Forest carbon offset (FCO) projects play an increasingly important role in mitigating climate change through market mechanisms in both compliance and voluntary markets. However, there are challenges and barriers to developing an FCO project, such as carbon leakage and cost-effectiveness. There have been few attempts to summarize and synthesize all types and aspects of existing challenges and possible solutions for FCO projects. This paper systematically reviews and discusses the current challenges involved in developing FCO projects, and then draws on the experience and lessons of existing projects to show how those challenges were addressed in world-leading voluntary carbon standards, namely the Verified Carbon Standard, the American Carbon Registry, the Climate Action Reserve, and Plan Vivo. These voluntary markets have rich experience in FCO projects and are responsible for a significant share of the market. From the 53 publications used in this analysis, three broad thematic categories of challenges emerged. These were related to methodology, socio-economic implications, and implementation. Methodological challenges, particularly additionality, permanence, and leakage, were the focus of 46% of the selected research papers, while socio-economic challenges, including transaction, social, and opportunity costs, were addressed by 35%. The remaining 19% of the research articles focused on implementational challenges related to monitoring, reporting, and verification. Major voluntary standards adequately addressed most of the methodological and implementational barriers by adopting various approaches. However, the standards did not adequately address socio-economic issues, despite these being the second most frequently discussed theme in the papers analyzed. More research is clearly needed on the socio-economic challenges involved in the development of FCO projects. For the development of high-quality forestry carbon offset projects, there are many challenges and no simple, universal recipe for addressing them. However, it is crucial to build upon the current science and move forward with carbon projects which ensure effective, long-term carbon sinks and maximize benefits for biodiversity and people; this is particularly important with a growing public and private interest in this field.

The scale of forest and landscape restoration is expected to increase during the UN Decade on Ecosystem Restoration and its contribution to the provision of critical ecosystem services to society. Several models of forest restoration may improve ecosystem services, including soil organic carbon (SOC) storage. A review was carried out to access: (1) the variability of SOC storage between worldwide forest restoration models and, (2) the effects of climate, soil class, soil texture, and vegetation type on SOC storage. We reviewed 119 primary studies with information on SOC and soil texture for different forest restoration models. The restoration models were grouped into four categories: natural regeneration, monocultures, agroforestry, and mixed forest. SOC data was extracted from these four restoration models, other land uses (cropland, bare land, grassland, and natural forest), climate regimes, and soil properties. The SOC storage in the forest restoration models and other land uses at a global scale ranged between 0.1 to 514 Mg ha⁻¹. The overall mean value for SOC storage was higher for natural regeneration (112 Mg ha⁻¹), followed by agroforestry (74 Mg ha⁻¹), mixed forest (73 Mg ha⁻¹), and monocultures (68 Mg ha⁻¹). However, the average SOC storage was similar among the four restoration models in the moist warm climate zone. The SOC storage mean value in the moist cool zone was 23% higher than the dry cool zone (81 and 62 Mg ha⁻¹, respectively), and 50% higher for the moist warm zone when compared to the dry warm climatic zone (74 and 38 Mg ha⁻¹, respectively). The SOC storage of the restoration models was positively related to soil depth (0.59; p < 0.01), clay content (0.29; p < 0.01), and stand age (0.17; p < 0.01). Globally, the mean values of SOC storage were 26, 66, and 139 Mg ha⁻¹ at zero − 10, zero − 30, and zero − 100 cm depths, respectively. In addition, sandy soils showed smaller mean values of SOC storage than medium to clay soils, especially in deeper soil layers. Furthermore, SOC storage was positively related between restoration models and other land uses (0.93; p < 0.01), suggesting a prominent effect of climate and soil properties on SOC. Forest restoration models showed larger SOC storage when compared to croplands and bare land, but in general it was smaller or similar when compared to pasture and natural forest.

