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The Eucalyptus genus is extensively planted in Brazil for industrial use, and with the expansion of forest frontiers and climate changes, studies are needed on how these changes affect wood density (WD). The aim of this study was to evaluate the effect of some climate variables on WD of an Eucalyptus urophylla clone for a 4–5 year period. WD from trees collected in 12 sites were evaluated. Five growth rings were identified using a magnifying glass, X-ray densitometry, and forest inventory. WD was correlated with temperature ( T), precipitation ( P), soil water deficit, ring width, and current annual increment. There was no variation in WD in the first 20 months among sites. From that age on, WD was mainly correlated with T ( r > 0.6). The 1 °C increase in T resulted in a WD reduction of 0.014 g cm−1, and increases of 10 m³ ha−1 in the final volume were related to an increase of 0.004 g cm−1 in WD. Researchers and managers should continue to put efforts into broad experimental networks to assess the effects of climate change on the adaptation and wood quality of Eucalyptus clones. Highlights The influence of climate on E. urophylla wood density was greater after the third year of growth. The mean air temperature was the best correlated climatic variable with E. urophylla wood density. The cross-site climatic gradient was more important in wood density variation of E. urophylla than the variability among the years.

Retention forestry can help achieve multiple objectives in production forests, but its effectiveness is often low due to high mortality of the trees retained. We assessed the potential of improving tree survival in a low-level retention system in mixed forests by comparing the retention of multiple species of solitary trees (dispersed retention) and two approaches to aggregated retention. We annually monitored 58 dispersed-retention sites (since 2001) and 21 aggregated-retention sites (since 2013) in Estonia. Eight-year total mortality was 45% for solitary trees (and 1%–4% annually thereafter) but only 8% for tree groups; special planning for wind protection provided little further reduction. These estimates do not include dieback-affected Fraxinus excelsior L. that had distinct mortality dynamics independent of the retention pattern. Ulmus spp. also died frequently within the groups due to a dieback disease. Mixed-species tree groups enabled partial retention of Picea abies (L.) H. Karst that has extremely poor survival when retained solitarily. Likely, ecological costs of aggregated retention include some loss of microhabitat quality of individual trees. An optimal retention strategy could combine tree groups (maximizing wind protection and patch integrity) and individual trees (maximizing tree-scale biodiversity qualities), which collectively would also spread the risks of diverse mortality agents.

The issue of forest trees biologically designed to withstand wind and slope stresses for improving tree anchorage and stability has been of interest to many forest ecologists for over 200 years. Asymmetry in architecture and function is a typical effect of biomechanical design. This review tried to find the architectural connectivity between belowground and aboveground organs of a tree based on a summary of observations of the asymmetric growth of crown, trunk, and root system. The asymmetrical aboveground growth is influenced by a complex interaction of tree species, age, neighborhood competition, wind, lighting, slope, and elevation. The asymmetrical belowground development is dependent on tree species, age, trunk leaning, wind, soil, and slope. Uneven water conduction, nutrient allocation, hormone content, and photosynthesis rate can influence the relationship of architectural mechanisms between the belowground and aboveground organs. The contradictory observations on the directional deformations of the root system (buttresses) reveal the particular prominence of combined effects of multiple factors. Future research should focus on the comprehensive understanding of the belowground and aboveground architectural relationships of different tree species. Our review provides novel insights into the connotations of root–shoot balance in biomass distribution of the individual plant organs.

White-tailed deer ( Odocoileus virginianus) have been overabundant in eastern North America for more than five decades, resulting in depauperate understories and ricocheting effects on higher trophic levels. Even after deer populations are reduced, understory plant communities may fail to recover for an unknown length of time due to persistent legacy effects. We surveyed understory plant communities in six deer exclosures and paired reference plots in northwestern Pennsylvania to determine the degree to which 19 years of deer exclusion was sufficient for recovery of species richness, diversity, percent cover, and understory structural complexity. We observed a 2.3-fold increase in tree cover and a 60% reduction in fern cover in the ground layer, as well as a 114-fold increase in foliage density between 80 and 200 cm above ground level, in exclosures compared to reference plots. However, the exclosures did not permanently support higher overall percent cover, species richness, or diversity in the ground layer, nor did we detect any meaningful divergence in community composition between exclosures and reference plots. We conclude that 19 years of release from chronic over-browsing are sufficient to restore understory structural complexity, but recovery of diversity in the ground layer will require more time or direct intervention.

Whitebark pine ( Pinus albicaulis) forest ecosystems in California are diverse and unique, yet their current status and condition are uncertain. Using a combination of geospatial and field plot data, we assessed patterns in the structure, composition, and health of whitebark pine ecosystems on national forests throughout the state of California to evaluate potential signs of declining ecosystem integrity. We found whitebark pine ecosystems to be structurally, compositionally, and functionally distinct among subregions of California, and all subregions displayed some evidence of declining ecological integrity. Whitebark pine forests in northern California exhibited signs of greater stand densification (Cascade–Klamath), potential encroachment by shade-tolerant conifer species (Cascade–Klamath and Warner Mountains), and increased tree mortality associated with mountain pine beetle outbreaks (Warner Mountains) than elsewhere in California. Whitebark pine stands in the Sierra Nevada showed signs of stand densification (central Sierra) and localized mountain pine beetle outbreaks (southern Sierra east). Notwithstanding these negative signs, much of the state’s whitebark pine ecosystems on national forestlands appear to be relatively healthy and intact compared to more northern latitudes. Active management may be required to restore whitebark pine ecosystems on national forests in California with declining integrity, including stands experiencing substantial stand densification, encroachment by shade-tolerant conifers, and mountain pine beetle outbreaks.

Airtankers are commonly used for initial attack (IA) to reduce the likelihood of wildland fires escaping containment efforts. We examined IA airtanker dispatch decisions for forest fires in Ontario, Canada, through an analysis of historical fire records from 2001 to 2019. A hurdle modelling approach that predicts the probability of airtanker(s) being dispatched and then the number of airtankers sent was used. Two different hurdle models were considered depending on the timing of the information available to the decision maker: a “fire report model” based upon the information available when a fire is first reported, and an “initial attack model” using information available at the time IA action began. Both models indicated that the most influential covariates for airtanker dispatch are the fire weather index, fuel volatility, observed fire rate of spread, fire size at IA, and cause of ignition. When evaluating the predictive ability of the models on a validation data set, the “initial attack model” performed better than the “fire report model”. Our models generally perform well when predicting none, one, or two airtankers on IA, but they generally underpredict when more than two airtankers are dispatched, which suggests risk-averse decision-making in fire management resource dispatching.

