner groups. • We highlight the need and effectiveness of additional institutional intervention to ensure equitable outcomes. [ABSTRACT FROM AUTHOR]

• The CH 4 fluxes from global forest soils are estimated. • MAT, MAP, soil BD, SOC, and TN were the key drivers of the forest soil CH 4 fluxes. • The CH 4 budget of global forest soils is 14.98 [7.96–21.73] Tg CH 4 yr−1. • Nearly 3.17% of the total area of global forest soils was a net CH 4 source. • The global mean CH 4 uptake in forest soils was 3.95 kg CH 4 ha−1 yr−1. Forest ecosystems play an important role in the global CH 4 cycle. Understanding and quantifying the contribution and distribution of CH 4 sinks and sources in global forest soils is vital for assessing realistic approaches to climate change mitigation. Here, we compiled a dataset of in situ global forest soil CH 4 fluxes from published data, incorporating 772 case studies covering boreal (n = 12), temperate (n = 369), subtropical (n = 208), and tropical (n = 183) forests and spanning 1991–2020 as a basis to build the mixed-effect model. Using the screened best model, we identified the main drivers and predicted the global distribution of the forest soil CH 4 flux. Our research revealed that global forest soil CH 4 uptake decreased significantly with increasing mean annual temperature (MAT), soil bulk density (BD), soil organic carbon (SOC), and soil total nitrogen (TN) but increased significantly with increasing mean annual precipitation (MAP). The global mean CH 4 uptake rate in forest soils was 3.95 ± 1.78 kg CH 4 ha−1 yr−1, with the total sink of 14.98 ± 6.75 Tg CH 4 yr−1. The soil CH 4 sinks in temperate and tropical forests contributed 84 % to the total sink of global forests. The CH 4 emission rate in global forest soils averaged 1.12 ± 1.11 kg CH 4 ha−1 yr−1, with the total source of 0.14 ± 0.14 Tg CH 4 yr−1. Nearly 3 % of the total area of global forest soils was a net CH 4 source. In summary, we identified the key drivers of forest soil CH 4 flux and improved previous estimates of the global CH 4 budget in forest soils. These findings can support decision-making related to forest management and greenhouse gas restrictions. [ABSTRACT FROM AUTHOR]

• Critical zone science includes long time scales and deep subsurface processes that can inform forest management. • Forest capacity for climate adaptation and mitigation is influenced by bedrock-mediated soil characteristics such as moisture and nutrient availability. • Managers can use bedrock-driven constraints on rock water storage to diagnose and forecast forest response to drought. • Forest planning for escalating pest outbreaks and fire can consider spatial patterns of deep water storage to identify areas of high risk or high mitigation potential. • Critical zone science contributes a range of open-source databases that can aid forest management planning. Forest management is under intensifying ecological and societal pressures amid the current geological epoch, which some see becoming the Anthropocene. These pressures extend to temporal and physical scales typical of geology; however, integrating geological processes into forest management has lagged behind the inclusion of shorter-term and surficial ecosystem processes. As such, we examine the field of critical zone science for connections that translate geologic knowledge to forest management and planning. Earth's critical zone is the thin near-surface zone spanning from the bottom of circulating groundwater to the top of the atmospheric boundary layer of forest canopies. We explore four case studies from regions of the U.S.A. to highlight how recent critical zone discoveries inform contemporary forest management challenges. Some examples of management-relevant research include mediation of the impacts of climate change on forest productivity across gradients in geology, aspect, and topography; the role of bedrock water storage on drought resistance; hydrology-vegetation interactions following pest outbreaks; and quantification of water partitioning and erosion following fire. The accelerated pace of critical zone discovery has been synchronous with increased availability of open-source data resources for forest managers to expand this framework in management and planning. [ABSTRACT FROM AUTHOR]

As compared to temperate and boreal forests, the majority of tropical forests are biodiverse, structurally-complex and high-functioning ecosystems, yet their potential attributes are vulnerable to anthropogenic disturbances and environmental factors. Here, we hypothesize that the biological, structural and functional attributes of tropical forests respond to water-related climatic and soil nutrient-related factors. Thus, we quantified 27 forest attributes and 20 environmental factors across 189 plots of Sri Lankan tropical forests. Our results suggest that environmental conditions were characterized by both water-related and temperature-related factors, and as such, both coarse-textured and compacted-structured soils determined soil conditions. Forest conditions were characterized by high species-functional diversity, structural complexity and aboveground biomass-related functions. We found strong positive effects of water-related climatic factors (particularly mean annual precipitation) followed by temperature-related climatic factors (i.e., growing degree days) but negligible positive to negative effects of textured-related (i.e., gravel contents) and nutrient-related (i.e., bulk density) soil factors on most of the biological, structural and functional attributes. Overall the biodiversity and carbon stocks of Sri Lankan tropical forests are likely to increase with water-energy balance and improved soil conditions, and thus, studied forests could offset a substantial quantity of anthropogenic carbon emissions to achieve carbon neutrality which can have both regional and global significance if protected from anthropogenic disturbances. Broadly, this study suggests that conservation practices should consider multiple environmental and biotic attributes of the tropical forests during forest management which can have a win-win situation for biodiversity conservation and climate change mitigation. [Display omitted] • The world's tropical forests are highly biodiverse but sensitive to drought. • Climate and soil regulated the forest attributes of Sri Lankan tropical forests. • Biodiversity and carbon stocks of the Sri Lankan tropical forests are likely to be increased with water-energy balance if conserved. • Sri Lankan forests could offset anthropogenic carbon emissions to achieve carbon neutrality. [ABSTRACT FROM AUTHOR]

