Canadian Journal of Forest Research

This paper adopts a comprehensive approach to integrating the wood forest product trade of China's provinces with the global market, utilizing over four million records of trade data from the Chinese Customs database and the United Nations Trade and Commerce database, creating a three-dimensional panel dataset structured by year—province—importing country. The paper decomposes the export trade share into extensive margin, quantity margin, and price margin, collectively referred to as the ternary margins of export, to analyze the impact of imported timber price fluctuations on these export margins of wood forest products. The findings indicate that fluctuations in imported timber prices increase uncertainty, thereby suppressing the growth of China's wood forest product export share, extensive margin, and quantity margin while increasing the price margin. Heterogeneity tests further reveal that the impact of imported timber price fluctuations is more pronounced for southern forest regions, labor-intensive wood products, and countries without a free trade agreement. Mechanism tests suggest that increasing forestry fixed asset investment intensity and enhancing timber supply capacity can help mitigate the uncertainty effects associated with imported timber price fluctuations. The paper proposes policy implications, including enhancing local timber supply resilience, strengthening government support for forestry, and reinforcing the supply chain.

Climate change has driven forest growth modellers to develop different climate sensitivity implementations (CSI) for their models. Among others, a model can rely on annual climate variables or average climate variables, such as 30-year normals. The novelty of this study was to develop a framework based on lifetime analysis to enable annual or average CSI in empirical models of tree mortality. Using this framework, we compared models of individual tree mortality based on an annual CSI with similar models relying on two average CSIs, one using interval-averaged climate variables, and the other, 30-year normals. We fitted these models to permanent-plot data of eight species in Ontario and tested the effects of summer and winter temperature as well as spring and summer precipitation in the models. Our results showed that the annual CSI was not superior to the average CSIs, but could be a valid alternative for some species. Warmer winter temperature was detrimental to the survival of Abies balsamea, Betula papyrifera, Picea glauca, and Pinus strobus, whereas greater spring and summer precipitation resulted in greater mortality occurrence for Picea mariana, Pinus banksiana, and Populus tremuloides. In most cases, the effects of climate variables were contrary to our initial hypotheses. We conclude that the effects of climate on tree mortality occurrence interact with other factors such as species distribution and ecophysiology.

Integrating climate change into strategic forest management is crucial for predicting forest dynamics and maintaining resource availability. However, there is no scientific consensus on how to integrate their climate-sensitive outputs into strategic forest planning. In this study, we propose a novel approach to incorporate climate change into a strategic forest planning model, Woodstock, using a parsimonious set of climate-sensitive stand yield tables and transition rules derived from the PICUS stand simulation model, calibrated for the Acadian forest region. Climate-sensitive yield tables were generated for the baseline and two climate forcing scenarios to dynamically capture climate effects on forest growth and composition. Initial forest conditions were grouped into four age classes for each stand type, with future conditions determined by three transition periods. Simulations predict a significant shift toward warm-adapted species, with red maple, white pine, and yellow birch becoming dominant, while cold-adapted species like balsam fir and spruce decline by 2120. Under high climate forcing, the merchantable wood volume is projected to decrease by 50%, indicating potential shortages and economic risks. The incorporation of climate change uncertainty into strategic forest planning is essential to reduce the risk of overutilization of forest resources. This research offers a novel and straightforward approach to integrating climate change into forest planning models.

Midrotation management including vegetation control and fertilization can improve growth and yield of southern pine stands. This study investigated the 12-year response of slash pine (Pinus elliottii), thinned at midrotation to additional treatments of herbicide, fertilization, liming (one site), and combinations of these treatments in the Coastal Plain region of Georgia, USA. There was a significant treatment x stand age interaction observed at the Ware County site for height (p<0.001), dbh (p<0.001) and individual tree green weight (p<0.001). The herbicide + NPK and herbicide treatments resulted in the most consistent growth improvements 0 to 4 years post-treatment compared to the untreated control. The lime + NPK and herbicide treatment resulted in the longest lived (4 to 12 years) significantly improved growth response. Results revealed no tested treatments improved growth during the 12-year study duration at the Wayne County site. Results from this study suggest that thinned slash pine stands with diagnostics indicating midrotation fertilization or vegetation control may be beneficial do not always respond as expected to inputs. When stands are responsive, single application midrotation treatments can offer long-term growth improvements, yet growth response can differ depending on time since application.

