Forests

16 pages, 1542 KB

Open AccessArticle

Distinct Roles of Forest Stand Types in Regulating Soil Organic Carbon Stability Across Depths

by Jiaxi Zhao, Liming Lai, Ye Mei, Yanming Zhao, Zimo Li, Yanxing Dou, Lin Hou, Qinghong Geng and Shuoxin Zhang

Forests 2025, 16(10), 1585; https://doi.org/10.3390/f16101585 - 15 Oct 2025

Abstract

Soil organic carbon (SOC) is the largest reservoir of terrestrial organic carbon and plays a pivotal role in regulating global climate dynamics. And there are some differences in SOC stocks under different forest stand types. But it is unclear whether this phenomenon is [...] Read more.

Soil organic carbon (SOC) is the largest reservoir of terrestrial organic carbon and plays a pivotal role in regulating global climate dynamics. And there are some differences in SOC stocks under different forest stand types. But it is unclear whether this phenomenon is related to SOC stability, especially stable components of SOC. Therefore, coniferous (Pinus tabuliformis), broad-leaved (Quercus aliena), and mixed forests were selected to explore the distributions and chemical structures of SOC components, as well as SOC stabilization mechanisms. Higher SOC contents but lower stability were observed under Quercus aliena forests. Contents of SOC and its components were lowest under Pinus tabuliformis forests. Yet the highest relative abundances of alkyl and aromatic carbon in mineral-associated organic carbon (MAOC) were found at 10–40 cm soil layers, with the highest MAOC/SOC. In contrast, MAOC/SOC was highest under mixed forests at 0–10 cm layer. Total nitrogen (TN), lignin, and silt contents were identified as key drivers of SOC stability. These findings indicated that mixed forest contributes more to enhancing SOC stability in topsoil, whereas coniferous forest promotes greater stability in subsurface layers. These results suggested that the functional complementarity among forest stand types may enhance carbon sequestration and promote the sustainability of forest management. Full article

(This article belongs to the Section Forest Soil)

17 pages, 3426 KB

Open AccessArticle

Specific Function and Assembly of Crucial Microbes for Dendroctonus armandi Tsai et Li

by Caixia Liu, Lingyu Liang, Huimin Wang, Zheng Wang and Quan Lu

Forests 2025, 16(10), 1584; https://doi.org/10.3390/f16101584 - 15 Oct 2025

Abstract

Dendroctonus armandi is a native bark beetle that infests healthy Pinus armandii Franch. in western China. The complex symbiotic relationships with diverse microbes are critical to hosts for survival and outbreak dynamics. Understanding the potential functions and assembly metabolisms of these symbiotic microbes [...] Read more.

Dendroctonus armandi is a native bark beetle that infests healthy Pinus armandii Franch. in western China. The complex symbiotic relationships with diverse microbes are critical to hosts for survival and outbreak dynamics. Understanding the potential functions and assembly metabolisms of these symbiotic microbes to host colonization are therefore crucial. Metagenomic analysis revealed that gut microbial communities differed from cuticular ones significantly. The cuticle exhibited greater fungal diversity, while the gut supported a significantly higher bacterial diversity. Our findings indicated that gut unclassified Burkholderiales, Escherichia, Bacteroides and Prevotella may play a crucial role in degrading terpenes, phenols and polysaccharides rather than cuticular microbes. Stochastic processes appeared to be served as the primary drivers shaping the core microbial community structures. Cuticular dominant and functional microbial community assemblies except for Escherichia may be primarily driven by stochasticity to adapt the unstable habitats. The direct comparison of gut and cuticular microbiomes may provide valuable insights into the specific functions of symbiotic microbes, and offer critical molecular data for broader understanding of symbiotic relationship between bark beetles and microbes. Full article

(This article belongs to the Special Issue Biological Control and Management of Tree Diseases and Insect Pests in Forests)

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22 pages, 1878 KB

Open AccessArticle

Decadal Changes in Ground-Layer Plant Communities Reflect Maple Dieback and Earthworm Invasion in National Forests in the Lake Superior Region, USA

by Tara L. Bal, Manuel E. Anderson, Mattison E. Brady, Julia I. Burton and Christopher R. Webster

Forests 2025, 16(10), 1583; https://doi.org/10.3390/f16101583 - 15 Oct 2025

Abstract

Northern hardwood forests of the Lake Superior region face a series of novel disturbance pressures including canopy dieback. Previous studies have linked regional sugar-maple (Acer saccharum) canopy dieback to introduced earthworms, which may have coinciding impacts on the ground-layer plant community. [...] Read more.

