Forests, Volume 15, Issue 6 (June 2024) – 146 articles

Drought intensity and frequency have increased in recent years, which poses significant threats to forest ecosystems, especially in the context of global climate change. This paper is aimed at summarizing the current state of research and global development trends regarding drought-induced tree mortality mechanisms in tree physiology. Developing a robust literature foundation will facilitate in-depth research and foster the exchange of knowledge related to this subject. A literature review was conducted using tools such as VOSviewer, CiteSpace, and the Bibliometrix R-package to review the literature from the Web of Science’s core database from 1985 to 2023. We intend to determine the current state and evolution of global research on drought-induced tree mortality mechanisms. The results reveal that research on drought-induced tree mortality mechanisms gained momentum predominantly in the last two decades, with a marked surge post-2012. The United States is the epicenter of research, leading the global scientific community with its preeminence in publication volume, citation rates, and the scope of collaborative networks, with China in close pursuit. Tree Physiology stands out as the leading journal in this domain, boasting 129 articles. McDowell NG emerges as the most prolific author, with an H-index of 41, underscoring his influence in the field. There is a clear upward trend in collaborations spanning authors, journals, research institutions, and countries. The analysis of frequently cited keywords and topic evolution suggests that drought and tree mortality will likely remain key research areas for the foreseeable future. The future of research on drought-induced tree mortality mechanisms in physiology is promising, as it emphasizes multidisciplinary approaches and global collaborations. Full article

Soybean meal (SM) adhesive is widely acknowledged as a viable substitute for traditional formaldehyde-based adhesives, given its ability to be easily modified, the utilization of renewable sources, and its eco-friendly characteristics. However, the application of SM adhesive in manufacturing has been impeded due to its restricted bonding capacity and inadequate water resistance. Researchers in the wood industry have recognized the significance of creating an SM-based adhesive, which possesses remarkable adhesive strength and resistance to water. This study endeavors to tackle the issue of inadequate water resistance in SM adhesives. Sodium lignosulfonate (L) was oxidized using hydrogen peroxide (HP) to oxidized lignin (OL) with a quinone structure. OL was then used as a modifier, being blended with SM to prepare SM-based biomass (OLS) adhesives with good water resistance, which was found practically through its utilization in the production of plywood. The influence of the HP dosage and OL addition on plywood properties was examined. The changes in the lignin structure before and after oxidation were confirmed using gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS). The curing behavior and thermal stability of OLS adhesives were analyzed using dynamic mechanical analysis (DMA) and thermogravimetric (TG) analysis. The reaction mechanism was also investigated using FT-IR and XPS. The outcomes indicated a decrease in the molecular weight of L after oxidation using HP, and, at the same time, quinone and aldehyde functionalized structures were produced. As a result of the reaction between the quinone and aldehyde groups in OL with the amino groups in SM, a dense network structure formed, enhancing the water resistance of the adhesive significantly. The adhesive displayed exceptional resistance to water when the HP dosage was set at 10% of L and the OL addition was 10% based on the mass of SM. These specific conditions led to a notable enhancement in the wet bonding strength (63 °C, 3 h) of the plywood prepared using the adhesive, reaching 0.88 ± 0.14 MPa. This value represents a remarkable 125.6% increase when compared to the pure SM adhesive (0.39 ± 0.02 MPa). The findings from this study introduce a novel approach for developing adhesives that exhibit exceptional water resistance. Full article

The 2015 reform of state-owned forest regions (SOFRs) in Northeast China required state-owned forest enterprises (SOFEs) to transfer their governmental and social roles to local authorities. This transition, however, created fragmented governance within forestry communities due to the absence of cooperative mechanisms between SOFEs and local governments. This study examines the economic effects of this governance fragmentation on SOFEs and explores the underlying mechanisms. The research combines new institutional economics and transaction cost theory to develop hypotheses and employs empirical analysis using fixed-effects models on data from 39 SOFEs, belonging to two forest industry groups from 2015 to 2022, collected through surveys and field investigations. The findings indicate that governance fragmentation has a significant negative impact on the economic performance of SOFEs. The high transaction costs incurred by SOFEs in achieving community co-governance with local governments are identified as a key mediating mechanism. These costs lead to resource dispersion and diminished trust between SOFEs and local governments. The economic impact of this governance fragmentation varies based on the economic conditions of the SOFEs, their operational scales, and the clarity of geographical management boundaries with local governments. To mitigate the adverse effects of governance fragmentation, the study suggests proactive institutional designs to reduce transaction costs. These findings offer new insights into the corporate social responsibilities of Chinese SOFEs and suggest improvements in the governance structures of forestry communities in SOFRs in Northeast China. Additionally, the study expands the application of transaction cost theory in public affairs governance and enhances quantitative research on the economic impact on enterprises. Full article

