Tree trunk instance segmentation is crucial for under-canopy unmanned aerial vehicles (UAVs) to autonomously extract standing tree stem attributes. Using cameras as sensors makes these UAVs compact and lightweight, facilitating safe and flexible navigation in dense forests. However, their limited onboard computational power makes real-time, image-based tree trunk segmentation challenging, emphasizing the urgent need for lightweight and efficient segmentation models. In this study, we present RT-Trunk, a model specifically designed for real-time tree trunk instance segmentation in complex forest environments. To ensure real-time performance, we selected SparseInst as the base framework. We incorporated ConvNeXt-T as the backbone to enhance feature extraction for tree trunks, thereby improving segmentation accuracy. We further integrate the lightweight convolutional block attention module (CBAM), enabling the model to focus on tree trunk features while suppressing irrelevant information, which leads to additional gains in segmentation accuracy. To enable RT-Trunk to operate effectively under diverse complex forest environments, we constructed a comprehensive dataset for training and testing by combining self-collected data with multiple public datasets covering different locations, seasons, weather conditions, tree species, and levels of forest clutter. Compared with the other tree trunk segmentation methods, the RT-Trunk method achieved an average precision of 91.4% and the fastest inference speed of 32.9 frames per second. Overall, the proposed RT-Trunk provides superior trunk segmentation performance that balances speed and accuracy, making it a promising solution for supporting under-canopy UAVs in the autonomous extraction of standing tree stem attributes. The code for this work is available at https://github.com/NEFU-CVRG/RT-Trunk.
South Florida’s natural forest ecosystems, including pine rocklands and hardwood hammocks, are threatened by land use change and urbanization, invasive species, and climate change. It is critical to understand the responses of these ecosystems to anthropogenic disturbances to conserve the remnants of the USA natural subtropical forests. Using dendrochronology, long-term growth patterns were characterized in three dominant native tree species: Bursera simaruba, Swietenia mahagoni, and Pinus elliottii. Core samples were collected from > 30 individuals of each species in hardwood hammocks (B. simaruba and S. mahagoni) and pine rocklands (P. elliottii) to examine growth patterns. Relationships between annual tree growth rates and climatic variables were assessed to address three questions: (1) What are the climatic drivers of growth in these three South Florida tree species? (2) Are their growth rates stable or changing through time? and (3) Are tree growth rates affected by urbanization? Standardized growth rates of the three species have changed through time, with small young trees showing accelerated growth through time, whereas larger, older trees showed declining growth rates. S. mahagoni and B. simaruba grew faster in urbanized parks than in more natural parks, whereas P. elliottii grew slower in urban parks. There were positive correlations between tree growth and the current year’s fall precipitation and no discernable effects of the current year’s monthly temperatures on growth rates of any of the species. These results suggest that the foundational tree species of the southern USA endangered pine rocklands and hardwood hammocks may be vulnerable to ongoing changes in precipitation and temperature as well as other environmental effects associated with urbanization.
The influence of global climate change on endangered species is of growing concern, especially for rosewood species that are in urgent need of protection and restoration. Ecological niche models are commonly used to evaluate probable species’ distribution under climate change and contribute to decision-making to define efficient management strategies. A model was developed to forecast which habitat was most likely appropriate for the Dalbergia odorifera. We screened the main climatic variables that describe the current geographic distribution of the species based on maximum entropy modelling (Maxent). We subsequently assessed its potential future distribution under moderate (RCP2.6) and severe (RCP8.5) climate change scenarios for the years 2050 and 2070. The precipitation ranges of the wettest month and the warmest quarter are the primary limiting factors for the current distribution of D. odorifera among the climatic predictors. Climate change will be expected to have beneficial effects on the distribution range of D. odorifera. In conclusion, the main limits for the distribution of D. odorifera are determined by the level of precipitation and human activities. The results of this study indicate that the coasts of southern China and Chongqing will play a key role in the protection and restoration of D. odorifera in the future.
The predominant causal agent of poplar leaf blight is the pathogenic fungus Alternaria alternata (Fr.) Keissl., which exhibits host specificity toward Populus species. To elucidate the molecular response mechanisms of A. alternata under fludioxonil fungicide stress, the fungus was cultured at the half-maximal effective concentration (EC₅₀) of fludioxonil. Transcriptomic and metabolomic profiles were analyzed using mycelia harvested under these conditions. Comparative analysis revealed 1,001 differentially expressed genes (DEGs) in the resistant strain (RS) relative to the wild-type strain (WT), comprising 628 upregulated and 373 downregulated genes. Concurrently, 524 differentially accumulated metabolites (DAMs) were identified, with 336 upregulated and 188 downregulated metabolites. KEGG pathway enrichment demonstrated pronounced upregulation in glycerophospholipid metabolism, α-linolenic acid metabolism, nucleic acid biosynthesis, and glycosylation processes. Conversely, arachidonic acid and galactose metabolism pathways were suppressed. Significant downregulation was observed in phosphatidylinositol signaling, aflatoxin biosynthesis, and cutin/suberin/wax biosynthesis pathways. Transcriptomic profiling further indicated that upregulated DEGs were predominantly associated with amino sugar/nucleotide sugar metabolism, ABC transporters, aflatoxin biosynthesis, and purine metabolism, while downregulated DEGs were enriched in N-glycan biosynthesis, endoplasmic reticulum protein processing, steroid biosynthesis, and riboflavin metabolism. Fludioxonil exerted substantial inhibitory effects on fungal growth, pathogenicity, and metabolic activity. Mechanistically, A. alternata counteracted fungicide-induced stress through modulation of its antioxidant defense system. This integrative multi-omics study delineates the dynamic gene expression and metabolic reprogramming in A. alternata under fludioxonil exposure, providing novel insights into potential molecular targets and informing the development of next-generation fungicidal strategies for phytopathogen control.
Forests play a vital role in mitigating climate change through their physiological functions and metabolic processes, including their ability to convert solar energy into biomolecules. However, further research is necessary to elucidate how structural characteristics of a forest and topographic settings influence energy conversion and surface temperature of a forest. In this study, we investigated a beech forest in central Germany using airborne laser scanning (ALS) point cloud data and land surface temperature (LST) data derived from Landsat 9 satellite imagery. We constructed 30 m × 30 m plots across the study area (approximately 17 km2) to align the spatial resolution of the satellite imagery with the ALS data. We analyzed topographic variables (surface elevation, aspect and slope), forest attributes (canopy cover, canopy height, and woody area index), as well as forest structural complexity, quantified by the box-dimension (Db). Our analysis revealed that LST is significantly influenced by both forest attributes and topographic variables. A multiple linear regression model demonstrated an inverse relationship (R2 = 0.38, AIC = 8105) between LST and a combination of Db, elevation, slope, and aspect. However, the model residuals exhibited significant spatial dependency, as indicated by Moran’s I test. To address this, we applied a spatial autoregressive model, which effectively accounted for spatial autocorrelation and improved the model fit (AIC = 746). Our findings indicate that elevation exerts the most substantial influence on LST, followed by forest structural complexity, slope, and aspect. We conclude that forest management practices that enhance structural complexity can effectively reduce land surface temperatures in forested landscapes.
A geomagnetic field is a significant factor during the growth and development of trees. Changes in the magnetic field (MF) will result in reactions at the biochemical, molecular, cellular and gene levels. However, it is not clear how a magnetic field affects metabolism and homeostasis under stressful conditions such as salinity. In this study, a novel method was developed of a static magnetic field (SMF) to investigate magnetobiological changes in trees. The results show that pre-treatment of poplar (Populus × euramericana ‘Neva’) cuttings with a static magnetic field significantly mitigated the negative effects of salinity stress on their growth and physiological activities. Biochemical assays revealed that several chemical messengers, including hydrogen peroxide (H2O2) and O2•−, were significantly improved in roots treated with salt, implying an increase reactive oxygen species. A static magnetic field also significantly increased proline concentrations, soluble protein contents, and CAT and SOD activities. Electrophysiological experiments further revealed that pre-treatment with a static magnetic field remarkably decreased salt-induced Na+ influx and H+ efflux which control plant salt tolerance. In pharmacological experiments, because the Na+/H+ correlation was closely related to the SMF-activated plasma membrane and Na+ antiporter activity alleviated the massive accumulation of salt-induced reactive oxygen species (ROS) within the roots. In addition, a static magnetic field dramatically increased the transcriptional activity of stress-responsive genes, including PtrRBOHD and PtrHA5. Together, these results indicate that SMF reduced Na+ influx by activating Na+/H+ antiporters and plasma membrane H+-ATPase to effectively maintain homeostasis by regulating the reactive oxygen species system and cytoplasmic osmotic potential. Ultimately, these static magnetic field methods improved salt tolerance in poplar cuttings, and, for future research, similar methods could be applied to other plants.