• Carbon stock in 12 major forest types along an elevational gradient (350–3450 masl) in the Indian Himalaya quantified. • A significant effect (p < 0.008) of elevation was observed on the forest structural variables, biomass and carbon stock. • Highest tree biomass and carbon stock values were found in the high-elevation forest types. • Climate-smart tree species suitable to the elevational belts in the region identified. • Our findings have immediate implications for climate change mitigation policy and practice. In an era of climate change, quantifying forest biomass and carbon stock along elevational gradients in mountainous areas assumes immediate relevance for carbon budgeting and forest management. Here, we carried out extensive field studies to quantify the tree biomass and carbon stock of major forest types along a wide elevational gradient (350–3450 m) in Jammu and Kashmir, a region located in the northwestern Himalaya. We adopted a stratified random cluster sampling approach to generate ground-based data on structural variables (diameter at breast height-DBH, stem height, basal area, stem density, species richness), and quantified biomass and carbon stock volume using allometric equations in 12 major forest types in the region. We found a significant difference in all the tree structural variables among the forest types. Our results show a significantly positive correlation between DBH and height, but a significantly negative correlation of stem density with DBH and height. We observed a higher basal area in the forest types between 1750 and 3350 m elevation, with the highest value (104.4 ± 29.0) found in Fir forest. We also found higher stem density values at mid- and high-elevations in comparison to low-elevation, but the trend was inconsistent. To evaluate the influence of elevation on the structural attributes, we fitted a Linear Regression Model (LM) for each variable, followed by F-test. We observed a significant effect (p < 0.008) of elevation on all the forest tree structural variables, species richness, biomass and carbon stock. All these variables, except species richness, showed a positive relationship with elevation. We found the highest aboveground-, belowground-, total biomass, and carbon stock in the forest types at high elevation above 1750 m. The most significant tree species in terms of biomass and carbon stock contribution was Abies pindrow , followed by Cedrus deodara and Pinus roxburghii , thus making them suitable tree species for forest conservation and restoration in this Himalayan region. Principal component analysis of anthropogenic disturbances revealed the fire mostly associated with the forest types dominated by P. roxburghii , stem cutting with those dominated by C. deodara, P. wallichiana and A. pindrow , and grazing with the high-elevation forest types. Overall, our study unravels the patterns of forest carbon stock along a wide elevational gradient in this Himalayan region, with immediate implications for climate change mitigation policy and practice in mountainous landscapes. [ABSTRACT FROM AUTHOR]

• Global forest sector model intercomparison of 81 future pathway scenarios. • Socioeconomic drivers have strongly influence forest sector model estimates. • Global forests could sequester 1.2–5.8 GtCO2e/yr over the next century. • Improved management can increase carbon and harvests without expanding forest area. • Climate policy assessments could better represent forest markets and management dynamics. Deforestation has contributed significantly to net greenhouse gas emissions, but slowing deforestation, regrowing forests and other ecosystem processes have made forests a net sink. Deforestation will still influence future carbon fluxes, but the role of forest growth through aging, management, and other silvicultural inputs on future carbon fluxes are critically important but not always recognized by bookkeeping and integrated assessment models. When projecting the future, it is vital to capture how management processes affect carbon storage in ecosystems and wood products. This study uses multiple global forest sector models to project forest carbon impacts across 81 shared socioeconomic (SSP) and climate mitigation pathway scenarios. We illustrate the importance of modeling management decisions in existing forests in response to changing demands for land resources, wood products and carbon. Although the models vary in key attributes, there is general agreement across a majority of scenarios that the global forest sector could remain a carbon sink in the future, sequestering 1.2–5.8 GtCO2e/yr over the next century. Carbon fluxes in the baseline scenarios that exclude climate mitigation policy ranged from −0.8 to 4.9 GtCO2e/yr, highlighting the strong influence of SSPs on forest sector model estimates. Improved forest management can jointly increase carbon stocks and harvests without expanding forest area, suggesting that carbon fluxes from managed forests systems deserve more careful consideration by the climate policy community. [ABSTRACT FROM AUTHOR]

