Search Results (55)

Diameter at Breast Height (DBH) is a key parameter in forest measurement. However, existing research has mostly focused on improving the accuracy of individual technologies, lacking a systematic synthesis of the evolutionary logic of measurement techniques and a standardized selection framework for forestry applications. To this end, this paper constructs a multi-level classification framework based on measurement platforms and technical principles, establishes for the first time a five-dimensional comprehensive evaluation system (covering accuracy, efficiency, cost, environmental adaptability, and automation) along with a hierarchical technology decision tree, and systematically analyzes the application logic of multi-source fusion technologies across three levels: ground-based, near-ground mobile, and aerial. The review indicates that traditional contact-based measurement has limited efficiency; modern remote sensing technologies (photogrammetry and LiDAR) offer significant advantages in automation and accuracy, but still face challenges such as high equipment costs, complex data processing, and poor environmental adaptability. Multi-source fusion and machine learning are key methods to overcome the limitations of single sensors and improve the robustness of DBH estimation. Finally, it is anticipated that with decreasing sensor costs and the advancement of intelligent algorithms, DBH measurement will continue to evolve toward automation, intelligence, and engineering practicality, providing technical support for large-scale, long-term, and repeatable forest monitoring. Full article

Forest canopy cover is a crucial indicator for measuring ecological functions. However, traditional plot-based measurement methods suffer from low efficiency and insufficient spatial continuity. Addressing issues in UAV RGB imagery—such as tree crown boundary adhesion, shadow interference, and texture confusion—this paper proposes a lightweight and edge-sensitive tree crown segmentation network. The model employs MobileNetV3-Large to replace the traditional U-Net encoder, significantly reducing parameter count and computational load while satisfying the potential for edge device deployment. In the decoding phase, a Semantic-guided Channel Compression and Focus (SCCF) module is designed to enhance semantic-guided channel compression and feature focusing. Furthermore, a Gradient-guided Morphological Tree Crown Attention Module (G-MTCAM) is proposed. By utilizing Gradient-Induced Center Difference Convolution (GI-CDC) and a variance-based statistical gating mechanism, this module constructs a dual-stream architecture for morphology and texture interaction, achieving precise cutting of tree crown boundaries and effective filtering of background noise. Additionally, a boundary-enhanced composite loss function is introduced to improve the accuracy of crown edge identification. Experimental results indicate that the proposed model achieves an IoU, Acc, and F1 score of 88.59%, 88.62%, and 93.77%, respectively. Compared to the classic U-Net, these represent improvements of 2.77%, 1.71%, and 1.44%, while the parameter count and computational cost are only 5.98 M and 6.71 GFLOPs. The forest Canopy Cover (CC) estimated based on the segmentation results shows high consistency with ground-based near-zenith canopy hemispherical percentage ($CH{P}_{0–30}$, denoted as $C{C}_{obs}$), with a correlation coefficient ($R^2$) exceeding 0.90. This verifies the effectiveness of the method in forest canopy structure monitoring and provides technical support for the application of consumer-grade UAVs in forestry surveys. Full article

(1) Since its introduction to China, pine wilt disease (PWD) has caused severe damage to coniferous forests in affected regions. The disease continues to expand northwestward, posing a significant threat to the ecological security of Xinjiang. (2) This study employed the maximum entropy (MaxEnt, version 3.4.4) model to predict potential areas for PWD transmission and suitable habitats for its vector insect, Monochamus saltuarius (Gebler, 1830). By integrating these results, the potential occurrence areas of PWD in Xinjiang were identified. (3) Human activities were the primary drivers of PWD spread, with factors related to scenic areas and overall human influence playing key roles. Altitude and isothermality were the main limiting factors for the vector insect. Potential PWD occurrence areas were identified, covering approximately 88% of the total coniferous forest area in Xinjiang. (4) High-risk regions include Urumqi City, Ili Kazakh Autonomous Prefecture, and Altay Prefecture. This study clarifies potential transmission routes and analyzes high-risk areas, providing a scientific basis for forestry authorities to implement targeted prevention and control measures. Full article

