Forests

16 pages, 2416 KiB

Open AccessArticle

Volcanic Impact Patterns in Tree Rings from Historical Wood in Northern Fennoscandia’s Old Churches

by Oleg I. Shumilov, Elena A. Kasatkina, Mauri Timonen and Evgeniy O. Potorochin

Forests 2025, 16(4), 573; https://doi.org/10.3390/f16040573 (registering DOI) - 26 Mar 2025

This study revealed a significant reduction in tree growth across northern Fennoscandia following the 1600 AD eruption of Huaynaputina in Peru, the most powerful volcanic event in South America over the past two millennia. In the analysis, we utilized six tree-ring chronologies, which [...] Read more.

This study revealed a significant reduction in tree growth across northern Fennoscandia following the 1600 AD eruption of Huaynaputina in Peru, the most powerful volcanic event in South America over the past two millennia. In the analysis, we utilized six tree-ring chronologies, which included the Finnish super-long chronology (5634 BC–2004 AD), the Kola Peninsula chronology (1445–2004 AD), and historical chronologies derived from old wooden churches in Finnish Lapland and Karelia, Russia. Using a superposed epoch analysis across these chronologies revealed a significant 24% (p < 0.01) decline in tree-ring growth in 1601 compared to the previous six years. The northernmost records, the Finnish super-long chronology (72%, p < 0.001) and the Sodankylä Old Church chronology (67%, p < 0.001), showed the most pronounced decreases. Statistical analysis confirmed significant (p < 0.05) similarities in tree-ring responses across all chronologies from 1601 to 1608. These findings underscore the reliability of using the 1600 Huaynaputina eruption as a chronological marker for dating historic wooden churches in northern Fennoscandia that were likely built between the late 17th and early 18th centuries. Additionally, analyzing church wood may provide insights into past climate patterns and environmental conditions linked to the eruption. Full article

(This article belongs to the Special Issue Wood as Cultural Heritage Material: 2nd Edition)

► Show Figures

Figure 1

11 pages, 11219 KiB

Open AccessArticle

An Accelerated Test Method for Evaluating the Performance of Wood Pole Fumigants

by Matthew J. Konkler, Thomas L. Woods, Randy S. Gross, Jeffrey J. Morrell and Gerald Presley

Forests 2025, 16(4), 572; https://doi.org/10.3390/f16040572 (registering DOI) - 26 Mar 2025

Abstract

Dazomet (tetrahydro-3,5-dimethyl-2H-1,3,5-thiadiazine-2-thione) is a solid fumigant that breaks down into gaseous methylisothiocyanate (MITC) in the presence of water, a process that can be enhanced by the addition of accelerant chemicals. Experiments to discover the ideal conditions for dazomet decomposition were largely performed at [...] Read more.

Dazomet (tetrahydro-3,5-dimethyl-2H-1,3,5-thiadiazine-2-thione) is a solid fumigant that breaks down into gaseous methylisothiocyanate (MITC) in the presence of water, a process that can be enhanced by the addition of accelerant chemicals. Experiments to discover the ideal conditions for dazomet decomposition were largely performed at the lab scale or on field-scale full utility poles or sections thereof. A rapid assessment method in wood commodities would improve the ability to assess a wider range of treatments to improve performance. Here, we present a method to test dazomet performance at the mesocosm scale in 102 × 152 mm (4 × 6-inch nominal) lumber. The protocol was trialed using two EPA-registered dazomet formulations to produce MITC under varying moisture conditions using different copper-containing accelerants. The test allowed the assessment of MITC levels at different locations and the full visual inspection of the treatment hole after splitting the block. MITC levels tended to be higher in the wood interior, closer to the treatment holes in test blocks. Below-ground portions also tended to have higher MITC levels at higher-moisture conditions. The method developed reduces the time required to test dazomet formulations and application methods in whole wood and will help improve the development of new dazomet formulations and application methods. Full article

(This article belongs to the Special Issue Wood Durability and Protection)

► Show Figures

Figure 1

24 pages, 31002 KiB

Open AccessArticle

Reducing Forest Fragmentation in Yunnan Province Dominated by Afforestation Projects

by Yan Ma, Shaohua Zhang, Kun Yang, Yan Rao, Xiaofang Yang, Wenxia Zeng, Jing Liu and Changyou Bi

Forests 2025, 16(4), 571; https://doi.org/10.3390/f16040571 - 25 Mar 2025

Abstract

As a critical ecological security barrier, Yunnan Province has significantly reduced forest fragmentation through ecological restoration programs in recent years. However, the optimization process of the forest landscape and the most effective ecological restoration projects remain unclear. Our study combined land use data [...] Read more.