The serious densification of human settlements necessitates an increase in the role and importance of green infrastructures in the overall functioning of urban ecosystems. Accordingly, the aim of the present study was to (1) assess the efficiency of air pollutant removal (potentially toxic elements) of three common ornamental trees (Tilia tomentosa Moench, Fraxinus excelsior L. and Pinus nigra J.F. Arnold) and (2) model the air quality regulatory services (removal of PM₁₀, PM_2.5 and NO₂). Three different approaches were applied—enrichment factor (EF) and metal accumulation factor (MAI) per tree species, as well as simulation modeling for the whole urban forest. The MAI values of the three studied species were found to be very similar, in the range of 22.35 to 23.08, which suggests that these species could be a good choice for planting in urban areas with worsened air quality. The highest EF values were observed for U (3–18), followed by As (1.6–2.56) and Sr (0.87–2.46). The potential of urban forests in countering air pollution was highlighted by three simulated scenarios for PM₁₀, PM_2.5 and NO₂ removal. The highest removal efficiency was calculated for evergreen species, followed by the mixed composition of deciduous (90%) and evergreen trees (10%), and the scenario with wholly deciduous trees had the lowest one. The contribution of nature-based solutions in meeting air quality standards and enhancing resilience in urban areas was clearly demonstrated. The functional complementarity of the different functional tree groups (coniferous, evergreen and deciduous broad-leaved species) was proven to be crucial for the support of both functional stabilities of the phytocenosis under diverse climatic conditions and during the change of seasonal cycles in the vegetation. Full article

Global climate changes are expected to profoundly shape species distribution. Quercus oxyphylla, a valuable evergreen broad-leaved tree species, is rigorously conserved and managed in China owing to its substantial scientific, economic, and ecological value. However, the impact of projected climate change on its future distribution and potential climatic drivers remains unclear. Here, a maximum entropy model (MaxEnt) was used to explore the distribution of Q. oxyphylla in China under current conditions and three future scenarios (SSP1-2.6, SSP2-4.5, and SSP5-8.5) for the 2050s and 2070s. We optimized the model using the ‘ENMeval’ package to obtain the best parameter combination (RM = 1, FC = LQHPT), and multiple evaluation metrics (AUC ≥ 0.9; TSS ≥ 0.6; Kappa ≥ 0.75) verified the high accuracy of the model and the reliability of the prediction results. We found the following: (1) The potential distribution of Q. oxyphylla spans across 28 provinces in China under current climatic conditions, predominantly in southern regions, with Sichuan exhibiting the largest suitable area for survival. The total suitable habitat covers 244.98 × 10⁴ km², comprising highly, moderately, and poorly suitable habitats of 51.66 × 10⁴ km², 65.98 × 10⁴ km², and 127.34 × 10⁴ km², respectively. (2) Under future climate conditions, the overall geographical boundaries of Q. oxyphylla are predicted to remain similar to the present one, with an increase of 10.29% in the 2050s and 11.31% in the 2070s. In the 2050s, the total suitable habitats for Q. oxyphylla under the three scenarios (SSP1-2.6, SSP2-4.5, and SSP5-8.5) might increase by 8.83%, 9.62%, and 12.42%, while in the 2070s they might increase by 10.39%, 17.21%, and 6.33%, respectively. (3) Moreover, the centroid of the suitable area is expected to migrate southwestward under the three scenarios in the future. (4) Annual precipitation, isothermality, and temperature annual range emerged as the main factors influencing the distribution of Q. oxyphylla, with contributions of 55.9%, 25.7%, and 13.5%, respectively. Our findings refined the spatial arrangement of Q. oxyphylla growth and revealed its climate resilience. This suggested that under climate change, Sichuan and Shaanxi are the optimal regions for cultivation and management, while appropriate conservation strategies should be formulated in Tibet and Hubei. Full article

Exploring the relationship between topography and forest multifunctionality enhances understanding of the mechanisms maintaining forest multifunctionality and proves beneficial for managing overall forest functions across different landscapes. Leveraging census data from a 20 ha subtropical forest plot, we investigated the topographic variations in individual functions, multifunctionality, and their interrelationships. Our results revealed that relative to lower elevations, higher elevations had higher woody productivity, sapling growth, and recruitment that drove higher average forest multifunctionality (FMA). However, forest multifunctionality at the 50% threshold level (FMt50) had no significant difference between high and low elevations. Compared with the valley and slope, higher woody productivity, higher sapling recruitment, and higher soil organic carbon stock drove higher forest multifunctionality (FMA and FMt50) in the ridge. These results indicate the ridge serves as a forest multifunctionality “hotspot” within the Tiantong 20 hm² plot. Additionally, relative to the low elevation, the degree of synergy among functions at the high elevation was significantly lower, indicating difficulties in attaining high forest multifunctionality at the high elevation. Our work underscores the importance of topography in regulating subtropical forest multifunctionality and relationships between forest functions at a local scale, suggesting that future forest management strategies (such as regulating synergistic or trade-off relationships between functions) should give particular attention to topographic conditions. Full article

