Annals of Forest Research is a semestrial open access journal, which publishes research articles and notes and critical review papers. Articles are peer-reviewed and should be original, of high scientific quality and of international interest. The journal scope is to cover aspects of both basic and applied research of all domain of forestry sciences and other related sciences, which contribute to forest sustainable management.
"Marin Drăcea" National Research-Development Institute in Forestry
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A case study on forest practitioners' perspectives on climate extremes: consensus on impacts and conflicts in responses
Climate extremes present significant challenges to the German forestry sector, impacting forest ecosystems, biodiversity, and overall forest health. This study examines the perspectives of forest practitioners regarding the impacts of climate extremes, such as drought, heat waves, storms, and heavy rainfall, as well as their proposed responses and potential conflicts. Utilizing a transdisciplinary approach, semi-structured interviews were conducted with 28 forest practitioners. The findings reveal that over 89% of practitioners acknowledge drought as the most significant climate extreme affecting forests, highlighting its detrimental impacts on tree health and forest ecosystems. Drought-related damage since 2018 has also resulted in significant economic losses and necessitates large-scale reforestation. Notably, two divergent management approaches were identified: those prioritizing wood production (FWP) tend to focus on economic viability and timber management strategies, while those emphasizing protection and recreation (FPR) concentrate on ecological sustainability and biodiversity conservation. There is a broad consensus on the impacts of climate change, but responses remain contested. Both groups agree on the importance of promoting mixed, multi-layered forest stands to enhance resilience to climate extremes. However, important differences remain: the FWP group advocates active interventions and favors conifer species such as spruce for economic reasons, while the FPR group emphasizes natural processes and prefers native species like beech. Although climate adaptation serves as a shared rationale, their underlying priorities differ considerably. These insights underscore the need for integrating diverse perspectives in forest management to effectively address the complexities of climate change, facilitating collaborative approaches that address both economic aspects and environmental co-benefits through integrated forest management.
forest management, resilience, stakeholder engagement, adaptive strategies, climate extremes, drought, storms, transdisciplinarity, sustainable forestry
Copyright (c) 2025 Annals of Forest Research
Sentinel-2 and environmental data as predictors of the spatiotemporal dynamics of bark beetle (Coleoptera: Scolytinae) - induced tree mortality in natural spruce forests
Biotic and abiotic disturbances affect forest ecosystems. Unlike sudden disturbances, bark beetle outbreaks are a gradual process. Bark beetle outbreak triggered by windstorm in Norway spruce (Picea abies) forests was analysed over a 6-year period (2016-2021) in mountainous conditions (890-2,100 m a.s.l.) with deep valleys and high ridges. The disturbance extent and dynamics were assessed via remote sensing (Sentinel-2 imagery) using a supervised maximum likelihood classification. Topographical variables, bark beetle-related spatial metrics and spectral indices were assessed for predictor importance for their influence on bark beetle-caused disturbance dynamics by boosted regression trees. The overall accuracy of the classification ranged from 87-92% (Kappa 0.84-0.89). Bark beetle spots were initiated mainly at relatively high altitudes and preferentially on exposed terrain. Spectral indices, such as the red-edge normalized difference vegetation index (RENDVI), played a consistent role across various years in predicting spot initiation. With respect to the spread of bark beetle spots, distance emerged as the most influential predictor across all years. Additionally, elevation and RENDVI had notable impacts on spot spreading. In the case of bark beetle spot initialization, the importance of different factors varied among years whereas for spot spreading distance was the most influential for each year.
Sentinel-2, bark beetle, disturbances, Ips typographus, Norway spruce, Picea abies
Mapping the monetary value of forest-based recreation: a case study in the Italian Carnic Prealps
In the last decades, ecosystem services are increasingly of interest to the scientific community and policy makers, due to their ability to improve people's physical and mental well-being. To better target forest management interventions, it is important to assign a spatially explicit monetary value to ecosystem services provided by forests. This study aims to defined a procedure to assess and map the monetary values of outdoor recreational in a case study in the north-east of Italy (Cansiglio Orientale forest). For that purpose, a zonal Travel Cost Method and a spatial analysis were implemented in order to map the outdoor recreation value in different forest areas. During the summer 2023, 118 questionnaires were collected through face-to-face administration on the site. The results showed an annual consumer surplus of 13,961,789 € that corresponds to 15.36 € per visit per person. According to the spatial analysis, accommodation facilities, points of interest, and roads and paths network are the elements that most affect the distribution of the outdoor recreation value.
ecosystem services; user perception; economic value; spatial analysis; Cansiglio Orientale forest (Italy)
Development of acorn discrimination model for warm-temperature evergreen oaks using hyperspectral analysis
We used hyperspectral analysis to distinguish between acorns of Japanese red oak (Quercus acuta Thunb.) and ring-cup oak (Quercus glauca Thunb.), two closely related species of the evergreen oaks. To accomplish this, 631 Japanese red oak acorns and 505 ring-cupped oak acorns were collected from the seed orchard in Jeju Island, Korea, and hyperspectral imaging was performed. Two types of hyperspectral devices, Corning and Korea Spectral Products (KSP), were used to calibrate images and extract regions of interest. Average spectra were obtained from the extracted regions of interest, and morphological variables were added to the Corning data to form a dataset. Partial least square (PLS) was used as the learning model, Standard normal variate, Multiplicative scatter correction, and Savitzky-Golay filtering were applied as preprocessing techniques, and competitive adaptive reweighted sampling and successive projection algorithm were applied as variable selection techniques ; and the combination of preprocessing method, the number of PLS components, and the number of selected variables were optimized.. The lightweight model was generated from the selected variables, and the performance was improved by combining the morphological variables. As a result, the lightweight model based on Corning dataset showed 45~85% accuracy, and the lightweight model based on the KSP dataset showed 75~90% accuracy. The model utilizing morphological variables in the Corning-based lightweight model showed a high accuracy of 98-100%, so we were able to discriminate the acorns of evergreen oaks between Q. acuta and Q. glauca. The results of this study are expected to serve as a basis for future model development for seed classification of hybrid oak acorns.
