Forest planning faces many uncertainties, yet existing decision support systems (DSS) seldom incorporate techniques to address them. This study explores how stochastic programming (SP) functionality could be added to forest DSSs to account for data uncertainty, aiming to investigate the added value of such functionality. An SP model was applied to a traditional long-term forest planning problem, and its quantitative performance was compared to deterministic optimisation. The user value of the DSS integration was explored in a workshop with potential users. The findings indicate that incorporating SP in a DSS is feasible both user-wise and for quantitatively improving the decisions, even if computational time and model complexity increase. Quantitatively, SP increased the total expected NPV by at least 2% compared to deterministic optimisation. Users involved in evaluating the SP integration acknowledged the benefits of using SP in forest planning, but expressed concerns about the increased complexity in problem specification and results interpretation. To enhance user adoption, the presentation of SP settings and outcomes should be done in a user-friendly manner, including intuitive visualisations and simplified summary statistics. This study underscores the potential of integrating SP in DSSs to improve long-term forest planning under data uncertainty.
Clear differentiation between natural and man-caused fires (NFs and MFs), and understanding their distinct behaviors and drivers, is essential for predicting fire dynamics and assessing impacts. However, these efforts remain challenging due to scarce direct ignition observations, requiring reliance on large-scale geospatial datasets and sophisticated analytical frameworks. This study classifies NFs and MFs across Mainland Southeast Asia (MSA) (2000-2020) to enhance understanding of their distinct patterns and inform mitigation strategies. By integrating land cover data with the Human Footprint Index (HFP) and lightning fire probability, we delineated NF- and MF-dominated regions across MSA. We found that the proportion of identified human-caused fire regions (61.5%) was substantially higher than that of natural fire regions (38.5%). Spatial-temporal analyses revealed divergent trends: a statistically significant decline in NFs contrasted with escalating MF activity, showing a close connection with population growth and concurrent habitat fragmentation. El Ni & ntilde;o-induced thermal anomalies further amplified wildfire frequency during drought periods. Notably, MFs showed a stronger correlation with moisture deficits and greater sensitivity to Ni & ntilde;o 3.4 index variability compared to NFs. To mitigate wildfire risks, policy efforts should prioritize (1) real-time forecasting systems for extreme aridity and (2) accelerated transition from slash-and-burn agriculture practices to sustainable land-use alternatives.
We assessed genetic diversity of naturally expanding Norway maple populations in Lithuania, focusing on potential genetic risks associated with spontaneous colonization. We genotyped 186 trees within a single forest stand and 390 trees across 21 populations in Lithuania at seven nuclear microsatellite loci. Significant bottleneck effects were detected, particularly in northern populations, where Norway maple presence is scarce. These northern populations exhibited the lowest genetic diversity (Ho = 0.57-0.65; FIS = 0.15-0.20) and elevated relatedness, in contrast to the more diverse north-eastern populations (Ho = 0.65-0.80; FIS = 0.04-0.10). Population differentiation was low (FST = 0.054***), and the genetic structure was more uniform than expected for a strictly entomophilous species. Bayesian clustering identified genetically distinct groups in north-eastern Lithuania. Genetic differentiation among genetic clusters within a single stand (FST = 0.098) was nearly twice that observed among populations in Lithuania. Our findings suggest that the spontaneous spread of Norway maple may result in (a) genetically eroded groups of closely related individuals, as observed in northern Lithuania, or (b) the development of internal genetic structuring within populations, leading to deviations from random mating and increased inbreeding. Such populations may require targeted genetic diversity enrichment.
Assessing boreal forest management's role in climate change mitigation requires an integrated approach. This study analyzes carbon dynamics in forest and wood products for a Norwegian forest using a dynamic vegetation model and a single-stand approach. We simulate forest regrowth over 180 years after one harvest event, followed by three regeneration scenarios, and compare results to a no-harvest case. We extrapolate the single-stand results and apply them to a landscape perspective with two harvest rates. A sensitivity analysis investigates the effects of changes in climate, avoided emissions, and product lifetimes. It takes 42-75 years for the regrowth alternatives to offset emissions, and the natural regeneration alternative sequesters and stores more carbon. Using residues for energy substitution yields negligible carbon benefits. At a landscape level, a 100% harvest rate prevents net sequestration; only the system with natural regeneration maintains carbon neutrality. A reduced rate preserves carbon pools and promotes long-term storage. When the regeneration scenarios are compared to the no-harvest alternative, the latter remains the most effective strategy. Changes in climate and avoided emissions can make the system with natural regeneration more favorable in the medium term. Trade-offs between sequestration and wood provisioning highlight the need for thresholds on resource extraction.
