Search Results (522)

Due to the explosive growth in cloud-native infrastructures, the attack surface has dramatically increased in modern enterprise identity systems, where privilege escalation has become a major security risk. Conventional rule-based intrusion detection systems fall short in identifying multi-hop privilege inheritance paths and lateral movements over heterogeneous and dynamic identity graphs. This study introduces PEGraphSec-Net, a graph-theoretical framework for detecting privilege-escalation-relevant identity behavior, modeling cloud identity interactions as dynamic heterogeneous graphs of users, services, roles, tokens, and workloads. The core contribution of this framework is a graph-based detection pipeline—an Identity Relationship Graph Constructor, a Privilege-Escalation Path Encoder, and a Temporal Graph Attention Detection layer—evaluated on privilege-escalation-relevant attack categories using a documented proxy identity-graph construction derived from the UNSW-NB15 network-traffic benchmark, and benchmarked against six non-graph tabular classifiers (CNN, LightGBM, XGBoost, Random Forest, SVM, and MLP) trained under identical preprocessing; this pipeline achieves 98.78% accuracy, a weighted F1-score of 0.98692 (macro F1-score of 0.91828), and an AUC of 1.000 on the held-out test partition. PEGraphSec-Net is further benchmarked against three graph neural network baselines (GCN, GAT, and GraphSAGE) trained on the identical identity-graph topology and node attributes; all three substantially underperform PEGraphSec-Net (best case, GraphSAGE: 63.66% accuracy, 0.239 macro F1-score), indicating that a large share of PEGraphSec-Net’s performance derives from its explicit privilege-path encoding and temporal attention mechanisms rather than from the graph topology alone. An Adaptive Containment and Isolation Engine and a Mitigation Policy Reinforcement Optimizer are further proposed as risk-scoring and reward-driven policy-learning components, whose contribution is validated through module-wise ablation on classification performance; live containment action and reinforcement-learning-specific evaluation are left for future validation. The term “privilege escalation” is used throughout to denote the evaluated proxy attack categories (Exploits, Backdoor/Backdoors, and Reconnaissance) under a documented, decade-old (2015) network-intrusion benchmark, rather than production cloud-native IAM behavior, for which native-dataset validation remains an open direction. SHAP-based interpretability analysis links the model’s top-ranked traffic-level features back to the identity-graph risk, role, and trust-transition attributes they populate, evidencing that the learned representation captures semantically meaningful identity-behavior patterns within this proxy setting. Full article

Forest canopy gaps are key indicators of forest dynamics, yet their vertical organization remains poorly quantified across forest types. While canopy gaps are commonly interpreted as signatures of disturbance regimes, their size distribution and vertical organization may also reflect intrinsic differences in stand structure, crown architecture, and density-dependent interactions. We hypothesize that the vertical distribution of canopy gap size differs among forest types, reflecting contrasting structural organization and developmental trajectories. Using airborne LiDAR, we quantified vertical gap size distributions in two Central African old-growth forest types: monodominant Gilbertiodendron dewevrei (GIL) and MIXED forests, across two sites in the Democratic Republic of the Congo (Lileko and Yangambi). We also derived structural ratios normalizing gap area by basal area and canopy height. Results show clear divergence in vertical gap profiles. GIL forests consistently exhibit lower canopy openness than MIXED forests. Between heights of 10 and 20 m, total gap area per hectare ranged from 39.11 (95% CI: 19.84–83.5) to 567.56 (95% CI: 229.44–707.48) m² ha⁻¹ in GIL forests, compared with 69.10 (95% CI: 55.28–123.51) to 1244.97 (95% CI: 784.73–1360.45) m² ha⁻¹ in MIXED forests across both sites. Structural ratios further confirm that GIL forests maintain smaller gap areas relative to basal area and canopy height. Overall, the results support the three study hypotheses, demonstrating that vertical gap size distributions and their normalization by stand structural attributes provide robust and transferable indicators for discriminating among Central African old-growth forest types and developmental stages, highlighting the importance of structural context for interpreting tropical forest dynamics. Full article