Accurately forecasting ecosystem services is critical for enhancing our understanding and improving management practices within nature reserves, particularly in light of climate change, land use/cover changes, and their complex interactions. However, existing studies often fail to fully consider vegetation response, constituting a gap in the comprehensive assessment of changes in ecosystem services. Therefore, a coupled model framework integrating climate change, land use change, and vegetation dynamics was developed to allow for the simulation of dynamic ecosystem service scenarios throughout the twenty-first century. The Jiulianshan National Nature Reserve in Jiangxi Province was considered as the study area. The results showed that ecosystem services and their synergistic effects will be optimized under scenarios that emphasize strict protection of ecological lands and incorporating the SSP1-2.6 scenario. However, sustaining optimized ecosystem services poses significant challenges in scenarios characterized by resource-intensive development and ongoing climate warming, as in the SSP5-8.5 scenario. Notably, discernible variations exist in balancing and synergizing the management of ecosystem services across diverse land uses and forest types. Our study underscores the importance of integrating vegetation response into the framework of ecosystem service forecasting, which is essential for assisting nature reserves in effectively addressing the multifaceted risks associated with climate change and rapid socio-economic development.
Exploring the formation and changes in tree microclimates can help improve the quality of urban green spaces. Temperature is an important indicator of microclimate, and tree temperature categories can be divided into ambient temperature and tree surface temperature (Tts), from which the mean radiation temperature (Tmrt) and thermal comfort values are derived. In this study, the summer microclimate of Ficus altissima in southern subtropical China was determined, focusing on soil (Ts), air (Ta), globe (Tg), and Tts. Tmrt and four commonly used thermal comfort indicators, i.e., predicted mean vote (PMV), physiologically equivalent temperature (PET), standard effective temperature (SET*), and universal thermal climate index (UTCI), were also calculated. The results showed that: (1) Tmrt can be used to explain both the cooling effect and to predict thermal comfort in the shade; (2) the PET indicator is more advantageous for analyzing thermal comfort in the microclimate of Ficus altissima; (3) Ts is not a suitable important indicator for predicting ambient temperatures and thermal comfort; and (4) the site-specific sampling method of the crowns or trunks can be used to accurately explain changes in the whole-plant thermal environment and thermal comfort, respectively.
Fires have historically played a natural role in shaping ecosystems, contributing to biodiversity and ecological renewal. However, in the Anthropocene, the interplay of climate change and human activities has exacerbated fire frequency and intensity, with cascading impacts on soil health, biodiversity, and ecosystem resilience. This study highlights the complex effects of fire on soil ecosystems, particularly in Mediterranean environments, by analysing the aftermath of the 2021 wildfire in Aspromonte National Park. The results of this research reveal the multifaceted impact of fire on soil composition and biological activity. Burned areas exhibited altered microbial communities, characterized by a higher biomass of bacteria and actinomycetes but reduced fungal presence, aligning with findings that fungi are more sensitive to heat than other microorganisms, particularly under moist conditions. Changes in enzyme activity, such as decreased oxidoreductase and hydrolase activities but elevated catalase activity, suggest significant metabolic adjustments among surviving microbial strains. Additionally, increased potassium, magnesium, sulphates, and total phenols in burned areas point to shifts in nutrient dynamics driven by the combustion of organic matter. Fire also impacted microarthropod communities but the rapid recovery of microarthropod communities that has been recognized by numerous authors suggests that fire may not universally impair soil biodiversity in Mediterranean environments. The transition zone played a critical intermediate role, retaining a higher organic matter content than the unburned zone, suggesting its potential as a buffer or recovery zone in post-fire dynamics. Microarthropod communities, while initially affected, demonstrated resilience in line with previous research, indicating that Mediterranean soils might possess adaptive mechanisms to recover from low- to moderate-severity wildfires. Importantly, the incorporation of ashes and partially burned organic material in such fires may lead to enhanced soil fertility, fostering bacterial and actinomycetes proliferation and facilitating ecosystem recovery.
Forests play a critical role in mitigating climate change by sequestering carbon, yet their responses to environmental shifts remain complex and multifaceted. This special issue, “Tree Rings, Forest Carbon Sink, and Climate Change,” compiles 41 interdisciplinary studies exploring forest-climate interactions through dendrochronological and ecological approaches. It addresses climate reconstruction(e.g., temperature, precipitation, isotopes) using tree-ring proxies, species-specific and age-dependent growth responses to warming and drought, anatomical adaptations, and methodological innovations in isotope analysis and multi-proxy integration. Key findings reveal ENSO/AMO modulation of historical climates, elevation- and latitude-driven variability in tree resilience, contrasting carbon dynamics under stress, and projected habitat shifts for vulnerable species. The issue underscores forests’ dual role as climate archives and carbon regulators, offering insights for adaptive management and nature-based climate solutions. Contributions bridge micro-scale physiological processes to macro-scale ecological modeling, advancing sustainable strategies amid global environmental challenges.
Commercially managed forests are often poor in terms of biodiversity. Saproxylic beetle species could be a useful bioindicating group for the conservation of forest stands. In recent decades, oak stands have been affected by a wide range of factors that have intensified stand decline. Saproxylic beetle richness was investigated in declining oak stands that have been consequently targeted for clearcutting due to concerns about insect pest outbreaks. The research was conducted at six managed oak forests, where we compared beetle occurrences in declining stands and in healthy stands that did not show any symptoms of decline. Beetles were collected using window traps placed on the basal and mid-trunk sections of trees. A total of 2925 adults belonging to 239 saproxylic beetle species were captured, of which 56 species are on the IUCN Red List. The results show that declining stands were richer in saproxylic species, and that the diversity of beetle species was greater in these stands. Approximately 1.4 times more species were caught within declining stands than in healthy ones (1.6 times for Red List species). Declining stands hosted more pest species (e.g., cambiophagous and xylophagous species). However, only low numbers of these species were recorded in these stands. In summary, results of this study suggest that decline of managed oak stands is creating a wide spectrum of habitats for many saproxylic species. Thus, salvage logging of declining oak trees can represent a natural trap and reduce local beetle biodiversity, mainly for saproxylic, endangered or low-mobility species that would be attracted by new suitable habitats.
Numerous clustering algorithms are valuable in pattern recognition in forest vegetation, with new ones continually being proposed. While some are well-known, others are underutilized in vegetation science. This study compares the performance of practical iterative reallocation algorithms with model-based clustering algorithms. The data is from forest vegetation in Virginia (United States), the Hyrcanian Forest (Asia), and European beech forests. Practical iterative reallocation algorithms were applied as non-hierarchical methods and Finite Gaussian mixture modeling was used as a model-based clustering method. Due to limitations on dimensionality in model-based clustering, principal coordinates analysis was employed to reduce the dataset’s dimensions. A log transformation was applied to achieve a normal distribution for the pseudo-species data before calculating the Bray–Curtis dissimilarity. The findings indicate that the reallocation of misclassified objects based on silhouette width (OPTSIL) with Flexible-β (– 0.25) had the highest mean among the tested clustering algorithms with Silhouette width 1 (REMOS1) with Flexible-β (– 0.25) second. However, model-based clustering performed poorly. Based on these results, it is recommended using OPTSIL with Flexible-β (– 0.25) and REMOS1 with Flexible-β (– 0.25) for forest vegetation classification instead of model-based clustering particularly for heterogeneous datasets common in forest vegetation community data.