Forest products trade has a critical role to play in both global economic development and environmental protection. Based on the trade data of global forest products, raw forest products, and processed forest products from 2000 to 2020, this paper constructed a trade network and analyzed its pattern by using indicators such as density, average distance, out-strength, and in-strength. The results show that from 2000 to 2020, the global trade network of forest products has been increasingly connected. Compared with the trade of raw material forest products, the trade network of processed forest products is more closely connected and its transport efficiency is higher. Countries with high GDP such as USA, China, and Germany are leading trading countries in forest products. Countries with abundant forest resources are the major exporters of raw forest products, while labor- and capital-abundant countries are major exporters of processed forest products. Countries with abundant labor and capital and high GDP are the main importers of raw forest products.

Over one billion people in the world depend on forests to meeting livelihood needs and more than half of them engage in community-based forest management. Community forestry has the potential of making important contributions in achieving the sustainable development goals; however, their positive effects on local livelihoods have been questioned. Actors, with their interests and power balance, can be important factors explaining the success of community forestry by shaping the decision-making process. Hence, the aim of our study was to analyze the economic performance of community forestry across the world, through its contribution to poverty reduction and explain how the economic outcome relates to the interests of the powerful actors. Community forestry from seven countries was analyzed including cases in Asia (Nepal, Indonesia, Vietnam), Africa (Namibia and Cameroon), and Europe (Germany and Albania). Data were collected with a sequence design method aiming to identify the participating actors and their power. A multivariate principal components analysis was conducted to capture the power dynamics within each community forestry. Results showed that community forestry programs do not always lead to poverty alleviation. The economic outcomes can be linked to the interests of the most powerful actors which in most cases do not desire a high economic outcome but rather promote contributions up to subsistence level.

Precommercial thinning could be a valuable tool for climate change adaptation, as it can promote stand diversity while increasing productivity. Softwood and hardwood stands are usually thinned following different methods, and we lack recommendations for application in mixedwood stands. We evaluated the effects of precommercial thinning on the growth and composition of balsam fir ( Abies balsameaL.)–birch stands dominated by paper and yellow birch ( Betula papyrifera Marsh. and Betula alleghaniensis Britt.), comparing methods and production objectives (systematic release-softwood, systematic release-mixedwood, crop-tree release-mixedwood, and crop-tree release-hardwood) in Québec (Canada). Precommercial thinning increased tree-level and stand-level growth, especially for both birches. Compared to the non-thinned control, thinning increased tree diameter at breast height annual increments by 60%–107%, with similar results among modalities. Thinning changed initial stand composition, but mixedwood production plots composition was similar to that of the control 15 years after treatment. Promoting diversity is often perceived to be made at the expense of wood production. Our results suggest that we can obtain both increased growth and maintain diversity. Precommercial thinning is currently suggested as an adaptation tool that can foster drought resistance. Based on our study, we suggest it could serve another purpose in climate-adapted forest management, that is, maintaining diversity and thus increasing resilience to disturbances.

Characterizing seedling stands with respect to their species proportions and co-occurring vegetation is important for monitoring the desired development of the forest stand. Related inventory information has traditionally been collected with costly field surveys and National Forest Inventory (NFI)-based models. Here, we present a novel fusion approach to combine remote sensing (RS)-based models and NFI-based models to predict seedling stand characteristics, i.e., height, density, and tending needs. We used the best linear unbiased predictor for the fusion of the NFI- and RS-based models. The NFI-based models were derived using NFI sample plots and stand features. The RS-based models were derived using airborne laser scanning and color–infrared images and separate field-measured data. NFI-based models were found to be rather unreliable (RMSE = 65%–115% for stem density and 59%–78% for height), but they were always available without the need for any additional RS data. RS-based models provided an RMSE of 41%–92% for stem density and 26%–45% for height. The fusion procedure used at the prediction stage consistently increased the accuracy of all variables of interest, but the improvements were minor. In addition, we classified the tending need in seedling stands if the height of the coniferous tree was less than 1 m compared to broadleaved trees. If we simulate the decision-making situation of tending needs, we can predict tending needs (91% user accuracy) fairly well for a stand.

Herbivores affect plants via direct consumption, but also indirectly via changes in the vegetation. These indirect effects may only manifest after decades of exposure and, as a result, their impact is rarely accounted for. To better understand the direct and indirect impacts of a large herbivore, moose ( Alces alces), on forests, we measured tree growth in areas that were both subjected to and excluded from herbivory for over 80 years. Growth data were gathered from five tree species, ranging from low to high palatability. We found that at small sizes, Betula papyrifera, a preferred species, benefited from herbivore exclusion. However, larger individuals grew more when exposed to herbivory, a response we attribute to lower competition in heavily browsed conditions. Populus tremuloides, a highly preferred tree, did not show any differences between levels of herbivory. Abies balsamea, a preferred winter browsed, was only marginally affected by browsing at smaller sizes. The two non-preferred species, Picea glauca and Picea mariana, did not show differential growth between herbivory levels. We conclude that herbivores can impact forests through both direct and indirect effects, that these effects are size specific, and that effects vary among species in ways not always predicted by consumption patterns.

Multi-year drought and climate change can impact tree growth, especially in California's Mediterranean climate where growing season rainfall is limited or absent. Active forest restoration has the potential to mitigate climate impacts by reducing stand density and conversion towards more resilient species' composition. We used dendrochronology methods to examine climate–growth relationships for coast Douglas-fir ( Pseudotsuga menziesii var. menziesii) trees in mixed multiaged stands near the species’ natural southern range margin. We found positive correlations of ring width with spring–early summer and prior October precipitation and an evapotranspiration index. Additionally, cooler spring temperature was negatively correlated with growth. We also studied tree resistance, resilience, and recovery from two multi-year drought events. Restoration treatments enhanced resistance and resilience to drought relative to trees growing in untreated plots. We did not detect differences in drought resistance and resilience between two common restoration methods, giving managers options for restoration to lessen drought impacts on tree growth.

Whole tree harvesting of forests may require compensation for losses of nutrients and alkalinity. The effects of three different practical ameliorative methods on spruce allometry, total biomass, and nutrient uptake were studied in an experiment in a 3-year-old Norway spruce ( Picea abies (L.) Karst.) stand in south-west Sweden. The treatments were one application of the fine fraction of logging residues, one application of granulated wood ash, two applications of an N-free vitality fertiliser, and untreated control. Analysis of covariance showed that spruce needle and stem allometry depended on treatment. Spruce fine root allometry was very variable, showing no discernible effect of treatment. Fine root distribution was shallower in treatments with higher graminoid biomass (vitality and wood ash). Vitality treatment increased average concentrations of Ca, Mg, and Zn in spruce total biomass. Ash treatment only increased the Zn concentration. The average N concentration was similar between treatments. Spruce total biomass per unit area was inversely correlated with graminoid biomass. Measurements of N uptake in spruce and graminoid biomass indicated that there was competition for N between spruce and graminoids. Thus, the effect of nutrient compensation on competition needs to be considered when predicting the effect on the growth of the target species.