• Aboveground biomass across forest strata was controlled by lower species evenness. • Species evenness mediates the divergent effects of stand age and topography on AGB. • Different trait identities depending on forest strata enhance AGB in each stratum. The relationships amongst environmental conditions, stand age, tree diversity, and trait identity with aboveground biomass (AGB) remain highly debated in forest ecosystems, but these relationships across forest strata (i.e., overstory and understory) remain poorly assessed in subtropical – warm-temperate forests. Here, we hypothesized that environmental conditions, stand age, tree diversity and trait identity jointly control AGB, but divergent species' functional strategies regulate AGB in different forest strata of subtropical – warm-temperate forests. To do so, we analyzed datasets from 72 plots across five sites in subtropical – warm-temperate forests of Jeju Island, South Korea. We used multimodel inference tests based on multiple linear regressions models and then piecewise structural equation modeling (pSEM) to assess the relationships amongst topographic factors, stand age, tree diversity (i.e., species, phylogenetic and functional diversity), and trait identity (i.e., community-weighted mean – CWM – of a trait values) and AGB in the overstory, understory, and whole community. The pSEMs showed that lower species evenness increased AGB in overstory and understory, but CWM of tree maximum height and seed mass enhanced overstory and understory AGB, respectively. Moreover, species evenness mediated the divergent effects of stand age and topography on overstory and understory AGB, respectively. This study shows that the effect of low species evenness on AGB is ubiquitous across forest strata, but divergent species' functional strategies also contribute to shaping AGB. We argue that species' functional strategies (i.e., the mass ratio effect) across forest strata and developmental stages should be taken into consideration for sustainable forest management to achieve the biodiversity conservation and carbon sequestration that underpins human wellbeing through climate change mitigation strategies. [ABSTRACT FROM AUTHOR]

The success and rate of forest regeneration has consequences for sustainable forest management, climate change mitigation, and biodiversity, among others. Systematically monitoring forest regeneration over large and often remote areas is challenging. Remotely sensed data and associated analytical approaches have demonstrated consistent and transparent options for spatially-explicit characterization of vegetation return following disturbance. Moreover, time series of satellite imagery enable the establishment of spatially meaningful recovery baselines that can provide a benchmark for identifying areas that are either under- or over-performing relative to those baselines. This information allows for the investigation and/or prioritization of areas requiring some form of management intervention, including guiding tree planting initiatives. In this research, we assess recovery following stand replacing disturbances for the 650 Mha forested ecosystems of Canada for the period 1985–2017, wherein ~51 Mha of Canada's forested ecosystems were impacted by wildfire, and ~ 21 Mha were impacted by harvesting. For quantification of forest recovery, we implement the Years to Recovery or Y2R metric using Landsat time series data based on the Normalized Burn Ratio (NBR) to relate the number of years required for a pixel to return to 80% of its pre-disturbance NBR value. By the end of the analyzed period, 76% of areas impacted by wildfire were considered spectrally recovered compared to 93% of harvested areas. On average, we found that harvest areas had more rapid spectral recovery (mean Y2R = 6.1 years) than wildfire (mean Y2R = 10.6 years) and importantly, that Y2R varied by ecozone, disturbance type, pre-disturbance land cover, and latitude. We used airborne laser scanning data to assess whether pixels that were considered spectrally recovered had attained United Nations Food and Agricultural Organization benchmarks of canopy height (>5 m) and cover (>10%) across four geographic regions representing different forest types. Overall, 87% and 97% of recovered pixels sampled in harvests and wildfires, respectively, had achieved at least one of the benchmarks, with benchmarks of height more readily achieved than benchmarks of cover. By analyzing spatial patterns of Y2R, we identified areas that had significant positive or negative spatial clustering in their rate of spectral recovery. Approximately 3.5–4% of areas disturbed by wildfire or harvest had significant positive spatial clustering, indicative of slower spectral recovery rates; these areas were also less likely to have attained benchmarks of height and cover. Conversely, we identified significant negative spatial clustering for 0.94% of areas recovering from harvest and 1.93% of areas recovering from wildfire, indicative of spectral recovery that was more rapid than the ecozonal baseline. Herein, we demonstrated that remote sensing can provide spatial intelligence on the nature of disturbance-recovery dynamics in forested ecosystems over large areas and moreover, can retrospectively quantify and characterize historic forest recovery trends within the past three decades that have implications for forest management, climate change mitigation, and restoration initiatives in the near term. • Landsat time series monitored forest disturbance and recovery for 32 years across 650 Mha. • Harvests spectrally recovered more rapidly (6.1 years) than wildfire (10.6 years). • Lidar-derived benchmarks of canopy cover (>10%) and height (>5 m) used for validation. • 87% and 97% of recovered harvest and wildfire samples achieved one of the benchmarks. • Nationally, 3.5%–4% of wildfire and harvest areas had slower than expected recovery. [ABSTRACT FROM AUTHOR]