Elucidating the regulatory mechanisms of environmental factors on seed dormancy and germination will provide guidance for tree regeneration. Toward understanding the coupled effect of light and temperature on dormancy release and germination of Pinus koraiensis seeds, we set up three light conditions (L200: 200 μmol m⁻² s⁻¹, L20: 20 μmol m⁻² s⁻¹, L0: 0 μ m⁻² s⁻¹) and four storage temperatures [T-5: − 5 °C (50 days), T5: − 5 °C (50 days) + 5 °C (50 days), T25: − 5 °C(50 days) + 5 °C (50 days) + 25 °C (50 days), T15: − 5 °C (50 days) + 5 °C (50 days) + 25 °C (50 days) + 15 °C (50 days)] using imbibed seeds, then quantified phytohormones gibberellic acid (GA₃) and abscisic acid (ABA) during the stratification. Germination percentage (G _P), mean germination time (T _M), and germination value (G _V) under 25/15 °C temperature and the three light conditions were then determined. Phytohormone levels and germination performances were significantly affected by light and temperature. No consistent trend was found between the phytohormone levels and G _P caused by light levels. Under the three light conditions, ABA concentrations in the embryo and endosperm decreased as storage temperature shifted from T-5 to T25 and increased from T25 to T15; GA₃ decreased in nearly all four storage temperatures. G _P reached 40–60% in T25 storage without light irradiance. In the three light conditions, G _P and G _V were higher at T5 and T25 than at T-5 and T15; so T5 and T25 are considered as optimum storage temperatures for dormancy release and germination. At optimum temperatures, light (L200, L20) significantly increased the G _P and G _V compared with the dark (L0). At L200 and L20, significant negative correlations between G _V and the ABA concentrations and positive correlations between G _V and GA/ABA in the seed embryo were found. Temperature played a more important role in primary dormancy release and germination; light was unnecessary for primary dormancy release. Light facilitated seed germination at optimum temperatures. The dormancy release and germination of P. koraiensis seeds were controlled by a decrease in ABA concentrations or an increase in GA/ABA induced by temperature variations.

Thinning is a necessary and complex forestry activity. The complexity increases due to theoretical disagreements, contradictory recommendations, and errors of modern practice, which require confirmation through long-time experiments. This article presents a summary of experimental results from plantations established 20–30 years ago and explains concepts of the theory, methods, and regime of thinning in permanent sample plots of pine stands in Gatchinsky forest of the Leningrad region. The research results allow for the clarification of growth patterns and age dynamics of pine stands subject to heavy, low thinning, as well as the results of applying the crown (high) thinning technique and a mixed treatment. A combined thinning and fertilization could improve wood quality and yield compared to conventional methods. Of particular scientific importance is the analysis of change in tree diameter classes during growth and after thinning. The research results allow for optimizing the treatment regime in pine plantations and reducing labor intensity by increasing the intensity of thinning and reducing the number of techniques.

Subri River Forest Reserve (SR) is the most extensive forest area in Ghana with an accompanying rich floral species. Over the years, logging from both legally prescribed and illegal operations remain the predominant forest disturbance in SR. Gap creation following logging is crucial in determining tree species composition and diversity. Hence, the study evaluated the composition and diversity of naturally regenerated tree species in logging gaps of different sizes and, again examined the roles of these tree species in fulfilling the economic and ecological agenda of sustainable forest management after logging in SR. Twelve gaps were randomly selected: 4 each were grouped into small size (≤ 200 m²), medium size (201–300 m²), and large size (≥ 300 m²). Data were gathered from 1 m² circular area at gap centres and repeatedly inside 1 m width strip along 20 m individual N-S-E-W transects. Species diversity differed significantly between gap sizes. Higher diversity indices were measured in large size gaps. Gap sizes shared similar species. There were significant differences among various height groupings of tree species across all three gap sizes. Pioneers preferred medium to large size gaps, while shade-tolerant tree species preferred small size gaps for their abundance. Vulnerable and Lower Risk Near Threatened tree species under Conservation Status and, Premium and Commercial tree species under Utilisation Status preferred small size gaps for their proliferation and conservation. Therefore, we recommend the single tree-based selective logging for ensuring creations of small to medium size (200–300 m²) gaps through adjustments to the logging permit process, revision of Allocation Quota Permit, strict adherence to the 40-year polycyclic selection system, along with more dedicated enforcement and monitoring. Changes along these protocols would tremendously facilitate natural regeneration of different suites of timber species resulting in the improvement of the overall biodiversity conservation associated with the forest, more sustainable forest harvests and more income to those who receive permits.