Diameter at breast height (DBH) is a crucial parameter for forest inventory. However, accurately estimating DBH remains challenging due to the noisy and incomplete cross-sectional points. To address this, this paper proposed a reliable DBH estimation method using terrestrial LiDAR points through polar coordinate transformation and progressive outlier removal. In this paper, the initial center was initially detected by rasterizing the convex hull, and then the Cartesian coordinates were transformed into polar coordinates. In the polar coordinate system, the outliers were classified as low and high outliers according to the distribution of polar radius difference. Both types of outliers were then removed using adaptive thresholds and the moving least squares algorithm. Finally, DBH was estimated by calculating the definite integral of arc length in the polar coordinate system. Twenty publicly available individual trees were adopted for the test. Experimental results indicated that the proposed method performs better than the other four classical DBH estimation methods. Furthermore, several extreme cases scanned using terrestrial LiDAR in practice, such as cross-sectional points with lots of outliers or larger data gaps, were also tested. Experimental results demonstrate that the proposed method accurately calculates DBH even in these challenging cases. Full article

UAVs are commonly used in forest fire detection, but the captured fire images often suffer from blurring due to the rapid motion between the airborne camera and the fire target. In this study, a multi-input, multi-output U-Net architecture that combines spatial domain and frequency domain information is proposed for image deblurring. The architecture includes a multi-branch dilated convolution attention residual module in the encoder to enhance receptive fields and address local features and texture detail limitations. A feature-fusion module integrating spatial frequency domains is also included in the skip connection structure to reduce feature loss and enhance deblurring performance. Additionally, a multi-channel convolution attention residual module in the decoders improves the reconstruction of local and contextual information. A weighted loss function is utilized to enhance network stability and generalization. Experimental results demonstrate that the proposed model outperforms popular models in terms of subjective perception and quantitative evaluation, achieving a PSNR of 32.26 dB, SSIM of 0.955, LGF of 10.93, and SMD of 34.31 on the self-built forest fire datasets and reaching 86% of the optimal PSNR and 87% of the optimal SSIM. In experiments without reference images, the model performs well in terms of LGF and SMD. The results obtained by this model are superior to the currently popular SRN and MPRNet models. Full article

This study evaluated the chemical and microbiological soil attributes in a silvopastoral system compared to well-managed pasture, degraded pasture, and Cerrado vegetation in Brazil. A randomized design with four replications was employed to collect soil samples at seven depths. These samples were analyzed for carbon (C), nitrogen (N), pH, phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), and cation exchange capacity (CEC). Soil microbial attributes were also evaluated at three depths during the dry and wet seasons. Carbon stocks in the evaluated systems varied (0–100 cm), with the highest stocks found in well-managed pasture (MP) (129.5 Mg C ha⁻¹), followed by the silvopastoral system (SPS) (106.6 Mg C ha⁻¹), and the lowest values in native vegetation (NV) (84.8 Mg C ha⁻¹) and degraded pasture (DP) (63.4 Mg C ha⁻¹). Higher pH and base sum were observed in MP. Soil microbial biomass (Cmic) did not differ between treatments during the wet season but was generally higher in MP and lower in DP during the dry season. MP effectively regulated the chemical and biological quality of the soil. The SPS demonstrated that it is possible to combine the cultivation of trees and pastures in the same area, contributing to the improvement of the chemical and biological attributes of the soil in the Brazilian Cerrado. Full article

Lignin, a complex and heterogeneous biopolymer derived from wood, holds immense potential as a sustainable feedstock for various industrial applications. Kraft pulping, a widely employed process in the paper industry, generates black liquor containing lignin along with other organic and inorganic compounds. The precipitation of lignin from black liquor offers an opportunity for valorization, contributing to the circular economy and reducing the environmental impact. Although the precipitation process of softwood lignin is extensively documented and outlined in the existing literature, the identical process originating from hardwood-derived black liquor poses challenges attributed to the distinct composition of hardwood. This study systematically investigates the individual and combined influences of temperature and pH on the precipitation of hardwood lignin from kraft black liquor, utilizing a factorial design to evaluate lignin functional characteristics. The characterization of the precipitated lignin was performed using various analytical techniques, mainly NIR, elemental composition, UV-VIS, and calorimetry. The results reveal remarkable interactions between temperature and pH, indicating their synergistic effects on lignin precipitation. The optimal conditions for hardwood lignin precipitation were identified and successfully upscaled during piloting experiments conducted under industrial conditions. This research provides valuable insights into the fundamental factors governing hardwood lignin precipitation from kraft black liquor and offers a basis for the development of efficient and sustainable lignin recovery processes in the pulp and paper industry. Full article

