Multiple Tree Species Research Articles

Regulation of exogenous sugars on the biosynthesis of key secondary metabolites in Cyclocarya paliurus.

The biosynthesis and accumulation of secondary metabolites play a vital role in determining the quality of medicinal plants, with carbohydrate metabolism often influencing secondary metabolism. To understand the potential regulatory mechanism, exogenous sugars (sucrose, glucose/fructose) were applied to the leaves of Cyclocarya paliurus, a highly valued and multiple function tree species. The results showed that exogenous sugars enhanced the accumulation of soluble sugar and starch while increasing the enzyme activity related to carbohydrate metabolism. In addition, the plant height was increased by a mixture of exogenous mixed sugars, the addition of sucrose promoted the net photosynthetic rate, while all types of exogenous sugars facilitated the accumulation of flavonoids and terpenoids. Based on weighted gene co-expression network analysis (WGCNA), two key gene modules and four candidate transcription factors (TFs) related to carbohydrate metabolism and secondary metabolite biosynthesis were identified. A correlation analysis between transcriptome and metabolome data showed that exogenous sugar up-regulated the expression of key structural genes in the flavonoid and terpenoid biosynthetic pathway. The expression levels of the four candidate TFs, TIFY 10A, WRKY 7, EIL 3 and RF2a, were induced by exogenous sugar and were strongly correlated with the key structural genes, which enhanced the synthesis of specific secondary metabolites and some plant hormone signal pathways. Our results provide a comprehensive understanding of key factors in the quality formation of medicinal plants and a potential approach to improve the quality.

Understanding Tree Mortality Patterns: A Comprehensive Review of Remote Sensing and Meteorological Ground-Based Studies

Land degradation, desertification and tree mortality related to global climate change have been in the spotlight of remote sensing research in recent decades since extreme climatic events could affect the composition, structure, and biogeography of forests. However, the complexity of tree mortality processes requires a holistic approach. Herein, we present the first global assessment and a historical perspective of forest tree mortality by reviewing both remote sensing and meteorological ground-based studies. We compiled 254 papers on tree mortality that make use of remotely sensed products, meteorological ground-based monitoring, and climatic drivers, focusing on their spatial and temporal patterns and the methods applied while highlighting research gaps. Our core results indicate that international publications on tree mortality are on the increase, with the main hotspots being North America (39%) and Europe (26%). Wetness indicators appear as the barometer in explaining tree mortality at a local scale, while vegetation indicators derived from multispectral optical sensors are promising for large-scale assessments. We observed that almost all of the studies we reviewed were based on less than 25 years of data and were at the local scale. Longer timeframes and regional scale investigations that will include multiple tree species analysis could have a significant impact on future research.

Conversion of pure Chinese fir plantation to multi-layered mixed plantation increases organic phosphorus accumulation and transformation within soil aggregates

Evaluation of the impacts of environmental factors and microbial communities on soil organic phosphorus (Po) availability is needed to clarify P cycling and regulate plantations productivity. However, the effects on Po accumulation and transformation of converting pure Chinese fir plantation to multi-layered mixed plantation and their regulatory mechanisms remain unclear. The aim of this study was to examine the impacts of the transformation of pure stand of Chinese fir (Cunninghamia lanceolata; PP) to mixed plantation with multiple tree species (C. lanceolata, Castanopsis hystrix, and Michelia hedyosperma; MP) on Po accumulation and transformation within topsoil (0–10 cm) aggregates in subtropical China. Our results showed that the soil organic carbon (SOC), total nitrogen (TN), ammonium nitrogen (NH4+-N), and available phosphorus (AP), as well as the carbon‑nitrogen ratio of soil (C/Nsoil) and carbon‑phosphorus ratio of soil (C/Psoil) were significantly higher (P < 0.05) of all aggregates in MP than those in PP. The quantities of soil microbial biomass C, N, P (MBC, MBN, and MBP) in all different aggregates were significantly greater (P < 0.05) in MP than in PP. The phospholipid fatty acid contents related to bacteria, fungi, arbuscular mycorrhizal fungi (AMF), and actinomycetes were significantly greater in all aggregate classes (P < 0.05) in MP relative to PP. The activities of all tested C, N, and P hydrolytic enzymes, as well as labile organic P, moderately labile organic P, moderately resistant organic P, and highly resistant organic P contents, were significantly higher of most aggregate size classes in MP. Finally, redundancy analysis (RDA) suggested that Po fractions were primarily affected by the NH4+-N, litterfall biomass (LF), carbon‑nitrogen ratio of litter (C/Nlitter), SOC and fine root biomass (FR). Our findings suggest that converting pure Chinese fir plantations into multi-layered mixed plantations may represent an effective management strategy for promoting organic P accumulation and transformation by regulating soil and microbial properties in degraded soils of Chinese fir plantations.

