Forests

17 pages, 2045 KiB

Open AccessArticle

Different Phosphorus Preferences Among Arbuscular and Ectomycorrhizal Trees with Different Acquisition Strategies in a Subtropical Forest

by Yaping Zhu, Jianhua Lv, Pifeng Lei, Miao Chen and Jinjuan Xie

Forests 2025, 16(8), 1241; https://doi.org/10.3390/f16081241 - 28 Jul 2025

Abstract

Phosphorus (P) availability is a major constraint on plant growth in many forest ecosystems, yet the strategies by which different tree species acquire and utilize various forms of soil phosphorus remain poorly understood. This study investigated how coexisting tree species with contrasting mycorrhizal [...] Read more.

Phosphorus (P) availability is a major constraint on plant growth in many forest ecosystems, yet the strategies by which different tree species acquire and utilize various forms of soil phosphorus remain poorly understood. This study investigated how coexisting tree species with contrasting mycorrhizal types, specifically arbuscular mycorrhizal (AM) and ectomycorrhizal (ECM) associations, respond to different phosphorus forms under field conditions. An in situ root bag experiment was conducted using four phosphorus treatments (control, inorganic, organic, and mixed phosphorus) across four subtropical tree species. A comprehensive set of fine root traits, including morphological, physiological, and mycorrhizal characteristics, was measured to evaluate species-specific phosphorus foraging strategies. The results showed that AM species were more responsive to phosphorus form variation than ECM species, particularly under inorganic and mixed phosphorus treatments. Significant changes in root diameter (RD), root tissue density (RTD), and acid phosphatase activity (RAP) were observed in AM species, often accompanied by higher phosphorus accumulation in fine roots. For example, RD in AM species significantly decreased under the Na₃PO₄ treatment (0.94 mm) compared to the control (1.18 mm), while ECM species showed no significant changes in RD across treatments (1.12–1.18 mm, p > 0.05). RTD in AM species significantly increased under Na₃PO₄ (0.030 g/cm³) and Mixture (0.021 g/cm³) compared to the control (0.012 g/cm³, p < 0.05), whereas ECM species exhibited consistently low RTD values across treatments (0.017–0.020 g/cm³, p > 0.05). RAP in AM species increased significantly under Na₃PO₄ (1812 nmol/g/h) and Mixture (1596 nmol/g/h) relative to the control (1348 nmol/g/h), while ECM species showed limited variation (1286–1550 nmol/g/h, p > 0.05). In contrast, ECM species displayed limited trait variation across treatments, reflecting a more conservative acquisition strategy. In addition, trait correlation analysis revealed stronger coordination among root traits in AM species. And AM species exhibited high variability across treatments, while ECM species maintained consistent trait distributions with limited plasticity. These findings suggest that AM and ECM species adopt fundamentally different phosphorus acquisition strategies. AM species rely on integrated morphological and physiological responses to variable phosphorus conditions, while ECM species maintain stable trait configurations, potentially supported by fungal symbiosis. Such divergence may contribute to functional complementarity and species coexistence in phosphorus-limited subtropical forests. Full article

(This article belongs to the Section Forest Ecophysiology and Biology)

25 pages, 5776 KiB

Open AccessArticle

Early Detection of Herbicide-Induced Tree Stress Using UAV-Based Multispectral and Hyperspectral Imagery

by Russell Main, Mark Jayson B. Felix, Michael S. Watt and Robin J. L. Hartley

Forests 2025, 16(8), 1240; https://doi.org/10.3390/f16081240 - 28 Jul 2025

Abstract

There is growing interest in the use of herbicide for the silvicultural practice of tree thinning (i.e., chemical thinning or e-thinning) in New Zealand. Potential benefits of this approach include improved stability of the standing crop in high winds, and safer and lower-cost [...] Read more.

There is growing interest in the use of herbicide for the silvicultural practice of tree thinning (i.e., chemical thinning or e-thinning) in New Zealand. Potential benefits of this approach include improved stability of the standing crop in high winds, and safer and lower-cost operations, particularly in steep or remote terrain. As uptake grows, tools for monitoring treatment effectiveness, particularly during the early stages of stress, will become increasingly important. This study evaluated the use of UAV-based multispectral and hyperspectral imagery to detect early herbicide-induced stress in a nine-year-old radiata pine (Pinus radiata D. Don) plantation, based on temporal changes in crown spectral signatures following treatment with metsulfuron-methyl. A staggered-treatment design was used, in which herbicide was applied to a subset of trees in six blocks over several weeks. This staggered design allowed a single UAV acquisition to capture imagery of trees at varying stages of herbicide response, with treated trees ranging from 13 to 47 days after treatment (DAT). Visual canopy assessments were carried out to validate the onset of visible symptoms. Spectral changes either preceded or coincided with the development of significant visible canopy symptoms, which started at 25 DAT. Classification models developed using narrow band hyperspectral indices (NBHI) allowed robust discrimination of treated and non-treated trees as early as 13 DAT (F1 score = 0.73), with stronger results observed at 18 DAT (F1 score = 0.78). Models that used multispectral indices were able to classify treatments with a similar accuracy from 18 DAT (F1 score = 0.78). Across both sensors, pigment-sensitive indices, particularly variants of the Photochemical Reflectance Index, consistently featured among the top predictors at all time points. These findings address a key knowledge gap by demonstrating practical, remote sensing-based solutions for monitoring and characterising herbicide-induced stress in field-grown radiata pine. The 13-to-18 DAT early detection window provides an operational baseline and a target for future research seeking to refine UAV-based detection of chemical thinning. Full article