hyperspectral analysis; seed identification; variable selection; evergreen oak; species classification
Field assessment of synthetic attractants and traps for the cerambycid beetles Tetropium castaneum L. and Tetropium fuscum (F.) in the Eastern Carpathians, Romania
Tetropium species, significant forest pests in some countries, are expected to pose an even more significant threat in the context of climate change and biological invasions. The potential impact is substantial, making detecting their presence and monitoring their populations crucial. The research presented in the paper aimed to test the response of adults of Tetropium castaneum (Linnaeus,1758) and Tetropium fuscum (Fabricius, 1787) to synthetic attractants similar to those used in other countries (two experiments) and to verify the effectiveness of three types of traps in their capture (one experiment). The experiments were conducted in six freshly clear-cutting areas located in spruce or mixed stands in the northern part of the Eastern Carpathians. In the first two experiments, carried out between 2015 and 2016, we investigated the response to fuscumol, both alone and in combination with host tree volatiles (monoterpenes and ethanol) released at different rates. We also tested a combination of (-)-alpha-pinene, ethanol, and aggregative pheromone of Ips typographus (C.Linnaues, 1758). Barrier traps were used in these initial experiments. The third experiment, conducted in 2017, evaluated the effectiveness of Crosstrap, Barrier, and MultiWit traps, all baited with lures of fuscumol, (-)-alpha-pinene, and ethanol. Numerous specimens of both species were caught in all experiments, namely 7,824-10,466 T. castaneum and 1,041-1,215 T. fuscum. The sex ratio (M/F) varied from 1:1.02 to 1.36:1 for the first species and from 1:1.03 to 1.55:1 for the second. All the baits tested were found to be significantly attractive to the adults of both species. The differences in average catches recorded in traps baited with fuscumol or combinations of attractants were statistically significant compared to those in unbaited traps. Additionally, the catches from traps baited with fuscumol and host volatiles differed significantly from those baited with fuscumol alone. However, there were no significant differences in the average catches of traps baited only with fuscumol compared to those baited with (-)-alpha-pinene, ethanol, and synthetic I. typographus pheromone. Baits containing fuscumol primarily attracted female insects, but when baits with host volatiles were added to those containing fuscumol, the proportion of males in the total catches increased. The Crosstrap and Barrier traps captured significantly more specimens of T. castaneum and T. fuscum than the MultiWit traps, with capture rates 3.20 to 5.57 times higher for T. castaneum and 4.81 to 8.56 times higher for T. fuscum. However, the differences between the Crosstrap and Barrier traps were not statistically significant. Fuscumol baits, whether used independently or alongside host tree volatiles, demonstrate significant attractiveness to beetles of both Tetropium species in Romania. Adding monoterpenes and ethanol lures creates a powerful synergistic effect, remarkably enhancing the allure of fuscumol, particularly for T. fuscum compared to T. castaneum. Moreover, a combination of (-)-alpha-pinene, ethanol, and aggregative pheromone of Ips typographus matches the attractiveness of fuscumol lures, making it an effective alternative. For effective detection and monitoring of Tetropium native or exotic species, fuscumol lures in conjunction with host volatile baits and Crosstrap or Barrier traps are recommended. This approach improves population monitoring and ensures reliable results.
black spruce beetle, brown spruce longhorn beetle, fuscumol, (-)-alpha-pinene, monoterpenes, ethanol, Ips typographus aggregation pheromone, Crosstrap, Barrier trap, MultiWit trap.
Fertility variability among clones and genetic diversity of seed crops at seed orchards of Chamaecyparis obtusa in South Korea
Chamaecyparis obtusa (Siebold & Zucc.) Endl., commonly known as Japanese cypress or hinoki cypress, is widely cultivated for its high-quality timber and ornamental use. Despite its economic and ecological importance, the species faces challenges in adapting to various climates, necessitating the distribution of high-quality seeds and seedlings. This study aims to enhance the genetic improvement and stability of seed production by analyzing fertility characteristics and genetic traits from two clonal seed orchards of C. obtusa in two locations (Gochang and Seogwipo), South Korea. We examined patterns of strobilus and cone production from 2020 to 2022, assessed effective parent numbers, genetic diversity, and heritability estimates, and analyzed parental contribution for the reproductive traits. Results indicated significant annual variation in strobilus and cone production among clones, with higher male fertility variance than female parents. The effective parent number and genetic diversity were generally maintained sustainably, though Seogwipo showed slightly lower diversity. The study underscores the need for management practices to balance clonal contributions, and sustain long-term productivity and genetic diversity in the seed orchards of C. obtusa. Future research should focus on understanding environmental influences on clonal contributions and refining selection criteria for superior clones in the advanced generation breeding program.
Japanese cypress, gene diversity, fertility variation, genetic parameter, effective parent number, cone production
Structural features of Peleș Park Forest: managing for ecosystem services provision
The Peleș Park Forest (PPF), a semi-natural peri-urban forest near Sinaia, Romania, is essential in providing ecological benefits and improving human well-being through recreation. As the urban population grows and stress-related health problems increase, green spaces are increasingly recognised for their restorative functions, including air purification, temperature regulation and mental health improvement. This study aims to develop a sustainable management framework that reconciles forest conservation with recreational value use by assessing forest structure, evaluating tourism-related stressors, and proposing adaptive management strategies. We assessed forest structure through tree diameter, height, volume, and crown health measurements, applying principal component analysis (PCA) to identify the main structural drivers. The results revealed a strong correlation between tree diameter and height, modulated by species composition and site conditions. They showed pronounced crown defoliation in the upper canopy layers, particularly among trees of lower wood quality. The findings suggest that uneven-aged stand structures, which support biodiversity and ecological resilience, are subject to tourism-related pressures such as soil compaction and vegetation damage.