In order to quantify within- and between-population variation in seed and seedling traits of Juglans mandshurica and reveal the relationship among genetic and environmental variations and select elite families, samples of 50 J. mandshurica families from five natural populations in Liaoning Province, northeast China, were taken to measure seed and seedling traits. The results show that all seed traits varied significantly among families within the population, but only kernel weight and kernel rate showed significant variations among populations. Average values of single seed weight, length, width, lateral diameter, and average size, and kernel weight and rate were 10.1 g, 43.0 mm, 29.2 mm, 28.1 mm, 33.4 mm, and 2.2 g and 22.5%, respectively. Significant variations were observed in seedling height and root collar diameter among families and interaction between families and blocks, but the block effects on height and root collar diameter were insignificant. Average values of height and root collar diameter were 94.0 cm and 8.7 mm, respectively. Family heritability of traits ranged from 0.6 gm (kernel weight) to 0.9 mm (seedling height). Correlation analysis showed a strong relationship among seed traits but a weak correlation between seed and seedling traits. Cluster analysis grouped the five natural populations of J. mandshurica into three significant clusters with different characteristics. The general combining ability analysis showed that most traits in one family (WD11) were higher, suggesting parental traits were excellent for selecting elite parent clones. Using the comprehensive evaluation method, five families with better seed traits and five families with better seedling traits were selected as elite materials with 10% selection rate. The genetic gains of these elite materials for seed weight, kernel weight, average seed size, kernel rate, seedling height, and root collar diameter were 13.1%, 10.3%, 4.1%, 2.4%, 29.7%, and 21.1%, respectively.

Determining the responses of candidate plants to salt stress is a prerequisite for selecting and breeding suitable plants with high salt tolerance to grow in coastal mudflat areas with high salinity. Here, 2-year cutting seedlings of Ilex purpurea Hassk. (local species) and I. integra Thunb. (introduced species) were grown in pots in a glasshouse and irrigated with a Hoagland-NaCl solution at 0, 24, and 48 h. Root samples were collected at 0, 1, 6, 24, and 72 h, and concentration of Na⁺ ion; content of proline, soluble carbohydrate, malondialdehyde (MDA), H₂O₂ and ascorbate; and activity of three key antioxidative enzymes were measured. Roots of I. integra accumulated relatively less Na⁺ and had less membrane lipid peroxidation and H₂O₂ during salt stress, thus indicating a relatively higher salt tolerance than roots of I. purpurea. Values for ascorbate content and antioxidant enzymatic activity suggest that the antioxidant ascorbate and antioxidative catalase may play substantial roles for scavenging reactive oxygen species in I. integra roots during salt treatment. Thus, I. integra is apparently more suitable for growing in local highly saline coastal mudflats.

Knowing what native trees can recruit on degraded areas allows selecting the best species to restore these sites. However, as this information is not often available, experimentation is required before large-scale planting. This study used ex situ experiments to make these decisions on recruitment. Competition with r-strategist plants, excessive solar radiation and water shortage commonly impair tree recruitment in open habitats. The experiments focused on the interactions among these factors and were conducted with three pioneer species from seasonally dry forests of northwest Argentina, Anadenanthera colubrina, Ceiba chodatii and Jacaranda mimosifolia. Seeds of each species were sown at two light levels (sunlight/shade), two rainfall levels (full/reduced) and two levels of interspecific competition (with/without competitor) in a tree nursery. Seedling emergence and survival were monitored over a year and the results indicate that species differentially respond to varying levels of light and water. Seedlings of A. colubrina tolerated water shortages under elevated solar radiation, which are desirable features for forest restoration. Seedlings of C. chodatii tolerated shade and drought, suggesting that they require shading for establishing in open areas. However, J. mimosifolia seedlings neither tolerated full sunlight nor water shortages, suggesting that this species requires shading and regular watering if used in reforestation. Regardless of the effects of light and water, the survival of all species was reduced by interspecific competition. These results highlight the importance of experimentation for selecting the best species for forest restoration and can enhance the cost/benefit ratios of these actions.