(This article belongs to the Section Forest Health)

► Show Figures

Figure 1

15 pages, 3952 KiB

Open AccessArticle

Prediction of the Potentially Suitable Area for Anoplophora glabripennis (Coleoptera: Cerambycidae) in China Based on MaxEnt

by Kaiwen Tan, Mingwang Zhou, Hongjiang Hu, Ning Dong and Cheng Tang

Forests 2025, 16(8), 1239; https://doi.org/10.3390/f16081239 - 28 Jul 2025

Abstract

Anoplophora glabripennis (Asian longhorned beetle, ALB) (Motschulsky, 1854) is a local forest pest in China. Although the suitable area for this pest has some research history, it does not accurately predict the future distribution area of ALB. Accurate prediction of its suitable area [...] Read more.

Anoplophora glabripennis (Asian longhorned beetle, ALB) (Motschulsky, 1854) is a local forest pest in China. Although the suitable area for this pest has some research history, it does not accurately predict the future distribution area of ALB. Accurate prediction of its suitable area can help control the harm caused by ALB more effectively. In this study, we applied the maximum entropy model to predict the suitable area for ALB. Moreover, the prediction results revealed that ALB is distributed mainly in northern, eastern, central, southern, southwestern, and northwestern China, and its high-fit areas are located mainly in northern, northwestern, and southwestern China. The average minimum temperature in September, precipitation seasonality (coefficient of variation), the average maximum temperature in April, and average precipitation in October had the greatest influence on ALB. The greatest distribution probabilities were observed at the September average minimum temperature of 16 °C, the precipitation seasonality (coefficient of variation) of 130%, the April average maximum temperature of 14 °C, and the October average precipitation of 30 mm. Furthermore, with climate change, the non-suitability area for the ALB will show a decreasing trend in the future. The intermediate suitability area will increase, while the low and high suitability areas will first increase and then decrease. Taken together, the potentially suitable areas for ALB in China include the Beijing–Tianjin–Hebei region and the Shanghai region in North China and East China, providing a deeper understanding of ALB control. Full article

(This article belongs to the Section Forest Health)

► Show Figures

Figure 1

14 pages, 1855 KiB

Open AccessArticle

Response of Tree-Ring Oxygen Isotopes to Climate Variations in the Banarud Area in the West Part of the Alborz Mountains

by Yajun Wang, Shengqian Chen, Haichao Xie, Yanan Su, Shuai Ma and Tingting Xie

Forests 2025, 16(8), 1238; https://doi.org/10.3390/f16081238 - 28 Jul 2025

Abstract

Stable oxygen isotopes in tree rings (δ¹⁸O) serve as important proxies for climate change and offer unique advantages for climate reconstruction in arid and semi-arid regions. We established an annual δ¹⁸O chronology spanning 1964–2023 using Juniperus excelsa tree-ring samples [...] Read more.

Stable oxygen isotopes in tree rings (δ¹⁸O) serve as important proxies for climate change and offer unique advantages for climate reconstruction in arid and semi-arid regions. We established an annual δ¹⁸O chronology spanning 1964–2023 using Juniperus excelsa tree-ring samples collected from the Alborz Mountains in Iran. We analyzed relationships between δ¹⁸O and key climate variables: precipitation, temperature, Palmer Drought Severity Index (PDSI), vapor pressure (VP), and potential evapotranspiration (PET). Correlation analysis reveals that tree-ring δ¹⁸O is highly sensitive to hydroclimatic variations. Tree-ring cellulose δ¹⁸O shows significant negative correlations with annual total precipitation and spring PDSI, and significant positive correlations with spring temperature (particularly maximum temperature), April VP, and spring PET. The strongest correlation occurs with spring PET. These results indicate that δ¹⁸O responds strongly to the balance between springtime moisture supply (precipitation and soil moisture) and atmospheric evaporative demand (temperature, VP, and PET), reflecting an integrated signal of both regional moisture availability and energy input. The pronounced response of δ¹⁸O to spring evaporative conditions highlights its potential for capturing high-resolution changes in spring climatic conditions. Our δ¹⁸O series remained stable from the 1960s to the 1990s, but showed greater interannual variability after 2000, likely linked to regional warming and climate instability. A comparison with the δ¹⁸O variations from the eastern Alborz Mountains indicates that, despite some differences in magnitude, δ¹⁸O records from the western and eastern Alborz Mountains show broadly similar variability patterns. On a larger climatic scale, δ¹⁸O correlates significantly and positively with the Niño 3.4 index but shows no significant correlation with the Arctic Oscillation (AO) or the North Atlantic Oscillation (NAO). This suggests that ENSO-driven interannual variability in the tropical Pacific plays a key role in regulating regional hydroclimatic processes. This study confirms the strong potential of tree-ring oxygen isotopes from the Alborz Mountains for reconstructing hydroclimatic conditions and high-frequency climate variability. Full article