Eucalyptus urophylla × E. grandis is a major hybrid species of timber plantations. However, our understanding of Eucalyptus mitochondrial genome, especially within the Myrtaceae family, is limited. In this study, we employed hybrid sequencing combining the Illumina and Oxford Nanopore sequencing to assemble and annotate the mitogenome (mtDNA) of E. urophylla × E. grandis. Our results reveal a structure characterized by one circular molecule, with a cumulative length of 483,907 base pairs (bp) and a GC content of 44.96%. The circular molecule collectively harbored 59 annotated genes. Among these, 38 were unique protein-coding genes (PCGs), accompanied by 18 transfer RNA (tRNA) genes and 3 ribosomal RNA (rRNA) genes. Our study also examined repetitive sequences, RNA editing sites, and intracellular sequence transfers within the mtDNA. Furthermore, we conducted a phylogenetic analysis between E. urophylla × E. grandis and 30 closely related species based on genetic affinities. The outcomes furnish a high-quality organelle genome for E. urophylla × E. grandis, thereby explaining basic insights into organelle genome evolution and phylogenetic relationships.
Land use/land cover (LULC) change monitoring is critical for understanding environmental and socioeconomic processes and to identify patterns that may affect current and future land management. Forest cover evolution in the Mediterranean region has been studied to better understand forest succession, wildfires potential, and carbon stock assessment for climate change mitigation, among other reasons. However, though multiple sources of current LULC exist, data from last century’s forest cover are less common, and are normally still reliant on locally orthophoto-interpreted data, making continuous maps of historical forest cover relatively uncommon. In this work, a pipeline based on image segmentation and random forest LULC modeling was developed to process three high resolution orthophotos (1956, 1989, and 2021) into LULC continuous land cover maps of Spain’s island of Ibiza. Next, they were combined to quantify forest evolution of Mediterranean Aleppo pine (Pinus halepensis Mill.) and to generate a continuous map of forest age classes. Our models were able to differentiate forestland with an accuracy higher than 80% in all cases, and were able to approximate forestland cover change since the mid-twentieth century, estimating 21,165 ± 252 ha (37.0 ± 0.4%) in 1956, 27,099 ± 472 ha (46.8 ± 0.8%) in 1989, and 30,195 ± 302 ha (52.8 ± 0.5%) in 2021, with a mean increase of 139 ± 6 ha (0.46 ± 0.02%, calculated from current forest cover estimate) per year. The most important variables for the identification of the forestland were the terrain slope and the image gray level or color information in all orthophotos. When combining the information from the three periods, the analysis of forest evolution revealed that a significant portion of current forest cover, approximately 15,776 ha, fell within the 75–120 year age range, while 5388 ha fell within the range of 42–74 years, and 9022 ha within the 10–41 years forest age class. Younger forests, except when mapped after known wildfires, were not considered due to the limitations of the methodology. When compared to forest age data based on ground measurements, significant differences were found among each of the remotely sensed forest age classes, with a mean difference of 13 years between the theoretical age class central value and the real observed plot average age. Overall, 63% of the forest inventory plots were assigned with the correct forest age class. This work will allow a better understanding of long-term Mediterranean forest dynamics and will help landowners and policymakers to better respond to new landscape planning challenges and achieve sustainable development goals.
Over the last century, the Mediterranean basin has been widely affected by the abandonment of farming activities, leading to a natural succession towards forested ecosystems. This process is resulting in a carbon (C) stock increase at an ecosystem level, often assessed through the measurement of aboveground biomass, while the contribution of soil organic carbon (SOC) remains unclear. We investigated C changes caused by secondary succession on previously grazed areas in central Italy, specifically focusing on the SOC pool. The natural succession is described through a chronosequence approach over four successional stages: pastures, shrublands, young and mature forests. Eight replicates per stage were studied, and C stock was estimated in the mineral soil down to a 30-cm depth, and in all other ecosystem C pools: aboveground and belowground biomass, deadwood and litter. In the mature forests, SOC stock was significantly higher (p < 0.05) than in pastures by 40 ± 8 Mg ha–1, corresponding to 28% of the total ecosystem C stock gain. The same trend was observed for aboveground biomass, the pool that increased the most (62 ± 23 Mg ha–1), with a 43% contribution to total ecosystem gain. Our results point to a substantial contribution of SOC to overall C stock during secondary succession in Mediterranean ecosystems.
Texas experienced the worst drought in its 100-year history in 2011, resulting in the death of approximately 300 million trees. The high number of sudden deaths had a significant impact on forest ecosystems. This study aimed to gain insight into the long-term and combined impacts of drought-induced forest tree deaths and their effects on biomass. This study used data obtained from 1797 National Forest Inventory (NFI) plots to analyze trends and major causes of changes in tree biomass at the sample plot level in East Texas forests over the past 20 years (2000 − 2019). In this study, forest trees in East Texas were divided into diameter at breast height (dbh), height, stand types, latitude, elevation, ecological zones, and FIA Unit. Principal component analysis (PCA) was also performed using drought intensity, drought duration, the four competing factor indicators, and the biomass loss rate of forest trees to better understand r drought impacts on forest trees. The results showed the lowest biomass loss rate of Pine species. Similarly, trees with shorter height and smaller dbh experienced a higher biomass loss rate. A higher biomass loss rate was observed in natural forests, West Gulf Coastal Plain and Plain and Southern East Texas ecoregion experienced higher biomass loss. Principal component analyses of drought intensity, drought duration, and the four competing metrics revealed that overall drought was the main contributor to biomass loss rates, and that drought intensity and drought duration had comparable effects on biomass loss rates.
Two leaf color variants red-leaf (R-type) and common-leaf (G-type) of Euonymus sacrosancta Koidz., were employed as experimental materials to elucidate the molecular mechanisms underlying chromatic transition. Physiological profiling identified anthocyanins and flavonoids as the predominant pigments responsible for the red foliar phenotype, which exhibited reduced chlorophyll and carotenoid accumulation but elevated soluble sugars and proteins. Comparative transcriptomic analysis revealed that differentially expressed genes (DEGs) between R-type and G-type were significantly enriched in flavonoid biosynthesis and carotenoid metabolism pathways. The up-regulation of 22 key genes of anthocyanin synthesis (e.g., CHS, CHI, LAR, LDOX and UFGT) in R-type may lead to the phenotype of red leaves through the increase of anthocyanin accumulation. The downregulated expression of 13 carotenoid synthesis-related genes (e.g., PSY, PDS and VDE) and 6 carotenoid degradation genes (e.g., ABA2, CYP707A and NCED) may lead to lower carotenoid content in R-type compared to G-type. Combined with weighted gene co-expression network analysis (WGCNA), five candidate genes (EsLAR, EsLDOX, EsPDS, EsCYP707A and EsABA2) were screened from two modules highly correlated with anthocyanin content in E. sacrosancta leaves. These genes may play key regulatory roles in leaf coloration and could serve as candidate genetic resources for leaf color improvement in E. sacrosancta. Additionally, transcription factors such as C2H2s, C3Hs, and WRKYs were identified as potential regulators in the formation of R-type in E. sacrosancta. This study provides the first systematic elucidation of the transcriptional regulatory network governing red-leaf formation in E. sacrosancta, establishing a critical theoretical foundation for molecular breeding in ornamental plants.