Northern hardwood forests of the Lake Superior region face a series of novel disturbance pressures including canopy dieback. Previous studies have linked regional sugar-maple (Acer saccharum) canopy dieback to introduced earthworms, which may have coinciding impacts on the ground-layer plant community. Dieback–earthworm interactions may lead to important longer-term changes in forest structure and function, but these relationships but have not been characterized. We sampled ground-layer plant communities in five national forest units in Michigan, Wisconsin, and Minnesota in 2010, and again just over a decade later in 2021. Non-metric multidimensional scaling ordination and indicator species analysis were used to assess relationships among ground-layer community composition and structure, functional traits, and environmental gradients including forest-floor condition and A. saccharum canopy dieback. Increases in dieback and earthworm disturbance in the decade between inventories were accompanied by a marked divergence in observed ground-layer plant community structure between national forests. Ordinations of 2021 data indicated a strengthening relationship between forest-floor condition and earthworm abundance. Our results suggest that earthworm impacts and A. saccharum dieback are driving changes in the ground layer on broad geographic and temporal scales, with short- and long-term implications for plant-community structure and function, and higher trophic levels. Full article

(This article belongs to the Section Forest Ecology and Management)

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14 pages, 1886 KB

Open AccessArticle

Age-Dependent Differences in Leaf Sulfur Assimilation and Relationship with Resistance to Air Pollutant SO₂

by Jinxia Feng, Luyi Wang, Wenxin Liu, Ying Gao and Xianchong Wan

Forests 2025, 16(10), 1582; https://doi.org/10.3390/f16101582 - 14 Oct 2025

Abstract

Two poplar varieties with different resistance to sulfur dioxide were subjected to different concentrations of SO₂ fumigation treatment. Young and mature leaves of Purui poplar (resistant) vs. 74/76 poplar (susceptible) were used to measure the changes in the activity of enzymes and [...] Read more.

Two poplar varieties with different resistance to sulfur dioxide were subjected to different concentrations of SO₂ fumigation treatment. Young and mature leaves of Purui poplar (resistant) vs. 74/76 poplar (susceptible) were used to measure the changes in the activity of enzymes and metabolite content. Among the five key enzymes involved in sulfur metabolism and sulfur metabolites, APR, SO enzyme, GSH, and sulfate content have the greatest impact on young leaves of Purui, followed by 74/76 young leaves. The results show that for both Purui and 74/76 poplar, young leaves have stronger sulfur metabolism ability than mature leaves, indicating that young leaves have stronger SO₂ resistance. Purui has stronger sulfur metabolism ability than 74/76 poplar, especially reflected in their young leaves. The comparison between young and mature leaves, as well as the comparison between resistant and susceptible varieties, mutually confirms that sulfur metabolism in leaves is an important mechanism for sulfur dioxide resistance. Full article

(This article belongs to the Section Forest Meteorology and Climate Change)

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18 pages, 1656 KB

Open AccessArticle

Stakeholder Perception and Priority Gaps in Ecosystem Services of Different Land-Uses in Rural Laos

by Bohwi Lee and Hakjun Rhee

Forests 2025, 16(10), 1581; https://doi.org/10.3390/f16101581 - 14 Oct 2025

Abstract

Conflicting priorities between policymakers and local communities often compromise conservation outcomes in landscapes reliant on natural resources. Understanding how diverse stakeholders value ecosystem services (ESs) across coexisting land uses is essential; however, empirical evidence from rural Southeast Asia remains limited. This study examined [...] Read more.

Conflicting priorities between policymakers and local communities often compromise conservation outcomes in landscapes reliant on natural resources. Understanding how diverse stakeholders value ecosystem services (ESs) across coexisting land uses is essential; however, empirical evidence from rural Southeast Asia remains limited. This study examined ES perceptions and priorities among community members (n = 500) and experts (n = 30) within a bamboo forest, rice paddy, and teak plantation in Sangthong District, Lao PDR. A two-step survey methodology was employed: initially assessing ES perceptions to filter locally relevant services using a ≥50% recognition threshold, followed by quantifying priorities for this subset through a 100-point allocation task. The results revealed a systematic divergence in priorities rooted in differing knowledge systems. Communities, grounded in traditional ecological knowledge (TEK), prioritized tangible provisioning and cultural services (e.g., food and raw materials). In contrast, experts emphasized regulating services (e.g., carbon sequestration and hazard regulation) and habitat services (e.g., biodiversity and habitat provision). Distinct “ES bundles” also emerged by land use: bamboo (raw materials and freshwater), rice (food and medicine), and teak (timber/bioenergy and regulating services). Our findings suggest a policy transition from single-objective management toward optimizing landscape-level ES portfolios, alongside institutionalizing participatory co-management that formally integrates local knowledge and enhances ES literacy. Full article

(This article belongs to the Special Issue Forest Ecosystem Services and Sustainable Management)

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53 pages, 5853 KB

Open AccessArticle

CO₂ Estimation of Tree Biomass in Forest Stands: A Simple and IPCC-Compliant Approach

by Marlen Brinkord, Björn Seintsch and Peter Elsasser

Forests 2025, 16(10), 1580; https://doi.org/10.3390/f16101580 - 14 Oct 2025

Abstract

Background: While forests are pivotal for climate change mitigation, robust CO₂ accounting is required to quantify their climate benefits. However, varying current methodologies complicate this process for practitioners. This study addresses the need for a low-threshold, IPCC-compliant CO₂ estimation method of [...] Read more.