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

► Show Figures

Figure 1

21 pages, 8413 KiB

Open AccessArticle

Characterization of Low-Temperature Waste-Wood-Derived Biochar upon Chemical Activation

by Bilge Yilmaz, Vasiliki Kamperidou, Serhatcan Berk Akcay, Turgay Kar, Hilal Fazli and Temel Varol

Forests 2025, 16(8), 1237; https://doi.org/10.3390/f16081237 - 27 Jul 2025

Abstract

Depending on the feedstock type and the pyrolysis conditions, biochars exhibit different physical, chemical, and structural properties, which highly influence their performance in various applications. This study presents a comprehensive characterization of biochar materials derived from the waste wood of pine (Pinus [...] Read more.

Depending on the feedstock type and the pyrolysis conditions, biochars exhibit different physical, chemical, and structural properties, which highly influence their performance in various applications. This study presents a comprehensive characterization of biochar materials derived from the waste wood of pine (Pinus sylvestris L.) and beech (Fagus sylvatica) after low-temperature pyrolysis at 270 °C, followed by chemical activation using zinc chloride. The resulting materials were thoroughly analyzed in terms of their chemical composition (FTIR), thermal behavior (TGA/DTG), structural morphology (SEM and XRD), elemental analysis, and particle size distribution. The successful modification of raw biomass into carbon-rich structures of increased aromaticity and thermal stability was confirmed. Particle size analysis revealed that the activated carbon of Fagus sylvatica (FSAC) exhibited a monomodal distribution, indicating high homogeneity, whereas Pinus sylvestris-activated carbon showed a distinct bimodal distribution. This heterogeneity was supported by elemental analysis, revealing a higher inorganic content in pine-activated carbon, likely contributing to its dimensional instability during activation. These findings suggest that the uniform morphology of beech-activated carbon may be advantageous in filtration and adsorption applications, while pine-activated carbon’s heterogeneous structure could be beneficial for multifunctional systems requiring variable pore architectures. Overall, this study underscored the potential of chemically activated biochar from lignocellulosic residues for customized applications in environmental and material science domains. Full article

(This article belongs to the Section Wood Science and Forest Products)

18 pages, 2069 KiB

Open AccessArticle

The Initial Impact of a Hydroelectric Reservoir on the Floristics, Structure, and Dynamics of Adjacent Forests in the Southern Amazon

by Jesulino Alves da Rocha-Filho, Marco Antônio Camillo de Carvalho, Fabiana Ferreira Cabral Gomes, José Hypolito Piva, Beatriz Schwantes Marimon, Oscar Mitsuo Yamashita and Ben Hur Marimon-Junior

Forests 2025, 16(8), 1236; https://doi.org/10.3390/f16081236 - 27 Jul 2025

Abstract

This study assesses whether the rise in water level—following three years of reservoir filling at the Teles Pires Hydroelectric Plant (135.6 km² water surface) in Southern Amazonia—has affected the floristic composition, structure, and dynamics of adjacent forests. We established 62 permanent plots [...] Read more.

This study assesses whether the rise in water level—following three years of reservoir filling at the Teles Pires Hydroelectric Plant (135.6 km² water surface) in Southern Amazonia—has affected the floristic composition, structure, and dynamics of adjacent forests. We established 62 permanent plots (2000 m² each) across a topographic gradient from the reservoir margin and conducted annual tree inventories for individuals with DBH ≥ 10 cm from 2014 to 2017. A total of 6322 individuals were recorded, representing 322 species, 210 genera, and 61 families. Fabaceae was the most abundant family, and the ten species with the highest importance value index (IVI) before reservoir filling remained dominant afterward. The forests exhibited high species richness and were characterized by a few common and many rare species. Mortality rates were highest within 10 m of elevation from the maximum reservoir level, indicating possible hydrological impacts, although no abnormal dieback or sharp shifts in floristic structure were observed. These results suggest limited short-term effects on species composition, but subtle changes in vegetation dynamics underscore the importance of long-term monitoring. Full article

(This article belongs to the Special Issue Tropical Forests, Water Cycle, Global Cycles of Greenhouse Gases and Climate Change)

20 pages, 1338 KiB

Open AccessArticle

Spatial Patterning and Growth of Naturally Regenerated Eastern White Pine in a Northern Hardwood Silviculture Experiment

by David A. Kromholz, Christopher R. Webster and Michael D. Hyslop

Forests 2025, 16(8), 1235; https://doi.org/10.3390/f16081235 - 26 Jul 2025

Abstract

In forests dominated by deciduous tree species, coniferous species are often disproportionately important because of their contrasting functional traits. Eastern white pine (Pinus strobus L.), once a widespread emergent canopy species, co-occurs with deciduous hardwoods in the northern Lake States, but is [...] Read more.