Forest Park, ecological functions, recreational value, forest structure, sustainable management.
Tree stem mean diameter reduction factor prediction through advanced modeling approaches
Sustainable management of natural resources relies on accurate modelling of forest attributes to prevent degradation. This study explores advanced modelling techniques, including Artificial Neural Networks (ANN) and Support Vector Regression (SVR), for estimating the mean stem diameter reduction factor (taper) of standing fir trees (Abies x borisii-regis Matff.). These methods are compared against traditional non-linear regression model (NLR), developed using the Levenberg-Marquardt optimization algorithm. The ANN models employ cascade correlation, generalized regression, and Bayesian regularization back-propagation architectures, while the ε-SVR approach is assessed for its robustness. The results show that support vector regression (ε-SVR) achieved the lowest relative errors in model fitting, improving by 0.60% over cascade correlation and generalized regression and by 0.67% over Bayesian regularization. Regarding generalization ability, the ε-SVR model performed best, with a relative error of 4.90%, which was slightly lower than cascade correlation (by 0.1%), generalized regression (by 0.01%), and Bayesian regularization (by 0.04%). A comparative analysis between machine learning approaches and standard regression revealed that the ε-SVR model had the lowest mean error (0.0715), while the non-linear regression (NLR) model showed a higher mean error of 0.0955, which means 1.35 times greater. These findings highlight the strong capability of machine learning methods in accurately estimating and predicting the diameter reduction factor of trees, effectively capturing its non-linear behaviour compared to traditional regression models. Overall, this study underscores the potential of advanced machine learning techniques to enhance accuracy and adaptability in sustainable forest management.
mean diameter reduction factor, cascade correlation, generalized regression, Bayesian regularization, support vector regression
The inevitable role of the oil market: Does its price really matter for forestry investment in China?
Delving into the intricate roles of oil prices holds the key to attaining sustainable growth of forestry investment in China. Utilising the full- and sub-sample approaches, this article aims to reveal the dynamically evolving relationships between oil price (OP) and forest investment (FI) in China. The quantitative outcomes underscore the complex interplay between OP and FI, highlighting favourable and unfavourable impacts. Notably, the findings indicate that a substantial surge in oil prices could potentially pose obstacles to forestry investment in China, whereas a decline in OP could serve as a stimulus. Nevertheless, it is imperative to acknowledge that this inference is not uniformly applicable when the effect turns positive, primarily influenced by sluggish economic conditions resulting from the global trade wars. Conversely, FI positively influences OP, underscoring that the decline in forestry investment in China could drive down oil prices through psychological and environmental factors. Amid escalating economic and energy uncertainties globally, essential policy suggestions will be proffered to China, aiming to ensure the robust development of the oil market and forestry investment.
Copyright (c) 2024 Annals of Forest Research
Investigation of the effects of tree species on air quality using i-Tree software: A case study in California
The USDA Forest Service has developed a unique software and tree modelling suite called i-Tree. Several of its instruments are capable of exploring the benefits of trees and forests for pollution mitigation, reduction of storm water runoff, carbon sequestration and storage. However, the system remains underutilized for investigating the effects of trees on air quality. In this study, counties in California (CA), United States, were selected using the i-Tree Landscape tool. Next, several characteristics including land cover details, forest details, population, air quality, carbon sequestration capacity, and air pollution removal capacity, were investigated. When considering the air quality situation in these counties, O3 and PM2.5 are the primary pollutants. The planting prioritization map of California was created based on population density, tree cover, plantable space, average PM2.5 and O3 concentration values, and the counties with the highest planting priority were selected using i-Tree Planting tool. Using this instrument, a case study on the modelling of the removal performances of these air pollutants by multiple new species (Turkey oak, Siberian elm, European hackberry, European white elm, Common ash, European silver birch, Velvet ash, Black alder, Bigleaf linden) in priority areas was conducted. The most effective modelled tree species in the area was found to be Turkey oak for its effects in improving air quality in general and O3 in particular. When compared to the effects of modelled trees, the effects of the existing public trees in California were determined to have a comparatively minor impact.
Ecological species groups and interspecific associations of dominant woody species in a seasonal tropical forest of Laos
The study of ecological species groups (ESGs) and interspecific interactions offers important insights into the mechanisms that drive tree species coexistence and enhances our understanding of plant community structure, function, and taxonomy. This study aimed to identify ESGs within a seasonal tropical forest in Phou Khao Khouay National Park, located in central Laos, and to investigate the key environmental factors influencing their distribution. Additionally, the study analysed community stability and interspecific associations among woody species using various statistical techniques, including Variance Ratio (VR), chi-squared tests, Association Coefficients (AC), and percentage of Co-occurrence (PC). To collect data, thirty-two permanent plots, each covering an area of 2500 m² (50 × 50 m), were established. In each plot, floristic data and species abundance were recorded, along with soil samples from two depths (0–10 cm and 10–20 cm) for physicochemical analysis. Vegetation data were classified using Two-Way Indicator Species Analysis (TWINSPAN), and differences between ESGs were evaluated using Analysis of Variance (ANOVA). Indicator Species Analysis (ISA) was applied to identify key species for each ESG, while Canonical Correspondence Analysis (CCA) was employed to explore the relationships between ESGs and environmental variables. The results revealed that the woody plant communities in the study area were relatively stable, exhibiting predominantly positive interspecific associations. Additionally, the distribution of the fosur identified ESGs showed a strong correlation with topographical factors – such as elevation, aspect, and slope – and soil properties, including pH, organic matter content, cation exchange capacity, total nitrogen, phosphorus, potassium, and soil texture. These findings underscore the importance of recognizing microhabitats that support the growth and conservation of woody plant species in Phou Khao Khouay National Park, offering valuable insights for future ecological research and conservation initiatives.