Background: While forests are pivotal for climate change mitigation, robust CO₂ accounting is required to quantify their climate benefits. However, varying current methodologies complicate this process for practitioners. This study addresses the need for a low-threshold, IPCC-compliant CO₂ estimation method of tree biomass in forest stands. Methods: We developed CO₂ yield tables by integrating segmented allometric biomass functions into fourth-generation yield tables, combining empirical data and simulations for Northwest Germany. Above- and belowground biomass was calculated, converted into CO₂, and compared with estimates from traditional expansion factors. An interactive R Shiny dashboard was designed to visualise results. Results: The main results of this article are the carbon yield tables, covering beech (Fagus sylvatica), oak (Quercus spp.), spruce (Picea abies), pine (Pinus sylvestris) and Douglas fir (Pseudotsuga menziesii), each across various yield classes and starting at age 1, thereby also encompassing the juvenile phase of forest stands. Our comparison with estimates from traditional expansion factors shows that the latter can substantially overestimate carbon content in forest stands compared to our results, ranging from 20% to 35%, with higher estimates for mature stands and improved representation of early growth. The interactive dashboard also allows readers to experiment with their own figures. Conclusions: The choice of CO₂ methodology profoundly affects results. Our yield tables and a calculation tool (dashboard) deliver a transparent, accessible tool for quantifying forest CO₂ stock, supporting sustainable management and carbon market participation. Full article

(This article belongs to the Special Issue Biomass Estimation and Carbon Stocks in Forest Ecosystems: 3rd Edition)

16 pages, 1948 KB

Open AccessReview

Process-Based Modeling of Forest Soil Carbon Dynamics

by Mingyi Zhou, Shuai Wang, Qianlai Zhuang, Zijiao Yang, Chongwei Gan and Xinxin Jin

Forests 2025, 16(10), 1579; https://doi.org/10.3390/f16101579 - 14 Oct 2025

Abstract

Forests play a pivotal role in the global carbon cycle, yet accurately simulating forest soil carbon dynamics remains a significant challenge for process-based models. This review systematically compares the mechanistic foundations of traditional models (e.g., Century, CLM5) with emerging microbial-explicit models (e.g., MEND), [...] Read more.

Forests play a pivotal role in the global carbon cycle, yet accurately simulating forest soil carbon dynamics remains a significant challenge for process-based models. This review systematically compares the mechanistic foundations of traditional models (e.g., Century, CLM5) with emerging microbial-explicit models (e.g., MEND), highlighting key differences in mathematical formulation (first-order kinetics vs. Michaelis–Menten kinetics), carbon pools partitioning (measurable vs. non-measurable experimentally), and the representation of soil carbon stabilization mechanisms (inherent recalcitrance, physical protection, and chemical protection). Despite advances in process-based models in predicting forest soil organic carbon (SOC), improving prediction accuracy, and assessing SOC response to climate change, current research still faces several challenges. These include difficulties in capturing depth-dependent variations in critical microbial parameters such as microbial carbon use efficiency (CUE), limited capacity to distinguish the relative contributions of aboveground and belowground litter inputs to SOC formation, and a general lack of long-term observational data across soil profiles. To address these limitations, this study emphasizes the importance of integrating remote sensing data and refining cross-scale simulation approaches. Such improvements are essential for enhancing model predictive accuracy and establishing a more robust theoretical basis for forest carbon management and climate change mitigation. Full article

(This article belongs to the Special Issue Prediction of Carbon and Nitrogen Cycles and Soil Functions in Forest Ecosystems: From Molecular Mechanisms to Landscape Management)

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40 pages, 31431 KB

Open AccessArticle

Effects of Fire Conditions on the Structural Optimization of Timber Trusses

by Matheus Henrique Morato de Moraes, Iuri Fazolin Fraga, Francisco Antonio Rocco Lahr, Fernando Júnior Resende Mascarenhas, Wanderlei Malaquias Pereira Junior and André Luis Christoforo

Forests 2025, 16(10), 1578; https://doi.org/10.3390/f16101578 - 14 Oct 2025

Abstract

This article examines how the time of exposure (0, 10, 20 and 30 min) to fire affects the optimal design of Howe timber trusses. The study integrates experimental characterization, thermal modeling (Eurocode 5 1995-1-2), and the bio-inspired Firefly Algorithm (FA). Five Brazilian species [...] Read more.