As a critical ecological security barrier, Yunnan Province has significantly reduced forest fragmentation through ecological restoration programs in recent years. However, the optimization process of the forest landscape and the most effective ecological restoration projects remain unclear. Our study combined land use data with 13 driving factors, including meteorological and socioeconomic data, to analyze the spatial distribution, temporal dynamics, and key ecological restoration programs of forest fragmentation using dynamic and static indexes, morphological spatial pattern analysis, boosted regression tree models, and partitioned statistical methods. We found that over the past 30 years, FF has significantly decreased. Fragmentation was higher before 2000 but has steadily declined, with eastern regions more fragmented than western areas. Forest landscapes have transitioned from degradation to recovery, with core forest areas expanding by 6997.72 km². Afforestation was the main driver, adding 238,109.21 km² of forest cover, while reforestation contributed 17,254.47 km², improving patch size and connectivity. Regionally, the southwest has lower fragmentation due to ample rainfall and reforestation efforts, while central and northeastern areas face higher fragmentation from drought, human activities, and urban expansion. Our study offers a scientific basis for formulating effective ecological restoration policies. Full article

(This article belongs to the Special Issue Remote Sensing Approach for Early Detection of Forest Disturbance)

► Show Figures

Figure 1

25 pages, 17010 KiB

Open AccessArticle

Estimation of Tree Species Diversity in Warm Temperate Forests via GEDI and GF-1 Imagery

by Lei Zhang, Liu Yang, Jinhua Sun, Qimeng Zhu, Ting Wang and Hui Zhao

Forests 2025, 16(4), 570; https://doi.org/10.3390/f16040570 - 25 Mar 2025

Abstract

Estimates of tree species diversity via traditional optical remote sensing are based only on the spectral variation hypothesis (SVH); however, this approach does not account for the vertical structure of a forest. The relative height (RH) indices derived from GEDI spaceborne LiDAR provide [...] Read more.

Estimates of tree species diversity via traditional optical remote sensing are based only on the spectral variation hypothesis (SVH); however, this approach does not account for the vertical structure of a forest. The relative height (RH) indices derived from GEDI spaceborne LiDAR provide vertical vegetation structure information through waveform decomposition. Although RH indices have been widely studied, the optimal RH index for tree species diversity estimation remains unclear. This study integrated GF-1 optical imagery and GEDI LiDAR data to estimate tree species diversity in a warm temperate forest. First, random forest plus residual kriging (RFRK) was employed to achieve wall-to-wall mapping of the GEDI-derived indices. Second, recursive feature elimination (RFE) was applied to select relevant spectral and LiDAR features. The random forest (RF), support vector machine (SVM), and k-nearest neighbor (kNN) methods were subsequently applied to estimate tree species diversity through remote sensing data. The results indicated that multisource data achieved greater accuracy in tree species diversity estimation (average R² = 0.675, average RMSE = 0.750) than single-source data (average R² = 0.636, average RMSE = 0.754). Among the three machine learning methods, the RF model (R² = 0.760, RMSE = 2.090, MAE = 1.624) was significantly more accurate than the SVM (R² = 0.571, RMSE = 2.556, MAE = 1.995) and kNN (R² = 0.715, RMSE = 2.084, MAE = 1.555) models. Moreover, mean_mNDVI, mean_RDVI, and mean_Blue were identified as the most important spectral features, whereas RH30 and RH98 were crucial features derived from LiDAR for establishing models of tree species diversity. Spatially, tree species diversity was high in the west and low in the east in the study area. This study highlights the potential of integrating optical imagery and spaceborne LiDAR for tree species diversity modeling and emphasizes that low RH indices are most indicative of middle- to lower-canopy tree species diversity. Full article

(This article belongs to the Special Issue Applications of Optical and Active Remote Sensing in Forestry)

► Show Figures

Figure 1

29 pages, 5296 KiB

Open AccessArticle

Structure and Composition of a Selectively Logged Miombo Woodland in Central Mozambique

by Américo Manjate, Eliakimu Zahabu, Ulrik Ilstedt, Andrade Egas and Rosa Goodman

Forests 2025, 16(4), 569; https://doi.org/10.3390/f16040569 (registering DOI) - 25 Mar 2025

Abstract

This study assessed the structure and composition of a Miombo woodland stand subjected to selective logging through a forest inventory, measuring all trees with DBH ≥ 10 cm across 34 plots (1 ha each) for diameter, height, stem quality, and health status. The [...] Read more.

This study assessed the structure and composition of a Miombo woodland stand subjected to selective logging through a forest inventory, measuring all trees with DBH ≥ 10 cm across 34 plots (1 ha each) for diameter, height, stem quality, and health status. The stand had a mean stem density of 255 stems/ha, basal area of 15 m²/ha, above ground biomass of 110 Mg/ha, and total volume of 145 m³/ha. The Fabaceae family, particularly Brachystegia spiciformis, dominated the composition. Diversity indices revealed moderate diversity (Shannon = 2.3, Simpson = 0.8, Pielou = 0.6), with a few dominant species. The diameter distribution followed a reverse J-shaped pattern typical of Miombo woodlands. The study (LevasFlor. (2024). Plano De Maneio Da LevasFlor, LDA) highlighted common features of selectively logged woodlands, including a low occurrence of large-diameter individuals from high-value commercial species, prevalence of disturbance-tolerant species, and limited regeneration for some species. These findings underscore the need for management strategies that balance ecological and socio-economic factors, mitigate logging impacts, promote regeneration, and ensure long-term sustainability. Effective policies are crucial for maintaining the ecological integrity and economic value of Miombo woodlands while addressing climate resilience and biodiversity conservation. Full article