We investigated the impact of water table (WT), monthly temperature, and precipitation of current and previous growing seasons on annual diameter growth of Scots pine in boreal drained peatlands. The data were collected from six sites across Finland. WT was monitored during 5-8 growing seasons depending on site during 2007-2014. The sites contained altogether 19 sample plots, where diameter growth from 339 trees was measured, resulting in 1,599 growth observations. Tree-level diameter growth was analysed using mixed linear models, including variables describing tree size, competition, and environment. The higher precipitation in June of the previous year and May of the current year increased diameter growth, whereas the higher temperature in July of the current year and the deeper WT in August of the previous year decreased growth. The results suggest that Scots pine grows better at shallow than deep WT in drained peatlands. This contradicts earlier findings that a deep WT is needed to support tree growth in drained peatlands. We suggest that the development of a mor layer on the peat is changing nutrient cycling and hydrology. The results encourage the avoidance of intensive drainage in forested peatlands, which may also diminish the adverse environmental impacts of peatland forestry.

Background tree mortality can be defined as the death of trees that naturally occurs as stands develop, in the absence of major or sudden stand disturbances. The phenomenon is often linked to ontogeny and competition and generally affects individual trees, unlike catastrophic mortality, which affects most trees in the stand. To forecast stand characteristics and to estimate how stand development could change in response to changing climate, it is necessary to quantify background mortality and to identify the most important factors involved. Using data from 10,045 permanent sample plots, we modeled background tree mortality for the 9 most abundant tree species of the eastern Canadian boreal forest. We used explanatory variables related to stand and tree ontogeny, competition, site characteristics and climate to calibrate the models. We found that an increase in age, competition and the presence of partial cut increased the mortality risk. However, the effect of DBH and site-related variables varied among species. We also found that higher temperatures, less precipitation, and higher aridity index values increased background tree mortality. According to mortality simulations under different future climate scenarios, background tree mortality could increase in the next decades for 6 of the 9 tree species studied.

Ring width variability affects the elasticity and strength of wood members. This study was conducted to determine which dispersion statistics of annual ring width distributions measured in cross section in European oak (Quercus robur L.) wood beams are useful as covariates in models for predicting modulus of elasticity (MOE) and modulus of rupture (MOR). For this purpose, 21 European oak trees growing in north-western Spain were felled, logged and sawn. The planks obtained were air-dried and surfaced into beams (50×100×2,000 mm), which were visually graded according to the UNE 56544:2022 standard. MOE, MOR, moisture content and density (determined according to EN 408:2010 standard) and abundance of sapwood and ring widths were determined in 30 beams apt for structural purposes. MOE was significantly related to standard deviation, variance and interquartile range of the ring width distribution in the beam. MOE was also related to mean ring width (r =-0.52, p<0.01) and maximum ring width per beam (r =-0.54, p<0.01), an easy to measure variable. MOR was also related to ring width distribution parameters, although yielding lower r values. The influence of ring width evenness and maximum ring width can be considered to improve visual strength grading standards for European oak timber.

Sandyzation areas in the Brazilian Pampa are highly degraded zones with reduced or absent vegetation and challenging soil conditions, making their recovery and economic use unfeasible. The objective of this study was to evaluate accumulated litter and physical-chemical attributes of the soil (up to one meter depth) in three land uses: sandyzation area (SN), fertilized Eucalyptus urophylla plantation after seven years of its implementation on sandyzation area (EC) and native grassland (GR). Accumulated litter and its carbon (C) and nitrogen (N) stocks were higher in EC. Higher levels of organic matter (OM) and aluminum (Al) and greater stocks of C, N, potassium (K), calcium (Ca), and magnesium (Mg) were found in GR soil. The sandyzation process leads to a significant deterioration in the chemical quality of the soil, with a reduction in the stocks of C, N, K, Ca, and Mg. The establishment of Eucalyptus combined with fertilization positively influences the OM and C contents in the most superficial layer of the soil. However, the lack of significant improvements in the overall physical-chemical quality of the soil suggests that ecological restoration efforts focused on native vegetation may be more effective in recovering soil quality in areas affected by sandyzation.