This article examines how the time of exposure (0, 10, 20 and 30 min) to fire affects the optimal design of Howe timber trusses. The study integrates experimental characterization, thermal modeling (Eurocode 5 1995-1-2), and the bio-inspired Firefly Algorithm (FA). Five Brazilian species (Cambará-rosa, Cupiúba, Angelim-pedra, Garapa, and Jatobá) were assessed in spans of 6, 9, 12, and 15 m. Each configuration was optimized 30 times with 120 agents, 600 iterations, and penalty treatments. In ambient conditions, Angelim-pedra and Garapa produced the lightest trusses, while under fire, simulated trusses with Jatobá wood properties provided the best performances, resulting in up to 35% mass reduction compared to trusses optimized with denser species under equivalent fire scenarios. Safety margins, defined through the Gross Mass Increase (GMI) index, quantify the additional structural mass required under fire in relation to the ambient design. GMI values ranged between 22% and 140% across the analyzed cases, quantifying the additional section demand under fire conditions relative to ambient design. To predict overdesign, regression equations were fitted using symbolic regression for the Index of Gross Area Correction Index (GACI), based on fire exposure time and resistant parameters, achieving R² above 0.85. The study provides guidelines for species selection, span sizing, and fire safety design. Overall, combining thermal analysis, bio-inspired optimization, and symbolic regression highlights the potential of timber trusses for efficient, safe, and sustainable roof structures. In addition, this study demonstrates the scientific novelty of integrating experimental characterization, Eurocode 5 thermal modeling, and metaheuristic optimization with symbolic regression, providing analytical indices such as the Gross Mass Increase (GMI) and Gross Area Correction Index (GACI). These results also offer practical guidelines for species selection, span sizing, and fire safety design, reinforcing the applicability of the methodology for engineers and designers of timber roof systems. Full article

(This article belongs to the Special Issue Characterization and Numerical Simulation of Solid Wood and Engineered Wood Products)

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17 pages, 1947 KB

Open AccessArticle

Reference Gene Identification and RNAi-Induced Gene Silencing in the Redbay Ambrosia Beetle (Xyleborus glabratus), Vector of Laurel Wilt Disease

by Morgan C. Knutsen and Lynne K. Rieske

Forests 2025, 16(10), 1577; https://doi.org/10.3390/f16101577 - 14 Oct 2025

Abstract

Management of invasive species is especially difficult when the organisms involved are endophagous and their interactions complex. Such is the case with laurel wilt disease (LWD), a lethal vascular condition caused by Harringtonia lauricola, the fungal symbiont of the non-native redbay ambrosia [...] Read more.

Management of invasive species is especially difficult when the organisms involved are endophagous and their interactions complex. Such is the case with laurel wilt disease (LWD), a lethal vascular condition caused by Harringtonia lauricola, the fungal symbiont of the non-native redbay ambrosia beetle (RAB), Xyleborus glabratus Eichoff (Coleoptera: Curculionidae). LWD has caused extensive mortality of coastal redbay, Persea borbonia, and is expanding to utilize additional lauraceous hosts, including sassafras, Sassafras albidum. Current management has not been successful in preventing its spread, warranting investigation into additional techniques. RNA interference (RNAi) is a highly specific gene-silencing mechanism used for integrated pest management of crop pests and currently being investigated for use in forests. When targeting essential genes, RNAi can cause rapid insect mortality. Here we focus on RAB, identifying for the first time species-specific reference genes for quantitative real-time PCR (qPCR) and assessing mortality and gene expression after oral ingestion of double-stranded RNAs (dsRNAs) targeting essential genes (hsp, shi, and iap). Our study validates reference genes for expression analyses and shows significant mortality and changes in gene expression for all three target genes. Our research aims to contribute to the development of innovative management strategies for this invasive pest complex. Full article

(This article belongs to the Section Forest Health)

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25 pages, 8808 KB

Open AccessArticle

Beyond Shade Provision: Pedestrians’ Visual Perception of Street Tree Canopy Structure Characteristics in Guangzhou City, China

by Jiawei Wang, Jie Hu and Yuan Ma

Forests 2025, 16(10), 1576; https://doi.org/10.3390/f16101576 - 13 Oct 2025

Abstract

This study examines the impact of canopy structural characteristics on pedestrians’ visual perception and psychophysiological responses along four roads in the subtropical city of Guangzhou: Huadi Avenue, Jixiang Road, Yuejiang Middle Road, and Huan Dao Road. A Canopy Structural Index (CSI) was innovatively [...] Read more.

This study examines the impact of canopy structural characteristics on pedestrians’ visual perception and psychophysiological responses along four roads in the subtropical city of Guangzhou: Huadi Avenue, Jixiang Road, Yuejiang Middle Road, and Huan Dao Road. A Canopy Structural Index (CSI) was innovatively developed by integrating tree height, crown width, diffuse non-interceptance, and leaf area index, establishing a five-tier quantitative grading system. The study used multimodal data fusion techniques combined with heart rate variability (HRV) analysis and eye-tracking experiments to quantitatively decipher the patterns of autonomic nervous regulation and visual attention allocation under different levels of CSI. The results demonstrate that CSI levels are significantly correlated with psychological relaxation states: as CSI levels increase, time-domain HRV metrics (SDNN and RMSSD) rise by 15%–43%, while the frequency-domain metric (LF/HF) decreases by 31%, indicating enhanced parasympathetic activity and a transition from stress to relaxation. Concurrently, the allocation of visual attention toward canopies intensifies. The proportion of fixation duration increases to nearly 50%, and the duration of the first fixation extends by 0.3–0.8 s. The study proposes CSI ≤ 0.15 as an optimization threshold, offering scientific guidance for designing and pruning subtropical urban street tree canopies. Full article