• Afforestation increases soil methane uptake compared to contiguous herbaceous land. • Maximum methane uptake driven by afforestation varies with stand age and density. • Afforestation effect on soil methane fluxes was mediated by their effect on soil water balance. • Modifying rotation time and stand stocking, afforestation may increase its potential as a CH 4 sink. Evidence suggests that tree plantations change soil methane (CH 4) fluxes (magnitude and/or direction of the fluxes) compared to herbaceous land (i.e. afforestation effect) due to the effect of trees increasing methanotroph bacteria abundance and enhancing soil gas diffusivity. However, the magnitude of this afforestation effect is highly variable across studies. Here, we evaluated whether the variation in the afforestation effect depends on forestry management strategies, described by stand age and density, as well as taxonomic identity of the tree species, and the interaction with climatic conditions. To this end, we conducted a meta -analysis using 47 paired samples of afforested and contiguous herbaceous land from 14 studies located in different biomes worldwide. We found that afforestation predominantly increases the capacity of soil net CH 4 uptake (i.e. more negative fluxes) compared to herbaceous land, but the magnitude of this effect was highly heterogeneous across paired samples. This heterogeneity was explained by environmental conditions, but significant effects of forest stand age and density were also found proving the importance of forest management on this ecological service. Soil net CH 4 uptake following afforestation increases with increasing stand age. Although the stand stocking effect could be tested with a limited number of studies (24 out of the 47 paired samples), the results suggest that net CH 4 uptake decreases with tree stocking (stand density) in the range of values up to 1500 individuals per ha. No change in CH 4 fluxes was observed above this high stand density. Contrary to our expectations, no effect of taxonomic identity of the trees considering the most planted genera (Pinus and Eucalyptus) was observed in the average soil CH 4 fluxes. Furthermore, a significant correlation between the afforestation effect on soil water content and CH 4 flux suggests that the most plausible cause of the increased soil net CH 4 uptake is driven by the forest impact on soil desiccation, which in turn increases in sites with higher water limitation (i.e. higher potential evapotranspiration and high temporal rainfalls variations within the ranges of the available studies). Finally, our study provides evidence that by modifying rotation time and stand stocking, afforested land may increase its environmental service as a sink of atmospheric CH 4. [ABSTRACT FROM AUTHOR]

Agroforestry is recognized as a friendly land-management practice because it can contribute to improve soil productivity, biodiversity conservation, ecosystem functions, climate change mitigation, landscape connectivity and the delivery of ecosystem services, optimizing livelihood benefits for people. The Atlantic Forest, a worldwide biodiversity hotspot, which presents large areas in natural regeneration and a promising scenario for ecological restoration has great potential for agroforestry. According to Brazilian legislation, the agroforestry conducted on remnants of Atlantic Forest depends on previous environmental authorization regarding both the vegetation management and the commercialization of native flora products. Although Brazilian legislation provides incentives for agroforestry, there are important barriers to its development regarding to the vegetation management for production, processing (enforcement of health and sanitation laws), and trading of timber and non-timber products. In the Rio Grande do Sul, the procedures for obtaining environmental authorization concerning the management and trading of native plants were too bureaucratic, unattractive, and infeasible for small rural landowners because the environmental legislation was not translated into effective public policies. Since the agroforestry and extraction of native flora products needs to comply with legislation and the key point is to guarantee the legal and sustainable origin of the products, and the management carried out, the appropriate procedure for the regularization of such practices is a certification of forest management. The SEMA's agroforestry certification (SAC) is a simplified procedure to legal compliance and sustainable management of native vegetation and mainly attends family farmers, indigenous peoples, maroons, and traditional populations. Until September 2019, nearly 130 landowners requested the SAC from 65 municipalities of Rio Grande do Sul. According to the applicants, around 99% of rural properties are considered small, ranging from 1.3 to 156 ha. Altogether, they add up to almost 380 ha of agroforestry in anthropic areas, some of them degraded by intense historical land use. The extraction of fruits and seeds and the planting of native tree species (59% and 48%, respectively) were the most mentioned agroforestry management by the applicants. The main products or species of interest mentioned were fruits and heart of palm from Euterpe edulis (52%), fruits of Citrus spp. (51%), native timber (49%), non-native fruits (44%), native Myrtaceae fruits (39%), other native fruits (32%), banana crops (29%), Yerba-mate (26%), non-native timber (16%), other non-native plants (9%), ornamental plants (9%), Butia catarinensis fruits (7%), and Butia odorata fruits (2%). The SAC has brought stakeholders (farmers, technical assistants, and researchers) closer to the environmental agency, creating a broad new regional agenda on agroforestry, and a myriad of conservation opportunities. The strengthening of agroforestry-support policies must be an important conservation strategy in the Atlantic Forest. However, to carry out such policies, it is necessary to create conditions and incentives beyond the legislative scope, translating the legal provisions to procedures and actions. • Despite legal incentives, barriers to agroforestry remain in Atlantic Forest. • Ordinary environmental licensing does not apply properly to agroforestry. • Certification of forest management guarantees legal compliance for agroforestry. • The SEMA's agroforestry certification took advantage of existing legal framework. • A bottom-up policy can encourage stakeholders to improve agroforestry. [ABSTRACT FROM AUTHOR]