The development of bioenergy projects, which play a major role in the ongoing energy transition, must rely on research by indicators. This type of research allows the establishment of criteria that can guide development choices on scientific bases. In order to promote the continuation and development of bioenergy projects as much as possible, it is very important to take an interest in the dimensions and socio-cultural issues of bioenergy. Based on a corpus of 257 articles sorted into two distinct phases, this paper analyzed 25 academic articles that specifically discussed and proposed socio-cultural indicators for the assessment and evaluation of bioenergy projects. We looked at how the indicators were used across the papers and identified differences and commonalities. This has led us to identify a total of 71 indicators and to propose 18 key indicators based on their widespread use and their ability to cover the socio-cultural dimensions of bioenergy production.

The wood of sugar maple trees (Acer saccharum Marsh.) is generally perceived as containing more defects, such as dark heartwood and wood rot, at the northern limit of its range compared to southern locations; however, assessments of these internal defects have primarily relied on direct observation, limiting the scope of analysis. To enable large-scale assessments, models are needed to estimate the internal quality of individual trees based on external defects. Accordingly, this study aimed to investigate the relationships between external and internal defects within sugar maple stems. Then, large-scale estimates of the importance of such defects were produced to understand the effects of site conditions and climate. Increment cores were sampled from 1,108 trees across 108 plots. Results revealed that the probability of wood rot and the proportion of internal defects were associated with the presence of cracks and fungal fruiting bodies. Also, colder sites increased the probability of wood rot as well as the proportion of the stem affected by internal defects. Moreover, the western Balsam fir-Yellow birch subdomain had both the highest probability of wood rot and the greatest proportion of internal defects. Future studies should examine how this spatial distribution could evolve with climate change.

Several studies have predicted a loss of quaking aspen (Populus tremuloides) from many western landscapes, but other studies have suggested that aspen persistence is driven by local site factors. Increased frequency of acute drought has been implicated as an important factor driving overstory mortality and reduced regeneration densities in the region. We investigated the relationship between aspen regeneration and site moisture availability potential using ecosystem type as a proxy. We hypothesized that aspen stands growing along perennial-flowing streams would support higher aspen regeneration densities than upland aspen stands. We compared stand structure, groundcover composition, and regeneration densities of nine riparian aspen stands with nine paired upland aspen stands in the Caribou-Targhee National Forest. Aspen regeneration densities were significantly higher in the riparian aspen stands (845. 3 + 318.7 stems ha-1) compared to the upland aspen stands (249.1 + 74.1 stems ha-1) for regeneration shorter than one meter (p = 0.0391). Riparian stands also exhibited significantly higher forb (p< 0.001) and graminoid (p < 0.001) cover compared to upland aspen stands, suggesting that riparian sites provided higher site moisture availability. We suggest that riparian areas may provide refugia for aspen in the future considering projections of increased incidence of acute drought.

Increasing the productivity of planted forests may efficiently provide an important part of the world’s growing demand for wood while protecting natural forests. In this study, we developed an integrated modelling framework to evaluate the financial impacts of improving productivity of planted forests by tree breeding. Using this framework, we compared three genetic improvement scenarios of white spruce plantations, a key reforestation species in North America, and evaluated the differences in the derived wood product assortments in terms of quantity, quality, and revenues. Favouring the production of wood volume appears as the best way to enhance financial gains from white spruce plantations in the current market. The scenario that focused on increasing tree height produced a greater volume of wood products and larger lumber pieces, which resulted in the greatest revenues. In comparison, favouring wood stiffness over volume led to poorer results, as the increased product quality was not sufficient to surpass the financial gain associated with greater wood volumes. While we successfully provided an evaluation of the product assortments derived from genetically improved plantations, the proposed framework would benefit from more data input to help maximize financial gains from a range of tree breeding strategies.

The utility of seed addition to promote tree regeneration can be greatly limited by animals that consume seeds. Moreover, given that restoration often occurs in forests where invasive shrubs are abundant, and evidence that invasive shrubs can increase granivory, it is important to explore whether methods for reducing granivory work equally well in invaded and uninvaded habitats. We used a multi-site field experiment spanning 160 days to explore whether coating seeds of Prunus serotina with capsaicin extract leads to reduced granivory in habitats with or without invasive shrubs (Rhamnus cathartica). Capsaicin-coated seeds were removed at a similar rate to uncoated seeds, but seeds in invaded plots had a 78.8% higher rate of removal compared to plots without invasive shrubs. Our findings suggest that managers seeking to encourage regeneration of native trees using direct seeding should consider invasive shrub removal as a top priority to limit the loss of seeds once sown.