Old-growth forests are recognized as key reference systems for biodiversity conservation and sustainable forest management, yet they remain rare and highly fragmented ecosystems across Europe. In this study, we developed and applied a quantitative, measurement-based framework to assess candidate old-growth beech stands by comparing their structural attributes with reference old-growth forests and with a broader set of beech forests from the National Forest Inventory (NFI). Specifically, we compared the structural attributes of two candidate old-growth (COG) beech stands to assess their degree of naturalness and their similarity to three reference old-growth (ROG) beech forests in the central Apennines. The approach integrated field-based structural measurements, deadwood quantification, dendrochronological assessment of dominant trees and diachronic aerial imagery evaluation, comparing COG stands with both ROG and other beech forests from the NFI database. The two COG stands differ clearly from common beech forests, exhibiting lower stem density, larger size variability, higher occurrence of large trees and of standing wood biomass. Stem diameter distributions followed a reverse J-shaped pattern, typical of uneven-aged and scarcely managed forests. Some very old trees were also found, especially at one of the two COG sites. These characteristics are largely comparable to the ROG beech forests, except for deadwood volumes, lower at the two COG forests. In addition, historical aerial imagery and tree-ring analysis suggested that these forests are intermediate stages along an old-growth gradient. Our findings demonstrate that a prolonged forest management abandonment of over 70 years can induce the development of old-growth attributes in Mediterranean mountain beech forests, even in stands previously coppiced or pastured for a long time. This study provides a replicable measurement-based approach for identifying and validating candidate old-growth forests, under current Italian regulations and contributes to conservation targets consistent with the EU Biodiversity Strategy for 2030. Full article

The coast redwood forest, populated by the ancient relict species Sequoia sempervirens, provides unique and essential ecological services along the Pacific coast of California. It is a haven for endemism and ecological diversity, offers habitat for threatened species, and is an important global terrestrial carbon sink. However, a long history of resource extraction has significantly impacted this ecosystem. Complex old-growth forests have largely been replaced with managed timber stands, and biological diversity has been reduced through the loss of habitat and basic ecological functions. Under natural conditions, coast redwood is highly resilient to disturbance, due to its propensity for basal and epicormic sprouting. The primarily clonal reproductive strategy of S. sempervirens allows for natural thinning as a stand matures, generally leading to the development of late-seral characteristics without the need for active restoration. The increasingly pervasive use of active silvicultural tools for restoration, such as forest thinning and commercial timber harvest, can create a density-driven cycle that requires periodic re-application of the treatment and hinders natural successional processes. In order to restore forest health and resiliency, natural successional processes inherent to coast redwood can be supported as a restoration alternative. Full article

Pinus pinaster Ait. forests have potential for resin tapping, a forestry activity that complements timber production and may increase the profitability of maritime pine stands. However, the viability of this co-production remains uncertain due to the potential effects of resin tapping on wood characteristics. The present study aimed to investigate the effects of resin tapping on the wood characteristics of maritime pine, in order to infer possible changes in wood quality, its utilisation, and, consequently, its value. The study was based on samples collected in Tresminas from resin-tapped trees (37.2 ± 6.0 years old and mean height of 15.8 ± 1.4 m) subjected to the traditional Portuguese resin tapping method for four consecutive years, and from non-resin-tapped trees (37.5 ± 8.9 years old and mean height of 14.1 ± 2.2 m). Samples were collected from different positions along the stem of resin-tapped trees (incision side, opposite side, and 50 cm above the last tapping incision) and compared with samples obtained from non-resin-tapped trees. Wood density, modulus of elasticity (MOE), modulus of rupture (MOR), extractives content, growth ring width and the number and area of resin ducts were evaluated. The effects of resin tapping on wood properties were assessed by comparing resin-tapped and non-resin-tapped trees, as well as different sampling positions within resin-tapped trees, using linear mixed-effects models. Mean comparisons were performed using Tukey’s test at a 95% significance level. No significant effects of resin tapping were observed on MOE or MOR between resin-tapped and non-resin-tapped trees. Wood from the incision side showed higher density (0.596 g·cm⁻³) and higher extractives content (7.49%). Resin-tapped trees produced a greater number of resin ducts after tapping; however, their area did not change. No significant differences were found in growth ring width between resin-tapped (1.75 mm) and non-resin-tapped trees (1.80 mm), although resin-tapped trees presented slightly narrower rings on average. Resin tapping in P. pinaster did not promote relevant changes in wood properties that would compromise its mechanical and physical performance. Although some alterations were detected, these were predominantly localised and restricted to the region adjacent to the tapping incision. Full article