Poplars (Populus L.) are fast-growing, widely distributed trees with high ecological, economic, and climate-mitigation value, making them central to diverse agroforestry systems worldwide. This study presents a comprehensive bibliometric and content-based review of global poplar-based agroforestry research, using Scopus and Web of Science databases and a PRISMA-guided screening process to identify 496 peer-reviewed publications, covering publications from 1987 to 2024. Results show a steady rise in scientific output, with a notable acceleration after 2013, dominated by agriculture, forestry, and environmental sciences, with strong international contributions and research themes focused on productivity, carbon sequestration, biodiversity, and economic viability. A wide range of Populus species and hybrids is employed globally, supporting functions from crop production and soil enhancement to climate mitigation and ecological restoration. Poplar-based systems offer substantial benefits for soil health, biodiversity, and carbon storage, but also involve trade-offs related to tree–crop interactions, such as competition for light reducing understory crop yields in high-density arrangements, management intensity, and regional conditions. Poplars provide a wide array of provisioning, regulating, and supporting ecosystem services, from supplying food, fodder, timber, and biomass to moderating microclimates, protecting soil and water resources, and restoring habitats, while supporting a broad diversity of agricultural and horticultural crops. However, several critical gaps—including a geographic research imbalance, socio-economic and adoption barriers, limited understanding of tree–crop interactions, and insufficient long-term monitoring—continue to constrain widespread adoption and limit the full realization of the potential of poplar-based agroforestry systems. Full article

Eucalyptus plantations have suffered severe damage from scarab grubs in recent years. To investigate the actual scarab species that damage Eucalyptus trees, continuous closed-net monitoring and monthly soil-digging surveys were conducted in Eucalyptus plantations in Lancang County, China, from 2024 to 2025. The primarily affected roots were covered with nylon mesh bags until the insects reached adulthood. A few adults were successfully collected from the damaged roots. The scarab species that infests Eucalyptus trees has been identified as Megistophylla grandicornis (Fairmaire, 1891). It exhibited a single generation annually in local Eucalyptus plantations. Adults emerge from late April to June, and larvae cause damage from July to November. Eucalyptus trees with severely damaged roots exhibit reduced growth vigor and are highly prone to windthrow and death, leading to substantial losses in forestry production. These preliminary results provide foundational data for recognizing Megistophylla grandicornis as a new root pest of Eucalyptus and establishing targeted larval-monitoring protocols in Eucalyptus plantations. Full article

The growing implementation of close-to-nature forestry practices in the management of northern forests, characterized by dispersed harvesting operations, has heightened the importance of minimizing damage to residual stands as a key aspect of sustainable forest management. The objective of this study is to examine and compare the resistance of various tree species and diameter classes to wounds incurred during logging operations of differing sizes, intensities, and locations. In addition, the research aims to assess temporal changes in wound characteristics, including healing and closure processes, across species. This long-term, 18-year investigation was conducted in the Kheyrud Forest, located within the Hyrcanian broadleaf forest region of northern Iran, to evaluate the dynamics of wound healing in residual trees following ground-based skidding operations. Through a comprehensive assessment of 272 wounded trees across six species, we demonstrate that species significantly influences healing ratio (Kruskal–Wallis, p < 0.01), with Oriental beech (Fagus orientalis Lipsky) (50.6%) showing superior recovery compared to the Chestnut-leaved oak (Quercus castaneifolia) (37.5%). Healing ratio decreased with larger diameter at breast height (DBH) (R² = 0.114, p < 0.01), while absolute healed area increased. Larger areas (>1000 cm²) reduced healing by 42.3% versus small wounds (<500 cm²) (R² = 0.417, p < 0.01). Severe wounds (deep gouges) showed 19% less healing than superficial injuries (p = 0.003). Circular wounds healed significantly better than rectangular forms (χ² = 24.92, p < 0.001). Healing ratio accelerated after the first decade, reaching 69% by year 17 (R² = 0.469, p < 0.01). Wound height (p = 0.117) and traffic intensity (p = 0.65) showed no statistical impact. Contrary to expectations, stem position had no significant effect on wound recovery, whereas wound geometry proved to be a critical determinant. The findings highlight that appropriate species selection, minimizing wound size (to less than 500 cm²), and adopting extended cutting cycles (exceeding 15 years) are essential for enhancing residual stand recovery in close-to-nature forestry systems. Full article