The peak of growing season (POG) represents the timing of the maximum capacity of vegetation photosynthesis and acts as a crucial phenological indicator for the carbon cycle in terrestrial ecosystems. However, little is known about how POG responds to extreme climate events such as drought across different biomes. Based on two drought indices, we analyzed the temporal–spatial pattern of drought and POG in China and then investigated how drought influenced the POG in different periods of the early season through correlation analysis. In general, a trend towards increased aridity and earlier POG was found in most areas. The impact of drought on POG differed among periods. On the one hand, an earlier POG enabled plants to reduce evapotranspiration and mitigate the risk of severe summer drought. On the other hand, the drought that occurred in spring impeded plant growth and caused a delay in spring phenology, thereby postponing POG. Summer drought led to an earlier POG in relatively dry biomes but inversely led to a later peak in photosynthetic activity in wetter biomes. We also observed a 1-month/2-month lagged effect of drought on POG in almost half of the areas and a 2-month/ 3-month cumulative effect of drought in the north of 50° N. These findings enhance our understanding of carbon uptake in terrestrial ecosystems by clarifying the mechanisms by which climate change impacts vegetation growth and photosynthetic activity. Full article

The composition, distribution, and growth of native natural forests are important references for the restoration, structural adjustment, and close-to-nature transformation of artificial forests. The joint species distribution model is a powerful tool for analyzing community structure and interspecific relationships. It has been widely used in biogeography, community ecology, and animal ecology, but it has not been extended to natural forest conservation and restoration in China. Therefore, based on the 9th National Forest Inventory data in Jilin Province, combined with environmental factors and functional traits of tree species, this study adopted the joint species distribution model—including a model with all variables (model FULL), a model with environmental factors (model ENV), and a model with spatial factors (model SPACE)—to examine the distribution of multiple tree species. The results show that, in models FULL and ENV, the environmental factors explaining the model variation were ranked as follows, climate > site > soil. The explanatory power was as follows: model FULL (AUC = 0.8325, Tjur R² = 0.2326) > model ENV (AUC = 0.7664, Tjur R² = 0.1454) > model SPACE (AUC = 0.7297, Tjur R² = 0.1346). Tree species niches in model ENV were similar to those in model FULL. Compared to predictive power, we found that the information transmitted by environmental and spatial predictors overlaps, so the choice between model FULL and ENV should be based on the purpose of the model, rather than the difference in predictive ability. Both models can be used to study the adaptive distribution of multiple tree species in northeast China. Full article

Yellow leaf disease (YLD) poses a significant challenge to areca palm cultivation, yet its etiology remains uncertain. During our investigation of YLD-affected areca palm plants, transcriptome sequencing revealed an RNA contig exhibiting striking similarities to the RNA-dependent RNA polymerase (RdRp) of ormycoviruses. Subsequent gene cloning techniques yielded the full-length sequence of this RNA, potentially representing either the complete or partial genome of a hitherto unidentified ormycovirus, tentatively named areca palm yellow leaf-associated ormycovirus (APYLaOMV). RT-PCR detection found that APYLaOMV is present in over 30% of YLD-affected areca palm samples but is absent in healthy ones, suggesting a potential link between APYLaOMV and YLD. In summary, these data could be valuable in understanding the etiology of YLD in areca palms. Full article

Dahurian larch (Larix gmelinii) is the dominant tree species in boreal forests, and its photosynthetic response to climate warming is important in modeling and predicting carbon cycling for boreal forest ecosystems. In 1983, seedlings of L. gmelinii from 11 provenances were transplanted into two common gardens with different climate conditions (control and warming climate). Forty years after the transplant, we investigated the response of leaf photosynthetic capacity to climate warming and its variation among provenances. The warming treatment significantly increased the maximum net photosynthetic rate (P_max-a), photosynthetic nitrogen use efficiency (PNUE), maximum carboxylation rate (V_cmax), maximum electron transport rate (J_max), triose phosphate utilization rate (TPU), mesophyll conductance (g_m), leaf nitrogen content (N_area), and chlorophyll content (Chl_m). P_max-a was significantly positively associated with V_cmax, J_max, TPU, g_m, and N_area, and the slope of the linear regression between P_max-a and V_cmax, J_max, and TPU was greater in the warming treatment. The responses of P_max-a, PNUE, V_cmax, J_max, TPU, N_area, and Chl_m to warming differed among provenances. As the aridity index of the original site increased, the magnitude of the warming treatment’s effect on P_max-a, V_cmax, J_max, and TPU represented a varying form of a bell-shaped curve. Overall, the warming treatment improved the photosynthetic capacity of L. gmelinii, but the extent of the improvement varied among provenances. These findings provide insights into the mechanisms underlying the responses of L. gmelinii to climate warming. Full article