Remote sensing contributes to characterizing forest structure across heterogeneous tropical regions, yet structural parameters used to compare Atlantic Forest phytophysiognomies remain limited, especially in fragmented landscapes affected by multiple drivers of forest loss and degradation. This study used Global Ecosystem Dynamics Investigation (GEDI) data to compare the structure of old-growth candidate forest polygons in four Brazilian Atlantic Forest phytophysiognomies: Dense Ombrophilous Forest (DOF), Mixed Ombrophilous Forest (MOF), Seasonal Semideciduous Forest (SSdF), and Seasonal Deciduous Forest (SDF). We analyzed canopy height (H), canopy cover (COVER), foliage height diversity (FHD), plant area index (PAI), and aboveground biomass density (AGBD) from GEDI L2B and L4A footprints acquired between 2019 and 2024. Structural differences among phytophysiognomies were significant for all variables (Kruskal–Wallis, p < 0.001), with small-to-moderate effect sizes (ε² ≈ 0.05–0.15). The strongest pairwise contrasts occurred for SDF–SSdF and SSdF–DOF, whereas MOF showed greater overlap with the other groups. Across variables, AGBD and H were the most consistent discriminators, and polygon-level summaries strengthened among-group separation. These findings show that GEDI-derived polygon-level metrics can support regional comparisons of forest structure among Atlantic Forest phytophysiognomies and help identify the strongest contrasts in fragmented landscapes. Full article

Picea koraiensis Nakai is a precious tree species in Northeast China with excellent traits, but research on thinning effects on its growth remains limited, especially regarding soil-thinning–growth interactions. This study focused on a 50-year-old Picea koraiensis plantation in the Mengjiagang Forest Farm, Jiamusi. Four thinning intensities were set: CK (no thinning), T1 (10%–20%), T2 (20%–30%), and T3 (40%–50%). Short-term (1–3 years) stand growth, soil properties, microbial biomass, and extracellular enzyme activities were measured, with stand volume and large-diameter timber yield estimated via self-established equations. Results showed that T3 significantly promoted average DBH (1.98 × CK) and tree height growth (1.60 × CK). T2 achieved the highest increases in stand volume (38.07 m³/ha) and large-diameter timber yield (56.02 m³/ha), exceeding other treatments by 1.20–7.12 m³/ha and 5.60–11.64 m³/ha, respectively. Stand growth indices were positively correlated with thinning intensity, soil microbial biomass carbon, and soil C/P ratio; DBH and height also correlated with soil catalase activity. Thinning intensity has a direct effect on stand growth. Meanwhile, observational data show that it is significantly correlated with changes in soil organic carbon fractions and soil extracellular enzyme activity, and these correlations may constitute potential pathways that indirectly affect stand growth. Moderate-intensity thinning (20%–30%) is recommended for scientific tending and large-diameter timber cultivation of middle-aged Picea koraiensis plantations in this region. Full article

All eastern hemlock-dominated forests in Ontario could be gone by 2075 given current trends, which demands rapid assessment to locate these endangered ecosystems. To date, however, neither the Canadian or Ontario governments have developed field assessment protocols or minimum standards for identifying old-growth forests that provide density and biomass estimates for the primary features of these forests. This study focused on the Catchacoma Forest, Canada’s largest eastern hemlock forest, and represents a first step towards establishing minimum standards for old-growth eastern hemlock forests in the Great Lakes-St. Lawrence Forest region. Rectangular plots were systematically placed along evenly spaced east–west transects at a 2% sampling intensity for the 181 ha study area and assessed for mother trees (MTs) and cut stumps. By a factor of 15X, the method developed was more efficient for covering larger areas compared to randomly placed and intensively sampled plots typically used for long-term ecological studies. Mean integrity (stumps/ha) was 0.006/ha and mean MT density was 149/ha with a range of 0–533/ha. Four MT forest types were identified including: eastern hemlock-dominant (47%; 194 MT/ha), white pine-dominant (26%; 123 MT/ha), other MT species-dominant (9%; 169 MT/ha), and eastern hemlock–white pine co-dominant (8%; 133/ha). MTs were absent from roughly 10% of the study area. Full article