Tradeoffs and limitations in determining tree characteristics using 3D pointclouds from terrestrial laser scanning: A comparison of reconstruction algorithms on European bech (Fagus sylvatica L.) trees
Terrestrial laser scanning (TLS) has quickly gained momentum in forestry as a fast and nondestructive alternative to determine tree shape and volume. Determining tree shape and volume is fundamental for a wide range of forestry applications, including the estimation of carbon stock and development of volume and biomass allometric models. However, tree shape and volume are often determined from TLS data based on different available algorithms, with direct implications on the measured tree feature. In this study we compared several algorithms for tree reconstruction from TLS data, with respect to their capacity to accurately determine tree characteristics such as diameter at breast height (DBH), tree height (H), stem volume (Vst) and total aboveground tree volume (Vtot). The following algorithms were compared using Bland-Altman limits of agreement (LoA): (i) TreeQSM, (ii) 3D Forest, (iii) RANSAC and (iv) Poisson. The data used for the comparison was collected from 10 sample plots, totalizing 40 European beech (Fagus sylvatica L.) trees, covering a DBH range from 6.2 cm to 76.0 cm and H range from 9.5 m to 36.2 m. The results showed that the algorithm used to analyse the TLS data affected notably the tree characteristics. The LoA were up to 3.65 m? for Vtot, up to 7.5 cm for DBH and up to 1.1 m for H, suggesting a rather weak agreement between algorithms. From our comparison, TreeQSM emerged as the most reliable algorithm for comprehensive trait reconstruction, while Poisson was well suited for stem volume estimation. Moreover, determining H seems to be less affected by the algorithm selection compared to DBH. Our findings raise awareness about algorithm selection in TLS data processing and highlight the importance of selecting an appropriate algorithm to meet the specific objective when using TLS to determine tree shape and volume.
The importance of standing deadwood in white-backed woodpecker (Dendrocopos leucotos) habitat from deciduous forests in central Romania
The white-backed woodpecker (Dendrocopos leucotos) is one of the bird species which depends on dead and dying trees as their most important habitat resource. Because of this, it is affected by forest management that removes deadwood and changes the structure of old stands. In Romania, its relations with the structures of forests with and without management, including standing deadwood, are not known. The main objectives of this study were the analysis of the most representative elements of snags in its specific habitat – mainly beech forest in low mountains from central Romania. Based on the presence-absence of species, by applying the standard woodpeckers monitoring protocol using a total of 25 fixed points we compared deadwood variables (snag density, volume, basal area) for the entire study area, regardless of forest structure and management, and for stands over 70 years old, as potentially suitable or optimum habitat for the species. The comparison between plots with and without analysed species shows several significant differences especially regarding the number of snags, volume and basal area mainly for stands older than 70 years. The PCA of the variables for the trees with a DBH > 10 cm explained 74.4% of the variance, but for the very large trees (DBH > 40 cm) this percent is the highest one (89.9%). At the same time, the values of several variables (e.g. snag volume, basal area) are similar or higher than those in various areas of Europe. As a main conclusion, these forests are suitable or optimal for white-backed woodpecker and the Romanian forest management can be considered "closer-to-nature" at least for beech stands but for maintaining and improving the species typical habitat structure a few conservation measures should be applied in addition.
Plant species richness and conservation status of protected and unprotected areas of Kohat District, Northern Pakistan
Kohat, located in northern Pakistan, holds ecological importance due to its distinct climate, diverse vegetation, and conservation concerns. This study hypothesizes that protected areas exhibit higher plant diversity and biomass than unprotected areas, primarily due to the impact of protection measures on domestic and wild animal activities. We assessed the abundance and diversity of native vegetation across 25 plots in protected and unprotected areas. Our findings revealed 67 native plant species, including 39 herbs, 18 shrubs, and 10 trees. Key tree species such as Grewia opptiva, Vachellia nilotica, and Senegalia modesta demonstrated higher basal areas in protected areas. In contrast, shrub species like Rhazya stricta, Withania coagulans, and Gymnosporia royleana exhibited higher densities in these areas. Species of conservation concern, such as critically endangered W. coagulans and nearly threatened G. royleana, were more prevalent in protected areas, suggesting the effectiveness of conservation measures. Additionally, locally important and consumable medicinal plant species, including Ajuga bracteosa, Amaranthus viridis, Peganum harmala, Sonchus arvensis, and Zygophyllum indicum revealed substantial abundance, richness, and distribution within protected areas. In conclusion, the study indicates that conservation measures, particularly protected areas, play a crucial role in safeguarding and preserving native plant communities and enhancing species richness.
plant diversity, medicinal plants, forest restoration, vegetation assessment, threatened species, semiarid climates
Diallel crossing (10x10) in Swiss stone pine. Juvenile-adult correlations and genetic gain for predicting forward selection
Swiss stone pine (Pinus cembra) is a viable solution for afforestation in the high mountain zone, at the upper limit of the forests, due to the species adaptation ability to the limiting climatic conditions. The aim of this study was to analyse the genetic variability, inheritance rate and juvenile-adult correlations, in a 26 years full-sib (10x10 complete mating design) trial, in order to predict the genetic gain of forward selection. In the spring of 2023, measurements and evaluations were carried out for all the existing trees, for Survival rate (Sr), growth (Diameter as breast height- Dbh, Trees' height- Th, Trees' volume- Tv) and quality traits (Forks, stem slenderness- Ss, branches' diameter- Bd, branches' finesse- Bf, defoliation- Def). The 90 cross-pollinated (CP) families registered 50% of Sr whereas the other 10 selfcross-pollinated (consanguineous) registered just 11% of Sr, and the majority of those trees are dominated and face extinction in the next years. Juvenile-adult correlations were highly significant (p<0.001), indicating that early selection (at the age of 14 years) might be efficient. At the trial age, based on the medium to high heritabilities, the forward selection of the best 10% individual trees from the top 20 of the 90 CP families, for Dbh, could be applied, which ensure at least 9.2% of genetic gain.