Afforestation on formerly cultivated or abandoned agricultural land is a common strategy to increase forest areas and enhance carbon sequestration. Deep soil ploughing before afforestation improves soil conditions, facilitating tree growth and carbon storage. This study assessed the growth and biomass parameters of Pinus sylvestris in 10- and 20 years old plantations established on deeply ploughed and non-ploughed soils in Lithuania. Biomass allocation and carbon and nutrient concentrations including N, P, K, Ca and Mg were analysed in aboveground biomass components. Deep ploughing in the 10 years old stands negatively impacted vertical growth and stem development but did not significantly affect overall biomass accumulation. In contrast, in the 20 years old stands, deep ploughing resulted in taller trees with larger diameters and higher biomass accumulation compared to non-ploughed sites. Biomass distribution within tree canopies varied between ploughed and non-ploughed sites, indicating diverse effects of deep ploughing. Carbon and nutrient concentrations in biomass components showed site-specific variations, with deep ploughing influencing carbon concentrations in needles and stem bark. Overall, deep ploughing showed potential for enhancing tree growth and biomass accumulation, with implications for carbon sequestration in forest ecosystems. These findings help us understand the impact of an alternative soil management practice, deep ploughing, on forest development and carbon dynamics.
Climate changes in cold-temperate zones are increasingly altering the state of climatic constraints on photosynthesis and growth, leading to adaptive changes in plant phenology and subsequent seasonal carbon assimilation. However, the spatio-temporal patterns of climatic constraints and seasonal carbon assimilation are poorly understood. In this study, the timing of peak photosynthetic activity (DOYpmax) was employed as a proxy for plant adaptive state to climatic constraints on growth to examine the spatio-temporal dynamics of DOYpmax. By using multiple remote sensing metrics, DOYpmax was characterized with changes in the solar-induced chlorophyll fluorescence (SIF) and leaf area index (LAI) from 2000 to 2018. Based on SIF, the DOYpmax was generally around day 190, while based on LAI was about 10 d later. Peak photosynthetic activity of forests occurs earlier compared to other vegetation types. Overall, the advanced DOYpmax were observed based on both SIF and LAI, with annual rates of 0.2 (P = 0.31) and 0.3 (P < 0.05) d, respectively. DOYpmax dynamics were influenced by hot temperature extremes and vapor pressure deficits (VPD) during the early growing season, regardless of sub-zone and different vegetation type. The generalized linear mixed model (GLMM) showed the largest contribution by hot extremes to DOYpmax dynamics accounted for 55.5% (DOYpmax_SIF) and 49.1% (DOYpmax_LAI), respectively, followed by VPD (DOYpmax_SIF: 23.1%; DOYpmax_LAI: 29.5%). These findings highlight the crucial role of climate extremes in shaping seasonal carbon dynamics and regional carbon balance.
The current trends in forestry in Europe include the increased use of continuous cover forestry (CCF) and the increased availability of tree-level forest inventory data. Accordingly, recent literature suggests methodologies for optimizing the harvest decisions at the tree level. Using tree-level optimization for all trees of the stand is computationally demanding. This study proposed a two-level optimization method for CCF where the harvest prescriptions are optimized at the tree level for only a part of the trees or the first cuttings. The higher-level algorithm optimizes the cutting years and the harvest rates of those diameter classes for which tree-level optimization is not used. The lower-level algorithm allocates the individually optimized trees to different cutting events. The most detailed problem formulations, employing much tree-level optimization, resulted in the highest net present value and longest optimization time. However, restricting tree-level optimization to the largest trees and first cuttings did not significantly alter the time, intensity, or type of first cutting. Computing times could also be shortened by applying accumulated knowledge from previous optimizations, implementing learning aspects in heuristic search, and optimizing the search algorithms for short computing time and good-quality solutions.
To investigate the genetic variation patterns of multiple traits in Pinus sibirica half_sibling families introduced to the Greater Khingan Range, this study aims to establish a comprehensive trait evaluation system based on genetic parameters and identify fast-growing, high-quality genetic materials. The findings provide scientific support for advanced-generation seed orchard development and multi-objective genetic improvement. A total of 66 half-sibling families from a 26-year-old trial plantation of the Tomsk seed source were evaluated. Eleven traits were measured, including growth traits (tree height, diameter at breast height, volume, and crown width), morphological traits (lateral branch diameter), wood quality traits (Pilodyn value), and needle traits (fresh weight, dry weight, moisture content, needle length, and needle width). Genetic parameters were estimated using variance component decomposition. Superior families with favorable performance in both growth and wood density traits were identified using Best Linear Unbiased Prediction (BLUP) weighted by genetic correlation coefficients. Additionally, individual tree selection was conducted based on growth traits using the index selection method. Significant genetic differences among families (Z ratio > 1.50) were observed for 10 traits, including growth, wood density, and needle traits. The phenotypic coefficient of variation (PCV: 5.05–62.50%) and genetic coefficient of variation (GCV: 2.19–13.81%) exhibited substantial heterogeneity. Volume displayed the highest variation (PCV = 62.50%, GCV = 13.81%), while the highest family heritability was observed for the needle length-to-width ratio (h2 = 78.30%), and the highest individual heritability was recorded for needle moisture content (H2 = 95.22%). Genetic correlations analysis revealed strong positive associations between volume and tree height (r = 0.880), diameter at breast height (r = 0.968), and Pilodyn value (r = 0.508). Using the BLUP method, 13 superior families (e.g., Families 59, 11, and 51) were identified, with an average genetic gain in volume of 13.377% and a family retention rate of 70%, significantly exceeding the population mean (65.10%). Through index selection, 94 elite individual trees were selected, 52.14% of which originated from superior families. The genetic gain in individual tree volume reached 26.80%, with the within-family gain for elite individuals increasing to 28.47%. This study establishes the first multi-trait genetic evaluation model for P. sibirica and proposes a “family-individual” collaborative selection strategy. The selected superior families achieved a volume genetic gain of 3.864–32.307% and an overall genetic gain of 2.729–20.069%, while elite individual trees exhibited a volume genetic gain of 16.328–52.716%. These findings would provide critical technical support for multi-objective breeding and seed orchard development in cold-temperate coniferous species.
Branch length and branch diameter are important characteristics that determine wood quality and yield. Development of static branch length and diameter models by incorporating individual tree variables, site quality and competition have been widely studied, while the climate effect has rarely been reported. In this study, mixed-effects climate-sensitive branch length and diameter models were developed based on 228 sample trees of Larix kaempferi from three latitude regions in China (approximate 42°N in Liaoning Province, 33°N in Gansu Province, and 30°N in Hubei Province). Results revealed that diameter at breast height, and crown ratio, sum of the basal areas of trees larger than the subject trees, dominant tree height, mean warmest month temperature, and summer precipitation substantially improved branch length model. Diameter at breast height, and crown ratio, ratio of the sum of DBH in sample plot to the subject tree, dominant tree height, mean warmest month temperature, and spring precipitation significantly improved branch diameter model. Compared with base model, mean square error reduction of mixed-effects branch length and diameter models were 32.9% and 44.1%, respectively. The relative contributions of covariates to branch length model were tree size (59.1%), site quality (25.7%), competition (13.5%), and climate (1.7%), and branch diameter model were tree size (57.0%), competition (21.9%), site quality (18.3%), and climate (2.8%). Relative contributions of covariates on branch length and diameter models from different latitude regions were different. Effects of competition on branch length model in Liaoning and Hubei were larger than climate, whereas climate in Gansu was larger than competition. As for branch diameter model, competition in Liaoning was larger than site quality, whereas site quality in Hubei and Gansu was larger than competition. The present study strengthened the importance of considering climate variables in developing branch length and diameter model. It is desirable to disentangle the different sources of variations in affecting branch length and diameter from different latitude regions to reduce the uncertainty in predicting branch characteristics under the condition of climate changing.
Soil microbial communities play a crucial role in forest ecological processes, but the differences between rhizosphere and non-rhizosphere soils, as well as their variations with stand ages remain unclear. We collected rhizosphere and non-rhizosphere soils in Castanopsis hystrix plantations at ages (6, 10, 15, 25, 30 and 34 years) in the southern subtropics and analyzed soil microbial communities using the phospholipid fatty acid (PLFA) method. There were significant differences in microbial communities between the two. Rhizosphere soils had higher total PLFAs and fungal to bacterial (F:B) ratios, and lower arbuscular mycorrhizal fungi to ectomycorrhizal fungi (AMF:EMF) ratios in the 34-year-old stand but microbial communities in non-rhizosphere soils showed no changes with stand age. Rhizosphere soils had higher total PLFAs and F:B ratios but lower AMF:EMF ratios. Further analysis revealed a strong correlation between fine root nutrients and rhizosphere soil PLFAs, indicating a closer interaction between root exudates and microbial communities. In contrast, non-rhizosphere soil PLFAs appeared to be more influenced by soil nitrogen availability. Overall, soil microbial communities exhibited significant differences between rhizosphere and non-rhizosphere soils over various stand ages. A strong correlation was observed between rhizosphere soil PLFAs and fine root nutrients, which may improve our understanding of forest management strategies.