Determining climatic and physiographic variables in Mexico's major ecoregions that are limiting to biodiversity and species of high conservation concern is essential for their conservation. Yet, at the national level to date, few studies have been performed with large data sets and cross-confirmation using multiple statistical analyses. Here, we used 25 endemic, rare and endangered species from 3610 sampling points throughout Mexico and 25 environmental attributes, including average precipitation for different seasons of the year, annual dryness index, slope of the terrain; and maximum, minimum and average temperatures to test our hypothesis that these species could be assessed with the same weight among all variables, showing similar indices of importance. Our results using principal component analysis, covariation analysis by permutations, and random forest regression showed that summer precipitation, length of the frost-free period, spring precipitation, winter precipitation and growing season precipitation all strongly influence the abundance of tropical species. In contrast, annual precipitation and the balance at different seasons (summer and growing season) were the most relevant variables on the temperate region species. For dry areas, the minimum temperature of the coldest month and the maximum temperature of the warmest month were the most significant variables. Using these different associations in different climatic regions could support a more precise management and conservation plan for the preservation of plant species diversity in forests under different global warming scenarios.

Plantations of woody tree species play a crucial role in ecological security along coastal zones. Understanding energy partitioning and evapotranspiration can reveal land–atmosphere interaction processes. We investigated energy fluxes, evapotranspiration, and their related biophysical factors using eddy covariance techniques in a black locust (Robinia pseudoacacia L.) plantation in 2016, 2018, and 2019 on the Yellow River Delta. Downward longwave radiation offsets 84–85% of upward longwave radiation; upward shortwave radiation accounted for 12–13% of downward shortwave radiation. The ratio of net radiation to downward radiation was 18–19% over the three years. During the growing season, latent heat flux was the largest component of net radiation; during the dormant season, the sensible heat flux was the dominant component of net radiation. The seasonal variation in daily evapotranspiration was mainly controlled by net radiation, air temperature, vapor pressure deficit, and leaf area index. Black locust phenology influenced daily evapotranspiration variations, and evapotranspiration was greater under sea winds than under land winds because soil water content at 10-cm depth was greater under sea winds during the day. Seasonal patterns of daily evaporative fraction, Bowen ratio, crop coefficient, Priestley–Taylor coefficient, surface conductance, and decoupling coefficient were mainly controlled by leaf area index. The threshold value of daily surface conductance was approximately 8 mm s⁻¹ over the plantation.

Forest degradation is a worldwide problem, although its causes vary due to geographical and climatic differences and man-made causes. In recent years, the Robinia pseudoacacia forest in the Yellow River Delta has suffered severe degradation. The causative mechanisms were investigated in the field over two years, and the results show that increased forest degradation was reflected by increased tree mortality, high leaf and soil sodium salt levels and groundwater depth. Average tree diameters decreased, and leaf chlorophyll and soil microbial contents decreased. Redundancy discriminate analysis (RDA) showed that degradation of the forest was correlated positively with soil salt content, but negatively with groundwater depth. Correlation analysis showed that 0.79%–0.95% soil salt content and above 1.20 m groundwater depth caused the death of R. pseudoacacia trees due to localized anthropogenic economic activities, such as rice farming, that disrupted the original water–salt balance. Measures are recommended to prevent further degradation and restore degraded forests.