Comparing efficiency, timing and costs of different walking paths in HMLS LIDAR survey
The technological innovation of terrestrial LIDAR systems has recently given forest planners greater access to key features on forest structure. The Hand Held Mobile Laser Scanner (HMLS) is a recently developed LIDAR tool that is particularly user-friendly and reliable. It is especially useful in the mapping of forest stands, thanks to its implementation of the Simultaneous Location and Mapping Algorithms (SLAM) algorithm. Thus, the present study investigates the ideal walking path to follow during HMLS scanning to survey trees and estimates the biometric parameters of forest stands by testing three distinct schemes. Specifically, two different forest ecosystems are considered in experimental HMLS LIDAR surveys, a beech-dominated deciduous forest and an oak-dominated deciduous forest. Finally, a cost/benefit analysis of each laser survey is analysed according to three walking path models (STAR, GRID, BORDER). A control analysis is also performed of the traditional method without LIDAR. This study contributes to the advancement of a growing body of research on Precision Forestry by considering different characteristics of the forest environment. Regarding practical application, the resulting evaluation of field survey technology can help foresters integrate these techniques into their basic tool kit for forest planning and management processes.
Exploring the association between adaptive and growth traits and within-individual genetic diversity in common beech (Fagus sylvatica)
Common beech (Fagus sylvatica L.) is one of Europe's most widespread forest tree species. In the actual context of climate change, this species has responded through its self-regulation mechanisms, proving a high plasticity. It is important to explore the specific mechanisms driving its response to climate change, taking into account silvicultural, phenological, and genetic perspectives and their interaction. Here, we tested for association between adaptive and growth traits and within-individual genetic diversity measured as individual heterozygosity (proportion of heterozygous loci per sampled individual), based on six genomic microsatellite markers (gSSRs, genomic simple sequence repeats) and six expressed sequence tag microsatellites (EST-SSRs) for 55 beech trees. We evaluated the spring and autumn phenology of beech trees sampled along an altitudinal gradient (560 - 1150 m) and the architectural traits using a non-destructive terrestrial laser scanning method (TLS). The effect of stand density at the onset of the growing season was evaluated by quantifying the competition through the Hegyi index. The onset of bud burst and senescence, as well as the length of the growing season, varied significantly and inversely proportionally with the altitudinal gradient. There was a difference of 14 days between the individuals located at the extremities of the altitudinal gradient in the onset of bud burst, 15 days in the onset of senescence, and 30 days in the length of the growing season. We obtained a very significant and positive correlation between altitude and bud burst and a very significant but negative one between altitude and the length of the growing season. An increase in tree competition directly implied a decrease in DBH and crown dimensions, especially by neighbours closer than 4 m. Stem's slenderness significantly increased with higher competition. Our results revealed a positive relationship between individual heterozygosity and the length of the growing season, as well as with the trunk volume and DBH. Higher individual heterozygosity was associated with a longer growing season, and a precocious onset of bud burst in beech. Higher heterozygosity was also associated with considerably higher total tree biomass. The genetic diversity was inversely proportional to stem forking. TLS shows great potential in extracting beech tree biomass indicators, but we still recommend using the conventional method as a complementary method for data validation, although it is time-consuming.
Prioritizing conservation areas based on contributions to rarity and beta diversity in Mediterranean forest ecosystems in Türkiye
The depletion of forest biodiversity arising from insufficient conservation of resources due to wood extraction, overgrazing, fire, and land use presents a significant challenge in the Mediterranean region. It becomes crucial to identify priority conservation areas for safeguarding biodiversity. We used plant species data taken from 800 plots in the Kuyucak mountain district, a typical Mediterranean forest ecosystem in Türkiye and maps of seven potential environmental predictors: elevation, aspect, slope, head index, topographical position index, landform characteristics, and bedrock geology. To assign priority areas for the conservation, local contribution to beta diversity (LCBD) and relative contribution to total rarity (RIRR) were examined with community metrics and environmental predictors, respectively. Correlation results showed that LCBD was positively related to rare species richness but negatively related to common species richness. RIRR was significantly associated with all the community metrics. According to the results of Random Forest regression models, elevation was the most important variable of LCBD, followed by slope, heat index, and pebblestone. For RIRR, the most contributed variables were elevation, heat index, limestone, and slope, respectively. The LCBD and RIRR Random Forest regression models were extrapolated along the Kuyucak mountain district, resulting in the creation of potential distribution maps for both LCBD and RIRR. Subsequently, from these maps, two distinct conservation value maps have been developed for the Kuyucak mountain district based on four conservation priority classes (Priority Class 1, Priority Class 2, Priority Class 3, and Priority Class 4): one employing a conservation cost approach and the other applying an ecology-centered approach. The results suggest that areas with elevated values of both LCBD and RIRR values are primarily situated below 1100 m on steep valley slopes, characterized by the presence of karstic limestone and intricate terrain. Compared to other areas, prioritizing the protection of such areas can provide greater benefits in contributing to ecological uniqueness. Keywords: Community rarity, Species contributions to beta diversity, Conservation priority, Ecological uniqueness, Indicator species analysis, Machine learning
Effect of Polyethylene glycol, temperature, and stratification in thirty plant species: Implications for conservation and management
Seed ecology is a fundamental view of a population's regenerative potential and under climate change needs investigation for proper management and conservation of plant populations. In the Mediterranean basin extreme rainfall variability is expected to prevail during the next decades. The aim of the study is to investigate the germination potential of thirty plant species by placing their seeds under gradients of water potentials with the use of polyethylene glycol, a polymer used to mimic water stress in seeds to assess their adaptive potential. We applied three different osmotic potentials (-0.03 MPa , -0.50 MPa, -1.56 MPa) using PEG6000 in seeds from thirty different plant species. Prior PEG treatment seeds grouped to non-stratified and stratified ones at +2°C for 1 month. Seeds were then germinated under either constant +21°C or alternate +25°C/+15°C temperature with 12-hours photoperiod. Germination was affected by PEG level, stratification and temperature which acted either independently or in combination, and the response to those factors was species specific. Most species that PEG had affected their germination, responded positively in water stress at -0.5 MPa and some of them further increased their seed germination under -1.56 MPa. However, in species where PEG had no effect, their germination response was driven by the other two factors either independently or in combination. Finally, there were also species that presented low germination, unaffected by the studied factors. The present study demonstrates the ability of several Mediterranean species to germinate under various levels of water stress and can be applied to species management and conservation strategies.