Intraregional trade of forest products is a critical component of regional and subregional timber markets in terms of supply chain planning and locating forest product manufacturing facilities. Based on a gravity trade model, we evaluated the various factors driving the interstate flows of softwood sawlog and roundwood pulpwood in the 13 southern US states: AL, AR, FL, GA, KY, LA, MS, NC, OK, SC, TN, TX, and VA. Biennial state-level panel data from 2011 to 2019 in 13 southern states were employed to estimate empirical sawlog and pulpwood trade models. The results suggest that state gross domestic product (GDP) of importing states, exporter and importer production, importer consumption, the distance between the trading partners, and the electronic logging device mandate are influential factors of softwood sawlog trade between the states. Similarly, state GDP, exporter pulpwood production, importer consumption, the distance between the trading partners, delivered timber prices, and pellet mill capacity in each state are found to be significant determinants of softwood pulpwood trade between the partners across the state borderlines. The findings provide forest managers and policy makers with additional insights on the growing bilateral timber trade dynamics in regional and subregional markets in the southern United States.

The development of stand survival models can provide an important basis for the sustainable management of forest resources. In a new approach developed in this study, parameters of four survival quantile regression models were predicted from a quantile associated with a current stand density. The curves from these quantile regression models were then used to project future stand density for that stand. A three-fold cross-validation revealed that the quantile regression approach outperformed the least squares method based on three evaluation statistics, especially for longer projection lengths. These results were consistent for all four survival models evaluated. The best survival model is Clutter–Jones model, without constraints, but its ln( N)–ln( Dq) trajectories ( N = stand density and Dq = quadratic mean diameter) from the quantile regression showed the linear self-thinning trend.

Statistical confidence in estimates of timber volume, carbon storage, and other forest attributes depends, in part, on the uncertainty in field measurements. Surprisingly, measurement uncertainty is rarely reported, even though national forest inventories routinely repeat field measurements for quality assurance. We compared measurements made by field crews and quality assurance crews in the Forest Inventory and Analysis program of the U.S. Forest Service, using data from 2790 plots and 51 740 trees and saplings across the 24 states of the Northern Region. We characterized uncertainty in 12 national core tree-level variables; seven tree crown variables used in forest health monitoring; three variables describing seedlings; and 11 variables describing the site, such as elevation, slope, and distance from a road. Discrepancies in measurement were generally small but were higher for some variables requiring judgment, such as tree class, decay class, and cause of mortality. When scaled up to states, forest types, or the region, uncertainties in basal area, timber volume, and aboveground biomass were negligible. Understanding all sources of uncertainty is important to designing forest monitoring systems, managing the conduct of the inventory, and assessing the uncertainty of forest attributes required for making regional and national forest policy decisions.

Spring leaf phenology is an important event for trees to determine carbon fixation during the growing season. However, less is understood about the intraspecific variation in spring leaf phenology and its relationship with the spring temperature requirements of conifers, which is problematic for accurately predicting the influence of spring climate warming on conifers. I monitored bud burst timing and the degree days required for bud burst for seedlings and large individuals of Abies sachalinensis (fir) and Larix kaempferi (larch) over two seasons in northern Japan. Contrary to my expectation, the degree days required for the bud burst of small individuals were similar to or larger than those of the large individuals for fir and larch. Consequently, the bud burst timing of small individuals was similar to or later than that of large individuals for fir and larch. Even when conifer species are in their early stage, the spring temperature requirement for bud burst is not necessarily less than that for large individuals, which is not the case for many broad-leaved species. These results indicate that for these two coniferous species, ontogenetic differences in temperature requirements are not necessary to be considered for the response of communities to spring climate change.

Individual tree recruitment is an important element needed to understand stand dynamics, as it influences both stand composition and productivity. Forest growth simulators usually include recruitment models. The quality of recruitment predictions can have long-term impacts on estimations of forest growth, ecosystem health and the commercial utility of managed forests. The main objective of this study was to develop a recruitment model for commercial-size trees (i.e., trees with a diameter at breast height > 9 cm) of 10 species groups using different dendrometric and environmental variables. The resulting model will be included in a growth simulator used to support forest management planning. We hypothesized that accounting for sapling density as a covariate would improve the recruitment model's predictive performance. Using empirical data from periodically measured permanent sample plots (1982–2019) located throughout the managed mixed hardwood forests of Quebec, we constructed models with and without sapling-related covariates and compared them on the basis of cross-validation model performance statistics. Our results show that including sapling density significantly improved model performance. From this, we conclude that adding sapling density as a covariate can significantly improve a recruitment model's predictive power for eastern mixed hardwood forests.

Estimating the volume of standing trees is a fundamental concern in forestry and is typically accomplished using one or more measurements of stem diameter along with formulae that assume geometric primitives. In contrast, technologies such as terrestrial Light Detection And Ranging (LiDAR) can record very detailed spatial information on the actual surface of an object, such as a tree bole. We present a method using LiDAR that provides accurate volume estimates of tree stems, as well as 2D rasters that display details of stem surfaces, which we call the “unwrapping method.” This method combines the concepts of cylinder fitting, voxelization, and digital elevation models. The method is illustrated and tested using a sample of standing trees, whereby we are able to generate accurate volume estimates from the point cloud, as well as accurate visualization of the scanned stem sections. When compared to volume estimates derived from Huber's, Smalian's, and Newton's formulae, the differences are consistent with previous studies comparing formula-derived volume estimates and water-displacement-derived volume estimates, suggesting the unwrapping method has comparable accuracy to water displacement.

Large-area growth estimates can be obtained by coupling growth model predictions with wall-to-wall remotely sensed auxiliary variables through a generalized hierarchical model-based (GHMB) inferential framework. So far, most GHMB variance estimators do not account for the residual errors of the submodels and their spatial correlations. This likely induces an underestimation of the true variance of the point estimator. In this study, we provide an example of large-area growth estimation obtained through the GHMB framework. To do this, we developed a new variance estimator that accounts for residual errors as well as potential spatial correlations among them. We tested this variance estimator through a simulation study and then used it to estimate the annual volume increment for a forest management unit in Quebec, Canada. Our results show that, contrary to our expectation, neglecting the residual errors of the different submodels leads to overestimating the true variance of the point estimator. We observed increases in the overestimation with small populations and spatially correlated residual errors. Our developed variance estimator corrected this overestimation and made it possible to derive reliable confidence intervals for annual volume increments at the population level.