Developing the Additive Systems of Stand Basal Area Model for Broad-Leaved Mixed Forests.

Stand basal area (SBA) is an important variable in the prediction of forest growth and harvest yield. However, achieving the additivity of SBA models for multiple tree species in the complex structure of broad-leaved mixed forests is an urgent scientific issue in the study of accurately predicting the SBA of mixed forests. This study used data from 58 sample plots (30 m × 30 m) for Populus davidiana × Betula platyphylla broad-leaved mixed forests to construct the SBA basic model based on nonlinear least squares regression (NLS). Adjustment in proportion (AP) and nonlinear seemingly unrelated regression (NSUR) were used to construct a multi-species additive basal area prediction model. The results identified the Richards model (M6) and Korf model (M1) as optimal for predicting the SBA of P. davidiana and B. platyphylla, respectively. The SBA models incorporate site quality, stand density index, and age at 1.3 m above ground level, which improves the prediction accuracy of basal area. Compared to AP, NSUR is an effective method for addressing the additivity of basal area in multi-species mixed forests. The results of this study can provide a scientific basis for optimizing stand structure and accurately predicting SBA in multi-species mixed forests.

Environmental Response of Tree Species Distribution in Northeast China with the Joint Species Distribution Model

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 &gt; site &gt; soil. The explanatory power was as follows: model FULL (AUC = 0.8325, Tjur R2 = 0.2326) &gt; model ENV (AUC = 0.7664, Tjur R2 = 0.1454) &gt; 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.

Wood defect detection based on the CWB-YOLOv8 algorithm

As an important renewable resource, wood is widely used in various industries. When addressing wood defects that limit the amount of wood used during processing, manual inspection and other technologies are not suitable for automated production scenarios. In this paper, we first establish our own dataset, which includes information about multiple tree species and multiple defects types, to enhance the overall applicability of the proposed model. Second, target detection technology involving deep learning is used for defect detection. The conditional parametric convolution (CondConv), Wise-IoU, and BiFormer modules are used to improve upon the latest YOLOv8 algorithm. Based on the experimental findings, the suggested approach exhibits notable improvements in terms of both the mAP@0.5 index and the mAP@0.5:0.95 index, surpassing the performance of the YOLOv8 algorithm by 3.5% and 5.8%, respectively. It also has advantages over other target detection algorithms. The proposed method can effectively improve wood utilization and automated wood processing technology.

Investigating the impact of temperature on growth rate of the root rot fungus, Gymnopus fusipes.