Scots pine (Pinus sylvestris L.) is a dominant tree species on nutrient-poor sandy soils in the Baltic region's hemiboreal forests. A final clear-cut in commercial stands is a common practice. However, the maintenance of relatively stable vegetation indices and ecological processes throughout the rotation promote new scientific and social debates. Overall, clear-cuttings disturb forest functions for a certain period, i.e., phytocenoses with forest-based species composition, biodiversity, and vegetation cover. Soil organic carbon (SOC) and nutrients can also be affected. As key indices, ground vegetation, SOC and main nutrients in the forest floor and in 40-cm topsoil layer were analysed in the clear-cuttings (not reforested) and in reforested 10-, 30-, and 101-year-old Scots pine stands in 2020. The results show an increase in species richness at the beginning of stand formation up to 30 years after clear-cutting; species typical of a mature forest occurred relatively quickly post-harvest. The mean mass of forest floor vegetation was negatively related to the richness of ground vegetation species. Forest floor pH consequently decreased with stand age. Higher SOC levels were in the mature stand. In the mineral topsoil layers, total SOC and total nitrogen were in the upper 10-cm layer in the 30-year-old stand. A post-harvest peak in mineral N concentration was observed and other nutrients, especially mobile P₂O₅, K₂O, Ca²⁺ and Mg²⁺, increased the clear-cuttings and in the 10-year-old stand compared to the mature stand.

Atmospheric deposition (dry and wet deposition) is one of the primary sources of chemical inputs to terrestrial ecosystems and replenishes the nutrient pool in forest ecosystems. Precipitation often acts as a primary transporting agent and solvent; thus, nutrient cycles in forests are closely linked to hydrological processes. We collected precipitation data during a growing season to explore variations in nutrient cycling and nutrient balances in the rainfall redistribution process (wet deposition) in a larch plantation in northeast China. We measured nutrient (

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Prescribed fire, although having low intensity and being able to reduce the risk of wildfire may modify soil properties in the short term, with possible increases in runoff and erosion risk. Soil mulching with vegetation residues is one of the most common post-fire management strategies. Residues of fern, which is abundant on the Mediterranean forest floor, may be used to replace straw for mulching fire-affected areas. However, the effects of prescribed fires are not completely understood, and there is no data regarding the use of fern to protect soil after fire in the literature. To fill this gap, selected soil chemical parameters were analyzed, on a comparative basis, in three Mediterranean forests (pine, oak and chestnut) in Calabria (Southern Italy). These parameters were measured immediately and one year after fire in unburned, burned and not treated, and burned and mulched soils. Changes in soil chemical properties among the different treatments were significant, and the effects of the prescribed fire and mulching were dependent on the time elapsed from their application and forest species. In general, mulching was not effective in limiting the changes in the monitored soil properties compared to the pre-fire values. Each forest species showed different temporal trends in changes of soil properties.

This paper presents a new approach to identifying the climate variables that influence the size of the area burned by forest wildfires. Multiple linear regression was used in combination with nonlinear variable transformations to determine relevant nonlinear forest wildfire size functions. Data from the Prague-East District of the Czech Republic was used for model derivation. Individual burned forest area was hypothesized as a function of water vapor pressure, air temperature and wind speed. Wind speed was added to enhance predictions of the size of forest wildfires, and further improvements to the utility of prediction methods were added to the regression equation. The results show that if the air temperature increases, it may contain less water and the fuel will become drier. The size of the burned area then increases. If the relative humidity in the air increases and the wind speed decreases, the size of the burned area is reduced. Our model suggests that changes in the climate factors caused by ongoing climate change could cause significant changes in the size of wildfire in forests.