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

► Show Figures

Figure 1

19 pages, 4981 KiB

Open AccessArticle

Hydraulic Parameters of Pressure–Volume Curves and Their Relationship with the Moisture Content of Live Fuels in Two Woody Species and an Epiphyte

by Fabiola Guerrero Felipe, Teresa Alfaro Reyna, Josué Delgado Balbuena, Francisco Fábian Calvillo Aguilar and Carlos Alberto Aguirre Gutierrez

Forests 2025, 16(4), 568; https://doi.org/10.3390/f16040568 - 25 Mar 2025

Abstract

Arid and semiarid ecosystems face significant water scarcity due to high evaporation rates exceeding precipitation. This study examines temporal variations in water relations of two woody species, Vachellia schaffneri (S. Watson) Seigler & Ebinger, and Prosopis laevigata (Humb. & Bonpl. ex Willd.) M.C. [...] Read more.

Arid and semiarid ecosystems face significant water scarcity due to high evaporation rates exceeding precipitation. This study examines temporal variations in water relations of two woody species, Vachellia schaffneri (S. Watson) Seigler & Ebinger, and Prosopis laevigata (Humb. & Bonpl. ex Willd.) M.C. Johnst, and one epiphyte, Tillandsia recurvata (L.) L. (Bromeliaceae), to assess their drought tolerance and water storage capacity. We hypothesized that species with greater water storage capacity would exhibit lower drought tolerance due to reduced osmotic adjustments, whereas species with lower storage capacity would maintain turgor through osmotic regulation and cell wall rigidity. Predawn and midday water potentials (Ψ_pd, Ψ_md) were measured, and pressure–volume (P–V) curves were used to derive parameters such as saturated water content (SWC), osmotic potential (π_o), turgor loss point (Ψ_TLP), relative water content at Ψ_TLP (RWC_TLP), bulk modulus of elasticity (ε), and full turgor capacitance (C_FT). Significant correlations were found between C_FT and Ψ_TLP (positive), π_o (positive), and ε (negative). P. laevigata and T. recurvata exhibited higher water storage capacities (41.46 and 26.45 MPa⁻¹, respectively) but had a lower ability to maintain cell turgor under drought conditions. In contrast, V. schaffneri exhibited the lowest water storage capacity (11.88 MPa⁻¹) but demonstrated the highest ability to maintain cell turgor (Ψ_TLP = −1.31 MPa) and superior osmotic adjustments (π_o = −0.59 MPa). Both V. schaffneri and P. laevigata exhibited rigid cell walls, whereas T. recurvata displayed greater elasticity in its cell structures. The lowest moisture content in V. schaffneri suggests increased flammability and fire spread potential. Future studies should focus on live fuel moisture content across more species, explore seasonal variations in hydraulic traits, and integrate these physiological parameters into fire risk models to enhance wildfire prediction and management. Full article

(This article belongs to the Section Forest Hydrology)

► Show Figures

Figure 1

17 pages, 1650 KiB

Open AccessArticle

Cespitose Population Structure and Dynamics of Rare Fraxinus sogdiana in the Yili River Valley, China

by Huaqing Liu, Yanyan Jia, Xinran Xie, Fan Yang, Wei Zhang and Yunfei Yang

Forests 2025, 16(4), 567; https://doi.org/10.3390/f16040567 (registering DOI) - 24 Mar 2025

Viewed by 67

Abstract

Fraxinus sogdiana Bunge is a class II key protected plant in China, known as the “living fossil of broad-leaved trees”. It is commonly found in multi-stemmed cespitose forms created by the sprouting of its root systems and stumps. We sampled plots in the [...] Read more.

Fraxinus sogdiana Bunge is a class II key protected plant in China, known as the “living fossil of broad-leaved trees”. It is commonly found in multi-stemmed cespitose forms created by the sprouting of its root systems and stumps. We sampled plots in the east and west of the Kashi River in the Xinjiang Yili F. sogdiana National Nature Reserve. We investigated the cespitose F. sogdiana by using population ecology methods in order to provide scientific information for the conservation and sustainable development of the species as well as for the management of the reserve. We chose diameter class structure instead of age class structure to establish a population static life table, draw population survival and mortality curves, calculate a population dynamic index, and use spectral analysis to explore the fluctuation cycle of the population. The results show that age classes II–IV, comprising 74.72%, 91.53%, and 81.77% of the two cespitose populations in the east and west of the Kashi River and the total population, respectively, showed that the populations had a growing age structure. Still, there were very few individuals in age class I. The survival curves tended to be the Deevey–II type, with peak mortality occurring at age class IX in the east of the Kashi River and age class V in the west of the Kashi River. The dynamic index of populations changed the V_pi in the east and west of the Kashi River and the total population were greater than 0, indicating they were growing-type populations, and the V′_pi of the east of the Kashi River population was closer to 0, meaning that this population was relatively more resilient to external disturbances. Spectral analysis revealed that the periodic fluctuation of the population was mainly controlled by the biological characteristics of the population. Additionally, the east of the Kashi River population and the total population exhibited obvious multi-harmonic small periodic fluctuations. We suggest that the habitat of the cespitose F. sogdiana populations should be protected and improved to strengthen the nurturing management of individuals of age classes I and II for maintaining the natural renewal and development of the population. Full article