Gymnopus fusipes is an understudied root rot pathogen associated with multiple tree species and is linked to episodes of oak decline across the United Kingdom and Europe. Although the reported distribution of G. fusipes is broad, many observations rely solely on visual identification of fruiting bodies, which can be unreliable, and lack confirmation by molecular and/or isolation data to verify this broad ecological range. Given the paucity of information regarding the true ecological distribution of G. fusipes, it is difficult to predict and model the potential distribution of the species under both current and future climate scenarios. In this study, to determine the growth capabilities of G. fusipes across a range of ecologically relevant temperatures, five geographically diverse isolates of G. fusipes were grown at five different temperatures ranging from 4-37°C, to determine the optimal temperature for G. fusipes growth, and to establish whether geographically diverse isolates exhibit local adaptation to temperature tolerance. Incubation temperature had a significant effect on G. fusipes growth rate, with 25°C representing the optimum (P<0.001). Isolates had differing growth rates at each of the temperatures, with an isolate from the UK having the highest overall growth rate across all five temperatures tested (P<0.001), and at the optimum, increased by a mean value of over 4915 mm2. Local adaptation to temperature tolerance was not found in the isolates tested. These data demonstrate the optimal incubation temperature for future laboratory studies on G. fusipes and provide the first data on the growth rate of this pathogen across ecologically relevant climate ranges that may inform land managers, modellers, and policy makers in predicting the current and potentially future geographical limits of this widespread root rot pathogen.

Summer habitat for the female Tricolored Bat (Perimyotis subflavus) in Tennessee, United States

Abstract The Tricolored Bat is an imperiled species due to white-nose syndrome. There is limited information available on roosting and foraging area use of the species to support planning and management efforts to benefit recovery in the Southeastern United States. Female tricolored bats exit hibernation and allocate energy toward disease recovery, migration, and reproduction. Providing and managing for summer habitat is 1 strategy to promote recovery. We sought to: (1) determine local- and landscape-scale factors that influence female Tricolored Bat roost selection; (2) quantify land cover use in core and overall foraging areas; and (3) define foraging area size and distances traveled by female tricolored bats in Tennessee. Bats in this study roosted in trees of variable sizes, in multiple tree species with large canopy volumes, and almost always roosted in trees with dead leaf foliage suspended in the canopy. Forest plots used by bats had trees averaging 30 cm diameter at breast height, basal areas averaging 27 m2/ha, contained multiple tree species, and comprised around a 50:50 ratio of canopy and subcanopy trees. Bats did not roost in coniferous forest areas and were only located in deciduous and mixed forest areas. Bats foraged near and directly over water, in open areas, and along forest edges. This study increases our knowledge on habitat requirements of the species in a temperate region dominated by unfragmented forests and many large water bodies and serves a baseline for management and efforts to benefit survival, reproduction, and population recovery.

Research on the Wood Density Measurement in Standing Trees through the Micro Drilling Resistance Method

To achieve a micro-destructive and rapid measurement of the wood density of standing trees, this study investigated the possibility of the unified modeling of multiple tree species, the reliability of the micro drilling resistance method for measuring wood density, the relationship between drilling needle resistance and wood density, and whether moisture content has a significant impact on the model. First, 231 tree cores and drill resistance data were sampled from Pinus massoniana, Cunninghamia lanceolate, and Cryptomeria fortunei. The basic density and moisture content of each core were measured, and the average value of each resistance data record was calculated. Second, the average drill resistance, the natural logarithm of average drill resistance, and absolute moisture content were used as independent variables, while the basic wood density was used as the dependent variable. Third, the total model of the three tree species and sub-model for each tree species were established through a stepwise regression method. Finally, the accuracy of each model was compared and analyzed with that of using the average basic density of each tree species as an estimated density. The estimated accuracy of the total model, sub model, and average wood density modeling data were 90.070%, 93.865%, and 92.195%, respectively. The results revealed that the estimation accuracy of the sub-model was 1.670 percentage points higher than that of the average wood density modeling data, while the estimation accuracy of the total model was 2.125 percentage points lower than that of the average wood density modeling data. Additionally, except for Cryptomeria fortunei, the natural logarithm of drill resistance significantly influenced the wood density model at a significance level of 0.05. Moreover, moisture content significantly affected the total model and sub-models of Pinus massoniana at a significance level of 0.05. The results indicated the feasibility of using the micro-drilling resistance method to measure the wood density of standing trees. Moreover, the relationship between wood density and drill resistance did not follow a linear pattern, and moisture content slightly influenced the drill needle resistance. Furthermore, the establishment of a mathematical model for each tree species was deemed essential. This study provides valuable guidance for measuring the wood density of standing trees through the micro-drilling resistance method.