Bamboo is a typical natural fiber-reinforced composite with excellent mechanical properties, which are determined by its special micro-structure. As the reinforcing phase, the vascular bundles play a central role in the control of the mechanical properties of bamboo macro-structure. To find the exact gradient variation of the mechanical properties of these continuously distributed vascular bundles within the bamboo culm, 4-year-old Moso bamboo was chosen to investigate the variation of locate-distribution, cross-section area, and mechanical properties of single vascular bundles along the longitudinal and radial directions with respect to their location from the base, middle, and top sections of bamboo culm, respectively. It shows that the spatial distribution of vascular bundles along the column is distributed exponentially from the inside to the outside of the culm. The cross-section area of the vascular bundles decreased exponentially from the inside to the outside along the radial direction. All the vascular bundles were then carefully separated from bamboo strips and tested via the tensile tests. Test results show that the longitudinal tensile strengths of vascular bundles ranged from 180.44 to 774.10 MPa, and the longitudinal Young’s modulus ranged from 9.00 to 44.76 GPa. The tensile strength of vascular bundles at the outer side was three times higher than that of the inner side, while Young’s modulus at the outer side was three to four times higher than that of the inner side. For all three height positions, the strengths and Young’s modulus of vascular bundles are all exponentially increased from the inner side to the outer side along the radial direction. This work will provide a basis for the highly processed product’s application of bamboo resources and a reference for further study on the trans-scale analysis of the mechanical properties of bamboo. Full article

Rutting measurements are a significant part of scientific research on the impact of forest vehicles on the forest soils and damage to the forest transport infrastructure. Although photogrammetric methods of measurement or measurements based on LiDAR (light detection and ranging) data are increasingly being used for rutting measurements, the previous research conducted using these methods indicated the challenge of recording water-filled ruts. For this reason, it is necessary to define a reliable method of rutting field measurement in lowland forest stands characterized by a high level of groundwater that fills the ruts shortly after the passage of forest vehicles. This research analyzed the measurement accuracy using a total station and a GNSS RTK device with a CROPOS correction base in relation to the measuring rod that represented the reference method. Based on recorded and processed data, ruts are displayed in two ways: as net and as gross value of rut depth. The analysis of net rutting revealed a statistically significant difference between the calculated rut depths based on measurements with a GNSS RTK device and other methods. On average, the net rutting measured by the GNSS RTK device was 2.86 cm smaller than that of the reference method. When calculating the gross rutting, which consisted of the net rut depth and the bulge height, no statistically significant difference was found between the measurement methods used. Based on this result, the bulge height was also analyzed, and showed a statistically significant difference between the data recorded by the GNSS RTK device and other methods. It can be concluded that measuring the depth of ruts with a total station gives accurate data and represents the optimal modern field measurement method for the same or similar terrain conditions. In contrast, the GNSS RTK device, which constantly gives higher elevation points, can be used to measure gross rutting. Full article

Forest ecosystems and urban parks are an integral part of the natural environment and the natural system of a city, where they form a mosaic of habitats resulting from the variation in soil cover due to human activities. The study was conducted in urban forests in five urban parks in Upper Silesia (southern Poland) and investigated the chemical properties and content of potentially toxic metals (PTMs) in the topsoil, which had an average thickness of 15 cm for all samples. The soil reaction ranged from acidic (pH = 4.7–5.1, in KCl) to slightly acidic (pH = 5.6, to neutral—6.6–7.2) at most sites. The organic carbon (OC) content was relatively high at all sites, ranging from 1.19 to 14.3%, with the highest total nitrogen (Nt) content being 0.481%. The average total phosphorus (Pt) content in the parks ranged from 310 mg kg⁻¹ to 684 mg kg⁻¹, while the highest values were 1840 mg kg⁻¹. The total Cr, Cu, Co and Ni content was within acceptable limits, while the Zn, Pb, Cd, As, Sr and Ba exceeded acceptable standards. In terms of content, Zn dominated the PTMs at each site (Zn > Pb > Ba > Sr > Cu > Cr > As > Ni > Cd > Co), while Ba and Pb alternated in taking second place (Zn > Ba > Pb > Sr > Cu > Cr > Ni > As > Co > Cd). Environmental indicators, such as the geoaccumulation index (Igeo), enrichment factor (EF) and potential ecological risk index (RI), showed that the analyzed soils are highly contaminated with PTMs. Among the sources of pollution in the urban forest are low emissions from coal combustion, industrial activities, water runoff from streets and proximity to transportation routes. Identification of PTM levels in urban parks will provide valuable information on the behavior of these metals, which is important in sustainable development and can help evaluate the local spatial development plans of urbanized areas. Full article

In Pinus massoniana, the methyl-D-erythritol-4-phosphate (MEP) pathway plays a crucial role in the biosynthesis of terpenoids. The fourth step of this pathway is specifically regulated by 4-(cytidine 5′-diphospho)-2-C-methyl-D-erythritol kinase (CMK). In this study, PmCMK (MW892445.1) was isolated. As a member of the GHMP kinase family, PmCMK exhibits homology with CMK genes across diverse species. The examination of relative expression patterns revealed that PmCMK exhibited higher expression levels in tissues of P. massoniana that are rich in resin. We successfully cloned the PmCMK promoter (1654 bp) and integrated it into a GUS reporter vector. This construct was then transformed into the leaves of tobacco (Nicotiana × sanderae) to assess transient expression patterns. The results demonstrated that the promoter was active not only in the roots, leaves, and stems of the tobacco plants but also exhibited varying expression levels in response to treatments with IAA, SA, MeJA, and PEG6000. This suggested that PmCMK expression was modulated by a variety of signals. It revealed that the expression of PmCMK was affected by different treatments. Further allogeneic expression studies showed that tobacco overexpressing PmCMK exhibited increased levels of chlorophyll and carotene compared to the wild type. This enhancement in content indicates that PmCMK has a significant role in isoprene biosynthesis. These findings provide valuable insights for future research aimed at elucidating the biosynthetic pathways of terpenoids and developing breeding strategies to enhance resin production in P. massoniana. Full article