(This article belongs to the Section Urban Forestry)

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31 pages, 16515 KB

Open AccessArticle

Trend Shifts in Vegetation Greening and Responses to Drought in Central Asia, 1982–2022

by Haiying Pei, Gangyong Li, Yang Wang, Jian Peng, Moyan Li, Junqiang Yao and Tianfeng Wei

Forests 2025, 16(10), 1575; https://doi.org/10.3390/f16101575 - 13 Oct 2025

Abstract

Under global warming, drought frequency and its severity have risen notably, posing considerable challenges to vegetation growth. Central Asia (CA), recognized as the largest non-zonal arid zone globally, features dryland ecosystems that are particularly vulnerable to drought stress. This research examines how plant [...] Read more.

Under global warming, drought frequency and its severity have risen notably, posing considerable challenges to vegetation growth. Central Asia (CA), recognized as the largest non-zonal arid zone globally, features dryland ecosystems that are particularly vulnerable to drought stress. This research examines how plant life in CA reacts to prolonged dry spells by analyzing multiple datasets, including drought indices and satellite-derived NDVI measurements, spanning four decades (1982–2022). This study also delves into the compound impact of drought, revealing how its influence on vegetation unfolds through both cumulative stress and delayed ecological responses. Based on the research results, the vegetation coverage in CA exhibited a notable rising tendency from 1982 to 1998. Specifically, it increased at a rate of 4 × 10⁻³ per year (p < 0.05). On the other hand, the direction of this trend shifted to a downward one during the period from 1999 to 2022. During this latter phase, the vegetation coverage decreased at a rate of −4 × 10⁻³ per year (p > 0.05). Vegetation changes in the study area underwent a fundamental reversal around 1998, shifting from widespread greening during 1982–1998 to persistent browning during 1999–2022. Specifically, 98.6% of the region underwent pronounced summer drought stress, which triggered a substantial rise in vegetation browning. The vegetation response to the accumulated and lagged effects of drought varied across seasons, with summer exhibiting the strongest sensitivity, followed by spring and autumn. The lagged effect of drought predominantly influences the vegetation during the growing season and spring, affecting 59.44% and 79.27% of CA, respectively. In contrast, the accumulated effect of drought is more prominent in summer and autumn, affecting 54.92% and 56.52% of CA. These insights offer valuable guidance for ecological restoration initiatives and sustainable management of dryland ecosystems. Full article

(This article belongs to the Special Issue Application of Remote Sensing in Vegetation Dynamics and Ecology—2nd Edition)

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25 pages, 24888 KB

Open AccessArticle

Assessing Synergistic Effects on NPP from a Refined Vegetation Perspective: Ecological Projects and Climate in Heilongjiang

by Tingting Xia and Jiapeng Huang

Forests 2025, 16(10), 1574; https://doi.org/10.3390/f16101574 - 12 Oct 2025

Abstract

Net Primary Productivity (NPP) serves as a key indicator of ecosystem health and productivity. However, most existing research focuses on primary land cover types, overlooking the dynamic response processes of NPP in refined vegetation types to multiple climate drivers. Furthermore, it lacks systematic [...] Read more.

Net Primary Productivity (NPP) serves as a key indicator of ecosystem health and productivity. However, most existing research focuses on primary land cover types, overlooking the dynamic response processes of NPP in refined vegetation types to multiple climate drivers. Furthermore, it lacks systematic analysis of the feedback mechanisms through which China’s Five-Year Plan (FYP) ecological projects regulate climate stress. This study, based on refined vegetation classification, systematically analyzes the dynamic changes in NPP in Heilongjiang Province from the 10th to the 13th FYP periods (2001–2020), with a focus on refined vegetation types. Results show that between 2001 and 2020, mixed-leaved forest emerged as the core driver of regional NPP change during the 12th FYP (NPP increase of +58.4 gC·m⁻²·a⁻¹). Although deciduous needle-leaved forest (DNF) showed the highest cumulative increase (+64 gC·m⁻²·a⁻¹), it experienced significant degradation (p < 0.01) in 57%–62% of its area during the 12th and 13th FYP periods. The dominant climate driver shifted from precipitation (positively correlated in 74% of the area during the 10th–11th FYPs) to drought stress dominated by vapor pressure deficit (VPD) (positive correlation increasing to 54%). Ecological projects mitigated the negative impact of temperature, reducing the area with negative correlations by 13%. Overall, the ecological policies of the FYP exerted a weak negative influence. However, forest vegetation was strongly regulated by VPD (SV = −0.61~0.59), while grasslands and croplands exhibited high sensitivity to temperature. These findings underscore the contrasting climate policy responses among plant functional groups, highlighting the urgent need for differentiated ecological management strategies. Full article

(This article belongs to the Special Issue Guidelines for Sustainable Forest Management: Vegetation and Soil and Water Conservation in Arid Areas)

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17 pages, 3393 KB

Open AccessArticle

Response of Soil Properties, Bacterial Community Structure, and Function to Mulching Practices in Urban Tree Pits: A Case Study in Beijing

by Yi Zheng, Jixin Cao, Ying Wang, Yafen Wei, Yu Tian and Yanchun Wang

Forests 2025, 16(10), 1573; https://doi.org/10.3390/f16101573 - 12 Oct 2025

Abstract

Soil degradation and poor fertility severely constrain vegetation growth in urban ecosystems, particularly in compacted and nutrient-depleted tree pits. Mulching has emerged as an effective strategy to improve soil quality and regulate soil–microbe–plant interactions, yet the combined use of organic and inorganic mulching [...] Read more.