The duration of snow cover has shortened in the boreal region, and the amount of seasonal snow decreased. This affects the coupling between soil and air temperatures and may thus lead to colder soil and deeper soil frost. We prevented snow reaching the forest floor for two winters in mature boreal forest and studied how that affects tree and forest floor processes. The studied species were Scots pine, Norway spruce, silver birch, and a dwarf shrub bilberry. Decreased soil temperature, due to the lack of snow cover, decreased forest floor respiration in winter and spring. Simultaneously, response of respiration to temperature seemed to increase, perhaps due to the exposure of forest floor vegetation to cold air temperature. Indeed, lack of snow cover induced mortality of bilberry, but the remaining ramets grew more in height and their average leaf size was larger likely to compensate for the lost plant biomass. Lack of snow cover also affected tree hydraulics as tree water uptake was decreased in spring, and the start of the sap season delayed in birch. Pine and birch tended to grow less in the snow exclusion treatment (differences not statistically significant), whereas spruce grew more. Coarse root traits, e.g. water content and cellular frost damages, were not affected by the snow exclusion treatment. The results of this case study increase our understanding on the effects of changing snow cover on spring-time tree and forest floor processes in mature boreal forest, but also reveal the need for further studies on mature trees.
While the fire protection function of tree bark has been extensively documented, other critical functions, including storage and mechanical support, have received less attention. In this study we examined: (1) the allometry of bark thickness (and biomass) against wood radius (and biomass) at a disc level, (2) differences in bark allocation between the ratio and the regression approaches, (3) differences between bark thickness and biomass as metrics of bark allocation, and (4) how bark allocation is associated with the evolution of wood from non-porous to diffuse-porous and ring-porous types. Thickness and biomass of bark and wood were measured using trunk discs of 88 individual trees of 36 species in a temperate forest characterized by a long fire interval. Allometric relationships of bark thickness (and biomass) against wood radius (and biomass) explained why both relative bark thickness and biomass decreased with increasing stem diameter. Variations in both among species varied by factors of 3.5 to 7.5 depending on the measurement methods. The ratio approach produced higher estimates of both relative bark thickness and biomass compared to the regression approach, while relative bark thickness was significantly lower than relative bark biomass. Ring-porous species exhibited higher bark thickness based on the ratio approach, which might reflect evolutionary adaptations where ring-porous species have developed thicker bark as protection: thermal insulation against freeze–thaw embolism coupled with carbohydrate reservoirs for hydraulic repair. The regression slope of bark allocation against wood density increased along the wood porosity gradient, demonstrating evolutionary biomechanical coordination between bark and wood. These findings highlight systematic coupling between bark and xylem multifunctionality.
To understand the roles of charcoal and ectomycorrhizal fungi (ECMF) on tree growth, which relates to the rehabilitation of forest ecosystems after forest fires, two experiments were set up in this study, the first was to determine the correct amount of charcoal for Japanese larch (Larix kaempferi Sarg.) seedling growth by applying oak charcoal to basic soil medium at ratios of 1:1, 1:2, 1:4 and 1:8 by volume. The second experiment investigated the combined effects of four types of charcoal: derived from oak wood, husks of buckwheat, rice and activated charcoal of larch wood, and two types of ECMF: Pt (Pisolithus tinctorius Pers.) and Ec (Pt + Rhizopogon spp. + Laccaria spp. + Scleroderma spp.) on the growth of Japanese larch seedlings. Our results show that growth was significantly stressed by large amounts charcoal applications. There were significant variations among the four types of charcoal on growth. We concluded that the addition of charcoal was the critical factor that influenced larch growth and ECMF formation. Rice charcoal and Ec stimulates the growth and nitrogen uptake of Japanese larch seedlings, thus the most suitable fungus and charcoal for practices is Ec-rice charcoal (1: 8 charcoal to basic soil).
Climate change is the most severe ecological challenge faced by the world today. Forests, the dominant component of terrestrial ecosystems, play a critical role in mitigating climate change due to their powerful carbon sequestration capabilities. Meanwhile, climate change has also become a major factor affecting the sustainable management of forest ecosystems. Climate-Smart Forestry (CSF) is an emerging concept in sustainable forest management. By utilizing advanced technologies, such as information technology and artificial intelligence, CSF aims to develop innovative and proactive forest management methods and decision-making systems to address the challenges of climate change. CSF aims to enhance forest ecosystem resilience (i.e., maintain a condition where, even when the state of the ecosystem changes, the ecosystem functions do not deteriorate) through climate change adaptation, improve the mitigation capabilities of forest ecosystems to climate change, maintain high, stable, and sustainable forest productivity and ecosystem services, and ultimately achieve harmonious development between humans and nature. This concept paper: (1) discusses the emergence and development of CSF, which integrates Ecological Forestry, Carbon Forestry, and Smart Forestry, and proposes the concept of CSF; (2) analyzes the goals of CSF in improving forest ecosystem stability, enhancing forest ecosystem carbon sequestration capacity, and advocating the application and development of new technologies in CSF, including artificial intelligence, robotics, Light Detection and Ranging, and forest digital twin; (3) presents the latest practices of CSF based on prior research on forest structure and function using new generation information technologies at Qingyuan Forest, China. From these practices and reflections, we suggested the development direction of CSF, including the key research topics and technological advancement.
Exotic tree species, though widely used in forestry and restoration projects, pose great threats to local ecosystems. They need to be replaced with native species from natural forests. We hypothesized that natural forests contain large, fast-growing, dominant native tree species that are suitable for specific topographic conditions in forestry. We tested this hypothesis using data from a 50-ha forest dynamics plot in subtropical China. We classified the plot into the ridge, slope, and valley habitats and found that 34/87 species had significant associations with at least one topographic habitat. There were 90 tree species with a maximum diameter ≥ 30 cm, and their abundances varied widely in all habitat types. In all habitat types, for most species, rate of biomass gain due to recruitment was < 1% of its original biomass, and rate of biomass gain due to tree growth was between 1 and 5% of its original biomass. For most species, biomass loss due to tree mortality was not significantly different than biomass gain due to recruitment, but the resulting net biomass increment rates did not significantly differ from zero. The time required to reach a diameter of 30 cm from 1 cm diameter for Altingia chinensis in the slope habitat, for Quercus chungii and Morella rubra in the ridge habitat and for Castanopsis carlesii in all habitats could be as short as 30 years in our simulations based on actual distributions of tree growth observed in the forest. Principal component analyses of maximum diameter, abundance and net biomass increment rates suggested several species were worthy of further tests for use in forestry. Our study provides an example for screening native tree species from natural forests for forestry. Because native tree species are better for local ecosystems, our study will also contribute to biodiversity conservation in plantations.