The Effect of Fire on Multiple Tree Species in the Eastern Deciduous Forest

Fire is a disturbance that serves to maintain the diverse mosaic of vegetation in the Eastern Deciduous Forest. However, our ability to reconstruct fire occurrence from hardwood tree scars still lags far behind our expertise in reconstructing fire history from conifers in the western United States. This study examines the fidelity of fire scaring in multiple tree species in the Big Oaks National Wildlife Refuge in Indiana, which is located in the central hardwood region of the Eastern Deciduous Forest. All 15 species, except for red oak, showed evidence of past fires, and most samples recorded multiple fire events. No fire scars were recorded in the latewood of the samples. Most of the fires scars occurred in the earlywood (May) suggesting the dormant season fires are likely associated with fires in March to April before the growing season begins. No synchronous fires were recorded across all sites, but fires occurred in 1981, 1982, 1984, 1985, and 1988 across multiple sites. This suggests that these were larger spreading fires. Establishment pulses were documented in association with fire events in 1981, 1984, and 1995, suggesting that fire may benefit the establishment or root sprouting of some hardwood species. Fourteen of the fifteen species that we sampled preserved fire scars, suggesting that the diverse suite of species in the Eastern Deciduous Forest is a viable sampling pool for examining fire history across this forest type.

Exploring the influence of tree species richness on vertical structure variability in young plantations using terrestrial laser scanning

Forest structure spatially varies at the landscape-scale (between-plot) but also local-scale (within-plot). Both scales of structural variability have significant impacts on forest ecosystem functioning and stability. However, we still have a limited understanding of how tree species richness affects the spatial structural variability. In this study, we disentangled within- and between-plot variability in stand structural variables depending on tree species richness level. Terrestrial laser scanning (TLS) technology, capable of developing forest vertical structure in 3D detail, was applied in the FORBIO tree diversity experiment at three sites in Belgium. One site was 9-year old (Hechtel-Eksel) and other two sites were 11-year old (Zedelgem and Gedinne). Each site included five different sets of one, two, three, and four tree species mixtures with one replica. At each plot, four single scan locations were used. Six stand structural variables were quantified based on TLS vertical plant profiles. We hypothesized that within-plot structural variability would increase with species richness, but that the between-plot structural variability would decrease with species richness. Our study revealed notable differences in structural variability between monocultures and mixtures across all sites examined. However, the relationship between tree species richness and structural variability patterns is site-dependent. Specifically, at the Zedelgem site, we observed increased within-plot variability and decreased between-plot variability with species richness, supporting the hypothesis that species richness drives stand structural variability. However, the hypothesized pattern was not as strong at the Hechtel-Eksel and Gedinne sites. Moreover, the various structural variables displayed contrasting responses to changes in species richness. These findings indicated the potential influence of tree species richness on within- and between-plot structural variability in young plantations, particularly in favorable site conditions with well-adapted species pools. Hence, afforestation measures would benefit from planting multiple tree species to initiate structurally complex stands by considering species richness level.