[Display omitted] • Climate smart forestry (CSF) indicators based on forest inventory are presented. • Indicators were projected under management scenarios with a simulation model. • National carbon stock increases with current management, but regions differ. • Trade-offs occur between mitigation, adaptation and ecosystem services (ES). • The presented framework can support policy in balancing ES in the context of CSF. Climate-smart forestry (CSF) has gained increasing attention in recent years. Yet, a framework to assess the three pillars of CSF, in terms of mitigation and adaptation to climate change and ecosystem service (ES) provision based on national forest inventory (NFI) data is currently lacking. In this study, we present an assessment framework of CSF based on forest indicators derived from NFI. To quantify the three pillars of CSF we defined 1) mitigation based on the forest carbon stock, 2) adaptation using biodiversity and susceptibility to disturbances caused by storm and bark beetles and 3) ES provision with timber production and protection against avalanches and rockfall. We demonstrate the application of this framework using Swiss NFI data and projections of future forest development under four different management scenarios. Our results show that, in general, the carbon stock is increasing at the national scale when current management practices are maintained. Increases are especially pronounced in the Jura and Southern Alps regions. Trade-offs occur between enhancing mitigation and adaption, and the sustainable provision of ES such as timber production. Scenarios with increased harvesting intensities lead to a higher timber supply in the short-term, while decreasing the carbon stock, biodiversity-related old-growth indicators and the protective function of forests. The indicator framework presented in this study provides a first methodological approach that can support policy making to balance the different forest services in the context of CSF. [ABSTRACT FROM AUTHOR]

• Ecosystem services have synergies and trade-offs between sustainability dimensions. • The complex nature of ecosystem model output make communicating findings difficult. • We developed modeled based CIs to evaluate forest management strategies. • Composites were systematically evaluated across three regions and climate periods. Forests provide a wide range of ecosystem services, and ecosystem models can be applied to assess the contribution of different forest management strategies to climate mitigation and adaptation. Complex model output and trade-offs between environmental, economic, and social sustainability dimensions are difficult to convey. To facilitate stakeholder communication, we developed composite indicators based on ten ecosystem service indicators obtained from ecosystem model simulations representing 19 forestry management strategies across three ecoregions and climate scenario projections in Sweden. Eight alternative composites were generated around a central framework addressing sustainability aspects in terms of wood production, preservation of biodiversity, climate change mitigation and adaptation (risk management). A combination of principal component analysis, exploratory factor analysis, Cronbach's coefficient alpha, and hierarchical cluster analysis was applied to account for the statistical relationships between indicators. Z-score normalization was superior to min-max normalization in capturing differences among management strategies. Two weighting schemes were applied, based on policy prioritizations between sub-components that reflected 1) current policy with an equal emphasis on production and biodiversity, and 2) a stronger focus on nature protection. Equal emphasis generated a larger range of scores (76.0 ± 21.2) than the focus on nature protection (32.0 ± 5.8), as the latter would provide less production benefits and thereby fewer trade-offs between production and other aspects. The final scores of the 19 management strategies fell within a variance boundary of each other, showing their contribution to different policy targets and the usefulness of combining strategies at the landscape level. The composites displayed agreement across regions and scenarios. They indicated that a shift from even-aged conifer monocultures towards a combination of continuous cover, broadleaf-mixture, and unmanaged would work well for balancing goals under changing climate conditions. [ABSTRACT FROM AUTHOR]

• 35,255 living trees and 22,482 deadwood pieces measured in 1391 forest plots. • C stocks in 13 forest types calculated with allometric equations calibrated for tree species, age and habitat type. • Current total ecosystem C quantified at 300 Mg ha−1 (17.2 Tg), 41% in biomass (living trees and deadwood) and 59% in soil. • Upper bounds of biomass C stocks from 94 Mg ha−1 for swamp pine forest to 223 Mg ha−1 for lime-oak-hornbeam forest. • The obtained upper bounds can serve as benchmarks in assessing C storage potential elsewhere. Specifying the upper bound of C storage in forest ecosystems allows an estimate of the amount of C that can be stored in the future. The Białowieża Forest in NE Poland is the last relic forest in the European lowlands. Still, it has been subject to various natural and human-induced disturbances and its C stock has been reduced. The main goal of our study was therefore to assess the current and potential C stock in the forest communities of the Białowieża Biosphere Reserve (597 km2), taking into account the diversity of habitats as well as different protection and management practices. For this we identified 13 forest communities and quantified their current C stock stored in all major pools (living trees, deadwood and soil). We used vegetation and soil data collected in 2018 at 1391 systematically distributed 0.04 ha forest plots (sampling grid 650 × 650 m). We used the concept of potential natural vegetation (PNV) and randomized upscaling of plot level current biomass C stock values to estimate the upper bounds of biomass C stocks possible to obtain at the stand level. We showed that the Białowieża Forest stores currently 300 Mg C ha−1 (17.2 Tg C), of which 41% is accumulated in biomass, with significant variation among different forest communities and management regimes. We obtained the upper bounds of biomass C stocks ranging from 94 Mg ha−1 for swamp pine forest to 223 Mg ha−1 for lime-oak-hornbeam forest. We estimated the gap between the current and potential C stock in biomass at 66 Mg ha−1 (3.8 Tg); 62% of the potential level is achieved in managed forests, and 76% in the National Park. Our findings may be used in planning forest management aimed toward long-term C storage, and the obtained upper bounds can serve as benchmarks in assessing C storage potential of similar forest types elsewhere. We also suggest that the potential of ecosystems to store C should be considered in the landscape context, i.e. by taking into account the spatial extent of PNV habitats and their unequal capacity to provide C storage service. [ABSTRACT FROM AUTHOR]