Mass production of Larix decidua & times; L. kaempferi seed in first-generation hybridization orchards (F1s) is hindered by wide variation in the proportion of hybrid seeds. Second-generation hybridization orchards (F2s) have therefore been established in Belgium and in France. Seed crops from F2 orchards produced 13-18% less viable seed/kg than F1s but with similar seed quality. Across 6 progeny trials, survival of F2s at age 9-10 was generally better than that of F1s as well as European (EL) and Japanese larch (JL) controls. The volume growth of the F2 hybrids was 7-36% lower than that of F1s across sites and orchards but exceeded that of EL and JL. Stem straightness varied between orchards, reflecting differences in the level of selection of parental clones: the French F2 orchard achieved much better straightness than F1s, EL, and JL, whereas the Belgian F2 orchard had a systematically lower proportion of straight stems than F1s (although its stem straightness generally matched or exceeded that of EL and JL). Second-generation hybridization orchards were thus shown to be a promising alternative to 1st-generation orchards for mass-producing hybrid seed. Further research is needed to identify optimal strategies for advanced hybridization.
The debarking of tree saplings by ungulates is a critical problem for conifer regeneration. However, how coarse woody debris (CWD), specifically fallen logs that act as nurse logs by providing microhabitats on their upper surface, influences the debarking of conifer saplings by ungulates remains poorly understood. We compared the frequency of debarking of Sakhalin fir saplings by sika deer between saplings growing on CWD and those growing from the ground in a subboreal mixed forest. The saplings growing from the ground were debarked more frequently than those growing on CWD, even though the saplings on CWD were more accessible to deer during the snowy period, when food resources for the deer are generally limited. More frequent occurrence of debarking on the saplings growing from the ground indicates the deer likely accessed the saplings on the ground during the non-snowy period. Furthermore, saplings with wider stems were debarked more frequently than those with smaller stems. This might have occurred because trees with wider stems with sufficient anchorage and stability are suitable for debarking. Less frequent occurrence of debarking on the saplings growing on CWD highlights the importance of the upper surface of CWD for conifer regeneration in the face of an increasing sika deer population.
Herbivory is a source of damage for Fennoscandia commercial stands. Silver birch (Betula pendula Roth) plantations are of increased interest to address the climate and biodiversity crises, but there are concerns about browsing risk. We inventoried 92 planted silver birch stands from a survey focused on browsing variables (e.g. symptom, severity, cause, and position), and one on tree measurements. We estimated ungulate density from national surveys and pellets observation. We assessed landscape characteristics (neighbouring land use/land cover classes and distance to roads). We observed considerable browsing risk for silver birch plantations, with 38 +/- 35% and 23 +/- 19% of planted birches browsed in younger and older stands, respectively, with mean height <5 and >5 m. Moose were considered responsible for almost half of browsing (44%), while other species accounted for a small amount (4.1%), the majority by unidentified cervids. Especially, crown damage in younger stands developed into vertical branches in older stands, leading to low stem external quality. In a model predicting the number of browsed stems at stand level, damage occurrences were dependent only on stand characteristics and abundance of browsing animals. Our analysis could not provide site selection recommendations for lower browsing risk sites. However, avoiding early damage seems the most crucial step.
Weevils are notorious pests in conifer regeneration, yet their impact on broadleaved species such as silver birch (Betula pendula) remains poorly understood. This study investigated the incidence and severity of weevil damage on newly planted birch saplings in southern Sweden and tested the effectiveness of Hylonox, a mechanical coating, against weevil attack. A field experiment was established across fresh and one-year-old clear-cuts and damage assessments were conducted over two growing seasons. Strophosoma melanogrammum was the most frequently observed weevil species, followed by Otiorhynchus carinatopunctatus, Hylobius abietis and Hylobius pinastri. Overall, 62% of the birch saplings showed bark damage by weevils, with mortality reaching 16% among the damaged individuals. Mortality was significantly higher in untreated saplings (30%) than in treated ones (21%). Weevil-associated leaf feeding affected 87% of saplings in 2024 and 49% in 2025, but severity was predominantly minor (<20% leaf area affected). Initial sapling height significantly affected both the incidence of bark damage and mortality, with shorter saplings experiencing higher mortality. Ungulate browsing was frequent (45% of saplings), often affecting terminal shoots. The results of this study suggest that weevils can damage birch during early establishment, although mortality is modest relative to that in conifers.