Establishing artificial sand-fixing shrubs is a key measure to curb dune flow and drive changes in the soil stocks and cycling of carbon and nitrogen. But our understanding of these dynamics across years of sand-fixing afforestation and the factors influencing them remains inadequate, making it hard to accurately assess its capacity to sequester carbon. To fill that knowledge gap, this study investigated soil organic carbon (SOC) and soil total nitrogen (STN) stocks in Mu Us Desert under artificial sand-fixing shrub stands of different ages (10, 30, 50, and 70 years old) vis-à-vis a mobile sand dune, to determine whether Caragana korshinskii afforestation improved stock characteristics and whether SOC and STN stocks were correlated during the restoration processes. The results showed that the pattern observed is consistent with an increase over time in the stocks of both SOC and STN. At 10, 30, 50, and 70 years, these stocks were found to be 1.8, 2.3, 3.2, and 5.5 times higher for SOC, and 1.3, 1.6, 2.1, and 2.7 times higher for STN, respectively, than those of the control (mobile sand) dune. Stocks of SOC and STN mainly increased significantly in the 0–10 cm soil layer. The SOC stock was correlated positively with the STN stock as well as the C:N ratio. The slope of the regression for the C:N ratio against stand age was positive, increasing slightly faster with afforestation age. Additionally, our findings suggest that during the establishment of artificial stands of shrubs, the size of the STN stock did not expand as fast as the SOC stock, resulting in an asynchronous N supply and demand that likely limits the accumulation of soil organic matter. This research provides important evidence for the sustainable development of desertified ecosystems. Full article

Natural regeneration is deemed essential for maintaining biodiversity and ecosystem stability. Previous studies, however, have primarily concentrated on regions exhibiting limited environmental and climatic variability, overlooking the classification of natural regeneration based on age and source. Research conducted at the mesoscale, characterized by increased environmental variability and the incorporation of neighborhood competition and understory-associated vegetation, enhances our comprehension of the multifaceted influences on natural regeneration. To comprehend this issue, this study implemented 60 plots, each measuring 20 m × 20 m, across five distinct areas of Chongqing, China. Twenty explanatory variables were chosen from five diverse categories: understory vegetation, neighborhood competition, stand structure, climatic factors, and environmental factors. And the naturally regenerated species were classified into seedlings and saplings, as well as endogenous and exogenous species, based on their age and origin. We examined the response of the different categories of natural regeneration to various factors and constructed a structural equation model (SEM) for significant factors to investigate their direct and indirect effects on natural regeneration. A total of 61 regenerated tree species belonging to 29 families and 42 genera were found in the study area, and the naturally regenerating species with high importance values were Quercus fabri, Robinia pseudoacacia, Alangium chinense, Cunninghamia lanceolata, and Ligustrum lucidum. It was found that neighborhood competition and understory-associated vegetation explained the largest proportion (more than 50%) of the variation in the different categories of natural regeneration, and forests with clumped distribution (W), a high mingling index (M) and strong competition (H) had a reduced natural regeneration capacity. Understory-associated herbs significantly reduced natural regeneration and the crowdedness index (C) significantly inhibited the understory-associated herbs, thus indirectly promoting natural regeneration. The shrub cover is significantly and positively correlated with the number of naturally regenerated plants and can be used as an indicator of a forest community’s regeneration potential. Understanding the differences in the importance of various factors at the mesoscale, as well as their direct and indirect impacts, can help us further comprehend the mechanisms of natural regeneration and provide a foundation for the sustainable development of forests. Full article

Exploring the spatial distribution of tourist attractions and comprehending the spatio-temporal behaviors of tourists within tourist attractions can provide local planning agencies, destination marketing organizations, and government departments with essential evidence for decision-making processes. This study examines the spatio-temporal behavior patterns of tourists in the Kushan Scenic Area by analyzing GPS trajectory data acquired from social media platforms. The investigation primarily utilizes three research methodologies: grid analysis, Markov chain, and K-means clustering. The grid analysis results reveal three spatial distribution patterns within the scenic area, while the outcomes from the Markov chain and K-means clustering delineate six tourist movement patterns, along with three choices regarding travel time. This finding holds significant practical implications for enhancing the attractiveness of scenic areas, optimizing spatial layout, and improving tourists’ experiences. Full article