• Fertilization on mineral soil only causes small short-lived N 2 O emissions. • High levels of N fertilizer do not change mineral forest soils to CH 4 sources. • Soil CH 4 and N 2 O fluxes are minor compared with the net ecosystem uptake of CO 2. Climate change mitigation strategies have increased the demand for wood products, resulting in an urgent need to increase wood production. One approach is to fertilize forest land, but this can influence greenhouse gas (GHG) fluxes within the ecosystem. The aim of this study was to examine the effects of forest N fertilization on soil CH 4 and N 2 O fluxes in young Norway spruce (Picea abies (L.) Karst.) stands in southern Sweden. The gas fluxes were measured using flow-through non-steady-state dark chambers. In the first, long-term, experiment, half of the stand was fertilized twice (once in 2014 and once in 2016) with 150 kg ha−1 of N, and gas flux measurements were taken throughout 2014–2017. In the second, dose, experiment, 0, 150, 300, or 450 kg ha−1 of N was added to the stand in April 2016, and gas flux measurements were taken during April-December 2016. The dose experiment showed that the sink strength of CH 4 decreased with increasing amounts of N; the long-term experiment indicated that repeated fertilization decreased the CH 4 sink strength over time. Additionally, the long-term experiment indicated that, while significantly higher N 2 O emissions were recorded in the fertilization years, this was not detected in subsequent years, suggesting the effect to be short-lived. In the dose experiment, fertilization tended to increase the N 2 O emissions relative to the amount of fertilizer. However, despite the significant effects of fertilization on these GHGs, the summed fluxes were a fraction of the net uptake of C at the sites, as recorded in another study. These findings suggest that fertilizing forest land with commercial NP or NPK fertilizers corresponding to 150 kg ha−1 of N, the level used in operational forestry in Sweden today, can be conducted without changing CH 4 and N 2 O fluxes to any great extent. [ABSTRACT FROM AUTHOR]

[Display omitted] • We assessed drivers of stand biomass and its increment in Tatra National Park. • Combinations of tree stands, soil and geomorphic features allows biomass estimation. • Stand age, species composition, and elevation are the most important biomass drivers. • Valley depth and elevation have the most pronounced positive impact on tree biomass increment. • Our results support increase of carbon budget modeling for mountain forests. The stands and soils of forest ecosystems are one of the most important carbon sinks in the terrestrial environment; thus, proper estimation of forest biomass increment is crucial to understand the rate of atmospheric CO 2 sequestration. Here, we propose a biomass and biomass increment estimation methodology using forest inventory data from 1991 to 2006 from the Tatra National Park (TNP), Western Carpathians, Poland. Using machine learning techniques (random forest), we showed, for the first time, that stand age, the proportion of Abies alba , Picea abies , and Pinus mugo , and elevation are the most important predictors of aboveground stand biomass. Stand biomass increment is driven by the proportion of P. mugo , A. alba , and P. abies , stand age, elevation, and valley depth. Our results showed that the primary drivers of forest biomass (stand age and species composition) could be modified by the geomorphic properties of the terrain, indicating their importance in the mitigation of negative climate change trends in forest landscapes. Additionally, we showed that the biomass increment assessment using repeated measurements differed from trends of age-based biomass models, indicating the need to consider site-specific factors (e.g., slope and aspect). The potential applicability of these results improves the accuracy of carbon budget modeling and supports decision-making in nature conservation and forest management. [ABSTRACT FROM AUTHOR]

• Above-ground biomass was compared in logged and intact primary tropical forests. • Tropical timber production forests accumulated most AGB over a 15-year period. • Plot spatial distribution best explained the variation in AGB. • Sustainable forest management restores the mitigation potential of natural forests. • Sustainable forest management is a natural solution to climate change. Tropical forests play a fundamental role in mitigating climate change through storage of carbon in above- and below- ground biomass. Their mitigation potential is, however, affected by significant greenhouse gas emissions through tropical deforestation or forest degradation. Mitigating degradation caused by conventional logging is therefore an important challenge for silvicultural management, and various reduced impact logging techniques seek to reduce biomass loss and other logging impacts during forest logging activities. Little knowledge exists about the potential of sustainable management for maintaining and restoring the climate change mitigation capacity of tropical forests. Our research contributes to knowledge about this potential, as our aim is to evaluate the above-ground biomass (AGB) stock of tropical forests managed for sustainable timber production and compare it with that of intact primary forests. We also determine the environmental and spatial factors that influence AGB. We estimated the AGB of 141 permanent sampling plots in Costa Rican tropical forests (71 plots set up in areas managed for timber production forests and 70 plots set up in areas with intact primary forests) using data for the 2000–2015 period. We compared the AGB of timber production forests with that of primary forest using linear mixed models and examined the relationship between forest AGB and climate, soil fertility and spatial variables (PCNM eigenvalues) using variation partitioning (VARPART) and multiple linear regression in the mixed model framework. Mean AGB was higher in forest plots set up in areas managed for timber production than in plots set up in areas with intact primary forests. In VARPART, spatial variables had the strongest effect on AGB with a small but significant effect of soil fertility. Regression showed potassium levels in the soil to be positively related to AGB. There was no significant effect of climate, probably because of the short temperature and precipitation gradients. Sustainable forest management in these Costa Rican forests managed for timber production has enabled them to store as much carbon in biomass as primary forests, due to the low intensity logging and sustainability criteria stipulated by the country's forestry legislation. As a result, sustainable forest management, in addition to providing a sustainable timber ecosystem service, is also a natural climate solution, maintaining the mitigation potential of Costa Rica's tropical forests in the current climate context. [ABSTRACT FROM AUTHOR]