The San Juan Islands are one of the few places where native temperate grasslands are found in western Washington State. These ecosystems are important reservoirs of biodiversity and sources of ecosystem services, support many rare and endemic species, and have profound cultural significance to the Coast Salish peoples. These ecologically and culturally valuable ecosystems have become scarce due to the combined pressures of changes in land use, the introduction of non-native invasive species, and the exclusion of fire from the landscape. A lack of historical context and ecological baseline knowledge has made it impossible to fully understand the long-term trends in the extent and distribution of this ecosystem. To address this knowledge gap, we used historical land cover data and multispectral imagery to create a high-resolution, spatially explicit database of grassland extent on the San Juan Islands at multiple time periods since the early years of Euro-American colonization. Our spatial analysis of these data revealed significant decreases in grassland extent between time periods, with an overall 77% net decrease in the extent of non-agricultural grasslands and a loss of 93% of the area of persistent, old-growth grasslands since 1890 across the region. These changes are primarily a result of conversion to agriculture and conifer encroachment or succession to forest. The spatial data and analyses created in this study help to develop the historical baseline of native temperate grasslands on the San Juan Islands, adding to our understanding of the lingering legacy that changes in land use have had on this ecosystem, with the potential to aid in the development of effective conservation and restoration practices. Full article

Tropical forests are facing escalating deforestation, while forest degradation, driven by a complex interplay of human-induced factors, emerges as an additional and compounding threat. In this context, regulated selective logging persists as an alternative to conciliate forest protection and economic development. This study synthesizes current knowledge on the impacts of logging, focusing on research trends, geographic distribution, ecological topics, and key variables like logging intensity, time since logging, and number of logging cycles. Since the 1970s, 641 papers listed on the Scopus platform have demonstrated a sharp increase in publication activity over the past five years, followed by a tendency toward stabilization. Papers were concentrated in Brazil and Malaysia, with few papers coming from other countries, particularly from Africa. Notably, 47% of the studies did not report logging intensity, and one-third focused almost exclusively on its impacts on forest physical structure, damage, or biomass—leaving a wide range of other topics largely unexplored until 2022. We refer to 13 topics with less than 20 studies in total, such as nutrient cycling, non-timber forest products, biological invasion, and key biological taxa. Herbs, epiphytes, fishes and amphibians were among the least investigated taxa across the regions. Furthermore, when controlling variables like region and logging intensity, most ecological topics had fewer than five dedicated studies. Research remains largely restricted to similar scenarios: first-cycle logging in old-growth forests, leaving substantial knowledge gaps. As logging operations are expected to increase, we argue for (1) mandatory long-term monitoring in logging regulations; (2) public access to monitoring data, reports and information related to regulated logging; (3) a global platform to exchange experience such as long-term monitoring, better practices, silvicultural approaches and sustainability assessment; (4) alignment among regulatory and certification agencies on sustainability standards; (5) capacity building initiatives; and (6) long-term experiments devoted to logging sustainability and better practices. Full article

Black locust (Robinia pseudoacacia L.) has exceptional growth capacity in nutrient-poor environments and is therefore widely used for afforestation and land reclamation on degraded soils. However, drought stress can restrict sapling growth, which undermines the success of their establishment. The effect of a product containing two endophytic strains (Trichoderma afroharzianum P. Chaverri, F.B. Rocha, Degenkolb & Druzhinina TR04 and Trichoderma simmonsii P. Chaverri, F.B. Rocha, Degenkolb & Druzhinina TR05) was studied on a black locust sapling stand under severe drought in eastern Hungary. The two-year-old saplings were root-soaked before planting in sandy soil. The growth of Trichoderma-treated plants improved by late spring. Compared to the control trees, average height increased by 25.75%, and root collar diameter was 21.96% larger. Treated plants also showed 9.1% higher chlorophyll content and 11.1% Normalized Difference Vegetation Index (NDVI). The reduced intercellular CO₂ concentration, together with slightly lower stomatal conductance and increased transpiration rate, suggests tighter stomatal regulation and altered water-use dynamics under drought conditions. These responses indicate improved short-term drought acclimation rather than enhanced carbon assimilation capacity. Pre-planting inoculation with endophytic Trichoderma strains provides a sustainable method to enhance the early establishment and drought resilience of black locust, thereby increasing the efficacy of forest restoration by improving the survival of black locust on challenging degraded sites. Full article

This study assessed phenotypic variation among open-pollinated half-sib families from a single relict population. Autochthonous silver fir (Abies alba Mill.) preserved in the Tisovik Reserve of Białowieża Forest represents the northeasternmost isolated relict population of the species in Europe. To secure its genetic resources and evaluate its breeding potential, a conservation plantation of open-pollinated half-sib families was established in the Hajnówka Forest District outside the natural species range. This study assessed the effects of half-sib family affiliation on the growth and phenotypic performance of almost two thousand 28–31-year-old trees representing 20 half-sib families and compared them with age-matched managed stands in the State Forests of Poland. Significant within- and among-family variation was observed for diameter at breast height (DBH) and height (H), while environmental factors had only marginal influence under the uniform site conditions of the plantation. Several half-sib families produced disproportionately high numbers of individuals with exceptional phenotypic performance, including DBH values exceeding 25 cm and height values surpassing those of managed stands. Based on a combined assessment of qualitative traits, selection differential, and 95th percentile values, 30 prototype plus trees were selected as sources of scions for establishing a future seed orchard. The outstanding growth parameters of these individuals correspond to stand ages of 40–65 years according to yield tables, despite their biological age of only 28–31 years. The results confirm the high breeding value and substantial genetic variability of the Tisovik population and demonstrate its potential for producing genetically diverse planting material adapted to lowland sites under changing climatic conditions. Full article