Links between tree phenology and wood traits in sessile oak (Quercus petraea (Matt.) Liebl.)
Tree phenology and wood traits are considered of foremost importance in understanding species' responses to the influence of climate change, thus the existence of a link between tree phenology and wood traits has become increasingly appealing in forestry research. The aim of this study was to explore the relationship between leaf flushing and wood traits (basic wood density, tree ring width, tree ring phenology, sapwood width and number of sapwood rings) in sessile oak (Quercus petraea (Matt.) Liebl.). We investigated trees with distinctive phenological behaviour (early flushing and late flushing) from three peripheral populations, one non-peripheral population and one sessile oak comparative trial close to the species eastern distribution range in the Eastern Carpathians. Covariance analysis, partial correlations, nonparametric statistics, and Principal Component Analysis were used to investigate the link between tree phenology, wood density, and some structural metrics. It was statistically confirmed that, at comparable ages and radial growth, the sessile oak trees exhibiting late leaf flushing had lighter basic wood density and greater density differences between sapwood and heartwood than early flushing trees. Independent of age, trees with intermediate flushing have wider rings, the formation of which is much earlier than in early flushing trees. At the same age, late trees from geographically peripheral populations have a higher number of sapwood rings. Also, the results revealed that peripheral populations had lower basic wood density, while this was not the case for peripheral provenances tested in the comparative trail established in an ecologically optimal area. These findings help us enlarge our understanding of the relationship between leaf flushing and wood traits, which could be useful for improving sessile oak management strategies near the eastern limit of the sessile oak natural range, which is becoming more and more critical in the context of the current climate changes.
Physiological and biochemical adjustments of the assimilatory system of advance regeneration of Norway spruce to cutting-induced changes in the environment
Various forestry practices (shelterwood systems, selective felling) promoted for the natural regeneration of Norway spruce can speed up the emergence of the advanced growth. Overstory removal can cause drastic environmental changes, resulting in the death of newly regenerated trees or blocking their growth. We studied changes in the content of photosynthetic pigments, parameters of chlorophyll a fluorescence, activity of antioxidant system enzymes in the needles of 20-year-old advance regeneration of Norway spruce and alteration of xylem radial growth rate in response to abrupt cutting-induced changes in the environment. Cutting led to inhibition of photochemical activity (the maximum photochemical efficiency of PSII (Fv/Fm), quantum yield of photosystem II (Y(II)) and relative electron transport rate (ETR) decreased), rearrangement of the pigment system (the content of chlorophyll a (Chl a) and chlorophyll b (Chl b) decreased, chlorophyll a/b (Chl a/b) ratio increased) and a sharp rise in non-photochemical quenching (NPQ). A year later, after clear-cutting, the needles had adapted to the new conditions. Low NPQ level was associated with increased Chl a content and Chl a/b ratio and upregulation of antioxidant enzymes. The activity of photochemical processes increased (Fv/Fm, Y(II), and ETR) and the radial xylem increment was promoted significantly. When using forestry practices involving overstory removal, it is necessary to consider that light intensity increase, associated reduction of air and soil humidity, as well as an increase in the air temperature, can have a negative effect on advance regeneration of Norway spruce growth after cutting down, effect that is reversed after one year.
reforestation, forest cutting, chlorophyll a fluorescence, photosynthetic pigments, antioxidant enzymes
Variation in strobilus and cone production in clonal seed orchards of Anatolian black pine
Anatolian black pine [Pinus nigra Arnold subsp. pallasiana (Lamb.) Holmboe] is an economically and ecologically important forest tree species with a natural distribution of 4.2 million ha, 32% of which is unproductive due to forest fire and other damages in Turkish forestry. The species is widely used in afforestation and conversion of unproductive forests by deploying genetically improved seed from seed orchards because of high adaptation capability to various environmental conditions, and a target species of national tree breeding programme of Anatolian black pine. Estimated variation in reproductive characters can be used as an important guide for managing of seed orchards. The number of cones, female and male strobili were studied in three seed orchards established in 1991, 1993 and 1985 composed of 30, 30 and 34 clones each. Five grafts of each clone were evaluated from each seed orchard for three consecutive years (2022-2024). This study estimated the variation of broad-sense heritability (H2) and the correlation among cone and strobili production at the graft and clone level. Positive and significant (p<0.05) relations were calculated between female and male strobili within year in all orchards both ramet and clone levels, together with significant (p<0.05) relations among years for cone productions in the orchards. Significant (p<0.05) differences were found for the characters among clones and among years within orchard. Year x clone and clone x ramet interactions were generally significant (p<0.05) for the characters. Female strobili seemed a good predictor for cone production. However, the heritability in broad sense was mostly on average below 0.5 for the characters in each seed orchard except of female strobili in an orchard in year-24. It indicated that the reproductive characters under environmental control, and they could give to reflect to management practices.