Analysis of spatial patterns to describe the spatial correlation between a tree location and marks (i.e., structural variables), can reveal stand history, population dynamics, competition and symbiosis. However, most studies of spatial patterns have concentrated on tree location and tree sizes rather than on crown asymmetry especially with direct analysis among marks characterizing facilitation and competition among of trees, and thus cannot reveal the cause of the distributions of tree locations and quantitative marks. To explore the spatial correlation among quantitative and vectorial marks and their implication on population dynamics, we extracted vertical and horizontal marks (tree height and crown projection area) characterizing tree size, and a vectorial mark (crown displacement vector characterizing the crown asymmetry) using an airborne laser scanning point cloud obtained from two forest stands in Oxfordshire, UK. Quantitatively and vectorially marked spatial patterns were developed, with corresponding null models established for a significance test. We analyzed eight types of univariate and bivariate spatial patterns, after first proposing four types. The accuracy of the pattern analysis based on an algorithm-segmented point cloud was compared with that of a truly segmented point cloud. The algorithm-segmented point cloud managed to detect 70–86% of patterns correctly. The eight types of spatial patterns analyzed the spatial distribution of trees, the spatial correlation between tree size and facilitated or competitive interactions of sycamore and other species. These four types of univariate patterns jointly showed that, at smaller scales, the trees tend to be clustered, and taller, with larger crowns due to the detected facilitations among trees in the study area. The four types of bivariate patterns found that at smaller scales there are taller trees and more facilitation among sycamore and other species, while crown size is mostly homogeneous across scales. These results indicate that interspecific facilitation and competition mainly affect tree height in the study area. This work further confirms the connection of tree size with individual facilitation and competition, revealing the potential spatial structure that previously was hard to detect.

The aboveground biomass (AGB) of shrubs and small trees is the main component for the productivity and carbon storage of understory vegetation in subtropical secondary forests. However, few allometric models exist to accurately evaluate understory biomass. To estimate the AGB of five common shrub (diameter at base < 5 cm, < 5 m high) and one small tree species (< 8 m high, trees’s seedling), 206 individuals were harvested and species-specific and multi-species allometric models developed based on four predictors, height (H), stem diameter (D), crown area (Ca), and wood density (ρ). As expected, the six species possessed greater biomass in their stems compared with branches, with the lowest biomass in the leaves. Species-specific allometric models that employed stem diameter and the combined variables of D²H and ρDH as predictors accurately estimated the components and total AGB, with R ² values from 0.602 and 0.971. A multi-species shrub allometric model revealed that wood density × diameter × height (ρDH) was the best predictor, with R ² values ranging from between 0.81 and 0.89 for the components and total AGB, respectively. These results indicated that height (H) and diameter (D) were effective predictors for the models to estimate the AGB of the six species, and the introduction of wood density (ρ) improved their accuracy. The optimal models selected in this study could be applied to estimate the biomass of shrubs and small trees in subtropical regions.

Accurate estimates of forest aboveground biomass (AGB) are critical for supporting strategies of ecosystem conservation and climate change mitigation. The Jiuzhaigou National Nature Reserve, located in Eastern Tibet Plateau, has rich forest resources on steep slopes and is very sensitive to climate change but plays an important role in the regulation of regional carbon cycles. However, an estimation of AGB of subalpine forests in the Nature Reserve has not been carried out and whether a global biomass model is available has not been determined. To provide this information, Landsat 8 OLI and Sentinel-2B data were combined to estimate subalpine forest AGB using linear regression, and two machine learning approaches–random forest and extreme gradient boosting, with 54 inventory plots. Regardless of forest type, Observed AGB of the Reserve varied from 61.7 to 475.1 Mg ha⁻¹ with an average of 180.6 Mg ha⁻¹. Results indicate that integrating the Landsat 8 OLI and Sentinel-2B imagery significantly improved model efficiency regardless of modelling approaches. The results highlight a potential way to improve the prediction of forest AGB in mountainous regions. Modelled AGB indicated a strong spatial variability. However, the modelled biomass varied greatly with global biomass products, indicating that global biomass products should be evaluated in regional AGB estimates and more field observations are required, particularly for areas with complex terrain to improve model accuracy.