Soil degradation and poor fertility severely constrain vegetation growth in urban ecosystems, particularly in compacted and nutrient-depleted tree pits. Mulching has emerged as an effective strategy to improve soil quality and regulate soil–microbe–plant interactions, yet the combined use of organic and inorganic mulching in urban landscapes remains underexplored. In this study, a one-year field experiment was conducted to evaluate the effects of four mulching treatments on soil bacterial community diversity and functional potential. Four treatments were applied green waste compost + wood chips (GW), green waste compost + wood chips + volcanic rocks (GWV), green waste compost + wood chips + pebbles (GWP), and a non-mulched control (CK). Organic mulching (GW) effectively reduced bulk density, enhanced cellulase and protease activities, increased bacterial community richness and balance, and enriched microbial genes associated with carbon and nitrogen metabolism, while organic–inorganic mulching further promoted soil nutrition and reshaped bacterial community structure. Soil pH, nitrogen content, and protease activity served as key drivers of bacterial community structure and function. These findings demonstrate that different mulching practices provide distinct ecological advantages, and together highlight the role of mulching in regulating soil–microbe–plant interactions and improving urban tree pit management. Full article

(This article belongs to the Special Issue Deadwood Decomposition and Its Impact on Forest Soil)

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17 pages, 8354 KB

Open AccessArticle

Feasibility of a Low-Cost MEMS Accelerometer for Tree Dynamic Stability Analysis: A Comparative Study with Seismic Sensors

by Ilaria Incollu, Andrea Giachetti, Yamuna Giambastiani, Hervè Atsè Corti, Francesca Giannetti, Gianni Bartoli, Irene Piredda and Filippo Giadrossich

Forests 2025, 16(10), 1572; https://doi.org/10.3390/f16101572 - 11 Oct 2025

Abstract

Urban trees are subjected to stressful conditions caused by anthropogenic, biotic, and abiotic factors. These stressors can cause structural changes, increasing the risks of branch failure or even complete uprooting. To mitigate the risks to people’s safety, administrators must assess and evaluate the [...] Read more.

Urban trees are subjected to stressful conditions caused by anthropogenic, biotic, and abiotic factors. These stressors can cause structural changes, increasing the risks of branch failure or even complete uprooting. To mitigate the risks to people’s safety, administrators must assess and evaluate the health and structural stability of trees. Risk analysis typically takes into account environmental vulnerability and tree characteristics, assessed at a specific point in time. However, although dynamic tests play a crucial role in risk assessment in urban environments, the high cost of the sensors significantly limits their widespread application across large tree populations. For this reason, the present study aims to evaluate the effectiveness of low-cost sensors in monitoring tree dynamics. A low-cost micro-electro-mechanical systems (MEMS) sensor is tested in the laboratory and the field using a pull-and-release test, and its performance is compared with that of seismic reference accelerometers. The collected data are analyzed and compared in terms of both the frequency and time domains. To obtain reliable measurements, the accelerations must be generated by substantial dynamic excitations, such as high wind events or abrupt changes in loading conditions. The results show that the MEMS sensor has lower accuracy and higher noise compared to the seismic sensor; however, the MEMS can still identify the main peaks in the frequency domain compared to the seismic sensor, provided that the input amplitude is sufficiently high. Full article

(This article belongs to the Section Forest Inventory, Modeling and Remote Sensing)

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21 pages, 4936 KB

Open AccessArticle

Transcriptome Analysis Reveals the Genetic Basis of Phenotypic Traits of Vaccinium uliginosum L. at Different Elevations in the Changbai Mountains

by Yue Wang, Jun Li, Luying Zhao, Kai Mu, Ruijian Wang and Qichang Zhang

Forests 2025, 16(10), 1571; https://doi.org/10.3390/f16101571 - 11 Oct 2025

Abstract

The morphological traits of Vaccinium uliginosum L., including plant height, leaf area, and fruit weight, have changed significantly across an elevational gradient in the Changbai Mountains. To elucidate the molecular mechanisms underlying these morphological variations, RNA-Seq technology was employed to identify differentially expressed [...] Read more.