Redwood (Sequoia sempervirens (Lamb. ex D. Don) Endl.) is a fast-growing, long-lived conifer native to a narrow coastal zone along the western seaboard of the United States. Redwood can accumulate very high amounts of carbon in plantation settings and continuous cover forestry (CCF) represents a highly profitable option, particularly for small-scale forest growers in the North Island of New Zealand. We evaluated the profitability of conceptual CCF regimes using two case study forests: Blue Mountain (109 ha, Taranaki Region, New Zealand) and Spring Creek (467 ha, Manawatu-Whanganui Region, New Zealand). We ran a strategic harvest scheduling model for both properties and used its results to guide a tactical-spatially explicit model harvesting small 0.7 ha units over a period that spanned 35 to 95 years after planting. The internal rates of return (IRRs) were 9.16 and 10.40% for Blue Mountain and Spring Creek, respectively, exceeding those considered robust for other forest species in New Zealand. The study showed that small owners could benefit from carbon revenue during the first 35 years after planting and then switch to a steady annual income from timber, maintaining a relatively constant carbon stock under a continuous cover forestry regime. Implementing adjacency constraints with a minimum green-up period of five years proved feasible. Although small coupes posed operational problems, which were linked to roading and harvesting, these issues were not insurmountable and could be managed with appropriate operational planning. Full article

Selection forestry sustains timber production and stand structural complexity via partial harvesting. However, regeneration initiated by harvesting may function as fuel ladders, providing pathways for fire to reach the forest canopy. We sought potential mitigation approaches by simulating stand growth and potential wildfire behavior over a century in stands dominated by coast redwood (Sequoia sempervirens (Lamb. ex. D. Don) Endl.) on California’s north coast. We used the fire and fuels extension to the forest vegetation simulator (FFE-FVS) to compare group selection (GS) to single-tree selection silviculture with either low-density (LD) or high-density (HD) retention on a 20-year harvest return interval. These three approaches were paired with six options involving vegetation management (i.e., hardwood control or pre-commercial thinning (PCT)) with and without fuels treatments (i.e., prescribed fire or pile burning), or no subsequent vegetation or fuel treatment applied after GS, HD, or LD silviculture. Fuel treatment involving prescribed fire reduced hazardous fuel loading but lowered stand density and hence productivity. Hardwood control followed by prescribed fire mitigated potential wildfire behavior and promoted dominance of merchantable conifers. PCT of small young trees regenerating after selection harvests, followed by piling and burning of these cut trees, sustained timber production while reducing potential wildfire behavior by approximately 40% relative to selection silviculture without vegetation/fuel management, which exhibited the worst potential wildfire behavior. Full article

Hilly mountainous regions are ecologically complex, featuring diverse environmental ecosystem services (ESs) and intricate interactions. However, the variability, drivers, and management of these ESs remain poorly understood, particularly in regions with significant topographical and climatic heterogeneity. This study focuses on the southern hilly mountain belt of China, examining five key ecosystem services: food production (FP), carbon storage (CS), water yield (WY), habitat quality (HQ), and soil conservation (SC). This study examines these ESs across long-term, pixel, and regional scales, exploring the interactive relationships and identifying the driving factors and cluster characteristics. The results indicate the following: (1) Over the past 23 years, although food production and carbon storage have increased, habitat quality has declined. (2) From a spatial perspective, the differences in trade-offs and synergies across the years are relatively small. However, significant differences are observed when considering continuous temporal change, and trade-off relationships are generally prevalent. Additionally, the distribution of trade-offs and synergies is also influenced by a combination of factors. (3) Climatic, vegetation, topographical, and socioeconomic factors are key factors influencing the distribution and changes in ESs. For instance, climate–vegetation interactions enhance carbon storage and soil conservation. Socioeconomic factors, though less impactful, optimize ESs through land management and policy. (4) We found that the ecological priority region covers the largest area, followed by the hilly agricultural development zone, the mountainous agricultural and forestry development zone, and the integrated ecological security zone. These findings deepen our understanding of ESs in hilly mountainous regions, providing actionable insights for enhancing conservation and sustainable management in complex landscapes. Full article