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

► Show Figures

Figure 1

20 pages, 39631 KiB

Open AccessArticle

Dehydration and Effectiveness Evaluation of Waterlogged Archaeological Wood: A Case Study of the Qiantang River Ancient Seawall

by Yongguo Chen, Zixuan Chen, Liang Ye, Zhiwei Pan, Xiaoting Fan, Yongzhuo Zhao, Zekai Qian, Zhen Wang, Ruiqi Zhang, Menghan Xuan and Yufan Yang

Forests 2025, 16(4), 566; https://doi.org/10.3390/f16040566 - 24 Mar 2025

Viewed by 38

Abstract

The waterlogged archaeological wood from the Qiantang River Ancient Seawall site faces significant preservation challenges due to its unique and complex preservation environment. Without targeted dehydration and consolidation treatments after excavation, these artifacts are at risk of severe deformation, cracking, or even complete [...] Read more.

The waterlogged archaeological wood from the Qiantang River Ancient Seawall site faces significant preservation challenges due to its unique and complex preservation environment. Without targeted dehydration and consolidation treatments after excavation, these artifacts are at risk of severe deformation, cracking, or even complete destruction. This study focuses on the waterlogged wood from Chaitang (bundled firewood structure) and Zhulong Shitang (bamboo–stone structure) within the ancient seawall, comparing two methods: ethanol dehydration and polyethylene glycol (PEG) dehydration. Both methods were combined with natural drying for comparative analysis. In addition to traditional metrics such as dimensional stability and weight percentage gain, the study employs a multidimensional evaluation framework, including colorimetric analysis, scanning electron microscopy (SEM), and X-ray diffraction (XRD), to comprehensively assess the effectiveness of dehydration and consolidation. Combining natural drying with PEG, although it may reduce the chromaticity of WAW to some extent, effectively fills cellular cavities, enhances diffraction peak intensity, improves dimensional stability, and effectively prevents cracking and deformation. The results provide differentiated treatment strategies for WAW from different historical periods and varying degrees of degradation. This study offers valuable insights and a scientific basis for the further restoration and preservation of the WAW from the Qiantang River Ancient Seawall. Full article

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

► Show Figures

Figure 1

23 pages, 3141 KiB

Open AccessReview

Forest Fragmentation and Forest Mortality—An In-Depth Systematic Review

by Debebe Dana Feleha, Luiza Tymińska-Czabańska and Paweł Netzel

Forests 2025, 16(4), 565; https://doi.org/10.3390/f16040565 - 24 Mar 2025

Viewed by 60

Abstract

In recent decades, forest fragmentation has been shown to directly increase forest mortality by increasing stress, damaging habitats, and heightening vulnerability to disturbances. It also disrupts local climates and ecological processes across various regions. Therefore, we aim to summarize the literature on forest [...] Read more.

In recent decades, forest fragmentation has been shown to directly increase forest mortality by increasing stress, damaging habitats, and heightening vulnerability to disturbances. It also disrupts local climates and ecological processes across various regions. Therefore, we aim to summarize the literature on forest fragmentation and forest mortality. The Web of Science Core Collection (WoSCC) database was searched using the PRISMA 2020 framework. We searched for publications from 1990 to 2023 and included research articles that reported on fragmentation and mortality. Out of the 159 articles found, we selected 119 research articles for systematic review. Our review documents that most studies on forest fragmentation and forest mortality tend to be relatively short-term, focused on a local or regional scale, and based on ground survey data. We identified articles from 35 countries and major hotspots for research on forest fragmentation and mortality. The results identified that the most underrepresented biomes are Mediterranean forests, woodlands and shrubs, boreal forests, and tropical and subtropical dry broadleaf forests. The longer the time horizon of the studies, the more neutral and positive effects of forest fragmentation are reported. These positive effects are more likely to be reported for temperate biomes and studies using field measurements. The study highlighted the importance of adopting a global perspective and integrating diverse methodologies to advance our understanding of forest fragmentation and mortality. Based on our findings, we recommend that future research on forest fragmentation and mortality should have a consistent geographic distribution, use varied methodologies, and perform the efficient integration of existing data types to improve the comparability and reliability of the results. Full article

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

► Show Figures

Figure 1

19 pages, 6109 KiB

Open AccessArticle

Using Unoccupied Aerial Systems (UAS) and Structure-from-Motion (SfM) to Measure Forest Canopy Cover and Individual Tree Height Metrics in Northern California Forests

by Allison Kelly, Leonhard Blesius, Jerry D. Davis and Lisa Patrick Bentley

Forests 2025, 16(4), 564; https://doi.org/10.3390/f16040564 - 24 Mar 2025

Viewed by 56

Abstract

Quantifying forest structure to assess changing wildfire risk factors is critical as vulnerable areas require mitigation, management, and resource allocation strategies. Remote sensing offers the opportunity to accurately measure forest attributes without time-intensive field inventory campaigns. Here, we quantified forest canopy cover and [...] Read more.