Diversity of Mycorrhizal fungi in Eastern Hemlock stands will significantly change with the effects of Hemlock Woolly Adelgid infestation in southwestern Nova Scotia, Canada

A foundation tree species, eastern hemlock (Tsuga canadensis) is threatened by the invasive hemlock woolly adelgid (Adelges tsugae) (HWA) in southwestern Nova Scotia, Canada. The loss of this key species and its heavily shaded ecosystems may alter the diversity of important mycorrhizal fungi in hemlock forests. Mycorrhizal fungi share a vital mutualistic relationship with their host trees; consequentially, understanding if and how the predicted eastern hemlock decline will affect mycorrhizal diversity is paramount. Using available literature, we discuss three major consequences of HWA on eastern hemlock ecosystems – changing forest composition, loss of old-growth trees, and increased insect stress on host trees – and how they will likely influence mycorrhizal communities as adelgid infestations intensify. Environmental variables are also discussed as another major influence on fungal diversity. We conclude that the mycorrhizal community of eastern hemlock forests will likely change significantly as old-growth hemlock is replaced with mixed forest. We also suggest that mycorrhizal community composition will shift in favour of generalist mycorrhizae which form symbioses with multiple tree species. These conclusions illuminate the future of hemlock forest fungi in southwestern Nova Scotia and underline the importance of conserving old-growth eastern hemlock forests and their unique fungal communities.

The Performance of Discriminative Tracking Algorithms for the Sway Frequency Measurement of Betula platyphylla Sukaczev (Individual Branch and Tree) under Artificial and Natural Excitation

The sway frequency is an important component of the dynamic characteristics of trees. Video-based methods can be used to measure the sway frequencies of trees. The key to successfully measuring tree sway frequency using video methods lies in whether the tracking method employed is appropriate. Based on six algorithms, i.e., Boosting, TLD, MIL, KCF, MOSSE and CSR-DCF, the tracking performance and accuracy of tree sway frequency measurements were investigated under two conditions: artificial excitation and environmental excitation. The results show that the following: (1) In terms of the tracking speed of tree sway, MOSSE &gt; KCF &gt; CSR-DCF &gt; Boosting &gt; MIL &gt; TLD. (2) The TLD algorithm is not suitable for tree sway tracking. Boosting, MIL, MOSSE, KCF and CSR-DCF can be used for tree sway tracking. (3) Boosting, MIL and MOSSE are suitable for measuring the sway frequency of artificially excited branches and environmentally excited trees. (4) KCF and CSR-DCF algorithms are not suitable for the measurement of branch sway frequency under artificial excitation conditions but can be used for the measurement of tree sway frequency under environmental excitation conditions. However, it should be noted that this experiment only takes a Betula platyphylla Sukaczev tree and a Betula platyphylla Sukaczev branch as the research object to verify the effectiveness and feasibility of each tracking method, and does not verify the generalization ability of the above methods (on multiple tree species and multiple trees).

Relationships among livestock, structure, and regeneration in Chilean Austral Macrozone temperate forests

A Macrozone is a socioecological region with shared geographic and demographic characteristics. Within the Chilean Austral Macrozone (43° to 56° SL), the native temperate forests serve as a crucial resource, offering multiple ecosystem services to local communities. These forests significantly support animal husbandry practices involving cattle, horses and sheep. However, introducing these exotic species affects natural regeneration and compromises their long-term sustainability. This study proposes a new classification of the temperate forests in the Chilean Austral Macrozone based on structure parameters and determine their relationships with animal husbandry and natural regeneration. Data were obtained from Chile's National Forest Inventory (NFI) (2001–2010), including 195 inventory plots (500 m2) with 21 tree species. We redefined the forest categories described in NFI according to the proportional basal area of each tree species at each plot. We used two levels of analysis: forest composition (Level 1), which includes general categories such as mono-specific (dominated by a single tree species), bi-specific (dominated by two tree species), and multi-specific forests (dominated by multiple tree species), and forest type (Level 2), which includes specific species (e.g., Nothofagus pumilio) or species groups (e.g., N. pumilio - N. dombeyi) with economic relevance. We evaluated the data using univariate and multivariate analyses. We found 18 forest types in the Austral Macrozone, in contrast to the three traditionally recognized forest types used in the NFI (e.g., lenga, evergreen, coihue de Magallanes). Livestock was observed in all forest types, where Nothofagus forests showed that regeneration in N. antarctica and N. pumilio were higher with livestock than without livestock breeding (Hedges' g > 0.51). The natural regeneration of the studied forests was influenced by animal husbandry, environmental variables (bioclimatic and topographic factors), and forest structure. Our data suggested the importance of using more forest types than the three classics to generate tools or recommendations that are more focused on the particularities of each one. The classification must be based on forest parameters obtained during NFI. The proposed forest type classification reflects the complexity and richness of the forests in a better way, which could improve forest management and the development of public policies related to climate change and sustainability. Finally, although livestock pressure was observed in all forest types, the impact over some areas (e.g., N. antarctica) needs special attention in the forest management and conservation planning for the Chilean Austral Macrozone.