In forests dominated by deciduous tree species, coniferous species are often disproportionately important because of their contrasting functional traits. Eastern white pine (Pinus strobus L.), once a widespread emergent canopy species, co-occurs with deciduous hardwoods in the northern Lake States, but is often uncommon in contemporary hardwood stands. To gain insights into the potential utility of hardwood management strategies for simultaneously regenerating white pine, we leveraged a northern hardwood silvicultural experiment with scattered overstory pine. Seven growing seasons post-harvest, we conducted a complete census of white pine regeneration (height ≥ 30 cm) and mapped their locations and the locations of potential seed trees. Pine regeneration was sparse and strongly spatially aggregated, with most clusters falling within potential seed shadows of overstory pines. New recruits were found to have the highest density in a scarified portion of the study area leeward of potential seed trees. Low regeneration densities within treatment units, strong spatial aggregation, and the spatial arrangement of potential seed trees precluded generalizable inferences regarding the utility of specific treatment combinations. Nevertheless, our results underscore the critical importance of residual overstory pines as seed sources and highlight the challenges associated with realizing their potential in managed northern hardwoods. Full article

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

18 pages, 1193 KiB

Open AccessArticle

The Importance of Native Trees and Forests: Smallholder Farmers’ Views in South-Western Rwanda

by Franklin Bulonvu, Gérard Imani, Myriam Mujawamariya, Beth A. Kaplin, Patrick Mutabazi and Aida Cuni-Sanchez

Forests 2025, 16(8), 1234; https://doi.org/10.3390/f16081234 - 26 Jul 2025

Abstract

Despite increasing interest in including indigenous and local people in forest restoration initiatives, their views on which species are most useful, or reasons behind not planting native tree species are often ignored. Focused on south-western Rwanda, this study addressed these knowledge gaps. We [...] Read more.

Despite increasing interest in including indigenous and local people in forest restoration initiatives, their views on which species are most useful, or reasons behind not planting native tree species are often ignored. Focused on south-western Rwanda, this study addressed these knowledge gaps. We carried out 12 focus group discussions with village elders to determine the following: main benefits provided by native forests, the native species they prefer for different uses, and the main barriers to species’ cultivation. Then, considering other key information from the literature, we performed a ranking exercise to determine which native species had the greatest potential for large-scale tree planting initiatives. Our results show that native forests provide 17 benefits to local communities, some of which cannot be replaced by plantations with exotic species. Among the 26 tree species identified as most useful for timber, firewood, medicine and fodder, ten were ranked as with the greatest potential for restoration initiatives. Of these, two had not been included in recent experimental plantations using native species in Rwanda, and none were considered among the priority species for domestication in Africa. Overall, our study highlights the need to better connect the ecological and social dimension of forest reforestation initiatives in multiple contexts. Full article

(This article belongs to the Special Issue Forests as Nature-Based Solutions: Ecosystem Services, Multiple Benefits, and Trade-Offs)

► Show Figures

Figure 1

30 pages, 4113 KiB

Open AccessArticle

Genetic Variation Associated with Leaf Phenology in Pedunculate Oak (Quercus robur L.) Implicates Pathogens, Herbivores, and Heat Stress as Selective Drivers

by Jonatan Isaksson, Marcus Hall, Iryna Rula, Markus Franzén, Anders Forsman and Johanna Sunde

Forests 2025, 16(8), 1233; https://doi.org/10.3390/f16081233 - 26 Jul 2025

Abstract

Leaf phenology of trees responds to temperature and photoperiod cues, mediated by underlying genes and plasticity. However, uncertainties remain regarding how smaller-scale phenological variation in cold-limited regions has been affected by modified selection pressures from herbivores, pathogens, and climate conditions, and whether this [...] Read more.

Leaf phenology of trees responds to temperature and photoperiod cues, mediated by underlying genes and plasticity. However, uncertainties remain regarding how smaller-scale phenological variation in cold-limited regions has been affected by modified selection pressures from herbivores, pathogens, and climate conditions, and whether this leaves genetic signatures allowing for projections of future responses. We investigated environmental correlates and genetic variation putatively associated with spring and autumn leaf phenology in northern range margin oak (Quercus robur L.) populations in Sweden (55.6° N–60.8° N). Results suggested that budburst occurred later at higher latitudes and in locations with colder spring (April) temperatures, whereas leaf senescence occurred earlier at higher latitudes. Several candidate loci associated with phenology were identified (n = 40 for budburst and 47 for leaf senescence), and significant associations between these loci and latitude were detected. Functions associated with some of the candidate loci, as identified in previous studies, included host defence and heat stress tolerance. The proportion of polymorphic candidate loci associated with budburst decreased with increasing latitude, towards the range margin. Overall, the Swedish oak population seems to comprise genetic diversity in phenology-related traits that may provide resilience to a rapidly changing climate. Full article