Pinewood nematode is a devastating forest pathogen and is considered a quarantine organism worldwide. First identified in China 40 years ago, the disease has been spreading since. In response, Chinese authorities have introduced new requirements for preventing and controlling the disease. This paper proposes a new and highly effective preventive drug, a trunk injection agent usable at normal temperatures. Its use is suggested for localized epidemic areas to reduce diseased and dead trees and as a preventive measure in adjacent non-epidemic areas to prevent the infection from spreading, particularly protecting important and ancient pine trees.Kindly check and verify corresponding affiliation is correctly identified.Checked
Petroleum extraction and its organic pollutants have numerous negative consequences on the composition and ecological function of grasslands, such as vegetation degradation, reduction in species diversity, and salinization. Thus, finding a comprehensive method for polluted soil and restoring grasslands faces many challenges, and the mechanism to influence soil environments and microbial community composition remains unclear. In this study, container experiments explored the potential of sulfonic acid group (–SO3H groups) modified biochar combined with isolated bacterium (named Y-1, Acinetobacter-spp.) on physicochemical properties and microbial communities of polluted soil. The results show that modified biochar and Y-1 combined addition had the highest petroleum degradation rate (39.4%), and soil nutrients such as dissolved organic carbon (DOC), cation exchange capacity (CEC), available nitrogen, invertase and urease activities in CK were decreased by 35.4, 12.1, 30, 43.2 and 32.5% compared to treatments. The contents of available phosphorus in CM treatment were increased 2.4 times compared to CK. The –SO3H groups efficiently improve salinity by accumulating Ca2+ and Mg2+ and inhibiting the aggregation of Na+. The correlation heatmap indicated that soil organic carbon, total nitrogen and CEC markedly interact with microbial communities. High-throughput sequencing indicated that the biomarkers enriched by the present integrated treatment are crucial for stimulating nitrogen and phosphorus cycles. The results indicate that -SO3H groups modified biochar, and Y-1 has great potential to serve as a novel bioremediation technology to remediate soil from petroleum pollutants and alkalization and achieve better restoration of degradation grasslands.
Pinus koraiensis (Sieb. et Zucc.) is a coniferous tree species naturally distributed in northeastern China. However, the effects of gene flow on its genetic diversity and structure remain unclear. This study investigates these dynamics in seven populations using ten microsatellite markers. The results show a high level of genetic diversity within the populations (Ho = 0.633, He = 0.746). In addition, molecular analysis of variance (AMOVA) shows that 98% of genetic diversity occurs within populations, with minimal differentiation between populations (Fst = 0.009–0.033). Gene flow analysis shows significant migration rates between specific population pairs, particularly C-TH (87%), LS-Y (69%) and TH-LS (69%), suggesting genetic homogenization. Bayesian clustering (STRUCTURE) supports admixture and weak population differentiation. Environmental factors, especially temperature-related variables, significantly influence genetic patterns. Partial Mantel tests and multiple matrix regression show strong correlations between genetic distance and adaptations to cold temperatures (bio6 and bio11). Overall, this study emphasizes the robust genetic diversification and high migration rates in the populations of P. koraiensis and highlights their resilience. These results emphasize the importance of incorporating genetic and ecological factors into conservation strategies for sustainable forest management. This research provides valuable insights into the complex interplay of genetic variation, gene flow and environmental influences in forest tree species and improves our understanding of their adaptive mechanisms.
Photodegradation is considered as a universal contributing factor to litter decomposition and carbon (C) cycling within the Earth’s biomes. Identifying how solar radiation modifies the molecular structure of litter is essential to understand the mechanism controlling its decomposition and reaction to shifts in climatic conditions and land-use. In this study, we performed a spectral-attenuation experiment following litter decomposition in an understory and gap of a temperate deciduous forest. We found that short-wavelength visible light, especially blue light, was the main factor driving variation in litter molecular structure of Fagus crenata Blume, Quercus crispula Blume, Acer carpinifolium Siebold & Zuccarini and Betula platyphylla Sukaczev, explaining respectively 56.5%, 19.4%, 66.3%, and 16.7% of variation in its chemical composition. However, the variation also depended on canopy openness: Only in the forest gap was lignin aromatic C negatively associated with C-oxygen (C–O) bonding in polysaccharides receiving treatments containing blue light of the full spectrum of solar radiation. Regardless of species, the decomposition index of litter that explained changes in mass and lignin loss was driven by the relative content of C–O stretching in polysaccharides and lignin aromatic C. The results suggest that the availability of readily degradable polysaccharides produced by the reduction in lignin aromatic C most plausibly explains the rate of litter photodegradation. Photo-products of photodegradation might augment the C pool destabilized by the input of readily degradable organic compounds (i.e., polysaccharides).
Leptocybe invasa is an invasive pest, native to Australia, which causes serious damage to Eucalyptus all over the world. Here, we monitored gall development in resistant and susceptible Eucalyptus clones to determine whether plant genotype affects the durations of the different gall stages. Gall development varied among six Eucalyptus clones that differed in susceptibility to L. invasa viz., PE-5, 316, 3011, PE-11, 3020 and P-13 in Punjab in a nethouse. In susceptible clones PE-5 and 316, L. invasa emerged from both green and pink galls. Five stages of gall formation were found: Stage 1 (tissue disruption), Stage 2 (gall development), Stage 3 (glossy pink), Stage 4 (dull pink) and Stage 5 (exit hole) in susceptible clones when adults emerged from pink galls. However, in resistant clones, adults emerged only from green galls, and galls formed in three stages. In the susceptible clones, when adults emerged from pink galls, the life cycle was 105–115 d; however, when adults emerged from green galls, the duration was significantly shorter (81–87 d). In the most-resistant clone, P-13, corky tissue formed after oviposition, and galls did not develop further. In the resistant clones (3020, PE-11 and 3011), adults emerged from green galls, and the life cycle lasted 90–96 d. When adults emerged from green galls in susceptible and resistant clones, Stage 1 lasted longer in resistant clones than in the susceptible; however, in susceptible clones, Stage 5 was longer. When adults emerged from pink galls in susceptible clones and from green galls in resistant clones, the life cycle was longer in susceptible clones. In susceptible clones, the number of emergence holes was significantly higher than resistant clones. Gall width and gall length also differed significantly between susceptible and resistant clones. The results showed that the Eucalyptus genotype had a significant effect on gall development induced by gall wasps.
Biological invasions, driven mainly by human activities, pose significant threats to global ecosystems and economies, with fungi and fungal-like oomycetes playing a pivotal role. Ink disease, caused by Phytophthora cinnamomi and P. × cambivora, is a growing concern for sweet chestnut stands (Castanea sativa) in Europe. Since both pathogens are thermophilic organisms, ongoing climate change will likely exacerbate their impact. In this study, we applied species distribution modeling techniques to identify potential substitutive species for sweet chestnut in the light of future climate scenarios SSP126 and SSP370 in southern Switzerland. Using the presence-only machine learning algorithm MaxEnt and leveraging occurrence data from the global dataset GBIF, we delineated the current and projected (2070–2100) distribution of 28 tree species. Several exotic species emerged as valuable alternatives to sweet chestnut, although careful consideration of all potential ecological consequences is required. We also identified several native tree species as promising substitutes, offering ecological benefits and potential adaptability to climatic conditions. Since species diversification fosters forest resilience, we also determined communities of alternative species that can be grown together. Our findings represent a valuable decision tool for forest managers confronted with the challenges posed by ink disease and climate change. Given that, even in absence of disease, sweet chestnut is not a future-proof tree species in the study region, the identified species could offer a pathway toward resilient and sustainable forests within the entire chestnut belt.
Rhododendron micranthum Turcz. is a shrub esteemed for its ornamental and medicinal attributes within the Changbai Mountain range of China. We selected 3-year saplings and subjected them to four distinct light conditions: full light (CK), 70% light (L1), 50% light (L2), and 30% light (L3) to investigate variations in morphology, photosynthetic responses, stomatal ultrastructure as well as the mechanisms through which these saplings adapt to differing lighting environments. The results indicate that L2 leaves exhibit significantly greater length, width, and petiole development compared to other treatments across varying intensities. Over time, chlorophyll content and PSII levels in L2-treated saplings surpass those observed in other treatments; Proline (PRO), malondialdehyde (MDA), and soluble protein (SP) contents are markedly lower under L2 treatment. Catalase (CAT) and superoxide dismutase (SOD) demonstrate significant correlations across various light conditions but respond differently among treatments, indicating distinct species sensitivities to light intensity while both contribute to environmental stress resistance mechanisms. Findings reveal that R. micranthum saplings at 50% light intensity benefit from enhanced protection via antioxidant enzymes, and shading reduces osmotic adjustment substances yet increases chlorophyll content. Stomatal length/width along with conductance rates and net photosynthesis rates for L2 exceed those of CK, suggesting an improved photosynthetic structure conducive to efficient photosynthesis under this condition. Thus, moderate shading represents optimal growth at 50% illumination, a critical factor promoting sapling development. This research elucidates the ideal environment for R. micranthum adaptation to varying light conditions supporting future conservation initiatives.