Quantifying forest structure to assess changing wildfire risk factors is critical as vulnerable areas require mitigation, management, and resource allocation strategies. Remote sensing offers the opportunity to accurately measure forest attributes without time-intensive field inventory campaigns. Here, we quantified forest canopy cover and individual tree metrics across 44 plots (20 m × 20 m) in oak woodlands and mixed-conifer forests in Northern California using structure-from-motion (SfM) 3D point clouds derived from unoccupied aerial systems (UAS) multispectral imagery. In addition, we compared UAS–SfM estimates with those derived using similar methods applied to Airborne Laser Scanning (ALS) 3D point clouds as well as traditional ground-based measurements. Canopy cover estimates were similar across remote sensing (ALS, UAS-SfM) and ground-based approaches (r² = 0.79, RMSE = 16.49%). Compared to ground-based approaches, UAS-SfM point clouds allowed for correct detection of 68% of trees and estimated tree heights were significantly correlated (r² = 0.69, RMSE = 5.1 m). UAS-SfM was not able to estimate canopy base height due to its inability to penetrate dense canopies in these forests. Since canopy cover and individual tree heights were accurately estimated at the plot-scale in this unique bioregion with diverse topography and complex species composition, we recommend UAS-SfM as a viable approach and affordable solution to estimate these critical forest parameters for predictive wildfire modeling. Full article

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

23 pages, 20340 KiB

Open AccessArticle

Forest Height and Volume Mapping in Northern Spain with Multi-Source Earth Observation Data: Method and Data Comparison

by Iyán Teijido-Murias, Oleg Antropov, Carlos A. López-Sánchez, Marcos Barrio-Anta and Jukka Miettinen

Forests 2025, 16(4), 563; https://doi.org/10.3390/f16040563 - 24 Mar 2025

Viewed by 80

Abstract

Accurate forest monitoring is critical for achieving the objectives of the European Green Deal. While national forest inventories provide consistent information on the state of forests, their temporal frequency is inadequate for monitoring fast-growing species with 15-year rotations when inventories are conducted every [...] Read more.

Accurate forest monitoring is critical for achieving the objectives of the European Green Deal. While national forest inventories provide consistent information on the state of forests, their temporal frequency is inadequate for monitoring fast-growing species with 15-year rotations when inventories are conducted every 10 years. However, Earth observation (EO) satellite systems can be used to address this challenge. Remote sensing satellites enable the continuous acquisition of land cover data with high temporal frequency (annually or shorter), at a spatial resolution of 10-30 m per pixel. This study focused on northern Spain, a highly productive forest region. This study aimed to improve models for predicting forest variables in forest plantations in northern Spain by integrating optical (Sentinel-2) and imaging radar (Sentinel-1, ALOS-2 PALSAR-2 and TanDEM-X) datasets supported by climatic and terrain variables. Five popular machine learning algorithms were compared, namely kNN, LightGBM, Random Forest, MLR, and XGBoost. The study findings show an improvement in R² from 0.24 when only Sentinel-2 data are used with MultiLinear Regression to 0.49 when XGboost is used with multi-source EO data. It can be concluded that the combination of multi-source datasets, regardless of the model used, significantly enhances model performance, with TanDEM-X data standing out for their remarkable ability to provide valuable radar information on forest height and volume, particularly in a complex terrain such as northern Spain. Full article

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

► Show Figures

Figure 1

23 pages, 7738 KiB

Open AccessArticle

A Deciduous Forest’s CO₂ Exchange Within the Mixed-Humid Climate of Kentucky, USA

by Ife Familusi, Maheteme Gebremedhin, Buddhi Gyawali, Anuj Chiluwal and Jerald Brotzge

Forests 2025, 16(4), 562; https://doi.org/10.3390/f16040562 - 24 Mar 2025

Viewed by 53

Abstract

Forests play a crucial role in carbon cycling, contributing significantly to global carbon cycling and climate change mitigation, but their capture strength is sensitive to the climatic zone in which they operate and its adjoining environmental stressors. This research investigated the carbon dynamics [...] Read more.