(This article belongs to the Special Issue Woody Plant Phenology in a Changing Climate, 2nd Edition)

► Show Figures

Figure 1

20 pages, 937 KiB

Open AccessArticle

Timber Industrial Policies and Export Competitiveness: Evidence from China’s Wood-Processing Sector in the Context of Sustainable Development

by Yulan Sun, Fangzheng Wang, Weiming Lin, Yongwu Dai and Jiajun Lin

Forests 2025, 16(8), 1232; https://doi.org/10.3390/f16081232 - 26 Jul 2025

Abstract

In the era of climate change, the strategic importance of forestry products for sustainable development is increasingly recognized. Amid a global resurgence of industrial policy aimed at addressing environmental challenges, this study investigates the impact of China’s central and provincial green industrial policies [...] Read more.

In the era of climate change, the strategic importance of forestry products for sustainable development is increasingly recognized. Amid a global resurgence of industrial policy aimed at addressing environmental challenges, this study investigates the impact of China’s central and provincial green industrial policies on the export competitiveness of wood-processing enterprises. Utilizing firm-level data from the China Industrial Enterprise Database and China Customs Export Database (2000–2013), we apply a double machine learning (DML) approach and construct a heterogeneous competitiveness model to evaluate policy effects along two dimensions: export quantity (volume and intensity) and export quality (product complexity and consumer-perceived quality). Our findings reveal a clear dichotomy in policy outcomes. While industrial policies have significantly improved export product complexity—reflecting China’s comparative advantage in labor-intensive production—they have had limited or even negative effects on export volume, intensity, and product quality. This suggests that current policy frameworks disproportionately reward horizontal innovation (product diversification) while neglecting vertical upgrading (quality enhancement), thereby hindering comprehensive export performance gains. Those results highlight the need for more balanced and targeted policy design. By aligning industrial policy instruments with both complexity and quality objectives, policymakers can better support the sustainable transformation of China’s forestry sector and enhance its competitiveness in global value chains. Full article

(This article belongs to the Section Forest Economics, Policy, and Social Science)

► Show Figures

Figure 1

21 pages, 958 KiB

Open AccessArticle

The Impact of Supply and Demand Shocks on Chinese Wood Market

by Yeheng Jiang, Haiying Su and Weicong Qian

Forests 2025, 16(8), 1231; https://doi.org/10.3390/f16081231 - 26 Jul 2025

Abstract

China’s timber market is very complex and heterogeneous, and is experiencing the impact of the construction of national reserve forests and the downturn in the real estate sector. By setting up a partial equilibrium model which reflects the heterogeneity of China’s wood market, [...] Read more.

China’s timber market is very complex and heterogeneous, and is experiencing the impact of the construction of national reserve forests and the downturn in the real estate sector. By setting up a partial equilibrium model which reflects the heterogeneity of China’s wood market, not only difference among domestic timber groups can be identified, but the dissimilarity of imported timber can also be differentiated from the aspects of species and sources. This model is capable of capturing the effects of macroeconomic conditions, forestry sector policies, and trade cost variations on China’s timber market structure. According to simulations of supply shocks, China’s large-diameter log capacity enhancement will have a noticeable crowding-out effect on imported timber, suggesting the diameter of logs is an important factor for market entities to make trade-offs between domestic and imported timber. Amidst both supply and demand shocks, the equilibrium quantity changes in China’s domestic small-diameter logs and imported timber are dominated by demand shocks, whereas the equilibrium quantity change in China’s domestic large-diameter logs is dominated by supply shocks; moreover, only domestic large-diameter logs realize quantity increase in double shocks; this improves China’s domestic timber supply structure, and is a good example of “opportunities in crisis” in the face of negative demand shocks. Full article

(This article belongs to the Special Issue Trends and Challenges for Management in Wood-Based Sector in the Digital Age)

13 pages, 897 KiB

Open AccessArticle

Recovery Following a Drought-Induced Population Decline in an Exudivorous Forest Mammal

by Ross L. Goldingay

Forests 2025, 16(8), 1230; https://doi.org/10.3390/f16081230 - 26 Jul 2025

Abstract

The likely increase in the frequency and severity of droughts with climate warming will pose an enormous challenge for the conservation of forest biodiversity. Documenting the response of species to recent droughts can inform future conservation actions. Mammals that breed and mature slowly [...] Read more.