Tree endophytic fungi play an important role in reducing insect herbivory, either by repelling them or killing them directly. Identifying which fungi show such activity could lead to new environmentally friendly pesticides. In this study, the Mediterranean basin climate conditions are projected to harshen in the next decades, will increase vulnerability of tree species to pest invasions. Endophytic fungi were isolated from wood and leaves of Quercus pyrenaica, Q. ilex and Q. suber and tested for virulence against adults of the mealworm beetle, Tenebrio molitor L. using a direct contact method. Only 3 of 111 sporulating isolates had entomopathogenic activity, all identified as Lecanicillium lecanii. The pathogenicity of L. lecanii on T. molitor resulted in a median lethal time (TL50) of 14–16 d. Compared with commercial products, L. lecanii caused faster insect death than the nematode Steinernema carpocapsae and nuclear polyhedrosis virus (no effect on T. molitor survival), and slower than Beauveria bassiana (TL50 = 5), Beauveria pseudobassiana (TL50 = 8d) and Bacillus thuriengensis (80% mortality first day after inoculation). Mortality was also accelerated under water stress, reducing TL50 by an additional 33%. Remarkably, water stress alone had a comparable effect on mortality to that of L. lecanii isolates. This study confirms T. molitor as a good model insect for pathogenicity testing and agrees with management policies proposed in the EU Green Deal.
Human activities contribute to elevated nitrogen input in terrestrial ecosystems, influencing the composition of soil nutrients and microbial diversity in forest ecosystems. In this study, we built four addition treatments (0, 20, 40, and 80 kg ha−1 a−1 N for 6 a) at a Korean pine plantation of different soil horizons (organic (O) horizon, ranging from 0 to 10 cm, and organomineral (A) horizon, extending from 10 to 20 cm) to evaluate responses of the structure of saprophytic fungal communities. Here, 80 kg ha−1 a−1 N treatment significantly decreased the community richness in soil A horizon with the Chao1 index decreasing by 12.68%. Nitrogen addition induced changes in the composition of saprophytic fungi community between the different soil horizons. The co-occurrence network and its associated topological structure were utilized to identify mycoindicators for specific fungi to both soil horizons and nitrogen addition levels. In soil O horizon, the mycoindicators included Penicillium, Trichoderma, Aspergillus, and Pseudeurotium across control, low, medium, and high nitrogen treatments. In soil A horizon, Geomyces, Cladophialophora, Penicillium, and Pseudeurotium were identified as mycoindicators. Structural equation modeling determined NH4 +-N as the key factor driving changes in saprotrophic fungal communities. Our study aimed to screen mycoindicators that can respond to the increasing global nitrogen deposition and to assess the roles of these mycoindicators in the saprophytic fungal community structure within Korean pine plantations in northeast China.
To better understand the effects of ground-level ozone (O3) on nutrients and stoichiometry in different plant organs, urban tree species Celtis sinensis, Cyclocarya paliurus, Quercus acutissima, and Quercus nuttallii were subjected to a constant exposure to charcoal-filtered air (CF), nonfiltered air (NF), or NF + 40, 60, or 80 nmol O3 mol–1 (NF40, NF60, and NF80) starting early in the summer of the growing season. At the end of summer, net CO2 assimilation rate (A), stomatal conductance (gs), leaf mass per area (LMA), and/or leaf greenness (SPAD) either were not significantly affected by elevated O3 or were even higher in some cases during the summer compared with the CF or NF controls. LMA was significantly lower in autumn only after the highest O3 exposures. Compared to NF, NF40 caused a large increase in gs across species in late summer and more K and Mn in stems. At the end of the growing season, nutrient status and stoichiometric ratios in different organs were variously altered under O3 stress; many changes were large and often species-specific. Across O3 treatments, LMA was primarily associated with C and Mg levels in leaves and Ca levels in leaves and stems. NF40 enriched K, P, Fe, and Mn in stems, relative to NF, and NF60 enhanced Ca in leaves relative to CF and NF40. Moreover, NF resulted in a higher Ca/Mg ratio in leaves of Q. acutissima only, relative to the other O3 regimes. Interestingly, across species, O3 stress led to different nutrient modifications in different organs (stems + branches vs leaves). Thus, ambient and/or elevated O3 exposures can alter the dynamics and distribution of nutrients and disrupt stoichiometry in different organs in a species-specific manner. Changes in stoichiometry reflect an important defense mechanism in plants under O3, and O3 pollution adds more risk to ecological stoichiometries in urban areas.
The increasing frequency of extreme weather events raises the likelihood of forest wildfires. Therefore, establishing an effective fire prediction model is vital for protecting human life and property, and the environment. This study aims to build a prediction model to understand the spatial characteristics and piecewise effects of forest fire drivers. Using monthly grid data from 2006 to 2020, a modeling study analyzed fire occurrences during the September to April fire season in Fujian Province, China. We compared the fitting performance of the logistic regression model (LRM), the generalized additive logistic model (GALM), and the spatial generalized additive logistic model (SGALM). The results indicate that SGALMs had the best fitting results and the highest prediction accuracy. Meteorological factors significantly impacted forest fires in Fujian Province. Areas with high fire incidence were mainly concentrated in the northwest and southeast. SGALMs improved the fitting effect of fire prediction models by considering spatial effects and the flexible fitting ability of nonlinear interpretation. This model provides piecewise interpretations of forest wildfire occurrences, which can be valuable for relevant departments and will assist forest managers in refining prevention measures based on temporal and spatial differences.
Evapotranspiration (ET), vapor pressure deficit (VPD) and water use efficiency (WUE) are crucial components of the hydrological cycle in forest ecosystems, serving as indicators that reflect the intricate coupling of carbon and water fluxes within the ecosystem. The cold temperate zone, being ecologically fragile and sensitive to climate change, accentuates the significance of exploring the variation characteristics of the dynamics of hydrological processes of a Larix gmelinii forest ET, VPD and WUE were measured in the June to August growing season and the April, May, September and October freeze–thaw period from 2011 to 2016. A structural equation model (SEM) quantitatively analyzed the impact of environmental factors on ecohydrological variables. The results reveal that: (1) Daily average ET in the growing season was significantly higher than in the freeze–thaw period. WUE showed the opposite. Peaks for both ET and VPD occurred in July. In contrast, the freeze–thaw period saw maximum ET and VPD, and minimum WUE in May. July and May emerged as the most active months for hydrological processes in the ecosystem; (2) During the growing season, VPD was influenced by relative humidity (RH) and temperature (Ta), ET responded negatively to solar radiation, and WUE negatively to VPD. Throughout the freeze–thaw period, the ecosystem experienced heat stress, and ecohydrological processes were influenced by Ta. This study provides valuable references for further research on hydrological cycles in forest systems within cold temperate zones.
Studying the reproductive system of the pine wood nematode, Bursaphelenchus xylophilus (Steiner & Buhrer) Nickle, will identify its characteristics and life cycle. This is crucial for developing more targeted control strategies. In this study, the development of the gonads and reproductive organs were observed using microscopy, gonad dissection, and DAPI staining techniques. Second-stage juveniles (J2) had gonads composed of four primordial germ cells (Z1, Z2, Z3, and Z4) that form the adult gonads by proliferation within 72 h at 25 °C. There were subtle differences in somatic gonad cell morphology between males and females, which developed from Z1 and Z4 in third-stage juveniles (J3). These differences became more pronounced at fourth-stage juveniles (J4) and adult stages. Z2 and Z3 germ cells underwent mitosis and two rounds of meiosis, ultimately developing into male and female gametes. Female vulval precursor cells and male cloacal cells developed rapidly during the J4 stage. These results provide a basis for identifying the expression sites and biological functions of key genes regulating reproductive system development. Based on this, in situ hybridization and RNA interference (RNAi) were used to determine the function of the Bxy-glp-1 gene to show that it is involved in vulval formation and spermatogenesis. The results of this study will lay the foundation for disrupting critical stages in the reproduction of B. xylophilus.