Community Forests (CFs) are considered as an important means of forest management, biodiversity conservation, poverty reduction and ecological sustainability all across the world. Present study is an attempt to understand if CFs in west Himalayan part of India (referred as Van Panchayat) is effective in performing such role of conservation and sustainable flow of goods and services. A total of 31 representative Van Panchayat Forests (VPFs) in western Himalaya were investigated to assess: (i) the ecological condition, and (ii) their status of management. In addition review of available literature was also carried out to understand global trends of knowledge on CFs, and to specifically know the focus of studies on VPs in the study region. A total of 1158 documents on CFs were obtained, of which 91 pertained to VPs/VPFs. These 91 studies were considered for detail assessment. Analysis of published literature on VPFs indicated larger leaning towards management and governance. However, in recent years (2011 onward) a shift towards ecological processes and climate change mitigation was noticed. Overall, the studied VPFs indicated the deteriorating state of ecological health. However, the forests having proper management had better ecological health i.e., higher species richness, tree density and regeneration. Species richness and contribution of native species was found high in VPFs established before 1980. Analysis across the elevation range reveals higher level of disturbances in VPFs located below 1500 m asl. While higher elevation (above 1500 m asl) performing better both with respect to ecological health and management status. The findings of the study call for urgent attention to bring back the glory of VPFs through policy interventions. Analysis of literature and primary observation suggest that the VPFs in west Himalaya with their existence for over 9 decades are fading the glory due to mismatched policy and practice priorities. The scenario can be changed with appropriate interventions to make these VPFs more relevant for local people as well as the emerging global targets of conservation and sustainable development. • Assessment was made on ecological condition and management status of VPFs. • Out of 1158 documents reviewed on CFs across the globe, 91 are related to VPFs. • Results reveals poor management and ecological health of most of the studied VPFs. • Ecological health of VPFs situated above 1500 m is comparatively better to < 1500 m. • Community rights and financial incentives is essential for better management of CFs. [ABSTRACT FROM AUTHOR]

• Tree above-ground biomass (AGB) were assessed in 302 secondary forest (SF) plots. • Ecological potential of SF and notable timber potential were identified. • AGB accumulation found in SF in wet climate with unfertile soils. • AGB accumulation in SF significantly higher in Costa Rica than in Nicaragua. • Non-environmental factors might affect secondary dynamics in each country. Sustainable management of secondary forests for timber production offers the opportunity to combine nature-based climate change mitigation with direct improvement of human livelihoods in the tropics, but this dual potential has rarely been explored. We characterized aboveground biomass (AGB) in secondary forests (SF) in Nicaragua and Costa Rica in whole stands (ecological potential), individual trees of timber species (total timber potential), and currently harvestable timber (harvestable timber potential). We also linked the three types of AGB potential to climate and soil factors. Data on 302 sample plots were collected, most from national forest inventories (NFIs) concerning 168 plots in Nicaragua and 134 plots in Costa Rica. We analyzed data from individuals ≥20 cm dbh, estimating biomass from field measurements of stem diameters, and wood density and tree height estimates from the BIOMASS package in R. We obtained climate data from CHELSA, soil data from the ISRIC world soils database and determined the relationship between the three AGB potentials and environmental variables using exploratory principal components analysis and general linear mixed models (GLMMs). A mean 51 Mg ha−1 AGB was found to be stored in trees ≥20 cm dbh in dry forests and 68 Mg ha−1 in wet forests. Maximum values were > 250 Mg ha−1 in both biomes, similar to primary forest values from the NFIs. Timber potential was high at 84% of the mean ecological potential of the study plots, with 73% in the currently harvestable category. Overall, both ecological and total timber potential AGB were significantly higher in wet than in dry forests, whereas currently harvestable timber potential was significantly higher in dry than in wet forests. The best GLMMs showed R2 = 0.31, 0.24 and 0.27 for ecological, total timber and harvestable timber potentials, respectively (P < 0.0001). All three models included soil clay and silt fractions, soil C/N ratio, mean annual precipitation and temperature seasonality. The GLMM for ecological potential included soil pH and climatic water deficit, while those for the two timber potentials included mean annual temperature. Overall, GLMMs indicate increasing timber AGB potential with increasing rainfall, decreasing climatic seasonality, and soil fertility. All three AGB potentials were significantly higher in Costa Rica than in Nicaragua in both biomes. This observed non-environmental "country effect" requires further study. [ABSTRACT FROM AUTHOR]