Soil organic carbon (SOC) is a key component of terrestrial carbon stocks, yet its spatial variability, recovery potential, and dominant controls across tropical forest succession remain insufficiently quantified. We combined field measurements from 40 natural forest plots on Hainan Island, China, with laboratory analyses and multi-source environmental data to assess topsoil SOC (0–20 cm) distribution, recovery potential, and regulatory drivers. In natural forests on Hainan Island, topsoil SOC stocks ranged from 33.06 to 62.60 Mg · C · ha⁻¹. Using the median (Q0.5) SOC of old-growth forests as the reference level, recovery potential ranged from 12.60 to 42.14 Mg · C · ha⁻¹. Topsoil SOC exhibited clear spatial heterogeneity across the island, with higher values in more continuous forest areas. Secondary forests generally exhibited lower current SOC but greater recovery potential, whereas old-growth forests showed higher and more stable stocks. Multivariate analyses revealed a clear successional shift in dominant controls: total phosphorus (TP) was the primary predictor in secondary forests, while total nitrogen (TN) dominated across the full gradient, particularly in old-growth forests. These findings highlight stage-dependent SOC regulation and the critical role of soil nutrient status in shaping tropical forest carbon recovery. Full article

Pinyon–juniper (PJ) woodlands, one of the most extensive mature and old-growth woodland types in the Western United States, provide critical ecological, cultural, and economic benefits but face increasing threats from climate change, altered disturbance regimes, invasive species, and pests. We developed the PJ Woodland Climate Adaptation Management Menu, a decision support tool designed to guide adaptive, climate-informed management of PJ ecosystems, particularly within the Colorado Plateau ecoregion. The menu was created through an iterative, collaborative process involving literature review, integration of strategies from existing adaptation frameworks, and extensive input from scientists, land managers, and community partners during workshops and focus groups. The menu links specific, evidence-based approaches to each of six broad strategies, including soliciting community input, mitigating disturbance, enhancing and maintaining biodiversity, conserving ecotones, timing actions for optimal outcomes, and accepting climate-driven changes when appropriate. It is intended for use with the Adaptation Workbook to help managers connect local goals and climate vulnerabilities to tailored management tactics. Hypothetical scenarios demonstrate the menu’s application to contrasting PJ woodland conditions, from die-off events to old-growth maintenance. Lessons learned during development underscore the value of early stakeholder engagement, cross-sector collaboration, and balancing diverse ecological objectives. This menu offers a flexible, transferable framework to strengthen climate resilience in PJ woodlands and serves as a model that could improve adaptation planning in other dryland forest ecosystems. Full article

The Muški bunar old-growth forest on Mount Psunj represents one of the rare preserved mixed ecosystems of sessile oak (Quercus petraea (Matt.) Liebl.) and European beech (Fagus sylvatica L.) in Southeastern Europe, providing an important reference for understanding natural forest dynamics. This study aimed to analyse stand structure, age distribution, growth dynamics, and disturbance regime based on repeated field surveys conducted in 1979 and 2021. The results revealed pronounced structural heterogeneity and clear interspecific differences. European beech dominates smaller- and medium-diameter classes, as well as a wider range of age classes, whereas sessile oak is primarily present in older and larger diameter classes. A very high growing stock (1155.81 m³ ha⁻¹) indicates exceptional stand productivity, with maximum cambial ages of 295 years for oak and 253 years for beech. Basal area increment analysis showed that both species maintain substantial growth at advanced ages. However, recent decades show divergence, with increasing growth in beech and stagnation or decline in oak. Importantly, growth releases in sessile oak were not accompanied by successful regeneration, indicating a decoupling between growth response and recruitment. Stand dynamics are mainly driven by low-intensity disturbances. These findings highlight the importance of old-growth forests as reference systems and improve understanding of species-specific responses to disturbance. Full article