The shape of leaf laminae exhibits considerable diversity and complexity that reflects adaptations to environmental factors such as ambient light and precipitation as well as phyletic legacy. Many leaves appear to be elliptical which may represent a ‘default’ developmental condition. However, whether their geometry truly conforms to the ellipse equation (EE), i.e., (x/a)² + (y/b)² = 1, remains conjectural. One alternative is described by the superellipse equation (SE), a generalized version of EE, i.e., |x/a| ⁿ +|y/b| ⁿ = 1. To test the efficacy of EE versus SE to describe leaf geometry, the leaf shapes of two Michelia species (i.e., M. cavaleriei var. platypetala, and M. maudiae), were investigated using 60 leaves from each species. Analysis shows that the majority of leaves (118 out of 120) had adjusted root-mean-square errors of < 0.05 for the nonlinear fitting of SE to leaf geometry, i.e., the mean absolute deviation from the polar point to leaf marginal points was smaller than 5% of the radius of a hypothesized circle with its area equaling leaf area. The estimates of n for the two species were ˂ 2, indicating that all sampled leaves conformed to SE and not to EE. This study confirms the existence of SE in leaves, linking this to its potential functional advantages, particularly the possible influence of leaf shape on hydraulic conductance.

Multi-generational planting of Eucalyptus species degrades soil quality but the introduction of legumes can improve soil fertility and microbial diversity. However, the effects of introducing non-legume native tree species on soil nutrients and bacterial community structure remain poorly understood. This study investigated the impacts of the conversion of third generation monoculture Eucalyptus plantations to mixed systems including Eucalyptus urograndis with Cinnamomum camphora (EC) and E. urograndis with Castanopsis hystrix (EH), on soil chemical and biochemical properties and bacterial community structure, diversity and functions. First generation E. urophylla plantations were the control. Results show that planting the third generation Eucalyptus led to a significant decrease in pH, organic matter, nutrient content, enzyme activities (invertin, acid phosphataes, and urease), and bacterial α-diversity compare to the controls. However, the mixed planting showed significant improvement in soil chemical and biochemical attributes and bacterial α-diversity, although the E. urograndis and C. hystrix planting had no improvement. Chloroflexi (oligotrophic bacteria) were significantly enriched in third generation Eucalyptus and Eucalyptus +  C. hystrix, while proteobacteria increased significantly in the E. urograndis with C. camphora plantings. The relative abundance of multiple metabolic pathways increased significantly in the third generation Eucalyptus plantations whereas membrane transport-related genes were enriched in soils of the mixed systems. The changes in bacterial community structures in the two mixed systems were driven by diversity, organic matter and acid phosphatase, while bacterial functions were affected by invertase,

-N, diversity and urease. These results suggest that the transformation of successive monoculture Eucalyptus plantations into mixed plantations reduces the depletion of soil nutrients and enhances the ecological function of soil microorganisms.

Nicotinamide treatment of plants and plant cell cultures has been shown to promote defense and decrease levels of DNA methylation. In the present study, we used RNA-seq technology to study overall changes in gene expression induced in roots of 3-month-old spruce (Picea abies) seedlings grown from nicotinamide-treated seeds to examine the molecular mechanisms underlying the defense promotion. Approximately 350 genes were identified as differentially expressed in roots after the seed treatment. Stress response genes, including transcription factors MYB77 and LHY and two chitinase enzymes, were generally upregulated, whereas genes thought to be involved in epigenetic regulation such as DDM1, known to promote DNA methylation, were present at high frequency among the downregulated genes. Across all samples, the expression of downregulated epigenetic-related genes was highly correlated with the nicotinamide treatment, indicating a common regulation. Our results support an earlier hypothesis regarding a potential role of nicotinamide as a defense-signal mediator.

Pine wilt disease (PWD) is currently one of the main causes of large-scale forest destruction. To control the spread of PWD, it is essential to detect affected pine trees quickly. This study investigated the feasibility of using the object-oriented multi-scale segmentation algorithm to identify trees discolored by PWD. We used an unmanned aerial vehicle (UAV) platform equipped with an RGB digital camera to obtain high spatial resolution images, and multi-scale segmentation was applied to delineate the tree crown, coupling the use of object-oriented classification to classify trees discolored by PWD. Then, the optimal segmentation scale was implemented using the estimation of scale parameter (ESP2) plug-in. The feature space of the segmentation results was optimized, and appropriate features were selected for classification. The results showed that the optimal scale, shape, and compactness values of the tree crown segmentation algorithm were 56, 0.5, and 0.8, respectively. The producer’s accuracy (PA), user’s accuracy (UA), and F1 score were 0.722, 0.605, and 0.658, respectively. There were no significant classification errors in the final classification results, and the low accuracy was attributed to the low number of objects count caused by incorrect segmentation. The multi-scale segmentation and object-oriented classification method could accurately identify trees discolored by PWD with a straightforward and rapid processing. This study provides a technical method for monitoring the occurrence of PWD and identifying the discolored trees of disease using UAV-based high-resolution images.