Retention forestry is the dominant practice in Northern Europe, with large-scale clear-cuts following natural disturbances becoming more frequent as the climate changes. Despite its widespread use, clear-cutting is criticized for its potential adverse effects on species diversity and ecosystem recovery, particularly in understory vegetation. This study examines early vegetation changes after large-scale clear-cutting in Latvia’s hemiboreal forests. The sampling was conducted in 2017 and 2020, three and six years post-harvest, using 210 systematically placed plots (1 × 1 m) to assess species abundance and vegetation cover across moss/lichen, herbaceous, and shrub/tree layers. The findings indicate that species diversity was initially higher following clear-cutting but declined after six years, with the herbaceous layer most affected. While clear-cutting temporarily increases species diversity, negative effects become evident over time. Recovery is prolonged, with succession progressing faster in wet areas. To fully understand the long-term impacts of clear-cutting, continued monitoring is necessary. Full article

Improved forage and living conditions in certain parts of Europe over the past few decades have led to alarming levels of ungulate densities. Consequently, the overabundance of red deer, roe deer, and fallow deer in the Western Plains of Romania has begun to generate issues in the development of young oak stands. In addition to causing damage to the agricultural sector and increasing the risk of vehicle collisions, ungulates are increasing pressure on the forestry sector, mainly through the browsing of young saplings. This study quantifies the levels of ungulate browsing in oak stands using a permanent sample grid of 42 plots in both natural and artificial regeneration areas. A total of 3223 individual saplings were measured, revealing browsing intensities of 49.65% in clearcut systems and 12.8% in continuous forest cover systems. With high ungulate densities identified as the main cause, the Sustainable Population Threshold was calculated using a complex set of indices and compared to the actual numbers of ungulates, both of which were translated into stock unit equivalents. A logistic regression model was developed based on silvicultural and wildlife indices to identify other factors influencing browsing occurrence. The findings indicate that the proportion of forested areas in the hunting ground and the type of silvicultural system are significant factors in the occurrence of browsing. The problem of ungulate overabundance clearly influences forest development, and new solutions should be identified in terms of both forestry and wildlife management. Full article

Forests are the largest terrestrial carbon reservoirs and the most cost-effective carbon sinks. Accurate estimation of forest aboveground biomass (AGB) can significantly reduce uncertainty in carbon stock assessments. However, due to the limitations of timely and reliable forestry surveys, as well as high-resolution remote sensing data, mapping high-resolution and spatially continuous forest AGB remains challenging. The Global Ecosystem Dynamics Investigation (GEDI) is a remote sensing mission led by NASA, aimed at obtaining global forest three-dimensional structural information through LiDAR data, and has become an important tool for estimating forest structural parameters at regional scales. In 2019, the GEDI L4A product was introduced to improve AGB estimation accuracy. Currently, forest AGB maps in China have not been consistently evaluated, and research on biomass at the provincial level is still limited. Moreover, scaling GEDI’s footprint-based data to regional-scale gridded data remains a pressing issue. In this study, to verify the accuracy of GEDI L4A data and the reliability of the filtering parameters, the filtered GEDI L4A data were extracted and validated against airborne data, resulting in a Pearson correlation coefficient ($\rho$) of 0.69 (p < 0.001, statistically significant). This confirms the reliability of both the GEDI L4A data and the proposed filtering parameters. Taking Liaoning Province as an example, this study evaluated three forest AGB maps (Yang’s, Su’s, and Zhang’s maps), which were obtained as nationwide AGB product maps, using GEDI L4A data. The comparison with Su’s map yields the highest $\rho$ value of 0.61. To enhance comparison accuracy, Kriging spatial interpolation was applied to the extracted GEDI footprint data, yielding continuous data. This $\rho$ value increased to 0.75 when compared with Su’s map, with significant increases also observed against Yang’s and Zhang’s maps. The study further proposes a method to subtract the extracted GEDI data from the AGB values of the three maps, followed by Kriging interpolation, resulting in $\rho$ values of 0.70, 0.80, and 0.69 for comparisons with Yang’s, Su’s, and Zhang’s maps, respectively. Additionally, comparisons with field measurements from the Mudanjiang Ecological Research Station yielded $\rho$ values of 0.66, 0.65, and 0.50, indicating substantial improvements over direct comparisons. All the ρ values were statistically significant (p < 0.001). This study also conducted comparisons across different cities and forest cover types. The results indicate that cities in eastern Liaoning Province, such as Dalian and Anshan, which have larger forest cover areas, produced better results. Among the different forest types, evergreen needle-leaved forests and deciduous needle-leaved forests yielded better results. Full article