Silicon (Si) is a beneficial element for many plant species, conferring resistance to drought and herbivory, but its effects on trees are less known. We studied responses of silver birch ( Betula pendula ), grown in peat, to liquid Si supplementation (Si concentration 0.65 mM) on 1) growth, 2) water economy and 3) element accumulation plus 4) feeding preference of an insect, Epirrita autumnata and a mammalian herbivore, Microtus agrestis . Plant growth was not affected but control (Si–) plants shed their old leaves earlier. Detached Si+ leaves lost water 11%-units less than Si–, and the integrated water-use efficiency based on ¹³C analysis was higher in Si+. Foliar Se was higher and Mn and S lower in Si+. Root Mg concentrations were higher and Pb lower in Si+. Epirrita autumnata did not prefer either treatment, but M. agrestis preferred Si– stems. Silicon improved birch water relations as indicated by the leaf drying resistance and increased water-use efficiency. The changes in metal accumulation were probably beneficial, but the lower S/Se ratio requires attention. Furthermore, Si decreased palatability to a mammalian herbivore. Using Si as fertilizer in nurseries could be possible to increase birch tolerance to water stress and herbivory.

The Finnish National Forest Inventory produces municipality level results either with an indirect model-based K nearest neighbor estimator or a direct design-based post-stratification estimator. Design-based approach is unbiased, but not always feasible due to low number of field plots. The K nearest neighbor estimator is lacking an analytical estimator for the variance. A composite estimator combining the indirect and direct estimates could be an attractive solution. In this article, estimators for small-area estimation are analyzed in a simulation experiment with varying size small areas and quality auxiliary data. The potential of estimators is assessed based on the true standard errors and RMSEs in the simulation experiment. Direct estimators and composite estimators work reasonably well with varying quality models, but the performance of indirect estimators is dependent on the quality of the model used. The performance of different estimators also depends on the size of the small areas. Linear models in which the weight of plots outside the target domain is smaller than those within the target domain, performed better than an unweighted model, suggesting that localizing the models for the small areas is beneficial. EBLUP approach also performed well, both in connection of a KNN model and a linear model.

This paper investigates the impacts of two taxation programs, the Forestland program (FL), based on a site value tax, and the Small Tract Forestland program (STF), based on a combination of a site value tax and a severance tax, on the optimal management of Douglas-fir in Western Oregon amidst timber price uncertainty. The study reveals that the optimal reservation prices are lower under the STF program, making it more advantageous for forest landowners in terms of tax liabilities. Specifically, the STF program leads to significantly lower tax payments ($185.8-$277.4 per acre) and tax burdens (6.0%-5.9%) compared to those of the FL program ($709.2-$1092.5 per acre; 22.9%-23.2%). When factoring in the harvest age, the STF program results in an increased harvest age, whereas the FL program remains fiscally neutral. The FL program exhibits a slightly progressive taxation system, while the SFT program displays a slightly regressive taxation system. Although our findings suggest that the STF program is a better option for landowners, a more detailed analysis regarding the impacts of these taxation programs on the overall welfare of the state's economy is required.

The root causes of forest tree regeneration failure are difficult to resolve, although numerous studies show ungulate herbivory, soil conditions, and competition from undesirable vegetation as likely contributors. To better understand the relative importance of each issue, we conducted a 7-year manipulative experiment to assess the interactive effects of white-tailed deer (Odocoileus virginianus) herbivory, soil acidity, and competing vegetation on tree regeneration in oak–hickory forests of central Pennsylvania, USA. Outcomes depended on initial tree seedling abundance, and all three factors had significant interactions. At low initial seedling abundance, fencing resulted in the greatest increase, but all treatments had a positive effect on seedling growth and abundance. At higher initial seedling abundance, abundance failed to recover 7 years after herbicide treatment and soil pH was an important predictor. When soil pH was >4.6 from lime application, seedling growth and abundance in unfenced controls with high initial abundance was comparable to the fenced-only treatment. Competing vegetation, assumed to be a symptom of excessive, long-term deer herbivory, does not seem to be the primary factor limiting tree regeneration in our study area. Ameliorating acid deposition warrants greater consideration as a management action because it could provide long-lasting benefits compared to short-term fence installations.