Pine wilt disease (PWD) is one of the most devastating diseases of Pinus spp. and is caused by the pine wood nematode (PWN), Bursaphelenchus xylophilus (Steiner & Buhrer) Nickle. To study adaptation of PWN to survive in hosts that differ in resistance, we examined the self-regulatory characteristics of PWN at the biological and molecular levels early in the interaction. Two-year-old susceptible Pinus thunbergii and resistant Pinus taeda were selected for this experiment, and changes in PWNs after inoculation were assessed. qRT-PCR was used to detect changes in genes related to PWN pathogenicity and detoxification. The results showed that the migration and reproductive abilities of PWNs in P. thunbergii were stronger than those of PWNs in P. taeda. After 7 d, the number of nematodes in P. thunbergii was approximately 3.2-fold higher than in P. taeda. After 15 d, the number of nematodes in P. thunbergii was approximately twofold higher than that in P. taeda. Because PWN can adjust its sex ratio after infection, we compared the sex ratio of uninoculated PWNs, to that in the two pine species. In P. thunbergii, the female to male ratio first decreased and then stabilized over time; in P. taeda first decreased and then increased. Relative fat accumulation in PWNs increased significantly after the PWNs entered the tree body; the accumulation rate in P. thunbergii was higher than in P. taeda at 7 d, but lower after 15 d. Scanning electron microscopy (SEM) showed significantly more bacteria on the surface of PWNs in P. taeda compared with PWNs in susceptible P. thunbergii. At 12 h after inoculation, the expression of genes related to cell-wall degradation (BxBeta1-4 and Bxpel1), effectors (BxCDP1, BxSapB1), and active oxygen metabolism (Bxy-ctl-1 and BxGST3) was 2–6 × higher in the resistant pine than in the susceptible one. In contrast, in PWNs, the expression of autophagy-related genes BxATG1 and BxATG16 was 1.5–2 times higher in P. thunbergii than in P. taeda. These results indicate that the interaction between PWNs and pine trees with different resistance levels elicits a series of physiological and molecular adaptations that affect nematode reproduction and virulence. This study will help elucidate the adaptive mechanisms of PWN in different pine trees.

Pine wilt disease caused by the pinewood nematode Bursaphelenchus xylophilus has led to the death of a large number of pine trees in China. This destructive disease has the characteristics of bring wide-spread, fast onset, and long incubation time. Most importantly, in China, the fatality rate in pines is as high as 100%. The key to reducing this mortality is how to quickly find the infected trees. We proposed a method of automatically identifying infected trees by a convolution neural network and bounding box tool. This method rapidly locates the infected area by classifying and recognizing remote sensing images obtained by high resolution earth observation Satellite. The recognition accuracy of the test data set was 99.4%, and the remote sensing image combined with convolution neural network algorithm can identify and determine the distribution of the infected trees. It can provide strong technical support for the prevention and control of pine wilt disease.

Photochromic wood was fabricated by coating microencapsulated photochromic material (MP)/polydimethylsiloxane composites onto wood using a simple drop-coating method. Urea-melamine–formaldehyde resin was used to microencapsulate the photochromic material (PM) via in situ polymerization. The concentration of the MP affected the photochromic property of the wood surface. The total color change (ΔE*) reached 82.2 when the concentration of the composite coating is 8%. Adhesion tests confirmed that the composite coating adhered firmly to the wood. This method is potentially useful for the production of functional wooden products, such as anti-counterfeiting materials and aesthetic wood.