clone, genetic variation, heritability, reproductive characters, seed orchards
Estimating canopy and stand structure in hybrid poplar plantations from multispectral UAV imagery
Accurate estimates of canopy structure like canopy cover (CC), Leaf Area Index (LAI), crown volume (Vcr), as well as tree and stand structure like stem volume (V_st) and basal area (G), are considered essential measures to manage poplar plantations effectively as they are correlated with the growth rate and the detection of possible stress. This research exploits the possibility of developing a precision forestry application using an unmanned aerial vehicle (UAV), terrestrial digital camera and traditional field measurements to monitor poplar plantation variables. We set up the procedure using explanatory variables from the Grey Level Co-occurrence Matrix textural metrics (Entropy, Variance, Dissimilarity and Contrast) calculated based on UAV multispectral imagery. Our results show that the GCLM texture derived by multispectral ortomosaic provides adequate explanatory variables to predict poplar plantation characteristics related to plants' canopy and stand structure. The evaluation of the models targeting the different poplar plantation variables (i.e. Vcr, G_ha, Vst_ha, CC and LAI) with the four GLCM explanatory variables (i.e. Entropy, Variance, Dissimilarity and Contrast) consistently higher or equal resulted to R2 ≥0.86.
Vegetation predicts soil shear strength in Arctic Soils: Ground-based and remote sensing techniques
Soil shear strength (SSS) is an important soil attribute that is influenced by vegetation. If aboveground biomass estimates can be used to predict soil shear strength, it would greatly enhance our ability to estimate SSS across large areas. Using data collected from 24 plots in Alaska, we analyzed the relationship between soil shear strength and ground-collected vegetation attributes and remotely sensed (RS) variables. We constructed both univariate and multivariate models to assess the predictive capabilities of the vegetation and RS variables. Total trees and total conifers were significant predictors of SSS, with a negative relationship existing between total trees/total conifers and SSS. Graminoid cover (%) was positively correlated with soil shear strength and was also a significant predictor of SSS. Of the RS variables, the bands B1 (0.443 μm), B2 (0.490 μm), and B3 (0.560 μm) from the Sentinel 2 satellite system were all significant predictors of SSS. A multivariate model improved model fit over the simple univariate models, with an R2 = 0.46. We have both demonstrated a connection between SSS and aboveground vegetation attributes for areas within interior Alaska and that it is possible to link SSS to RS variables using a multivariate model.
Long-term persistence of butterfly diversity in a sustainably managed forest ecosystem
In recent decades, intensification in land use has led to severe losses of biodiversity across major parts of the world. Studies from Central Europe revealed severe decline of insect diversity across agro-environments, but to a lower extent in forest ecosystems. Sedentary specialist species are suffering particularly, while mobile generalist species are much less affected. Numerous species are also disappearing from nature reserves. On the long run, biodiversity presumably can only be maintained in ecosystems of sufficient size, but is lost in small and isolated habitats. In order to test this assumption, we conducted butterfly counts over a period of 20 years in a large, heterogeneous and sustainably used forest ecosystem in southern Germany. We found no significant changes in diversity and abundance over the two decades of study. However, our data revealed a significant shift in species´ community structure over time, with the proportion of generalist species increasing and the proportion of specialist species decreasing. These changes are most likely due to changes in habitat structures. At the beginning of our study, wind-blows resulting from the heavy storms in the late 1990s represented open areas, but subsequently reforested in the wake of natural succession. Since these temporary open habitats had attracted a particularly high number of specialised species, the observed changes are probably due to these natural processes in a forest ecosystem. In general, our results show that heterogeneous ecosystems of large size may preserve a species-rich butterfly community in the long run.
Opportunity to integrate machine management data, soil, terrain and climatic variables to estimate tree harvester and forwarder performance
The Cut-to-Length (CTL) harvesting system is nowadays predominant in the field of mechanized forest operations, consisting mainly in harvesters and forwarders forestry machines. These machines are equipped with an On-Board Computer (OBC) that collects a large amount of information concerning machine parameters such as harvested timber, travelled distance or fuel consumption. Stream machine data are sent to the machine fleet management system (FMS) on cloud, stored and automatically summarized on hourly, daily, weekly, or monthly basis. Understanding the benefits of data mining techniques - in finding trends and patterns - exploiting FMS database in relation to topographic and climatic condition is still an ongoing open research question. The present work aims at verifying if and how machine´s performance indicators (e.g. fuel consumption) recorded and summarized on a hourly basis by the FMS are influenced by site specific parameters, such as terrain morphology, soil type, wet soil condition, and weather conditions, derived from open source portal. A specific methodology in machine data acquisition and datasets implementation has been set in this study. The dataset results in a combination of three sub-datasets, consequently merged, filtered and analyzed. A first sub-dataset is made up of "machine data", a second is made up of "environmental data", and a third set of data is made of "climatic data". The obtained results revealed that the combination of different data sources' provides significant insight into understanding machine performance. Moreover, the integration of terrain morphology and climatic data have direct impact on the machine fuel consumption, harvester machine in particular. However, in order to address specific interactions among variables with greater robustness, further investigations into this project will consider the whole set of variables on a smaller scale (e.g., case study) with higher data resolution.