The morphological traits of Vaccinium uliginosum L., including plant height, leaf area, and fruit weight, have changed significantly across an elevational gradient in the Changbai Mountains. To elucidate the molecular mechanisms underlying these morphological variations, RNA-Seq technology was employed to identify differentially expressed genes (DEGs), key metabolic pathways, and associated biological functions of V. uliginosum at seven elevations in the Changbai Mountains. A total of 1190 DEGs significantly associated with morphological variations were identified. These genes are mainly involved in lipid synthesis, carbohydrate metabolism, energy metabolism, and signal transduction. Redundancy analysis (RDA) revealed that fatty acyl-ACP thioesterase B (FATB) and ribulose-bisphosphate carboxylase small subunit (cbbS) exhibited a significant association with morphological variation. Integrated analysis indicated that high-altitude plants likely enhance lipid synthesis and cell wall stability while also inhibiting photosynthesis and carbohydrate metabolism. The regulatory mechanisms underlying hormone signal transduction may be relatively complex, as evidenced by the enhanced activity of gibberellin and reduced biological effects of auxin, abscisic acid, and ethylene. This study is the first to provide transcriptomic evidence elucidating the genetic basis of altitudinal morphological adaptation in V. uliginosum, integrating phenotypic traits with gene expression profiles across an elevational gradient. Full article

(This article belongs to the Section Genetics and Molecular Biology)

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19 pages, 5177 KB

Open AccessArticle

Short-Term Effects of N Deposition on Soil Respiration in Pine and Oak Monocultures

by Azam Nouraei, Seyed Mohammad Hojjati, Hamid Jalilvand, Patrick Schleppi and Seyed Jalil Alavi

Forests 2025, 16(10), 1570; https://doi.org/10.3390/f16101570 - 11 Oct 2025

Abstract

Atmospheric nitrogen input has been a severe challenge worldwide. The influences of N deposition on carbon cycling, loss, and storage have been recognized as a critical issue. This study aimed to assess the immediate responses of soil respiration to different N deposition treatments [...] Read more.

Atmospheric nitrogen input has been a severe challenge worldwide. The influences of N deposition on carbon cycling, loss, and storage have been recognized as a critical issue. This study aimed to assess the immediate responses of soil respiration to different N deposition treatments in radiata pine (Pinus radiata D. Don) and chestnut-leaved oak (Quercus castaneifolia C. A. Mey) plantations within 12 months. N treatments were performed monthly at levels of 0, 50, 100, and 150 kg N ha⁻¹ year⁻¹ from October 2017 to September 2018. Litterfall was collected and analyzed seasonally for its mass and C content. Within the 0–10 cm depth of mineral soil in both plantations, parameters such as total nitrogen, pH, microbial biomass carbon (MBC), organic carbon (OC), and fine root biomass were measured seasonally. Soil respiration (Rs) was determined through monthly measurements of CO₂ concentration in the field using a portable, closed chamber technique. The control plots exhibited the highest Rs during spring (2.96, 2.85 μmol CO₂ m⁻² s⁻¹) and summer (2.92, 3.1 μmol CO₂ m⁻² s⁻¹) seasons in oak and pine plantations, respectively. However, the introduction of nitrogen significantly diminished Rs in both plantations. Moreover, N treatments caused a notable reduction of soil MBC and fine root biomass. Soil microbial entropy and the C/N ratio were also significantly decreased by nitrogen treatments in both plantations, with the most prominent effects observed in summer. The observed decline in Rs in N-treated plots can be attributed to the decrease in MBC and fine root biomass, potentially with distinct contributions of these components in the pine and oak plantations. Our findings suggested that N-induced alteration in soil carbon dynamics was more pronounced in the oak plantation, which resulted in more SOC accumulation with increasing N inputs, while the pine plantation showed no significant changes in SOC. Full article

(This article belongs to the Section Forest Soil)

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20 pages, 21172 KB

Open AccessArticle

Landscape Metric-Enhanced Vegetation Restoration: Improving Spatial Suitability on Loess Plateau

by Sixuan Du, Jiarui Li and Xiang Li

Forests 2025, 16(10), 1569; https://doi.org/10.3390/f16101569 - 11 Oct 2025

Abstract

Ecological restoration of the Loess Plateau plays a pivotal role in mitigating land degradation and promoting regional sustainability. In this study, landscape pattern metrics were integrated into the MaxEnt model to evaluate the influence of landscape configuration on restoration planning. Nine representative species [...] Read more.

Ecological restoration of the Loess Plateau plays a pivotal role in mitigating land degradation and promoting regional sustainability. In this study, landscape pattern metrics were integrated into the MaxEnt model to evaluate the influence of landscape configuration on restoration planning. Nine representative species from three vegetation strata—herbs, shrubs, and trees—were selected based on ecological suitability. A comprehensive set of variables, including environmental, anthropogenic, and landscape metrics, was constructed for modeling. Results demonstrate that incorporating landscape metrics significantly enhanced the spatial explanatory power, providing a robust supplement to traditional ecological restoration assessments. Distinct responses to landscape structure were observed among vegetation types: herb species were more sensitive to patch aggregation and connectivity, shrubs preferred regular edges and larger patch size, while tree species favored extensive, low-fragmentation core habitats. Vertical structure optimization revealed that while large areas were suitable for single vegetation layers, composite vegetation configurations were more appropriate in certain central and southern subregions. These findings underscore the importance of landscape structure in guiding restoration strategies and serve as a basis for designing ecologically coherent and spatially targeted vegetation restoration plans on the Loess Plateau. Full article