As part of the global effort to mitigate climate change effects, New Zealand’s Climate Change Commission has recommended the establishment of 300,000 ha of native trees across the country by 2035. To achieve this goal, significant improvement in seedling production and field establishment is needed. Across New Zealand, there is a trade-off between seedling size and early seedling establishment success; plants grown in large pots are more resistant to weeds, pests and frost; however, they are more expensive and take longer to grow. We tested this trade-off between cost and establishment success by raising seedlings of twelve key native species in three container grade sizes: small, large, and revegetation grade, and tracking their success across five sites around Rotorua, in the Central North Island of New Zealand. After two-year post-planting, we found that high-quality sites and larger container systems tended to promote higher survival and faster early growth (plant height and root collar diameter). Some species, such as Kunzea ericoides and Leptospermum scoparium, survived and grew well (> 75%) even when raised in small container sizes. Other species such as Sophora microphylla had very low survival (< 25%) even when raised in revegetation container grade sizes. If the quality of the planting site is high, the container size seems to be less important for most species. Other species such as Aristotelia serrata, Cordyline australis, Plagianthus regius and Podocarpus totara appear to depend more on site quality. In conclusion, nursery container systems for raising New Zealand native plants should be chosen based on the biology of the species, nursery management practices, quality of the planting site, and a balance between cost and benefit for each situation.
Snowpack in the Northern Hemisphere is gradually disappearing due to rising global temperatures. Snowmelt water is a critical water resource for vegetation in the arid areas of the Northeast Tibetan Plateau. We used a random forest model to analyze the main factors influencing tree growth and using structural equation modelling to examine the pathways through which snowpack affected vegetation growth. The results show that soil moisture, controlled by snowmelt water, dominates the radial growth of Qinghai spruce (Picea crassifolia Kom.). At the same time, snow melt on vegetation is affected by both elevation and land cover. Atmospheric circulation patterns regulated by North Atlantic sea surface temperatures determine spring snowpack variability in this area. In future scenarios based on the Coupled Model Intercomparison Project Phase 6 (CMIP6) simulations, snowpack will continue to decrease, presenting significant constraints to the growth of vegetation.
Nitrogen and phosphorus (NP) deposition can change the nutrient input of forest ecosystems. The effects of NP deposition on soil aggregate need to be analyzed to propose effective environmental management strategies. In this study, representative Korean pine mixed forests and Korean pine plantations in northeastern China were selected. Soil samples were sieved to obtain four different particle sizes of soil aggregates (> 2, 2–0.25, 0.25–0.053, and < 0.053 mm). Four NP treatments were applied to simulate N and P deposition, and an indoor incubation experiment was conducted over a period of 360 d. Total nitrogen, microbial nitrogen, dissolved organic nitrogen, hydrolyzed nitrogen, NH4+–N, NO3−–N content, and extracellular enzyme activities of NAG, LAP, and AP were determined. Different fractions of N responded differently to NP addition. Lower NP addition had a greater promoting effect on aggregate N compared to higher NP addition. NAG was the main extracellular enzyme affecting N in both forest types. NP addition had a greater effect on the extracellular enzyme activities of the soil aggregates from the Korean pine plantations. These results enhance our understanding of the effects of NP addition on soil nitrogen within temperate forest ecosystems.
Climate change is a global phenomenon that has profound impacts on ecological dynamics and biodiversity, shaping the interactions between species and their environment. To gain a deeper understanding of the mechanisms driving climate change, phenological monitoring is essential. Traditional methods of defining phenological phases often rely on fixed thresholds. However, with the development of technology, deep learning-based classification models are now able to more accurately delineate phenological phases from images, enabling phenological monitoring. Despite the significant advancements these models have made in phenological monitoring, they still face challenges in fully capturing the complexity of biotic-environmental interactions, which can limit the fine-grained accuracy of phenological phase identification. To address this, we propose a novel deep learning model, RESformer, designed to monitor tree phenology at a fine-grained level using PhenoCam images. RESformer features a lightweight structure, making it suitable for deployment in resource-constrained environments. It incorporates a dual-branch routing mechanism that considers both global and local information, thereby improving the accuracy of phenological monitoring. To validate the effectiveness of RESformer, we conducted a case study involving 82,118 images taken over two years from four different locations in Wisconsin, focusing on the phenology of Acer. The images were classified into seven distinct phenological stages, with RESformer achieving an overall monitoring accuracy of 96.02%. Furthermore, we compared RESformer with a phenological monitoring approach based on the Green Chromatic Coordinate (GCC) index and ten popular classification models. The results showed that RESformer excelled in fine-grained monitoring, effectively capturing and identifying changes in phenological stages. This finding not only provides strong support for monitoring the phenology of Acer species but also offers valuable insights for understanding ecological trends and developing more effective ecosystem conservation and management strategies.
Tropical forests, critical for global carbon storage and biodiversity, are failing to adapt at the pace required by accelerating climate change. A comprehensive study by Aguirre-Gutiérrez et al. (Science 387:eadi5414, 2025) analyzing four decades of data from 415 forest plots and 250,000 trees across the Americas reveals significant mismatches between functional trait shifts (e.g., leaf area, wood density, photosynthetic capacity) and climatic pressures. Survivor trees tracked climatic changes at less than 8% of the necessary rate, while recruits achieved only 22%, leaving ecosystems increasingly vulnerable. Lowland forests exhibited stronger trait responses compared to nutrient-limited montane forests, but neither aligned with future climate projections. By 2100, projected temperature rises (~ 4 °C) and precipitation declines (~ 20%) may push forests into “no-analog” climates, surpassing adaptive thresholds. These lags threaten carbon sequestration, biodiversity, and ecosystem stability, underscoring the urgent need for emissions reduction, conservation of climate refugia, and assisted migration strategies to mitigate irreversible biome transitions.
Both abiotic conditions and management influence the success of forest restoration. Despite growing interest and practical effort in restoring degraded forest landscapes, understanding of how disparate factors, such as terrain, soil conditions, climate and silvicultural treatments, directly or collectively control species performance and shape community recovery remains limited. In this study, we assessed how topography and management intervention affect seedling survival and growth in the early stages of restoration. To do so, we established seven experimental plots, each measuring 20 m × 20 m (400 m2) subdivided into 48 subplots, in coarse, anthropogenic grassland on a mid-elevation mountain slope in Hong Kong, and planted a total of 3975 native tree seedlings belonging to 12 tree species within them. To characterise topography, we modelled the elevation, slope, convexity and aspect of each subplot. Two types of tree guard (enclosed blue plastic sleeve and open yellow mesh), two types of fertiliser (organic and inorganic) and cardboard weeding mats were used to assess the impact of management interventions on the establishment of the seedlings. Survivorship, height and basal diameter were measured at 1, 2 and 4 years after planting. We used generalised linear models to examine the effect of these factors and their interactions on seedling survival, and we applied linear models and hierarchical partitioning to explore their relative importance in determining the relative growth rate (RGR) of each species. The most parsimonious models were selected using the Akaike Information Criterion. Survivorship was 98.1%, 95.2% and 86.4% across all plots in the first, second and fourth year, respectively. On average, topographic and management variables explained 1.48–3.34% of total variation in RGR, respectively, for all species. The models revealed that type of tree guard, aspect and elevation were the most important factors explaining RGR and survival. Results of hierarchical partitioning by species and growth period showed that the key determinants of performance vary by species and shift over the course of early seedling establishment, emphasising the importance of both spatial and temporal scales in the restoration of degraded tropical forests. Our findings support the use of enclosed tree guards and fertiliser to improve survivorship and growth across a range of broadleaved Asiatic species. All potential limiting factors pertaining to both site factors and management, as well as their interactions, should be considered in restoration planning to maximise restoration success.