Integrating traditional ecological knowledge into habitat restoration: implications for meeting forest restoration challenges

BackgroundTraditional ecological knowledge (TEK) helps tribal communities adapt to socio-ecological changes, improving the long-term sustainability of their livelihood strategies and fostering social–ecological resilience. TEK provides thorough understanding of ecosystem dynamics, as well as how they relate to societal norms, practices, and resource use patterns. The integrity of TEK is often in jeopardy due to changes in belief systems, regional languages, traditional ways of subsistence, and disruption of traditional social–ecological systems. Landscape restoration has the ability to promote self-determination while safeguarding the livelihoods, beliefs, cultural, and biodiversity of indigenous peoples. However, there is a substantial knowledge gap on how TEK might aid ecosystem restoration, particularly in elephant corridors.MethodsThe current study focused on gathering traditional ecological knowledge on the woody tree species from the Dering-Dibru Saikhowa Elephant Corridor using semi-structured interviews, group discussions, and direct observations. The acquired data were applied to heat map cluster analysis and ordination techniques using R software version 4.0.0.ResultsTraditional usage information of 31 tree species utilized for food, fodder, timber, fuelwood, medicinal, and livelihood by local people was gathered. Most of the species utilized locally belonged to the families Combretaceae and Fabaceae. The species were classified into single, double, or multi-uses based on the extent of utilization. Azadirachta indica, Phyllanthus emblica, and Syzygium cumini (six each) had the highest utilization, while Mesua ferrea had the lowest. Chionanthus ramiflorus, Artocarpus heterophyllus, and Dillenia indica were among the plants valuable to wildlife, providing both forage and habitat for a wide variety of birds and animals. Artocarpus heterophyllus, Averrhoa carambola, Mangifera indica, P. emblica, Psidium guajava, and S. cumini were among the plants important for the livelihoods of the local community. Our findings demonstrated that local people were knowledgeable about the plant species to use as pioneer species, such as Bombax ceiba, Albizia lebbeck, D. indica, S. cumini, P. emblica, Lagerstroemia speciosa, and Alstonia scholaris, for habitat restoration in a diverse habitat. We classified the habitat of the enlisted species into different categories, and two clusters (clusters 1 and 2) were identified based on the similarity of woody species in different habitats. We prioritized multiple tree species for eco-restoration using the information collected through TEK. We planted 95,582 saplings on 150 hectares in the Dering-Dibru Saikhowa Elephant Corridors’ degraded habitat patches, which will serve as future reference site for landscape rehabilitation. Out of total saplings planted, 56% of the species were linked to native communities through ethnobotanical uses, as well as providing connectivity and habitat for elephant movement, 16% of all woody species are pioneer species to colonize a degraded habitat, 15% of all woody species are preferred food and foraging by wildlife, and 13% of the species as a source of livelihood for local people, incorporating social, economic, cultural, and biodiversity benefits into the restoration framework.ConclusionThe current study also provides insights how the TEK can assist with aspects of ecological restoration, from reference ecosystem reconstruction and adaptive management through species selection for restoration, monitoring, and evaluation of restoration effectiveness.