Forests play a crucial role in carbon cycling, contributing significantly to global carbon cycling and climate change mitigation, but their capture strength is sensitive to the climatic zone in which they operate and its adjoining environmental stressors. This research investigated the carbon dynamics of a typical deciduous forest, the Daniel Boone National Forest (DBNF), in the Mixed-Humid climate of Kentucky, USA, employing the Eddy Covariance technique to quantify temporal CO₂ exchanges from 2016 to 2020 and to assess its controlling biometeorological factors. The study revealed that the DBNF functioned as a carbon sink, sequestering −1515 g C m⁻² in the study period, with a mean annual Net Ecosystem Exchange (NEE) of −303 g C m⁻²yr⁻¹. It exhibited distinct seasonal and daily patterns influenced by ambient sunlight and air temperature. Winter months had the lowest rate of CO₂ uptake (0.0699 g C m⁻² h⁻¹), while summer was the most productive (−0.214 g C m⁻² h⁻¹). Diurnally, carbon uptake peaked past midday and remained a sink overnight, albeit negligibly so. Light and temperature response curves revealed their controlling effect on the DBNF trees’ photosynthesis and respiration. Furthermore, clear seasonality patterns were observed in the control of environmental variables. The DBNF is a carbon sink consistent with other North American deciduous forests. Full article

(This article belongs to the Collection Forests Carbon Fluxes and Sequestration)

► Show Figures

Figure 1

25 pages, 20509 KiB

Open AccessArticle

Basin Ecological Zoning Based on Supply–Demand Assessment and Matching of Green Infrastructure: A Case Study of the Jialing River Basin

by Mao Feng, Yunyan Li, Lihua Xu and Tao Zhang

Forests 2025, 16(4), 561; https://doi.org/10.3390/f16040561 - 24 Mar 2025

Viewed by 70

Abstract

Intensive anthropogenic disturbances have driven significant spatial disparities and progressive fragmentation of forest-based green infrastructure (GI) that delivers vital ecosystem services across river basins. To address these challenges, delineating ecological management zones and developing spatially targeted GI optimization measures are imperative for safeguarding [...] Read more.

Intensive anthropogenic disturbances have driven significant spatial disparities and progressive fragmentation of forest-based green infrastructure (GI) that delivers vital ecosystem services across river basins. To address these challenges, delineating ecological management zones and developing spatially targeted GI optimization measures are imperative for safeguarding regional ecological security and advancing nature-based solutions in coupled human–water–forest systems. Focused on the mainstream area of the Jialing River Basin, we establish an ecological optimization zoning system that reconciles forest ecosystem resilience with regional development equity. By using morphological spatial pattern analysis, landscape pattern analysis and the In-VEST model, the GI supply capacity was assessed from three dimensions: element composition, structural configuration, and ecosystem services. The demand intensity was evaluated based on environmental governance pressure, urban expansion demand and social development needs across counties. Supply–demand matching was analyzed using quadrant-based mismatch typology and coupling coordination degree model. The results reveal that the following: (1) supply-deficit counties are predominantly located in the middle and lower reaches of the basin, characterized by high urbanization and economic development; (2) supply-surplus and high-level balanced counties cluster in the ecologically conserved upper reaches; (3) low-level balanced counties are concentrated in agricultural zones; (4) the overall coordination degree of supply and demand show a preliminary state of coordination. Based on these findings, the basin was classified into five zones at the county level: GI restoration, management, rehabilitation, enhancement, and conservation. Tailored ecological management measures and policies were formulated for each zone to advance sustainable basin development. Full article

(This article belongs to the Special Issue Forest Management Planning and Decision Support)

► Show Figures

Figure 1

1 pages, 510 KiB

Open AccessCorrection

Correction: Tang et al. Effects of Oasis Evolution on Soil Microbial Community Structure and Function in Arid Areas. Forests 2025, 16, 343

by Junhu Tang, Haiqiang Zhu, Xinyu Ma, Zhaolong Ding, Yan Luo, Xiaofei Wang, Rui Gao and Lu Gong

Forests 2025, 16(4), 560; https://doi.org/10.3390/f16040560 - 24 Mar 2025

Viewed by 42

Abstract

In the original publication [...] Full article

(This article belongs to the Section Forest Soil)

18 pages, 5113 KiB

Open AccessArticle

Analysis of the Application of Machine Learning Algorithms Based on Sentinel-1/2 and Landsat 8 OLI Data in Estimating Above-Ground Biomass of Subtropical Forests

by Yuping Wang, Steven Hancock, Wenquan Dong, Yongjie Ji, Han Zhao and Mengjin Wang

Forests 2025, 16(4), 559; https://doi.org/10.3390/f16040559 - 23 Mar 2025

Viewed by 194

Abstract

Accurate monitoring of aboveground biomass (AGB) in subtropical forests plays an important role in maintaining biodiversity and the balance of forest ecosystems. It is of high importance to explore how machine learning models can improve the ability and accuracy of AGB estimation of [...] Read more.