Fungal diversity in chestnut galls induced by Dryocosmus kuriphilus from Basilicata Region (Southern Italy)
In recent years, the Asian chestnut gall wasp (ACGW) Dryocosmus kuriphilus has been reported to have a high incidence in Italy and other Mediterranean basin countries. In 2021-2022, a study was undertaken in the Basilicata Region (Southern Italy) to investigate the relationship between the galls produced by ACGW on sweet chestnut (Castanea sativa Mill.) and fungal pathogens. In particular, the fungal diversity from green and necrotic galls collected from two important sweet chestnut sites (Melfi and Rionero in Vulture) was investigated. Nineteen fungal taxa were identified based on their morphological and molecular traits. In both localities, the most frequent species isolated from green and necrotic galls were Gnomoniopsis castaneae, Colletotrichum acutatum, and Pestalotiopsis sp. It is essential to understand the role played by the galls as an inoculum source for sweet chestnut fungal pathogens, particularly for G. castaneae, an emerging pathogen of which biology is still poorly understood. Findings from the present study stressed that the complex relationship between host-insect-microbial community needs to be elucidated to be able to control the pathogenic fungi and consequently maintain sweet chestnut trees' health as they play a key role in the local agriculture (horticulture, forestry) and subsidiary economy
Integration of Terrestrial Laser Scanning and field measurements data for tree stem volume estimation: Exploring parametric and non-parametric modeling approaches
Terrestrial laser scanning (TLS) has emerged as a powerful tool for acquiring detailed three-dimensional information about tree species. This study focuses on the development of models for tree volume estimation using TLS data for even aged Fagus sylvatica L. stands located in the western part of the Southern Carpathians, Romania. Both parametric and non-parametric modeling approaches were explored, leveraging variables extracted from TLS point clouds such as diameter at breast height (DBH), height, crown radius, and other relevant crown and height parameters. Reference data were collected through high-precision field measurements across 76 circular Permanent Sample Areas (PSA) spanning 500 m2 each. A multi-scan approach was implemented for TLS data collection, involving four scanning stations within each PSA. Concurrently, parametric (regression equations) and non-parametric (Random Forest - RF) models were applied, leveraging all TLS-derived variables to explore potential enhancements in volume estimation accuracy. Among the parametric models, the most effective performer was the one featuring solely DBH as an input variable. The RF non-parametric model yielded more accurate stem volume estimates (RMSE = 1.52 m3*0.1ha-1; RRMSE = 3.62%; MAE = 1.22m3*0.1ha-1) compared to the best-performing regression model (RMSE = 5.24 m3*0.1ha-1; RRMSE = 12.48%; MAE = 4.28 m3*0.1ha-1). Both types of models identified DBH as the most important predictive variable, while the RF model also included height and crown related parameters among the variables of importance. Results demonstrate the effectiveness of the non-parametric RF model in providing accurate and robust estimates of tree stem volume within even aged European beech stands. This highlights the significance of TLS data, increasingly employed in diverse forest inventory and management applications. Nevertheless, additional research and refinement of the proposed models are needed. This includes thorough validation across various forest ecosystems and continued efforts to enhance the accuracy of tree height determination from point cloud data.
Recreation in suburban forests – monitoring the distribution of visits using the example of Rzeszów
The research aimed to determine the actual distribution of visits in suburban forests in the temperate climate zone, using the Rzeszów metropolitan area as an example. The study also examined whether there is a correlation between the number of visitors to the forests and weather conditions: average daily air temperature, total daily precipitation, and the maximum sustained wind speed within a day. The distribution of visits was determined based on a 365-day monitoring of recreational traffic intensity using a sensor in the form of a pyroelectric detector. Weather data for each day of observation were obtained from a meteorological station. An average of 51 daily visitors was recorded (29 on weekdays and 101 on weekends and holidays). Most people visited the forest during the vacations, in August (14.7%) and July (14.1%), and least in winter: in February (2.7%) and December (3.4%). It was observed that the number of visits to the forest increased with the rise in average daily air temperature. In contrast, as the maximum sustained wind speed increased throughout the day, the number of visits decreased. There was no clear correlation between the number of visits and the total daily rainfall, except for weekends and holidays (number of visits decreased with the increase in rainfall). The number of visitors to suburban forests was more influenced by public holidays than weather conditions. Many forest visitors were significantly more frequently observed on holidays and weekends than weekdays. More than half of all visits occurred on weekends. Forests were most frequently visited on Sundays (38.2%). Suburban forests were visited from 5 AM to 10 PM, with shorter weekend hours (from 6 AM to 8 PM). The results obtained in the study can be valuable for managing recreational activities in suburban forests.
Landscape fragmentation and connectivity as key variables on occurrence of human-wildlife interactions
Human-wildlife interactions (HWI) are one of the most highly studied topics from the fields of wildlife management and are reported to be increasing globally as anthropogenic lands uses expand into wild lands, especially in mountainous areas where forest habitats are in the proximity of human settlements. The upper Prahova Valley in south-central Romania provides habitat to several native charismatic wildlife species. Since 1990 this area has become a major tourist destination now characterized by a high density of major transport infrastructures and homes. To assess how the changes in land use have affected HWIs, from September 2018 to August 2019, we discussed with 370 local citizens from the cities of Sinaia, Bușteni and Predeal. We developed maps of wildlife habitat fragmentation and connectivity and superimposed them over the locations with the HWI hotspots. According to the results, over 50% of the hotspots identified where located in areas exhibiting the greatest level of fragmentation, and the species frequently involved in interactions were the brown bear (Ursus arctos), wild boar (Sus scrofa), and red fox (Vulpes vulpes). The maps suggest that habitat fragmentation could represent a primal cause for the regions' high frequency of animal descents into settlements, since wildlife habitats and ecological corridors are affected by the fragmentation of anthropogenic infrastructures especially in the proximity of major settlements. As a conclusion, our results highlight the need for sustainable landscape planning in order to optimize biodiversity management and diminish interactions between humans and wild animals, based on: a) mapping the areas characterized by high quality wildlife habitats and including them into a system of strict protection, b) developing or enhancing wildlife ecological corridors to favour animal movement between intact ecosystems, and c) regulating the expansion of human infrastructures in the proximity of strictly protected habitats.