Salvage logging is a controversial tool for post-wildfire management that removes fire-killed trees. We use a generalized randomized experimental design to fulfill two main objectives: (1) quantify the immediate (1-year post-harvest) effects of salvage logging on stand structure, fine and coarse woody fuel loadings; and (2) use pre- and post-empirical field data and the Fire and Fuels Extension to the Forest Vegetation Simulator (Reinhardt and Crookston 2003) to simulate post-wildfire dead woody fuel succession and snag dynamics. We compared the effects on woody fuel loadings of two salvage logging prescriptions: (1) seed tree harvest, thin to 3.4 m2·ha−1; and (2) full salvage of all merchantable timber, relative to unlogged controls. There was substantial block-level variability in the implementation of the treatments and in their immediate effects on fine fuel loading, complicating comparison of the two prescriptions. Overall, salvage logging did reduce snag basal area and, relative to unlogged controls, significantly increased measured fine woody fuel loading (10 and 100 h). Simulated snag fall was rapid, with a mean predicted snag basal area loss of 61% within 10 years. Future long-term monitoring of permanent field plots will supplement model predictions and provide valuable data to inform post-wildfire management decisions.

We evaluated area-based approaches (ABAs) to light detection and ranging (lidar) predictions of plot- and stand-level forest attributes (tree count, height, basal area, volume, aboveground biomass, broadleaf/conifer, and diameter at breast height — “diameter”). ABA methods included post-stratification (PS), ordinary least squares (OLSs) regression, k nearest neighbors ( kNN), and random forest (RF). This study was conducted on the Savannah River Site in South Carolina, USA. Plot- and stand-level predictions were validated against fixed-radius 0.04 ha (0.1 acre) plots in 49 ≈2.0 ha (5 acre) stands. Our findings demonstrate that lidar can be incorporated operationally into forest inventory systems to provide stand-level inferences for a wide range of forest attributes. Volume predictions for specific diameter classes, however, often fared poorly (root mean squared error (RMSE) > 100%) for the methods we explored, especially for larger (less common) diameter trees. Stand-level results were consistently better than pixel-level results (10–200+ percentage points). kNN and RF performed similarly and better than OLS and PS, but RF was the most robust to model configurations, while kNN has practical advantages such as simultaneous predictions of many attributes.

Wildfires are increasing in importance in many regions of the Canadian boreal forest and are an ongoing risk for forest management activities. We simulated the effects of fires on long-term harvest levels on the 59 forest management units of the province of Québec, Canada, for the 2020–2100 period. Different climate change pathways (stable, RCP 4.5 or 8.5) and salvage logging rates (20% or 70% of mature burned stands) were simulated. Changes in forest flammability due to climate change, species migration, and forest management were also considered. Under stable climatic conditions, the decline in potential harvest levels due to fire, based on 50 simulations per scenario, ranged between 3% and 33% (mean = 11%) when high salvage logging rates were simulated, compared to 6%–45% (mean = 20%) for low salvage rates. Climate change caused increases in burn rates between −3% and 39% for RCP 4.5 and between 33% and 69% for RCP 8.5 at the end of the 21st century, depending on fire zones. However, the effects of these modified burn rates on harvest levels did not differ substantially from those of baseline burn rates, probably because the projected burn rates were highest during the later part of the simulations (2070–2100), when their impacts on harvest level calculations were limited. This study indicates that potential harvest levels calculated without considering wildfires are likely to be non-sustainable.

Elevated atmospheric nitrogen (N) deposition can alter forest biogeochemistry leading to adverse impacts on terrestrial ecosystems. Experimental studies often apply N to the forest understorey at greatly elevated loads, bypassing important canopy interactions. Using a narrow N deposition gradient (0, 5, 10, 15, 20, and 25 kg N·ha−1·year−1), we measured changes in jack pine ( Pinus banksiana Lamb.) forest biogeochemistry in the bituminous sands region of northern Alberta, Canada after 5 years of above-canopy N additions. The canopy intercepted approximately 46% of applied N across all treatments, but during the final year, N interception was reduced to 7% in the highest treatment. Nitrogen concentrations in nonvascular organisms increased with treatment and N was also immobilized in decomposing litter in the highest treatment. Otherwise, vascular plant biomass, foliar chemistry, and soil processes exhibited no relationship with treatment over 5 years. This work suggests that jack pine forests in the region have a high capacity to immobilize N inputs over the short-term (5 years), which restricts other biogeochemical responses traditionally associated with elevated N deposition.

We determine the economic revenues and optimal forest management of uneven-aged loblolly pine, longleaf pine, and slash pine forests considering timber and carbon benefits in the southeastern United States. Our results show that uneven-aged management of southern pines generates positive total revenues, with the exception of those stands managed with high residual basal areas and long cutting cycles. The uneven-aged management of pine forests is economically more attractive with loblolly pine stands than with longleaf pine or slash pine for all cutting cycles and residual basal areas; on average, loblolly pine returns $1389.60·ha−1 more than slash pine and $1500.70·ha−1 more than longleaf pine for all cutting cycles. For uneven-aged loblolly pine forests, our results suggest that landowners should experience highest profits with the shortest viable cutting cycle (10 years) and a medium-high residual basal area (11.5 m2·ha−1). For uneven-aged longleaf pine forests, landowners would be economically better off with a longer cutting cycle (20 years) and a lower residual basal area (6.9 m2·ha−1). Notably, uneven-aged management of longleaf pine and slash pine for timber production becomes unprofitable with low-medium or high residual basal areas (9.2–11.5 m2·ha−1).

We investigated how the surrounding environment influences the growth of dominant trees and their responses to temperature and insect epidemics in boreal forests of eastern Canada. We focused on 82 black spruce and jack pine focal trees in stands spanning a double gradient of species diversity and soil texture within a 36 km2 area of western Quebec. For these trees, we compared their diameter at breast height, growth rates, temperature–growth relations, and growth during insect defoliator epidemics. We used linear models to study how surrounding tree attributes and soil properties affected the growth of focal trees. Models showed that tree growth responses and responses to temperature and insect epidemics were generally negative with higher intraspecific competition and positive with greater tree species diversity. Growth of both species benefitted from lower soil sand content. Our research offers novel insights on the potential role of the surrounding environment, notably tree competition and species diversity, in mitigating the vulnerability of eastern Canada's boreal trees to anthropogenic climate change and insect epidemics.