Accurate monitoring of aboveground biomass (AGB) in subtropical forests plays an important role in maintaining biodiversity and the balance of forest ecosystems. It is of high importance to explore how machine learning models can improve the ability and accuracy of AGB estimation of different types of subtropical forests under the conditions of active and passive open-source remote sensing (RS) data. In this study, the subtropical forests in the Pu’er region of Yunnan Province were used as the research object, and backscattering coefficients, mean reflectance, and textural features from Sentinel-1, Sentinel-2, and Landsat 8 OLI open-source RS data were used as the data source. We classified the subtropical forests into three basic forest types: broadleaf forest, coniferous forest, and mixed forest. Based on filtering and analyzing RS features, we performed forest AGB inversion using Random Forest (RF), Support Vector Regression (SVR), and eXtreme Gradient Boosting (XGBoost). The results show that: (1) VH-related texture features in Sentinel-1, and red-edge band features, IR band features, and texture features in Sentinel-2 and Landsat 8 OLI are sensitive to changes in forest AGB. (2) Among the three nonparametric methods, the XGBoost algorithm had the highest estimation accuracy with an MAE of 10.05 t/ha and RMSE of 12.43 t/ha in coniferous forests; the second estimation accuracy in mixed forests with an MAE of 20.18 t/ha and RMSE of 25.33 t/ha; and the estimation accuracy in broad-leaved forests with an MAE of 25.22 t/ha and RMSE of 32.32 t/ha. (3) The accuracy of estimating forest AGB by combining multiple RS data is higher than the estimation results using a single RS data. We found that the VH features of SAR data contribute more to the inversion of high-precision forest AGB; the XGBoost model has the strongest robustness and the highest accuracy in the AGB inversion of subtropical forests using multisource RS data. (4) The spatial autocorrelation of the samples themselves also needs to be taken into account when modeling forest AGB estimates. Full article

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

► Show Figures

Figure 1

21 pages, 10812 KiB

Open AccessArticle

Tree Risk Assessment of Date Palms with Aerial Roots Using Minimally Invasive Technologies

by Cheng-Jung Lin, Ping-Hsun Peng and Cheng-Yi Cheng

Forests 2025, 16(4), 558; https://doi.org/10.3390/f16040558 - 21 Mar 2025

Viewed by 94

Abstract

This study assessed the health risks of date palms in Taiwan with aerial root growth using visual tree assessment and minimally invasive testing. The phenomenon of aerial root growth on the outer side of the trunk is presumed to be a growth response [...] Read more.

This study assessed the health risks of date palms in Taiwan with aerial root growth using visual tree assessment and minimally invasive testing. The phenomenon of aerial root growth on the outer side of the trunk is presumed to be a growth response of the palm to adapt to environmental changes, while the distinct dark stem tissue band between the decayed and sound stem tissue in the cross-section is likely a result of stem tissue variation. Key external defects included leaning and insect damage, while acoustic tomography confirmed internal structural variability but required accuracy improvements. Drilling resistance tests showed that healthy palms had the highest resistance near the cortex, decreasing toward the center, while decayed palms exhibited significant amplitude reductions. These findings highlight the need for comprehensive palm health assessments and provide a scientific basis for improved urban palm management and conservation. Full article

(This article belongs to the Section Forest Health)

► Show Figures

Figure 1

16 pages, 2546 KiB

Open AccessArticle

Stable Leaf Area Index Despite Shifts in Biomass Allocation and Leaf Traits: A Case Study in a Young European Beech Forest Under Intense Tree Competition

by Bohdan Konôpka, Jozef Pajtík and Vladimír Šebeň

Forests 2025, 16(4), 557; https://doi.org/10.3390/f16040557 - 21 Mar 2025

Viewed by 76

Abstract

Young forest stands from natural regeneration are characterized by high competitive pressure and dynamic changes over time, especially in the initial growth stages. Despite their increasing area in the temperate zone, they have received significantly less scientific attention than old forest stands. Therefore, [...] Read more.

Young forest stands from natural regeneration are characterized by high competitive pressure and dynamic changes over time, especially in the initial growth stages. Despite their increasing area in the temperate zone, they have received significantly less scientific attention than old forest stands. Therefore, our research was conducted on young, over-dense European beech (Fagus sylvatica L.) forest originating from natural regeneration, grown in central Slovakia, Western Carpathians. Repeated measurements of tree height and stem diameter measured on the base within a beech stand revealed significant temporal changes in their relationship. Over 16 years, height increased more than stem diameter. Both Lorey’s height and mean diameter d₀ showed continuous growth, with Lorey’s height increasing 3.5-fold and mean diameter increasing 2.8-fold. The height-to-diameter ratio increased until stand age 15, then briefly declined before rising again. Stand density decreased over time, with the sharpest decline occurring between ages 15 and 16 (dropping from 843 to 599 trees per 100 m²). Mortality rates peaked at age 16, with an average annual rate of 9.4% over the entire observation period (2008–2023). Specific leaf area (SLA) was negatively related to tree size, and its value was smaller in 10- than in 20-year-old stands. The increase in SLA was driven by greater leaf area relative to leaf weight. Additionally, allometric relationships showed that branch and leaf contributions to aboveground biomass decreased with tree size within the stand but were greater in the older stand than in the younger growth stage. Estimated aboveground biomass was 667 ± 175 kg per 100 m² in the 10-year-old stand and 1574 ± 382 kg per 100 m² in the 20-year-old stand, with stems contributing the majority of biomass. Leaf Area Index (LAI) remained similar across both stand ages, while the Leaf Area Ratio (LAR) was nearly twice as high in the younger stand. These findings highlight dynamic shifts in beech stand structure, biomass allocation, and leaf traits over time, reflecting growth patterns and competition effects. The outputs indicate that competition in young forest stands is a dominant force in tree mortality. Understanding key interactions in young stands is crucial for sustainable forest management, as these interactions influence long-term stand stability and ecosystem functions. Full article