Taper models have been widely used and treated as the primary means of calculating tree volume. However, constructing taper models is challenging in practice due to the high cost and time involved in measuring stem diameters. Therefore, we designed twenty new taper measurement schemes that increase the stem diameter measurement interval (diameter above breast height) by two to five times. The taper models were evaluated by predicting stem diameter, volume, and merchantable height of two conifer species (Pinus sylvestris var. mongolica and Larix gmelinii) in Northeastern China. Results showed that the variable-exponent taper model of Kozak (2004) performed best for both species, while diameters can be measured every 2 m above 4 m. In addition, for both species, reducing the diameter measurement required for modeling by one-third to one-half does not increase the error in predicting the entire stem profile. This study will provide additional insights for collecting taper measurement data through traditional destructive sampling.

This study investigates competing vegetation effects on foliar and total plant-derived nutrient ratios, nutrient use efficiency (NUE), and foliar nutrient content and concentration of ecosystem components using vector analysis for 19-year-old Douglas-fir (Pseudotsuga menzeisii (Mirb.) Franco), western hemlock (Tsuga hereophylla (Raf.) Sarg.), western redcedar (Thuja plicata Donn ex D. Don), and grand fir (Abies grandis (Dougl.) Lindl.) stands in Oregon's Coast Range and for Douglas-fir and western redcedar in Oregon's Cascade foothills. Treatments included the Control, which received no spring release herbicide applications, and vegetation management (VM), which received 5 years of spring release herbicide applications, reducing competing vegetation abundance. VM increased the NUE of N, P, Mg, S, and Cu across all species when calculated with total plant-derived carbon and of all nutrients when calculated with stemwood carbon. VM often produced more harvestable and plant-derived carbon per unit nutrient fixed, improving the NUE of stands managed for carbon sequestration and timber. Species showed different stand nutrient requirements, evident through foliar and plant-derived nutrient ratios and their relationship with biomass production. Grand fir may obtain larger biomass increments for a given P:N ratio in plant-derived tissue and may be efficient in P-limited Coast Range sites.

Forestry is an important component of Canada’s economy with British Columbia (BC) contributing almost half to the national roundwood production. Yet, the country’s timber supply and forest economy are threatened by climate change, with increased frequency and severity of natural disturbances and changes in forest productivity. Mountain pine beetle (Dendroctonus ponderosae) outbreaks are endemic in BC, but the latest climate change-driven outbreak has resulted in a cumulative loss of over half of all merchantable pine, leading to a mid-term timber supply shortage. In this study, we investigate the potential of commercial thinning and alternative planting regimes based on species diversification and assisted species migration to mitigate the anticipated decrease in timber supply in BC. We simulated the long-term effects of these management options in a case study area in interior BC, using a toolbox that combines management- and research-oriented data and models. We found that combining commercial thinning and species diversification has the best potential to mitigate future timber supply shortages in BC. We discuss the limits of this toolbox approach and identify research needs and recommendations for future studies aiming at modelling cumulative effects of management, climate change, and natural disturbances on timber supply.

We studied responses of needle terpene concentrations and resin canal characteristics to warming in Scots pine (Pinus sylvestris) and Norway spruce (Picea abies) seedlings grown in a controlled field set-up in eastern Finland. Warming was simulated during the growing seasons using infrared heaters that increased air temperature in study 1 (2016–2019) by 1°C and in study 2 (2019–2020) by 2°C and 4°C, compared to ambient conditions. Terpenes were sampled in study 1 from non-matured current year and matured previous year needles in June 2019, and study 2 from mature current-year needles in August 2020. In study 1, we also studied resin canal anatomy. We found that 1°C elevation of temperature caused two-fold increase in concentrations of total terpenes, oxygenated monoterpenes and sesquiterpenes of non-matured current year needles of Norway spruce. Further, it caused 1.3-1.8-fold increases in sesquiterpene concentrations both in unmatured and matured needles of Scots pine. It also decreased resin canal diameter of mature needles in Norway spruce. In study 2, the stronger warming treatments did not affect terpene concentrations of matured current-year needles in either species. Based on our findings, even minor elevation of temperature may affect terpene concentrations of non-mature needles in boreal conifers.