Tree stumps are a potentially significant source of renewable energy, but their extraction may result in significant adverse impacts on ecosystems. To assess mid-term effects (up to 8 years after harvesting) of stump removal on nutrient status and young stand development in mesotrophic Latvian hemiboreal forests, we evaluated soil and soil solution chemistry, subsequent young stand growth, and foliar micro- and macroelement status in five sites where above-ground whole-tree harvesting (WTH) was compared to above-ground WTH with additional stump biomass removal (WTH + SB). Post-harvest soil organic carbon stocks and C/N ratio declined more after the WTH + SB than after WTH while soil nitrogen stocks increased. No additional acidification of the soil solution caused by stump removal was observed, and the inconsistent pattern of nutrient concentration change in soil solution (partial increase of phosphates, calcium and magnesium in WTH + SB relative to WTH, no clear response of nitrates) reflected site-specific conditions. N concentration in planted Norway spruce needles did not differ consistently between the treatments, and foliar nutrient concentrations of the regenerated stands were mostly within the typical range of similar forest site types in Latvia. Mean tree height was significantly greater after WTH compared to WTH + SB in sites with monodominant regeneration.
The growth process shapes the structure of trees in forest, and the rate the stems thicken over time is linked with wood properties such as ring width and wood density. This study investigated the potential of bi-temporal terrestrial laser scanning (TLS) for measuring the secondary growth of coniferous trees and assessing wood properties derived from core samples using X-ray microdensitometry over a nine-year period in boreal forests. TLS-derived DBH measurements demonstrated high agreement with reference data (r > 0.96). Volumetric secondary growth ($\Delta v$Delta v) slightly outperformed basal area increment ($\Delta g$Delta g) in capturing secondary growth dynamics as moderate correlations were found between TLS-derived estimates and mean ring width (RWm; r = 0.60-0.67). In contrast, correlations with ring basal-area-weighted wood density (WDg) were weak but statistically significant (r = -0.16 to -0.18) for both TLS and core-sampled measurements. The findings suggest that TLS can be used to measure secondary growth, but the ability to predict wood density of coniferous species via secondary growth measurements - neither with TLS nor core-sampling - is limited due to internal anatomical factors not captured by external measurements. Overall, these findings support the integration of TLS into forest monitoring frameworks, as it provides equally reliable yet more versatile data than callipers for measuring secondary growth.
While forests are generally regarded as beneficial for water quality, forest management can significantly impact water quality, even if sustainable forest management practices are applied. Fellings alter water balance and nutrient cycling, while forest roads with impermeable surfaces fragment ecosystems and enhance runoff. Road construction often requires extensive landscape modification and material relocation, which increases substance leaching and erosion. In the present study, water quality parameters and nutrient export were monitored over eight years (2016-2023) in a forested catchment (2212 ha) and its sub-catchments. During this period, 15.8 km of forest roads were constructed, and fellings occurred across 18.8% of the catchment. Fellings increased nitrogen compound concentrations and export, with effects persisting for four-five years. Runoff patterns strongly controlled the export of total nitrogen, calcium, and dissolved organic carbon. The onset of fellings and higher felling intensities raised total suspended solids levels, though high variability masked statistical significance. Calcium and potassium concentrations also increased during periods of more intense felling, though their export patterns closely followed runoff dynamics. Road construction increased calcium and total suspended solids concentrations.
Climate change is shifting the suitable habitats for many tree species northwards. Large parts of southern Sweden are projected to become unsuitable for Norway spruce by the end of this century. With the majority of forests in Sweden under management, spruce plays an important role, both economically and in natural ecosystems. Despite its significance, there is limited understanding of whether current trends in spruce prevalence align with the projected changes in habitat suitability. In this study, we addressed this gap by analysing projected range shifts for Norway spruce between 2005 and 2095 under two climatic scenarios (RCPs) and compared them with long-term forest inventory data. Our results show that: (1) In southern Sweden (G & ouml;taland), large parts (59.1% for RCP 4.5 and 85.7% for RCP 8.5) of current spruce stands (as by 2005), are projected to fall into areas unsuitable for spruce by 2095. (2) Observed trends in growing stock between 2005 and 2020 are often opposite to those projected for changes in suitability, though trends varied between counties. (3) The growing stock of young trees is increasing across all regions. Combined, these results show a clear mismatch between projected spruce habitat suitability under climate change and current management practices.
Vegetation Optical Depth (VOD) data, derived from satellite microwave observations, are sensitive to above-ground biomass (AGB) and vegetation water content. While VOD is extensively used for global AGB estimation, its relationship with forest structural attributes in boreal forests remains inadequately understood, particularly during the growing season. This study explores the dependencies between forest structural attributes, including height, basal area, volume, Leaf area index, and AGB, and L- and X-band VOD during the growing season in boreal forests in Finland and Sweden. The analysis revealed that L-VOD values increased with increasing values of height, basal area, volume, and LAI (R = 0.37-0.55); conversely, X-VOD values did not exhibit a significant relationship within our study area. Our study revealed a weak to moderate relationship between forest structure and VOD within managed boreal forests. Additionally, the sensitivity of the relationship between VOD and forest structural attributes varied between summer months, with the strongest correlations observed in June for L- and X-VOD. Both VOD bands showed variability beyond the explanatory capacity of forest structural attributes, including AGB. This consideration should be taken into account when developing AGB products for boreal forests and using L- and X-band VOD datasets.