The likely increase in the frequency and severity of droughts with climate warming will pose an enormous challenge for the conservation of forest biodiversity. Documenting the response of species to recent droughts can inform future conservation actions. Mammals that breed and mature slowly may be especially vulnerable to drought-induced disruption to breeding. The yellow-bellied glider (Petaurus australis, Shaw, 1791) is a threatened low-density, arboreal marsupial of eastern Australia. Following a severe drought in 2019, one population had declined by 48% by 2021. The present study investigated whether this population had recovered 3–4 years (2022 and 2023) after that drought. Audio surveys of this highly vocal species were conducted at 42 sites, sampling > 1000 h per year, and producing recordings of 2038–2856 call sequences. The probability of occupancy varied little across the two survey years (0.92–0.97). Local abundance in 2023 had returned to pre-drought levels (45% of occupied sites had ≥3 individuals compared to 6% in 2021). These findings show a recovery from a drought-induced decline required at least 3 years, in keeping with the slow life history traits of this species. This study highlights the importance of considering a species’ life history strategy when evaluating its sensitivity to drought. Full article

(This article belongs to the Section Forest Biodiversity)

21 pages, 3566 KiB

Open AccessArticle

Dendrometer-Based Analysis of Intra-Annual Growth and Water Status in Two Pine Species in a Mediterranean Forest Stand Under a Semi-Arid Climate

by Mehmet S. Özçelik

Forests 2025, 16(8), 1229; https://doi.org/10.3390/f16081229 - 26 Jul 2025

Abstract

Stem radius growth (GRO), tree water deficit (TWD), and maximum daily shrinkage (MDS) were monitored throughout 2023 in a semi-arid Mediterranean forest stand in Burdur, Türkiye, where Pinus nigra subsp. pallasiana (Lamb.) Holmboe and Pinus brutia Ten. naturally co-occur. These indicators, derived from [...] Read more.

Stem radius growth (GRO), tree water deficit (TWD), and maximum daily shrinkage (MDS) were monitored throughout 2023 in a semi-arid Mediterranean forest stand in Burdur, Türkiye, where Pinus nigra subsp. pallasiana (Lamb.) Holmboe and Pinus brutia Ten. naturally co-occur. These indicators, derived from electronic band dendrometers, were analyzed in relation to key climatic variables. Results indicated that P. brutia had a longer growth period, while P. nigra exhibited a higher average daily increment under the environmental conditions of 2023 at the study site. Annual stem growth was nearly equal for both species. Based on dendrometer observations, P. brutia exhibited lower normalized TWD and higher normalized MDS values under varying vapor pressure deficit (VPD) and soil water potential (SWP) conditions. A linear mixed-effects model further confirmed that P. brutia consistently maintained lower TWD than P. nigra across a wide climatic range, suggesting a comparatively lower degree of drought-induced water stress. GRO was most influenced by air temperature and VPD, and negatively by SWP. TWD was strongly affected by both VPD and SWP, while MDS was primarily linked to minimum air temperature and VPD. Moreover, MDS in P. brutia appeared more sensitive to climate variability compared to P. nigra. Although drought limited stem growth in both species during the study year, the lower TWD and higher MDS observed in P. brutia may indicate distinct physiological strategies for coping with drought. These findings offer preliminary insights into interspecific differences in water regulation under the particular climatic conditions observed during the study year in this semi-arid Mediterranean ecosystem. Full article

(This article belongs to the Section Forest Ecophysiology and Biology)

► Show Figures

Figure 1

16 pages, 1913 KiB

Open AccessArticle

Stem Volume Prediction of Chamaecyparis obtusa in South Korea Using Machine Learning and Field-Measured Tree Variables

by Chiung Ko, Jintaek Kang and Donggeun Kim

Forests 2025, 16(8), 1228; https://doi.org/10.3390/f16081228 - 25 Jul 2025

Abstract

Accurate estimation of individual tree stem volume is essential for forest resource assessment and the implementation of sustainable forest management. In South Korea, traditional regression models based on non-destructive and easily measurable field variables such as diameter at breast height (DBH) and total [...] Read more.

Accurate estimation of individual tree stem volume is essential for forest resource assessment and the implementation of sustainable forest management. In South Korea, traditional regression models based on non-destructive and easily measurable field variables such as diameter at breast height (DBH) and total height (TH) have been widely used to construct stem volume tables. However, these models often fail to adequately capture the nonlinear taper of tree stems. In this study, we evaluated and compared the predictive performance of traditional regression models and two machine learning algorithms—Random Forest (RF) and Extreme Gradient Boosting (XGBoost)—using stem profile data from 1000 destructively sampled Chamaecyparis obtusa trees collected across 318 sites nationwide. To ensure compatibility with existing national stem volume tables, all models used only DBH and TH as input variables. The results showed that all three models achieved high predictive accuracy (R² > 0.997), with XGBoost yielding the lowest RMSE (0.0164 m³) and MAE (0.0126 m³). Although differences in performance among the models were marginal, the machine learning approaches demonstrated flexible and generalizable alternatives to conventional models, providing a practical foundation for large-scale forest inventory and the advancement of digital forest management systems. Full article

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

► Show Figures

Figure 1

19 pages, 2786 KiB

Open AccessArticle

Performance of Oriented Strand Boards Made with Jack Pine Strands Produced by an Innovative Strander-Canter

by Rosilei Garcia, Alain Cloutier, Irsan Alipraja, Roger E. Hernández and Ahmed Koubaa

Forests 2025, 16(8), 1227; https://doi.org/10.3390/f16081227 - 25 Jul 2025

Abstract

Canadian sawmills commonly use chipper-canters to process softwood logs into squared lumber and wood chips for pulp mills. However, the declining demand for newsprint and print paper has led to an oversupply of wood chips, resulting in economic losses and environmental concerns. To [...] Read more.