Wild edible mushrooms are non-timber forest products highly valued as food supplements and a source of income for rural communities. The objective is to quantify the use and knowledge of wild edible mushrooms across forest socio-ecosystems of central México. We conducted 40 household structured surveys in five Mestizo communities in the state of Michoacán (central-western México) to evaluate their mycological knowledge. We also compare the knowledge of these Mestizo people with that of the surrounding Indigenous communities. We compiled and updated a list of the wild edible mushrooms used in the whole state, which contains 243 mushroom species used out of the 371 used in México. Here, in these five communities, we recorded 13 species currently used (a median of seven). In four communities, 1 kg of mushrooms on average is collected per harvesting trip, whereas in one of the communities, people extracted 3 kg of mushrooms per trip on average and 5–15 kg per season, respectively. The most used and valued species were Amanita basii, Amanita jacksonii, and Hypomyces lactifluorum. Despite being highly valued resources, land managers do not include mushrooms in the decision-making process for planning forest management. We found that knowledge and use of wild edible mushrooms in Mestizo communities are lower than those in regional Indigenous communities in localities with similar climate and forest vegetation. Fungal resources like wild edible mushrooms in the area are therefore underutilized, making forested areas more vulnerable to land-use change. Promotion of mycological knowledge may contribute to enhancing forest conservation policies.

Assisted gene flow according to expected climate gradients is considered as a forest management strategy to mitigate impacts of environmental change on forest growth. However, the effects of seed translocation on wood properties and lumber quality remain unknown. This study evaluated the effect of provenance origin on lumber production and quality at rotation age in two white spruce provenance trials established in contrasting environments in eastern Canada. Based on 108 sample trees, which resulted in 943 pieces of lumber, average volume production per tree at the southernmost site was twice that of the production at the northern site. Provenance had a significant influence on growth and lumber strength in the first sawlog but had no effect on lumber stiffness and wood density. Although visual grade yields of No. 2 and better were high in both trials (over 86%), the machine stress rated (MSR) grade potential and percentage of lumber that met the bending stiffness design values of the visual grades were generally low (12%–26%). Hence, plantation-grown lumber should preferably be machine stress rated to ensure its fitness for structural applications in buildings. Management strategies aiming to efficiently sequester carbon should primarily maximize volume productivity in northern sites, as moving seed sources north still reduces provenance productivity, while breeding programs should aim to prevent decrease in lumber stiffness due to augmented productivity and shortened rotation cycles.

Natura 2000 contracts in the European Union aim to maintain or restore natural habitats to a favorable conservation status. This article aims to analyze the cost-effectiveness of Natura 2000 forest contracts at the individual level of intervention areas in France. The level of long-term biodiversity was assessed using ex ante and ex post levels of conservation status, evaluated on a 100-point scale. Data collection was conducted on the contract areas using a combination of plotless and line intersection sampling methods. Cost-effectiveness was analyzed by modeling a cost function of conservation measures that is estimated simultaneously with the ex ante and ex post biodiversity equations. We performed an empirical illustration based on a small number of observations, and, therefore, the results deserve to be confirmed using larger databases. The conservation measures implemented in the contracts studied had a significant effect on maintaining and restoring biodiversity. Nevertheless, we found pronounced diseconomies of scale and low cost-effectiveness. This suggests the possibility of less ecologically ambitious contracts with lower average costs. Our results also recommend new targeting and prioritizing rules to implement more cost-effective conservation measures (e.g., veteran trees) in a less costly context (e.g., targeting main tree species in larger intervention areas). These recommendations could make Natura 2000 contracts significantly more cost-effective.

The reproductive ecology of the semi-serotinous species black spruce ( Picea mariana (Mill.) BSP) in northern boreal forests remains poorly understood. There is a general lack of data on cone/seed production and viability as a function of biotic tree-level characteristics and abiotic variables. No studies currently exist to quantify these differences over a large gradient in temperature, elevation, and precipitation. Extensive physical, ecological, dendrometric, and reproductive data were collected from young to very old black spruce stands in northern Quebec. ANOVA and general linear mixed models were used to examine interannual cone production, and the relative importance of the biotic and abiotic explanatory factors in determining total cone production; length of the cone-bearing zone; filled seeds per cone; proportion of filled seeds; and seed viability. The results illustrate that the reproductive ecology of black spruce in northern cold forests is mainly explained by biotic variables such as age and diameter at breast height, and by abiotic variables related to temperature such as elevation, length of the growing season, and growing degree-days. Black spruce exhibits a lower reproductive potential in northern cold forests, making it possibly less resilient to increased fire frequency, particularly in unproductive and very young or very old stands.

The predicted increase in frequency and intensity of boreal forest fires is considered a significant source of carbon dioxide emissions and linked with the degradation of permafrost covering more than half of Russia. Here we analyzed the stand structure and growth of East Siberian larch forests in response to fire severity. We measured 23 sites in the southern part of eastern Siberia along a latitudinal transect with a length of more than 1500 km. Live tree volume differed significantly across geographical regions ( p 3·ha−1), with higher values in forests burnt with low severity. Similarly, volume of coarse woody debris decreased from south to north. The volume of dead standing trees, on the other hand, increased from south to north. The distribution of trees by diameter class in some areas showed clear evidence of fires, with small trees being absent to rare in forests burnt at high severity. The impact of severe fires on stand volume was negligible at the southern sites, potentially associated with rapid regeneration of birch. Birch is an important component of larch forests near the southern boundary of the permafrost, which may contribute to larch forests in the southern part of the study transect being less vulnerable to wildfires compared to northern larch forests.

High productivity in forest harvesting requires efficient forwarding. Planning is complicated by multiple choices of routes and their order, the number and types of assortments, the loading sequence, and pile organization at the landing. This paper develops and tests a decision support tool for forwarder routing with sequential co-loading of assortments. Input data are the harvester production file (including Global Navigation Satellite Systems tracking), placement of landing, and machine specifications. The trail network is generated from the harvester production data when devising routes to pick up all log piles, including specific assortments and volumes. Multiple assortments can be loaded along each route, and a certain loading sequence of assortments is preferred and (or) required. Sorting time during co-loading varies, depending on the assortment combinations and bunk loading pattern. Route planning is modeled using a set-partitioning problem, and the solution method is a metaheuristic based on repeated matching. In addition to routes and loading sequences, solutions include the organization of assortment piles at the landing, depending on the total volume of each assortment. The tool produces similar results to those attained by skilled forwarder operators on five clearcuts (3–11 ha) in northern Sweden, when the results are compared with data from actual forwarder production files.