In western North America, quaking aspen stands (Populus tremuloides Michx.) have predominantly been described as low flammability, “fireproof” forests, but the specific relationship between aspen stand composition, fuel characteristics, and potential fire behavior is not fully understood. We investigated surface and canopy fuel characteristics in 80 aspen stands in Utah, U.S., that spanned gradients of tree species composition from aspen to conifer dominance and stand development from early to late stages. We quantified fuel type and load, measured fuel moisture content in representative stands across two summer seasons, and modeled flame lengths in each stand. Fuel type and load varied greatly across stands, though late development, conifer-dominated stands had significantly higher (∼2–5 times) fine dead woody and litter load and significantly lower (∼2–5 times) live understory herbaceous load compared to pure aspen stands. Fuel moisture content did not vary by stand type. Modeled flame lengths were lowest in pure aspen stands, and flame lengths increased linearly with decreasing aspen composition, suggesting that potential surface fire behavior increases as a seral aspen stand progresses through succession to conifer dominance.

The objective of this study was to identify the most effective system for predicting parameters of the Weibull function that characterize diameter distributions of black pine (Pinus nigra Arn.) stands in Turkey. We examined three Parameter Recovery methods: the Moment Recovery method, based on diameter moments (diameter variance and quadratic mean diameter), the Percentile Recovery method, relying on diameter percentiles (the 31st and 63rd percentiles), and the Hybrid method, which combines elements of both approaches. Within each of the three methods, we derived regression coefficients from four estimation approaches: Seemingly Unrelated Regression (SUR), Cumulative Distribution Function Regression (CDFR), Maximum Likelihood Estimator Regression (MLER), and Stand Table Regression (STR). Our findings demonstrated that the Moment Recovery method exhibited superior performance compared to the Percentile Recovery and Hybrid methods. Additionally, the MLER approach surpassed the other three estimation techniques. Notably, the Moment Recovery method, coupled with regression coefficients estimated through MLER, emerged as the top-performing combination overall. These results hold significant implications for the development of a diameter distribution growth and yield model tailored to black pine stands in Turkey.

I outline the “definitional problem” in forest insect outbreak analytics and show how it is related to the “counting problem” in dendroentomology and the “forecasting problem” in forest insect population dynamics, through the ubiquitous presence of non-stationary complex periodicity. Using real-world examples from the spruce budworm (Choristoneura fumiferana Clem.) system, I show that regardless how outbreak patterning is characterized—whether by peak impact, cycle frequency, interval duration, or interval severity—the distribution in pattern attributes appears to be extremely variable, regardless how the data are processed through definitional filters. I show that this extreme variability is an unavoidable and key feature of the system’s dynamics and argue that it needs to be viewed as an object of study, instead of a nuisance problem to be swept under the rug. The single biggest opportunity for rapid gains in spruce budworm predictive ecology is determining the environmental and ecological factors that separate high-intensity from low-intensity outbreak cycling.

Knowledge of wood property variation within trees is critical for understanding age effects on wood formation and for improved utilization of forests, and maps provide an effective way to efficiently summarize and visually represent variability. Despite the importance of maps, examples for North American conifers are rare. Most studies focus on plantation grown trees, with the majority examining loblolly and radiata pine. For these species almost all maps can be categorized into two groups related to tracheid differentiation processes. One group includes properties related to secondary cell wall formation, e.g. density, and the second relates to tracheid enlargement, e.g. tracheid length. Maps for trees from natural forests are largely limited to density and are highly variable indicating site effects are large. The degree of variation within a species made it impossible to develop conclusions regarding general patterns of variation as with plantation grown trees. The identified density maps are consistent with the three radial variation patterns defined by Panshin and de Zeeuw (1980) (Type 1 (increase), 2 (decrease then increase), and 3 (decrease)). A focused research effort to better visualize wood property variation is required, particularly for species demonstrating Type 2 and 3 radial density patterns.