Mycorrhizal Fungal Diversity Associated with Six Understudied Ectomycorrhizal Trees in the Republic of Korea.

Mycorrhizal fungi are key components of forest ecosystems and play essential roles in host health. The host specificity of mycorrhizal fungi is variable and the mycorrhizal fungi composition for the dominant tree species is largely known but remains unknown for the less common tree species. In this study, we collected soil samples from the roots of six understudied ectomycorrhizal tree species from a preserved natural park in the Republic of Korea over four seasons to investigate the host specificity of mycorrhizal fungi in multiple tree species, considering the abiotic factors. We evaluated the mycorrhizal fungal composition in each tree species using a metabarcoding approach. Our results revealed that each host tree species harbored unique mycorrhizal communities, despite close localization. Most mycorrhizal taxa belonged to ectomycorrhizal fungi, but a small proportion of ericoid mycorrhizal fungi and arbuscular mycorrhizal fungi were also detected. While common mycorrhizal fungi were shared between the plant species at the genus or higher taxonomic level, we found high host specificity at the species/OTU (operational taxonomic unit) level. Moreover, the effects of the seasons and soil properties on the mycorrhizal communities differed by tree species. Our results indicate that mycorrhizal fungi feature host-specificity at lower taxonomic levels.

Discriminative feature constraints via supervised contrastive learning for few-shot forest tree species classification using airborne hyperspectral images

In scenarios where sample collection is limited, studying few-shot learning algorithms such as prototypical networks (P-Net) is a keynote topic for supervised multiple tree species classification. In a previous study, we improved the P-Net by combining the feature enhancement algorithm based on the convolutional block attention module and several popular data augmentation methods in the computer vision domain, the classification accuracy can be significantly increased, and the degree of model overfitting can be reduced. However, there is a clear boundary between the data augmentations and the feature enhancement algorithm, which is manifested in that data augmentations are only used to enrich the diversity of the learned samples, but cannot directly affect the construction of the objective function, thus limiting the ability of data augmentations. In fact, in the supervised contrastive learning research, data augmentation methods are often used to generate positive samples of an anchor image to construct the objective function, i.e. supervised contrastive loss. The core idea for solving such a boundary problem is to use contrastive learning to make the anchor image close to its positive samples and the negative samples away from each other. Inspired by this, we introduced supervised contrastive learning in the P-Net, i.e., SCL-P-Net, which takes the discriminative feature representations as the constraints of the prototype clustering algorithm. In SCL-P-Net, data augmentation methods can not only extend the sample distribution, but also be used to construct the supervised contrastive loss directly. The study involves four airborne hyperspectral image datasets related to tree species classification, including the GFF-A and GFF-B datasets collected from Gaofeng Forest Farm in Nanning City, Guangxi Province, South China, the Xiongan dataset from Matiwan Village in Xiongan New Area, Hebei Province, North China, and the Tea Farm dataset from Fanglu Tea Farm in Changzhou City, Jiangsu Province, East China. The highest overall accuracy (OA) for the four datasets is 99.23% for GFF-A, 98.39% for GFF-B, 99.30% for Xiongan, and 99.54% for Tea Farm. It is concluded that the proposed SCL-P-Net classification framework can achieve multiple tree species classification with high-precision. Without changing the basic classification framework of P-Net, the introduction of supervised contrastive learning makes the combination of the data augmentations and the feature enhancement algorithm and plays a positive role in improving the distinguishability between samples.