Canadian sawmills commonly use chipper-canters to process softwood logs into squared lumber and wood chips for pulp mills. However, the declining demand for newsprint and print paper has led to an oversupply of wood chips, resulting in economic losses and environmental concerns. To address this issue, a strander-canter capable of producing both softwood cants and strands for oriented strand board (OSB) presents a promising alternative. This study evaluates the feasibility of using jack pine strands generated by a novel strander-canter equipped with a cutterhead for OSB strand production. Strands were generated from frozen and unfrozen logs under varying cutting parameters and incorporated in the core layer of the panels. Industrial aspen strands were used for the surface layers. OSB panels were assessed for mechanical and physical properties following the CSA O325:21 standard. Strand size distribution and vertical density profiles were also analyzed. The results indicated that panels made from jack pine strands demonstrated bending and internal bond properties that were either comparable to or superior to those of the control panels. However, including jack pine strands in the core layer increased the thickness swelling of the panels. Full article

(This article belongs to the Special Issue Properties and Uses of Value-Added Wood-Based Products and Composites)

► Show Figures

Figure 1

21 pages, 3397 KiB

Open AccessArticle

Climate-Driven Habitat Shifts and Conservation Implications for the Submediterranean Oak Quercus pyrenaica Willd.

by Isabel Passos, Carlos Vila-Viçosa, João Gonçalves, Albano Figueiredo and Maria Margarida Ribeiro

Forests 2025, 16(8), 1226; https://doi.org/10.3390/f16081226 - 25 Jul 2025

Abstract

Climate change poses a major threat to forests, impacting the distribution and viability of key species. Quercus pyrenaica Willd., a marcescent oak endemic to the Iberian Peninsula (Portugal and Spain) and southwestern France and a structural species in submediterranean forests, is particularly susceptible [...] Read more.

Climate change poses a major threat to forests, impacting the distribution and viability of key species. Quercus pyrenaica Willd., a marcescent oak endemic to the Iberian Peninsula (Portugal and Spain) and southwestern France and a structural species in submediterranean forests, is particularly susceptible to shifts in temperature and precipitation patterns. Aiming to assess its potential loss of suitable area under future climate scenarios, we developed high-resolution spatial distribution models to project the future habitat suitability of Q. pyrenaica under two climate change scenarios (SSP3-7.0 and SSP5-8.5) for the periods 2070 and 2100. Our model, which has an excellent predictive performance (AUC of 0.971 and a TSS of 0.834), indicates a predominantly northward shift in the potential distribution of the species, accompanied by substantial habitat loss in southern and lowland regions. Long-term potential suitable area may shrink to 42% of that currently available. This, combined with the limited natural dispersal capacity of the species, highlights the urgency of targeted management and conservation strategies. These results offer critical insights to inform conservation strategies and forest management under ongoing climate change. Full article

(This article belongs to the Special Issue Climate and Land-Use Change Effects on the Biogeography of Woody Plant Species and Biodiversity Conservation)

► Show Figures

Figure 1

21 pages, 7145 KiB

Open AccessArticle

Derivation and Application of Allometric Equations to Quantify the Net Primary Productivity (NPP) of the Salix pierotii Miq. Community as a Representative Riparian Vegetation Type

by Bong Soon Lim, Jieun Seok, Seung Jin Joo, Jeong Cheol Lim and Chang Seok Lee

Forests 2025, 16(8), 1225; https://doi.org/10.3390/f16081225 - 25 Jul 2025

Abstract

International efforts are underway to implement carbon neutrality policies in rapidly changing climate conditions. This situation has strongly demanded the discovery of novel carbon sinks. The Salix genus has attracted attention as a promising carbon sink owing to its rapid growth and efficient [...] Read more.

International efforts are underway to implement carbon neutrality policies in rapidly changing climate conditions. This situation has strongly demanded the discovery of novel carbon sinks. The Salix genus has attracted attention as a promising carbon sink owing to its rapid growth and efficient use as a biofuel in short-rotation cultivation. The present study aims to derive an allometric equation and conduct stem analysis as fundamental tools for estimating net primary productivity (NPP) in Salix pierotii Miq. stand, which is increasingly acknowledged as an important emerging carbon sink. The allometric equations derived showed a high explanatory rate and fitness (R² ranged from 0.74 to 0.99). The allometric equations between DBH and stem volume and biomass derived in the process of stem analysis also showed a high explanatory rate and fitness (R² ranged from 0.87 to 0.94). The NPPs calculated based on the allometric equation derived and stem analysis were 11.87 tonC∙ha⁻¹∙yr⁻¹ and 15.70 tonC∙ha⁻¹∙yr⁻¹, respectively. These results show that the S. pierotii community, recognized as the representative riparian vegetation, could play an important role as a carbon sink. In this context, an assessment of the carbon absorption capacity of riparian vegetation such as willow communities could contribute significantly to achieving carbon neutrality goals. Full article