The Real-Time Kinematic (RTK) method is currently the most widely used method for positioning using Global Navigation Satellite Systems (GNSSs) due to its accuracy, efficiency and ease of use. In forestry, position is a critical factor for numerous applications, with GNSS currently being the preferred solution for obtaining such data. However, the decreased performance of GNSS observations in challenging environments, such as under the forest canopy, must be considered. This paper analyzes the performance of a survey-grade GNSS receiver under coniferous/deciduous tree cover. Unlike most previous research concerning this topic, the focus here is on employing a methodology that is as close as possible to real working conditions in the field of forestry. To achieve this, short observation times of 30 s were used, with corrections received directly in the field from a Continuously Operating Reference Station (CORS) of the national RTK network in Romania. In total, 84 test points were determined, randomly distributed under the canopy, with reference data collected by topographical surveys using total station equipment. In terms of the overall horizontal accuracy, an RMSE of 2.03 m and MAE of 1.63 m are found. Meanwhile, the overall vertical accuracy is lower, as expected, with an RMSE of 4.85 m and MAE of 4.01 m. The variation in GNSS performance under the different forest compositions was found to be statistically significant, while GNSS-specific factors such as DOP values only influenced the precision and not the accuracy of observations. We established that this methodology offers sufficient accuracy, which is application-dependent, even if the majority of GNSS solutions were code-based, rather than carrier-phase-based, due to strong interference from the vegetation. Full article

Farm tractors represent a possible option for forwarding operations in continuous cover forestry, given the generally lower removal intensities, relatively high dispersion of timber, and heightened concerns regarding the environmental impact of operations. This study evaluated the performance of a farm tractor fitted with an externally operated crane and a bunk for forwarding operations, using field-documented data on operational speed, production, and fuel use, as well as data from high-resolution video recordings for a detailed time-and-motion study. Using this knowledge, performance simulations were run based on extraction distance and log size, to describe the variability in fuel use, cycle time, and productivity, and to estimate the operational cost. The results of the simulation showed important differences in operational speed across different work elements, involving machine movement. Although the extraction distance had effects, log size was found as the important factor driving the variability in cycle time, productivity, fuel use, and cost. The differences in performance based on the variability in extraction distance and log size may serve as a guideline for operational planning, costing, and environmental assessment regarding emissions under various operating conditions. Full article

In European mountains most beech forest areas have been managed for timber production. This practice has reduced the availability of biomass for the whole forest-dwelling species assemblage and of deadwood for the saproxylic community. Despite most of Italy’s beech stands having a long history of management, its effects on forest species remain poorly understood. To address this gap, we studied beetle abundance and diversity in five beech-dominated forests with increasing management intensity in central Italy’s Apennines (Tuscany). We assessed if forests with similar management intensity exhibited comparable patterns in beetle diversity, abundance, and commonness versus rarity. Three forests were managed with even-aged shelterwood; one was managed with continuous cover forestry; and one was old-growth. We found 25 beetle families and 195 species across all sites with similar total abundance and richness. However, the representation of the most abundant families varied among sampling sites (ANOVA test: always significant for the total abundance of the most abundant families: F ≥ 2.77, d.f. = 4, p ≤ 0.038). The old-growth forest harbored more threatened species than managed sites. Saproxylic assemblages were similar between the recently cut site and the old-growth forest, and between shelterwood and continuous cover sites. While the similarity gradient among the whole species assemblages reflected geographical proximity, the similarity gradient among saproxylic assemblages reflected the successional proximity among forest management systems. Our research underscores the effects of management on beetle diversity, offering insights for sustainable forestry. Full article