Green infrastructures (e.g., forests, parks, and other types of green spaces) in urban areas provide people with a huge volume of ecosystem benefits. However, the quality of urban green infrastructure varies among cities in different countries/regions, and key ecological processes, maintaining mechanisms, and policy decision routes remain unclear. Here, we recognize four themes that link studies from the Asia-Pacific and European regions presented in this Editorial: (1) indicators and services of urban green spaces; (2) assembly of and changes in diverse plant communities; (3) utilization and evaluation of urban forest landscape; and (4) patterns and drivers of urban agro-forestry systems. These investigations enlarge our understanding on the theoretical exploration and methodological innovation of urban forestry studies in response to the changing environment, and shed some light on routes to achieve sustainable development goals in the context of rapid urbanization. Full article

Fallow deer is one of the most widespread alien mammals in Europe. We documented the response of the roe deer population shortly after the fallow deer was introduced to a hunting ground in central Poland. Mean roe density dropped from 17.6 ind./100 ha to 10.5 ind./100 ha after the alien species was introduced. In the reference area, where fallow deer was absent, the roe deer density did not change in the analogue study period. At both study sites, mean roe deer productivity before fallow deer introduction was similar (1.6 juv./female). However, in the first study area, the productivity dropped to 1.4, while in the reference study area, it slightly increased to 1.75. The presence of fallow deer influenced roe deer space use negatively, i.e., the number of pellet groups of roe deer decreased with an increase in the number of fallow deer feces. Overall, the introduction of the fallow deer was successful and the population grew quickly. Yet, the economic impact of its introduction was far from satisfactory. At the same time, its negative influence on the roe deer was apparent. This shows that the fallow deer is an alien species threatening local biodiversity. Full article

This study aims to assess the global progress in research on the impact of forest therapy on mental health by using bibliometric analysis. We analyzed the relevant literature from the Web of Science Core Collection (WoSCC) database by utilizing software tools such as Bibliometrix (Version 4.1), VOSviewer (Version 1.6.19), and CiteSpace (Version 6.3.R1). There appears to be a growing trend in annual publication volumes from 2006 to 2023. Miyazaki was identified as the most prolific author in this field. Japan and South Korea lead in research contributions, while China has the highest number of publications. The International Journal of Environmental Research and Public Health is the journal with the most publications and citations in this area. Recent keyword clustering reveals an increasing frequency of studies on anxiety and urban green spaces. Research findings suggest that exposure to negative air ions and compounds released by plants can stimulate the five human senses, reduce cortisol levels, and improve mental health. Although studies have demonstrated significant effects of forest therapy in alleviating stress, anxiety, and depression, more large-scale and long-term studies are needed for further evidence. Additionally, it is crucial to explore the impact of different forest types, terrains, altitudes, climates, and air conditions on the effectiveness of forest therapy on mental health. Full article

In Hokkaido, northern Japan, bareroot Sakhalin fir seedlings are conventionally planted in spring and fall, following strip site preparation that alternates managed and unmanaged strips. However, this method requires seven years of weeding due to encroachment of evergreen dwarf bamboo. Given diminishing forest labor availability, a shortage of workers for planting and weeding operations has become a problem in reforestation following clearcutting. We examined whether comprehensive mechanical site preparation (MSP) could reduce weeding frequency by preventing regrowth of dwarf bamboo and whether container seedlings could extend the planting season into summer. Over eight years, the survival and growth of summer-planted bareroot and container seedlings were examined on a fully MSP-treated site with only one weeding operation in the fifth year. Full-site MSP resulted in a shift of the vegetation from dwarf bamboo to deciduous plants, leading to high survival and growth rates of Sakhalin fir seedlings despite minimal weeding. Container seedlings exhibited superior establishment and maintained higher survival rates over eight years than bareroot seedlings. However, planting on the forwarder trail decreased seedling growth, and ultimately decreased survival under rare summer drought. Our findings indicate that container seedling summer planting and full-site MSP may represent an alternative approach to reforestation of Sakhalin fir, potentially reducing the need for weeding and extending the planting season. Full article

Lianas are a crucial component of karst seasonal rainforests, yet research on them has predominantly focused on non-karst regions. Consequently, their abundance and species richness remain relatively understudied within karst ecosystems. We aimed to document the abundance and species richness of lianas and investigate their relationships with abiotic and biotic factors, based on data from a fully mapped 15 ha plot in a karst seasonal rainforest of Nonggang (SW China). Structural equation models (SEMs) were employed to estimate the path coefficients and variation of dependent variables, enabling a comprehensive analysis of the factors affecting the abundance and species richness of liana. Within the 15 ha plot, a total of 23,819 lianas were identified, encompassing 113 species from 34 families. These lianas constituted 24.16% of the total woody plant density and 33.44% of the species present, but only 4.32% of the total woody plant basal area. Lianas are primarily influenced by abiotic factors, especially elevation and phosphorus (P), with less impact from biotic factors. Our findings reveal that lianas, despite constituting a relatively small percentage of the total woody plant basal area, significantly contribute to the density and diversity of the forest. Notably, abiotic factors such as elevation and phosphorus availability predominantly shape the distribution and richness of lianas, highlighting the importance of these environmental variables. The findings offer valuable insights for future liana studies and the preservation of karst forests’ biodiversity. Full article