• carbon uptake by above-ground biomass is higher in unmanaged beech stands. • thinning does not alter growth-climate sensitivity. • resistance to extreme weather events decreases with increasing tree productivity. • close-to-nature forestry may be preferable at sites with higher incidence of heat and drought events. European beech plays a prominent role in the adaptation of European forests to and mitigation of climate change. Forest management may increase the mitigation potential of beech forests by accelerating carbon accumulation in tree biomass, but little is known about the interaction between the rate of biomass expansion in beech and its sensitivity to climate variation or its resistance to extreme drought episodes. A 60-year thinning experiment in beech forests in Central Europe was used to generate tree-ring width series describing past radial growth of dominant, co-dominant and sub-dominant beech trees. Randomisation applied to daily climate data was used to find the period of the year during which climate best explains beech growth. Results show that carbon uptake by above-ground biomass is higher in unmanaged stands and that thinning does not affect beech growth sensitivity to climate. Further, this study shows that average daily temperature amplitude and precipitation in March-July are the best predictors of radial growth in beech at lower-elevation sites. In a key finding, this research shows that site quality and thinning intensity increase tree size, which in turn lowers their resistance to drought. Using forest management to increase the productivity of European beech may thus increase its vulnerability to climate change. [ABSTRACT FROM AUTHOR]

• Older forests are approximately 1.7 K cooler than younger forests at annual scale. • The albedo dominates the warming effect. • The latent and sensible heat fluxes predominate the cooling effect. • Forest management should consider forest age to react on future climate change. Forest age structures have been reported to be substantially influenced by natural and anthropogenic disturbances worldwide. However, related biophysical feedback to climate is not well understood. This study aims to investigate the biophysical impact of changes in forest age on surface temperature and illustrate the mechanisms underlying such temperature differences. To this end, we use data from five paired evergreen needleleaf forest (ENF) eddy covariance towers in North America. Results show that older ENF is 1.7 K cooler than younger ENF at annual scale. The latent and sensible heat fluxes of older forests dominate an average cooling effect of −1.9 K, which counteracts albedo-driven warming (+2.3 K). Additional warming effect is further offset by emissivity (−1.1 K) and incoming radiation (−0.5 K). Our results confirm that considering forest age may facilitate improved forest management to local climate mitigation and adaptation in future climate change. [ABSTRACT FROM AUTHOR]

At present, global warming is an indisputable fact, and more and more attention has been paid to the impacts of climate warming on global ecological environments. Forests play increasing significant roles in regulating global carbon balance and mitigating climate change. Therefore, to understand the response mechanisms of the carbon budget of global forest ecosystems to future climate change, an improved version of the FORest ecosystem Carbon budget model for CHiNa (FORCCHN) and future Representative Concentration Pathway (RCP) scenario RCP4.5 and RCP8.5 were applied in this study. The results demonstrated that the global forest ecosystems will play a major role in the carbon sink under the future two climate change scenarios. In particular, the average carbon budget of global forest ecosystems under RCP4.5 scenario was estimated to be 0.017 kg(C)·m−2·yr−1 from 2007 to 2100. The future carbon sink areas of global forest ecosystems will increase significantly. Under RCP4.5 and RCP8.5 climate scenarios, the carbon sink areas of global forest ecosystems during 2026–2100 would be significantly been expanded than those in 2007–2025, with increases of 83.16–87.26% and 23.53–29.70%, respectively. The impacts of future climate change on carbon budget of global forest ecosystems will significantly vary between different regions. The carbon budget of forests will be enhanced in the northern hemisphere and significantly weakened in the southern hemisphere under the future two climate change scenarios. The carbon sink regions of global forests will be mainly distributed in the middle and high latitudes of the northern hemisphere. In particular, the forests' carbon budget in northeastern and central Asia, northern Europe and western North America will increase by 40% ~ 80%. However, the carbon budget of forests will decrease by 20% ~ 40% in the most regions of the southern hemisphere. In northern South America and central Africa, the forests' carbon budget will be reduced by more than 40%. In the future, in some areas of southern hemisphere, where the forests' carbon budget was predicted to be reduced, some measures for improving forest carbon sink, such as strengthening forest tending, enforcing prohibiting deforestation laws and scientific forest management, and so on, should be implemented to ensure immediate mitigation and adaptation to climate change. • We quantitatively evaluated the role of global forest in terrestrial carbon cycle. • We explored the spatial-temporal dynamics of future global forest carbon budget. • We simulated the responses of global forest carbon budget to future climate change. • Individual-based carbon budget model FORCCHN and remote sensing outputs were used. [ABSTRACT FROM AUTHOR]