Epigaeic arthropods have been used worldwide as indicators of post-disturbance recovery in many different types of ecosystems. We used them to evaluate the merit of different reclamation prescriptions applied to areas disturbed by oil and gas exploration and extraction. We compared the short-term effects of different mechanical and chemical site preparation techniques on the epigaeic arthropod fauna of previously reclaimed borrow pits in arrested succession with results from plots in untreated disturbed sites and undisturbed adjacent forest. In general, arthropod diversity increased and abundance decreased with the severity of soil disturbance involved in the silvicultural prescription. We place arthropod communities into four discrete groups reflected in the treatments and the environmental characteristics of the sites: forest species, grassland species, species primarily found in herbicide plots, and species found in disturbed soil. Individual borrow pits accounted for a significant amount of variation in faunal assemblages, suggesting that site location, vagaries of colonization, or disturbance history play a significant role in how the fauna recovers post disturbance. Our study provides baseline data required to document the trajectory of recovery in these sites. Long-term monitoring is essential to evaluate the relative usefulness of reclamation prescriptions in meeting targets established by law.

To assess wildfire risk linked to lightning-caused wildfires, the present study tests the spatial- and temporal-scale distribution variability of lightning fires in Western Canada between 1981 and 2018. We examined clustering, trends, distances between clusters, and the fire season. For this study, the nearest neighbours, K-function, Moran's I, Mann–Kendall, and the Getis-ord Gi* statistics were used. These statistics were visualized by a Space Time Cube model with a hexagon grid. Lightning-ignited wildfires cluster spatially up to 270 km with an observed overall nonsignificant decreasing trend for the number of fires. Overall, northeastern Alberta, central Saskatchewan, and southeastern British Columbia show clustering of lightning fires. In June, there is significant clustering in northwestern and eastern Alberta, while in July fires cluster in northeastern Alberta and in southeastern British Columbia. In August, fire clusters occurred only in southeastern and south-central British Columbia. These results highlight regions that are experiencing persistent lightning fire clustering activity. This provides a focal point to assess wildfire risk to communities and values at risk, while informing local and regional management agencies in preparedness, resource capacity management, and detection. Additionally, it provides a baseline for future research into biophysical modelling of wildfire initiations.

Eastern white cedar ( Thuja occidentalis) and red spruce ( Picea rubens) contribute to the biodiversity and resilience of mixedwood forests. However, cuts that remove most or all the forest cover can cause the decline of these species. Among partial cutting options, the irregular shelterwood system (ISS) can create successful conditions for the development of advance regeneration and enrichment planting. We studied 6 years of ecophysiology of lower advance regeneration and planted seedlings of eastern white cedar and red spruce growing under a first ISS cut according to three cutting intensities: light cut (35% removal, 20 m2·ha−1 residual basal area), moderate cut (42%, 18 m2·ha−1), and heavy cut (52%, 15 m2·ha−1). Light-saturated photosynthesis and height growth of planted cedar and both spruce types decreased with increasing cutting intensity, in response to an increase in competing vegetation. Therefore, to limit the negative impact of competing species on cedar and spruce regeneration, we recommend protecting tall advance regeneration (2 m+) during partial cut operations and using large-sized containerized seedlings (40–50 cm height) for enrichment planting. Results also suggest that a mechanical release could help optimize the physio-morphology and growth of both regeneration types of cedar and red spruce.

We examined the performance of sweetgum ( Liquidambar styraciflua L.), cherrybark oak ( Quercus pagoda Raf.), and loblolly pine ( Pinus taeda L.) in two-species pine–hardwood mixtures (sweetgum : loblolly pine and cherrybark oak : loblolly pine) at various planting densities (1482–1976 trees per hectare (TPH)) over 23 years in northern Louisiana, USA. Species were planted in alternating rows with hardwood establishment occurring 1 year prior to loblolly pine. Mixtures were also compared to loblolly pine monocultures at a common density (1482 TPH) to assess whether mixing improved productivity. Sweetgum exerted more competitive pressure on loblolly pine than cherrybark oak. At final measurement, sweetgum survival statistically exceeded that of loblolly pine across mixture density. Moreover, sweetgum cumulative basal area and volume growth nearly tripled that of loblolly pine in balanced high-density mixtures (1976 TPH, 50 pine : 50 hardwood). In contrast, cherrybark oak basal area and volume growth did not significantly exceed loblolly pine at any density. At a common density (1482 TPH), loblolly pine monoculture cumulative basal area and volume significantly exceeded those of mixtures with sweetgum and cherrybark oak by 19% and 24%, respectively. Collectively, these results indicate that growing loblolly pine in mixture with these two species did not produce complementary interactions and negatively affected stand-level growth.

Women forest owners control a significant share of private forests in Finland, but they are often underrepresented in forest-related surveys. It also seems that women forest owners are less active in performing forestry work or selling wood; however, the information on women forest owners is sparce. The purpose of this study is to deepen understanding of the association between women forest owners’ activities and their ownership objectives. The study analysed a large survey ( n = 6468) collected as part of the Finnish Forest Owner 2020 research project. Overall, women forest owners were found to be less active in many aspects compared to their men counterparts. With k-means clustering, four different clusters of women forest owners with different ownership-objective profiles were identified. Differences in ownership activities between the clusters were compared using Pearson's chi-square test. Multi-objective women forest owners were more active than other women owners. Moreover, women forest owners who valued nature and recreation were less active than other women forest owners. This might indicate the lack of service-dominant logic in forestry-related services. By providing a more detailed understanding of women forest owners, the results aid the design of more equal and inclusive forest policies and forest services.

The vegetation and fire history at the Coastal Douglas-fir (CDF) and Coastal Western Hemlock (CWH) boundary on east-central Vancouver Island was reconstructed. A basal non-arboreal assemblage at the most inland site likely represents an open parkland community during the cold early late-glacial interval. Widespread Pinus woodland followed under cold, dry climate, yielding to closed-canopy mixed conifer forest as climate moistened. While fire disturbance was initially rare, it increased in the late-glacial mixed conifer forest. In the early-Holocene, dry coastal temperate forest replaced the mixed-conifer assemblage. Fire disturbance was widespread, characterized by frequent, possibly lower severity burns. These CDF-like forests expanded northward and westward under warm, dry conditions, attaining maximum extent 9500 – 10 500 calendar years before present, retreating thereafter towards the modern CDF–CWH boundary, which established ∼6000 years ago as climate moistened. Quercus garryana communities were scattered along the coast at this time, maintained by surface fire. Throughout the remainder of the record, the forest canopy closed as modern forests developed and a mixed-severity fire regime developed. The extended early-Holocene range of CDF-like forest suggests that the existing CWHxm biogeoclimatic subzone may be replaced by CDF stands with climate change.