In the context of ecological civilization construction in China, interregional ancient trees are important natural and cultural resources, and it is vital that they are effectively protected and utilized according to their spatial distribution and regional conditions in order to provide a balance between local economic development and the ecological environment. This article analyzes the spatial heterogeneity of 26,842 ancient trees and explores the underlying natural and human factors by using geoinformatics–based techniques (i.e., the nearest neighbor index, kernel density, spatial autocorrelation, and the geographically weighted regression model) in Henan Province, Central China. The research findings conclude that: (1) The interregional ancient trees show positive spatial autocorrelation, and the aggregation effect in Western Henan is the most significant. (2) The growing environment and elevation exert a more obvious influence on the spatial pattern of interregional ancient trees. (3) The main influencing factors per region are different, for example, historical culture in Western Henan, water source and elevation in Southern Henan, and the growing environment in Eastern Henan, while ancient trees in Northern Henan have a weak relationship with each factor. This research facilitates political strategy making for sustainable development and the protection of interregional ancient trees. Full article

This work presents the results of the homogenization of the color of sapwood and false heartwood Fagus sylvatica L. into a uniform color shade due to the influence of the temperature of saturated moist air and saturated water steam in individual steaming modes. The results of analyses of the influence of temperature within 24 h point out the different changes in the color of the sapwood and the wood of the false heartwood when the uniform color of the beech wood is achieved by the steaming process. By steaming beech wood with a false heartwood saturated with moist air at a temperature of t_I = 95 °C during τ = 24 h, the color of the sapwood does not merge with the color of the wood of the false heartwood. The sapwood darkens and, on the other hand, the wood of the false heartwood slightly lightens, while the significant color contrast is removed, but the color homogenization in the individual zones does not occur. The unification of the colors in individual zones occurs during the steaming process at a temperature of saturated water steam t_II ≈ 105 °C in 18 h, where the resulting brown color is identified in the color space CIE L*a*b* by the values of the lightness L* = 61.3 ± 2.2 and of the red color a* = 12.4 ± 1.3 and yellow color b* = 19.5 ± 1.4. The most pronounced homogenization of the color occurs through the steaming process at a temperature of saturated water steam t_III ≈ 120 °C, where the wood acquires a uniform dark brown–gray color in a time of τ ≈ 9 h steaming. The coordinates of the color-homogenized steamed beech wood are L* = 55.9 ± 1.9, a* = 12.3 ± 1.2, and b* = 19.6 ± 1.3. The unification of the colors by the steaming process is achieved by darkening both the sapwood and the wood of the false heartwood. In the overall color homogenization, the sapwood and the wood of the false heartwood do not participate equally in the steaming process. While the total color difference between the sapwood and a color homogenized state is quantified by the value ∆E_tI* = 8, ∆E_tIII* = 22.7, the total color difference in the wood with a false heartwood is only ∆E_tI* = 1.9, ∆E_tIII* = 11.8. Full article

Phellinotus (Polyporales) is a common genus of wood-decay fungi in tropical and subtropical areas, endemic to the Seasonally Dry Tropical Forest (SDTF) biome. However, Phellinotus diversity remains unexplored, despite being a major threat to living trees. Therefore, this study is aimed at confirming and characterizing through morphological and molecular data the first isolates of Phellinotus teixeirae in Pithecellobium dulce (Fabaceae) trees (locally referred to as ‘Chiminango’) from the endangered Colombian SDTF biome. Fifteen fungal specimens were recovered from living P. dulce trees, in the urban area and at the Universidad del Valle campus, and classified as P. teixeirae based on taxonomical descriptors. Phylogenetic relationships were inferred from a four-loci dataset (ribosomal and gene-coding regions), including 82 taxa covering 3991 nucleotide positions. The analysis recovered seven highly supported (>90% bootstrapping) monophyletic taxa of the ‘Phellinotus Clade’, and confirmed the new distribution range of P. teixeirae (100% bootstrap support), which extends approx. 1000 km north in the Neotropics. Hierarchical stratified Analysis of MOlecular VAriance (AMOVA) provided a clear genetic distinction between species (70% of variation, p-value = 0.001) and low differentiation among country of origin within species (11%, p-value = 0.044). Discriminant Analysis for Principal Components (DAPC) indicated complex clustering including closely related species, probably a signal of recent radiation and weak species boundaries. Median-joining haplotype network analysis identified unique haplotypes, which may correlate with new host colonization and population expansion (Tajima’s D ≤ −0.5). In conclusion, this study provides the first assessment of the genetic diversity of P. teixeirae in a novel geography (SDTP) and host tree (P. dulce). However, increasing the number of isolates remains critical to understand further the genus’ distribution patterns and drivers of genetic diversity. Full article