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

► Show Figures

Figure 1

13 pages, 1975 KiB

Open AccessArticle

Morphology and Molecular Phylogenetic Characterization of Novel Tar Spot Disease-Causing Fungi on Fabaceae Trees in Thailand

by Sukanya Haituk, Anuruddha Karunarathna, Dulanjalee Lakmali Harishchandra, Saruta Arayapichart, Chiharu Nakashima, Rampai Kodsueb, Sararat Monkhung and Ratchadawan Cheewangkoon

Forests 2025, 16(4), 556; https://doi.org/10.3390/f16040556 (registering DOI) - 21 Mar 2025

Viewed by 71

Abstract

Tar spot diseases have a huge impact on various plants by reducing the photosynthesis surface and allowing secondary severe infections on the host. Phyllachoraceae species causing tar spots infect both monocot and dicot plants and are known as obligate parasites. In the current [...] Read more.

Tar spot diseases have a huge impact on various plants by reducing the photosynthesis surface and allowing secondary severe infections on the host. Phyllachoraceae species causing tar spots infect both monocot and dicot plants and are known as obligate parasites. In the current study, two different tar spot disease symptoms were observed on Pterocarpus macrocarpus and Dalbergia sp. in northern Thailand. The phylogeny of a combined matrix of LSU, SSU, and ITS and morphology revealed that both causal species of tar spot diseases belong to the genus Neophyllachora. Furthermore, these results showed that these are novel species of the genus Neophyllachora, N. pterocarpi-macrocarpae on P. macrocarpus and N. dalbergiae on Dalbergia sp. with high bootstrap supports. Full article

(This article belongs to the Special Issue Pathogenic Fungi in Forest)

► Show Figures

Figure 1

23 pages, 5082 KiB

Open AccessArticle

Four Decades of Cover Change, Degradative, and Restitution Stages of Mangrove Forest in Douala-Edea National Park, Cameroon

by Coleen Mumbang, Gordon N. Ajonina and George B. Chuyong

Forests 2025, 16(4), 555; https://doi.org/10.3390/f16040555 - 21 Mar 2025

Viewed by 86

Abstract

This Study delves on changes in the extent of mangroves over a 42 years span in the Douala-Edea NP, Cameroon. Mangroves are valuable ecosystems that provide significant biological, environmental, ecological, and cultural functions. To inform the development of management plans for the ecosystem’s [...] Read more.

This Study delves on changes in the extent of mangroves over a 42 years span in the Douala-Edea NP, Cameroon. Mangroves are valuable ecosystems that provide significant biological, environmental, ecological, and cultural functions. To inform the development of management plans for the ecosystem’s sustainability, it is crucial to evaluate how their land cover, levels of degradation, and phases of restitution have changed. GIS and remote sensing techniques were used to classify and analyze Landsat images from 1980 to 2022 categorized into nine classes: bare ground, Nypa palms, settlements, coastal sedimentation, river sedimentation, regeneration, matured mangroves, dense forest, and water body. Using the Markovian chain approach, the changes noted during the period were utilized to forecast future trends up to 2052. Findings demonstrated that the mature mangrove area decreased throughout the study. The surface area covered by mature mangroves was 80,628.78 hectares in 1980, which decreased by 7.31%, 1.51%, 3.70%, and by 17% for the overall period of 42 years. Additionally, a gain of 6.84% from 1980 to 2022 was observed, probably from artificial mangrove regeneration. Settlements, invasive Nypa palms, bare ground (resulting from over-exploitation), and the sedimentation of rivers and coast primarily replaced mangroves. The prediction derived indicated the continuous decline in mangroves if not fully protected by law. The gazettement to National Park and recent promulgation of two laws are steps in providing the needed protection. These results provide vital information to direct future mangrove conservation actions in the recently gazetted Douala-Edea National Terrestrial and Marine Park and other mangrove blocks along the Gulf of Guinea. Full article

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

► Show Figures

Figure 1

Journal Menu

Journal Browser

Forests, Volume 16, Issue 4 (April 2025) – 19 articles

Further Information

Guidelines

MDPI Initiatives

Follow MDPI