Mixed forests are expected to be highly productive carbon (C) sequestering ecosystems. The study reports the effect of stand age on net ecosystem production (NEP) in a hemiboreal mixed forest chronosequence composed of silver birch and Norway spruce. The biometric C budgeting method was applied in seven chronosequence mixed stands aged between 20 and 70 years. Average NEP across the studied development classes ranged from 3.8 to 5.3 tC ha-1 yr-1. The highest value of NEP, 7 tC ha-1 yr-1, was estimated for a 30-year-old middle-aged stand. The main driver shaping the annual NEP of the stands along the successional gradient was the net primary production (NPP) of trees, while the contribution of the ground vegetation was minor. Annual cumulative soil heterotrophic respiration (Rh) varied between 4.1 and 5.5 tC ha-1, irrespective of stand age. Birches produced the major share (61%) of the annual aboveground litter input to the soil while the belowground C input through fine root production was largely formed of spruces (63%). The studied birch-spruce mixed stands on fertile soils acted as strong C sinks. Still compared to the literature data for corresponding pure stands, no overyielding effect of mixed stands was revealed.
Stand biomass in boreal forests has gained recognition for its crucial role in carbon cycling. While stand biomass is influenced by multiple factors, including stand age, tree species, and site fertility, stand age is often considered the most important factor. Most research has focused on conifer stands, with limited attention to foliage biomass and belowground biomass in peatland sites dominated by deciduous tree species. This study examined foliage and coarse root biomass allocation in three downy birch (Betula pubescens Ehrh.) stands on drained peatland sites in Central Finland. The stands represented three developmental classes: young (10 years), middle-aged (50 years), and mature (80 years). Results showed that foliage biomass ranged from 0.7 t ha-(1) to 6.6 t ha-(1)(1), peaking in the middle-aged stand compared to the young and mature stands. Additionally, coarse root biomass in the 0-50 cm peat layer totaled 0.45 t ha-(1), 2.50 t ha-(1), and 1.10 t ha-(1) for the young, middle-aged, and mature stands, respectively, with 77% occurring in the top 20 cm layer. These findings enhance our understanding of biomass allocation patterns, particularly foliage biomass, over time and their impact on litter inputs into the soil.
The ash dieback epidemic spreading across Europe has created an urgent need to propagate ash (Fraxinus excelsior) trees with demonstrable resistance to the disease, both to support restoration of ash populations in the landscape and to advance research. Seed propagation remains the most effective approach to preserve the high genetic diversity of F. excelsior populations. It ensures the retention of genetic variation critical for long-term adaptability to environmental change. We employed an embryo extraction technique originally developed by Raquin et al. ([2002]. Rapid seedling obtaining from European ash species Fraxinus excelsior (L.) and Fraxinus angustifolia (Vahl.). Ann For Sci. 59:219-224. https://doi.org/10.1051/forest:2002009), which we adapted to retain high germination rates using a simplified protocol. Our findings are primarily observational, aimed at demonstrating the practicality and effectiveness of the adapted method. We compare our experience with the original protocol and highlight the improvements in efficiency. Additionally, we propose that this simplified technique could be adopted by conservation volunteers and other non-specialists to support local efforts in growing genetically diverse ash populations for restoration projects.
This study examines the market acceptance of timber construction in Finland by identifying and evaluating key opportunities and challenges influencing its adoption. Positioned within the broader transition to sustainable building practices, timber offers environmental and esthetic advantages but faces regulatory, economic, and technical barriers. Using a two-phase methodology, literature review and empirical stakeholder survey, the study applies an assessment framework, the Timber Construction Evaluation Number, adapted from Failure Mode and Effects Analysis and reports uncertainty-aware rankings and consensus assessment. Survey responses from 34 industry professionals were used to prioritize eight challenges and eight opportunities across three dimensions: impact, frequency, and feasibility. The findings reveal that the most critical barriers were lack of knowledge and expertise in multi-storey timber construction and compliance with regulations and fire safety concerns. The most prominent opportunities were esthetic and comfort appeal of timber and its environmental sustainability traits. Findings are offered as contextual prioritization for decision support rather than population generalization.