Woody Species Composition, Structure, and Diversity of Dindin Natural Forest, South East of Ethiopia

Information on species composition, structure, and diversity is essential to introduce and select different management activities to improve the forest productivity. Accordingly, species composition, structure, diversity, and regeneration status of trees were assessed in the Dindin natural forest. In this forest, trees or shrubs having ≥2.5 cm diameter at breast height and height &gt;1.5 m were identified and measured in 35 quadrats of 20 m × 20 m. Regeneration status was assessed in 5 m × 5 m subplots that were laid within each main plot to sample seedling and sapling. Woody species diversity, density, basal area, and importance value index were calculated. To prioritize conservation efforts, the study utilized factors such as the importance value index, seedling and sapling densities, and population structure. A total of 42 woody tree species representing 30 families were recorded in the forest. The diversity and evenness of woody species in the Dindin forest were 2.66 and 0.70, respectively. Woody species density was 1403 individual ha−1, and the total basal area was 35.54 m2ha−1. About 480 seedlings per hectare were recorded in the Dindin forest. The research yielded practical insights into the dominance, population structure, importance value, and regeneration status of tree species. The analysis of population structure indicates that certain dominant species are experiencing inadequate regeneration. In addition, multiple nondominant shrubs and tree species within the forest are also at risk of extinction due to insufficient regeneration. Therefore, these important findings play a crucial role in the formulation and implementation of effective strategies to restore and rehabilitate the studied forest.

Integration of transcriptomic and metabolomic analysis unveils the response mechanism of sugar metabolism in Cyclocarya paliurus seedlings subjected to PEG-induced drought stress

Cyclocarya paliurus (Batal.) Iljinskaja is a multiple function tree species used for functional food and valued timber production. Carbohydrates, especially water-soluble carbohydrates, play an important role in osmotic protection, signal transduction and carbon storage. Under the circumstance of global climate change the abiotic stress would restrict the development of C. paliurus plantation, whereas there is few knowledge on the regulatory mechanisms of sugar metabolism under drought stress in C. paliurus. To investigate the drought response of C. paliurus at molecular level, we conducted an integrated analysis of transcriptomic and metabolomic of C. paliurus at three PEG-induced drought stress levels (0%: control; 15%: moderate drought; 25%: severe drought) in short term. Both moderate and severe drought treatments activated the chemical defense with lowering relative water content, and enhancing the contents of soluble protein, proline and malondialdehyde in the leaves. Meanwhile, alterations in the expression of differentially expressed genes and carbohydrate metabolism profiles were observed among the treatments. Weighted gene co-expression network analysis (WGCNA) showed 3 key modules, 8 structural genes (such as genes encoding beta-fructofuranosidase (INV), sucrose synthase (SUS), raffinose synthase (RS)) and 14 regulatory transcription factors were closely linked to sugar metabolism. Our results provided the foundation to understand the response mechanism of sugar metabolism in C. paliurus under drought stress, and would drive progress in breeding of drought-tolerant varieties and plantation development of the species.

Locally Isolated Trichoderma harzianum Species Have Broad Spectrum Biocontrol Activities against the Wood Rot Fungal Species through Both Volatile Inhibition and Mycoparasitism.

Pathogenic root/wood rot fungal species infect multiple urban tree species in Singapore. There is a need for sustainable and environmentally friendly mitigation. We report the local Trichoderma strains as potential biocontrol agents (BCAs) for pathogenic wood rot fungal species such as Phellinus noxius, Rigidoporus microporus, and Fulvifomes siamensis. Isolated Trichoderma strains were DNA-barcoded for their molecular identities and assessed for their potential as a BCA by their rate of growth in culture and effectiveness in inhibiting the pathogenic fungi in in vitro dual culture assays. Trichoderma harzianum strain CE92 was the most effective in inhibiting the growth of the pathogenic fungi tested. Preliminary results suggested both volatile organic compound (VOC) production and direct hyphal contact contributed to inhibition. SPME GC-MS identified known fungal inhibitory volatiles. Trichoderma harzianum strain CE92 hyphae were found to coil around Phellinus noxius and Lasiodiplodia theobromae upon contact in vitro and were possibly a part of the mycoparasitism. In summary, the work provides insight into Trichoderma inhibition of pathogenic fungi and identifies local strains with good potential for broad-spectrum BCAs against root/wood rot fungi in Singapore.