The applicability of height to crown base (HCB) appears to be particularly broad given the important impact on explaining tree growth dynamics. Given the high cost of measuring HCB, accurate prediction with a few trees is popular in forestry practice. In this study, a fixed-effects model (FEM), a mixed-effects model (MEM), and quantile regressions (QR) were adopted to predict HCB using data from natural secondary forests of Dahurian larch ( Larix gmelinii Rupr.) in Northeastern China. Corresponding calibration techniques were applied to trees with different sample designs (random selection, the thickest tree selection, the intermediate tree selection, and the thinnest tree selection) and sample sizes (1–10 trees per plot). The results showed that all models achieved accurate HCB predictions. The QR calibration technique of 3-quantiles achieved simple and accurate consequences compared to 5-quantiles and 9-quantiles. MEM displayed the most robust and superior statistics. The selection of the two thickest trees was recommended for the MEM. For FEM and QR, the sample size should be exceeded by 5. Generally, a combination of MEM and sampling two thickest trees per plot to predict HCB is recommended as a win–win solution that neither sacrifices model prediction accuracy nor minimizes the required measurement cost.

Gap dynamics play a crucial role in forest regeneration by creating favourable regeneration and survival niches for some plant species. Nonetheless, potentially overriding factors, such as ungulate browsing, could limit or eliminate this gap dynamic-related regeneration. The deleterious effects of browsing may be exacerbated for slow-growing species such as northern white cedar ( Thuja occidentalis L.), a tree highly selected by white-tailed deer ( Odocoileus virginianus Zimmerman). We therefore aimed to understand how deer browsing and gap dynamics interact to affect cedar regeneration and hypothesized that cedar regeneration benefits from natural gaps but that deer browsing could override this effect. We inventoried natural canopy gaps along a spatiotemporal gradient of deer habitat use. We evaluated cedar regeneration abundance, tree height, and various gap, stand, and competition metrics. We found that deer browsing pressure greatly limited cedar regeneration; however, when deer populations decreased, cedar regeneration abundance increased within a decade, even after prolonged browsing pressure, and increased further over time. Our study illustrates that cedar regeneration can be favoured by gap creation and deer population control.

When combining multi-temporal airborne laser scanning (ALS) data sets, forest height growth assessments can be compromised due to variations in ALS acquisitions. Herein, we demonstrate the importance of assessing and harmonizing the vertical alignment of multi-temporal ALS data sets used for height growth calculations. Using four ALS acquisitions (2005–2018) in a temperate mixedwood forest, we developed an ALS data harmonization approach and quantified the impact of the harmonization on derived height periodic annual increment (PAI), comparing the ALS-derived PAI to PAI derived from non-harmonized ALS data sets and field measurements. We found significant differences in PAI derived from harmonized and non-harmonized data, and these differences were greater for shorter growth intervals. Data harmonization resulted in a consistent PAI series that reduced uncertainties associated with the different ALS acquisitions. Although overall there was a strong relationship between field and ALS height measures ( R2 ≥ 0.88), we found a weak relationship between the field- and ALS-derived PAI ( R2 = 0.12). We identified systematic errors in field-based tree height measures in plots with complex crowns, tall trees, and restricted visibility. We demonstrate the need for harmonizing multi-temporal ALS data sets for the generation of PAI and, likewise, highlight the need of carefully scrutinize field-measured heights and associated increments.

Representing the spatial distribution of trees and competition interactions in growth models improves growth prediction and provides insights into spatially explicit forecasts for precise silvicultural interventions. However, this information is rarely taken into account over large areas because obtaining the spatial distribution of individual trees and estimating their competition is both expensive and time consuming. Airborne laser scanning enables rapid estimation of tree height and other attributes over large areas. In this study, we implemented an individual tree detection approach to first extract tree attributes of Pinus radiata D. Don plantations, and second to use this spatially explicit information on tree location and competition to forecast potential tree height, defined as a maximum projected tree height at rotation age. To do so, using a chronosequence of tree heights, we developed a tree height growth model using a Chapman–Richards function, utilizing the effect of inter-tree competition and stand-level top height (TH) on the tree height growth. The results showed that using chronosequence of heights, competition, and TH resulted in accurate predictions of potential tree height (root mean square error = 2.9 m; mean absolute percentage error = 0.154%). We concluded that individual tree height growth is significantly influenced by competition, with increased competition values associated with reductions in potential height growth by 22.2% at 30 years.

Wildfire-mediated changes to forests have prompted numerous studies on post-fire forest recovery of coniferous forests. Given climate change, a growing body of work demonstrates that conifer regeneration in temperate and boreal forests is declining, a phenomenon often termed “regeneration failure.” However, the definition and parameters are numerous and variable. Characterization of drought also varies greatly, thus hindering the ability to compare results among areas. This review discusses new perspectives on conifer regeneration failure and places these studies into the context of drought and fire activity. We focus this review on three forest types where conifer regeneration failure is well documented: western boreal forests, cold mixed-conifer forests, and dry pine forests. To place the challenges to conifer tree regeneration in the context of regional climate trends, we present a novel regional analysis that summarizes drought conditions prior, during, and following the year of a large wildfire. We demonstrate the need to assess failure in the context of specific forest dynamics and well-defined metrics. For example, tree establishment may historically occur over longer periods, and current and future climate may exacerbate this and not promote pre-fire forest structure and composition. Many forests are undergoing rapid change and the type, magnitude, and causes of changes need to be compared among areas. As such, we should be cautious of quantifying “regeneration failure” and drought without providing spatial and temporal context.

Upslope shifts in plant distributions are often attributed to warming climate and lengthening of the growing season; however, biotic interactions may also contribute. The impacts of pests and pathogens are often sensitive to climate change and can vary along the climatic gradient associated with elevation. American beech ( Fagus grandifolia) has moved upslope throughout the northeastern United States. Meanwhile, beech growth and longevity have decreased as a result of beech bark disease (BBD), a decline disease caused by the introduced European felted beech scale insect ( Cryptococcus fagisuga) and native fungi from the genus Neonectria. Within a forested landscape spanning 250–1150 m elevation, we examined the relationships between elevation, beech demography and BBD to explore whether release from BBD at higher elevation may contribute to the upslope expansion of beech. Beech has shifted upslope at a rate of 1 m⋅year−1 coincident with lower mortality, higher recruitment, faster growth, lower BBD severity, and higher sapling densities at higher elevations. We suggest that climatic constraints on the beech scale insect at high elevations has led to a lower impact of BBD, which contributed to higher rates of beech growth, survival, and recruitment and in turn facilitated the regional upslope shift of beech.