(This article belongs to the Section Forest Ecology and Management)

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16 pages, 3417 KB

Open AccessArticle

Roll Angular Velocity and Lateral Overturning Tendency of a Small-Tracked Forestry Tractor Under No-Sideslip Dynamic Driving Conditions

by Yun-Jeong Yang, Moon-Kyeong Jang and Ju-Seok Nam

Forests 2025, 16(10), 1568; https://doi.org/10.3390/f16101568 - 11 Oct 2025

Abstract

In this study, a driving test was conducted using a small-tracked forestry tractor with a scale of 1/11 in the shape of an actual tractor to assess safety under dynamic conditions. The driving conditions resulting in lateral overturning were derived. Additionally, an angular [...] Read more.

In this study, a driving test was conducted using a small-tracked forestry tractor with a scale of 1/11 in the shape of an actual tractor to assess safety under dynamic conditions. The driving conditions resulting in lateral overturning were derived. Additionally, an angular velocity sensor was used to analyze the variation in roll angular velocity with driving conditions. Driving condition variables comprised obstacle height, ground slope angle, and driving speed. Obstacle height had five levels between 0 and 40 mm in 10 mm intervals, and ground slope angle had 11 levels at 5° intervals from 0° to 50°. Driving speed had three levels: 0.07, 0.11, and 0.13 m/s. The ground slope angle resulting in lateral overturning in the driving scenario was lower than that in non-driving under all conditions. Roll angular velocity increased as obstacle height and tractor driving speed increased. However, ground slope angle did not significantly affect angular velocity. Roll angular velocity at the moment of lateral overturning was about 90 deg/s regardless of driving conditions. A certain critical angular velocity was found to induce lateral overturning, and adjusting the driving method such as reducing driving speed and making turns when the roll angular velocity of the tractor approached the critical value improved safety. However, the quantitative results from the small tractor cannot be directly applied to full-size tractors. Although numerical values may differ, this study focused on capturing the overall trends in lateral overturning considering various driving conditions. Future studies can improve the practical applicability of these findings by determining the critical angular velocity of various full-size tractors. Full article

(This article belongs to the Section Forest Operations and Engineering)

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17 pages, 3042 KB

Open AccessArticle

Enhancing Distance-Independent Forest Growth Models Using National-Scale Forest Inventory Data

by Byungmook Hwang, Sinyoung Park, Hyemin Kim, Dongwook W. Ko, Kiwoong Lee, A-Reum Kim and Wonhee Cho

Forests 2025, 16(10), 1567; https://doi.org/10.3390/f16101567 - 10 Oct 2025

Abstract

National-scale long-term forest ecosystem surveys based on systematic sampling offer a robust framework for detecting temporal growth trends of specific tree species across regions. The National Forest Inventory (NFI) of the Republic of Korea serves as a vital source for analyzing long-term forest [...] Read more.

National-scale long-term forest ecosystem surveys based on systematic sampling offer a robust framework for detecting temporal growth trends of specific tree species across regions. The National Forest Inventory (NFI) of the Republic of Korea serves as a vital source for analyzing long-term forest dynamics on a national scale by providing regularly collected large-scale forest data. However, various limitations, such as the lack of individual-level and spatial interaction data, restrict the development of reliable individual tree growth models. To overcome this, distance-independent models, compatible with the structure and data resolution of the NFI, provide a practical alternative for simulating individual tree and stand-level growth by utilizing straightforward attributes, such as diameter at breast height (DBH). This study aimed to analyze the growth patterns and construct species-specific models for two major plantation species in South Korea, Pinus koraiensis and Larix kaempferi, using data from the 5th (2006–2010), 6th (2011–2015), and 7th (2016–2020) NFI survey cycles. The sampling points included 117 and 171 plots for P. koraiensis and L. kaempferi, respectively. An additional matching process was implemented to improve species identification and tracking across multiple survey years. The final models were parameterized using a distance-independent model, integrating the estimation of potential diameter growth (PG) and a modifier (MOD) function to adjust for species- and site-specific variabilities. Consequently, the models for each species demonstrated strong performance, with P. koraiensis showing an R² of 0.98 and RMSE of 1.15 (cm), and L. kaempferi showing an R² of 0.98 and RMSE of 1.14 (cm). This study provides empirical evidence for the development of generalized and scalable growth models using NFI data. As the NFI increases in volume, the framework can be expanded to underrepresented species to improve the accuracy of underperforming models. Ultimately, this study lays a scientific foundation for the future development of tree-level simulation algorithms for forest dynamics, encompassing mortality, harvesting, and regeneration. Full article

(This article belongs to the Section Forest Inventory, Modeling and Remote Sensing)

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