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

► Show Figures

Figure 1

24 pages, 12938 KiB

Open AccessArticle

Spatial Distribution of Mangrove Forest Carbon Stocks in Marismas Nacionales, Mexico: Contributions to Climate Change Adaptation and Mitigation

by Carlos Troche-Souza, Edgar Villeda-Chávez, Berenice Vázquez-Balderas, Samuel Velázquez-Salazar, Víctor Hugo Vázquez-Morán, Oscar Gerardo Rosas-Aceves and Francisco Flores-de-Santiago

Forests 2025, 16(8), 1224; https://doi.org/10.3390/f16081224 - 25 Jul 2025

Abstract

Mangrove forests are widely recognized for their effectiveness as carbon sinks and serve as critical ecosystems for mitigating the effects of climate change. Current research lacks comprehensive, large-scale carbon storage datasets for wetland ecosystems, particularly across Mexico and other understudied regions worldwide. Therefore, [...] Read more.

Mangrove forests are widely recognized for their effectiveness as carbon sinks and serve as critical ecosystems for mitigating the effects of climate change. Current research lacks comprehensive, large-scale carbon storage datasets for wetland ecosystems, particularly across Mexico and other understudied regions worldwide. Therefore, the objective of this study was to develop a high spatial resolution map of carbon stocks, encompassing both aboveground and belowground components, within the Marismas Nacionales system, which is the largest mangrove complex in northeastern Pacific Mexico. Our approach integrates primary field data collected during 2023–2024 and incorporates some historical plot measurements (2011–present) to enhance spatial coverage. These were combined with contemporary remote sensing data, including Sentinel-1, Sentinel-2, and LiDAR, analyzed using Random Forest algorithms. Our spatial models achieved strong predictive accuracy (R² = 0.94–0.95), effectively resolving fine-scale variations driven by canopy structure, hydrologic regime, and spectral heterogeneity. The application of Local Indicators of Spatial Association (LISA) revealed the presence of carbon “hotspots,” which encompass 33% of the total area but contribute to 46% of the overall carbon stocks, amounting to 21.5 Tg C. Notably, elevated concentrations of carbon stocks are observed in the central regions, including the Agua Brava Lagoon and at the southern portion of the study area, where pristine mangrove stands thrive. Also, our analysis reveals that 74.6% of these carbon hotspots fall within existing protected areas, demonstrating relatively effective—though incomplete—conservation coverage across the Marismas Nacionales wetlands. We further identified important cold spots and ecotones that represent priority areas for rehabilitation and adaptive management. These findings establish a transferable framework for enhancing national carbon accounting while advancing nature-based solutions that support both climate mitigation and adaptation goals. Full article

(This article belongs to the Special Issue Forest Inventory and Forest Carbon Assessments with Remote Sensing Technologies)

► Show Figures

Graphical abstract

18 pages, 3675 KiB

Open AccessArticle

Mechanical Property Prediction of Wood Using a Backpropagation Neural Network Optimized by Adaptive Fractional-Order Particle Swarm Algorithm

by Jiahui Huang and Zhufang Kuang

Forests 2025, 16(8), 1223; https://doi.org/10.3390/f16081223 - 25 Jul 2025

Abstract

This study proposes a novel LK-BP-AFPSO model for the nondestructive evaluation of wood mechanical properties, combining a backpropagation neural network (BP) with adaptive fractional-order particle swarm optimization (AFPSO) and Liang–Kleeman (LK) information flow theory. The model accurately predicts four key mechanical properties—longitudinal tensile [...] Read more.

This study proposes a novel LK-BP-AFPSO model for the nondestructive evaluation of wood mechanical properties, combining a backpropagation neural network (BP) with adaptive fractional-order particle swarm optimization (AFPSO) and Liang–Kleeman (LK) information flow theory. The model accurately predicts four key mechanical properties—longitudinal tensile strength (SPG), modulus of elasticity (MOE), bending strength (MOR), and longitudinal compressive strength (CSP)—using only nondestructive physical features. Tested across diverse wood types (fast-growing YKS, red-heart CSH/XXH, and iron-heart XXT), the framework demonstrates strong generalizability, achieving an average prediction accuracy (R²) of 0.986 and reducing mean absolute error (MAE) by 23.7% compared to conventional methods. A critical innovation is the integration of LK causal analysis, which quantifies feature–target relationships via information flow metrics, effectively eliminating 29.5% of spurious correlations inherent in traditional feature selection (e.g., PCA). Experimental results confirm the model’s robustness, particularly for heartwood variants, while its adaptive fractional-order optimization accelerates convergence by 2.1× relative to standard PSO. This work provides a reliable, interpretable tool for wood quality assessment, with direct implications for grading systems and processing optimization in the forestry industry. Full article

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

► Show Figures

Figure 1

Journal Description

Forests

Latest Articles

Journal Menu

Journal Browser

Highly Accessed Articles

Latest Books

E-Mail Alert

News

Topics

Conferences

Special Issues

Topical Collections

Further Information

Guidelines

MDPI Initiatives

Follow MDPI