Relatively few comparative studies exist of nitrogen (N) uptake by ectomycorrhizal (EM) and nonmycorrhizal roots under controlled conditions. Instantaneous and long-term N uptake by EM and nonmycorrhizal roots of lodgepole pine seedlings ( Pinus contorta (Douglas) var. latifolia (Engelm.)) were compared after 9–12 months of preconditioning under high or low N supply, with NH4+ and NO3− in proportions of 90:10 and 10:90. EM roots were inoculated with Amphinema byssoides or Laccaria bicolor. Instantaneous net NH4+, NO3−, and H+ fluxes were measured simultaneously on seedling roots with a microelectrode ion flux measurement system, and seedling organ biomass and N content were measured to infer long-term N uptake. Net NH4+ uptake was observed in EM roots of lodgepole pine but NH4+ efflux was observed in nonmycorrhizal roots. Greater instantaneous N uptake in EM roots was supported by higher root and shoot N contents in seedlings associated with L. bicolor than in noninoculated seedlings. Absence of NH4+ efflux in EM roots suggests that root colonization by EM fungi has the potential to reduce futile cycling of NH4+. EM lodgepole pine appeared to prefer NH4+ over NO3− as an N source and instantaneous NH4+ uptake rates were higher in NH4-starved roots. H+ efflux was observed in most roots. Future work should focus on a greater variety of EM species to explore differences among species in N uptake.

Vegetation restoration is widely used to reduce soil erosion and control soil degradation, which is conducive to improving soil quality. Aerial seeding is an effective vegetation recovery method that has been applied in large areas with severe soil erosion in China. Pinus massoniana is not only a typical native coniferous tree species, but also a pioneer tree species for vegetation recovery in subtropical China. This study evaluates the soil quality of aerially seeded P. massoniana plantations of different stand ages and examines the vegetation factors affecting soil quality. Principal component analysis and Pearson correlation analysis were used to determine the minimum data set (MDS) for developing a soil quality index. The relationship between soil quality and vegetation factors was analyzed using redundancy analysis. The MDS was established with soil bulk density, field water capacity, non-capillary porosity, total nitrogen, soil organic matter, and pH. The results showed that the soil quality significantly increased with vegetation recovery age at 0–20 and 20–50 cm soil depths. The soil quality of the surface layer was mainly affected by understory vegetation and litter, whereas that of the deep layer was mainly affected by trees. Therefore, the appropriate management of P. massoniana forest, achieved by appropriately extending forest management rotation, replanting broad-leaved trees, and minimizing the damage to understory vegetation and litter, is essential for effectively improving soil quality.

Basic wood density (BWD) is a functional characteristic important to quantify carbon storage and is related to tree growth and its survival. We investigated BWD variability among tree species, populations, and forest types across the Atlantic Forest biome in Rio de Janeiro state, Brazil. We sampled and measured 576 trees of 83 species in 28 natural ecosystems in the Dense Ombrophilous Forest, Seasonal Semi-deciduous Forest, and the Restinga Forest. Stem wood from two different heights at each tree was acquired using a drill borer; discs were removed from branches in 20% of the height from 39 trees. BWD means increased from 0.42 for the most humid ecosystem to 0.675 g⋅cm−3 from the driest ecosystem. We identified changes in the wood as a result of climatic variables particular to different typologies, such as increased wood density in areas with lower precipitation and higher temperatures, were also observed within species, but with little difference in means. We identified three groups of species according to their BWD, different in mean height and diameter. The branches can be used to estimate tree wood density.

Incense-cedar ( Calocedrus decurrens (Torr.) Florin) is a drought-resistant conifer species native to the western United States that is host to few lethal pests and pathogens. Quantifying its survival and growth after planting is important for defining its potential place within future silvicultural prescriptions. Our objectives are to understand the impact of (1) spacing and herbivore protectors on seedling survival, (2) spacing on growing space occupancy after 19 years, and (3) spacing on individual tree and stand characteristics. The use of herbivory protection had a positive influence on seedling survival (96% survival with protection; 92% survival without protection). After 19 years, including drought conditions, 89% of planting spots were occupied by a live tree. Mean live crown ratios occurred across a narrow range, from 89.4 to 97.8, indicating a lack of differentiation at this phase of stand development. Wider spacing treatments resulted in the expected trade-off of larger individual tree sizes but lower stand-level volume. Because of persistent live crowns, thinning and pruning are potential strategies not only to reduce fire risk but also to improve timber quality. Our results also support the contention that incense-cedar is a species well-adapted to the anticipated future climate.

Tree stems have been identified as globally significant methane (CH4) sources; however, little information exists on emissions from tree wounds and branches. CH4 emissions can occur from the decomposition of anaerobic heartwood, which is also associated with wounds; CH4 may also be transported through the transpiration stream and emitted from branches. We compared CH4 emissions between tree stems and branches and assessed whether trees with major wounds emit more than those without. CH4 fluxes were measured from stems, branches, and wounds (classified as major or minor) of two dominant tree species in an upland temperate forest, and from the soil, and scaled up to the stand level. Branches and stems of both species emitted CH4, and the per unit area emission rates from branches were similar to (or in some cases greater than) stems. Trees with major wounds had greater CH4 emission rates than those without, from unblemished sections of their stems and from the wounds. At the stand scale, branches, stems, and wounds accounted for 83%, 9%, and 8% of net CH4 emissions from trees, respectively, and collectively offset 63% of the soil CH4 sink. These results indicate that tree branches and wounds can be important CH4 sources in forests.

Landscape-level studies such as those on forest management planning and carbon accounting rely on large-area growth projections provided by forest growth models. Nowadays, most of these models are individual tree-based models. The detailed input they require and their complexity are a challenge for the integration into a landscape-level study. A possible alternative consists of approximating the complex model through a meta-model. A meta-model mimics the behaviour of the original model, while being simpler in terms of input and computation. In this study, we developed a Bayesian meta-modelling approach that can be used to obtain a simplified growth model from an individual tree-based model. The approach was exemplified through a real-world case study, namely a forest management unit in the province of Quebec, Canada. Using a Markov chain Monte Carlo method, we managed to fit meta-models based on the Chapman–Richards equation or its derivative for the main potential vegetation types. This meta-modelling approach has the advantages of ( i) being an effective method of upscaling, ( ii) providing simple meta-models suitable for landscape-level studies, and ( iii) ensuring a proper error propagation from the original individual tree-based model into the meta-model.