Forests

Forest phenology is sensitive to climate change, and its responses affect many land surface processes, resulting in a feedback effect on climate change. Human activities have been the main driver of climate change’s long-term shifts in temperature and weather patterns. Forest phenology, understood as the timing of the annual cycles of plants, is extremely sensitive to changes in climate. Quantifying the responses of temperate forest phenology under an elevational range of topographic conditions that mimic climate change is essential for making effective adaptive forest ecosystem management decisions. Our study utilized the Google Earth Engine (GEE), gap filling, and the Savitzky–Golay (GF-SG) algorithm to develop a long-time series spatio-temporal remote sensing data fusion. The forest phenology characteristics on the north slope of Changbai Mountain were extracted and analyzed annually from 2013 to 2022. Our study found that the average start of the growing season (SOS) on the north slope of Changbai Mountain occurred between the 120th–150th day during the study period. The end of the growing season (EOS) occurred between the 270th–300th day, and the length of the growing season (LOS) ranged from the 110th–190th day. A transect from the northeast to southwest of the study area for a 10-year study period found that SOS was delayed by 39 d, the EOS advanced by 32 d, and the LOS was gradually shortened by 63 d. The forest phenology on the north slope of Changbai Mountain showed significant topographic differentiations. With an increase of 100 m in altitude, the mean SOS was delayed by 1.71 d (R² = 0.93, p < 0.01). There were no obvious trends in EOS variation within the study area altitude gradient. LOS decreased by 1.23 d for each 100 m increase in elevation (R² = 0.90, p < 0.01). Forests on steep slopes had an earlier SOS, a later EOS, and a longer LOS than forests on gentle slopes. For each degree increase in slope, SOS advanced by 0.12 d (R² = 0.53, p = 0.04), EOS was delayed by 0.18 d (R² = 0.82, p = 0.002), and the LOS increased by 0.28 d (R² = 0.78, p = 0.004). The slope aspect had effects on the EOS and the LOS but had no effect on the SOS. The forest EOS of the south aspect was 3.15 d later than that of the north aspect, and the LOS was 6.47 d longer. Over the 10-year study period, the phenology differences between the north and south aspects showed that the LOS difference decreased by 0.85 d, the SOS difference decreased by 0.34 d, and the EOS difference decreased by 0.53 d per year. Our study illustrates the significance of the coupling mechanism between mountain topography and forest phenology, which will assist our future understanding of the response of mountain forest phenology to climate change, and provide a scientific basis for further research on temperate forest phenology. Full article

Plants are often exposed to drought stress, and decreases in the soil water content can prevent plants from reaching their full genetic potential. Populus davidiana Dode belongs to the genus Populus, and it is a temperate deciduous tree that is cold and drought tolerant. To investigate the mechanism of P. davidiana response to drought stress, transcriptome analysis was performed on drought and control treatments of P. davidiana. We identified 10230 differentially expressed genes (DEGs). Most DEGs were enriched in pathways related to transcriptional regulation and hormone signal transduction, ROS metabolism, lignin synthesis, and the sugar metabolism process in two contrasting groups. Compared with the control condition, soluble sugars, proline, and POD activity were all increased under drought stress. In addition, Na⁺, K⁺, and Ca²⁺ were all higher under drought stress than in the control. These results not only revealed the mechanism of tolerance to drought stress in P. davidiana, but also promoted the development and application of drought-tolerant genetic resources in P. davidiana. Full article

The Gleditsia genus has various uses, including those for medicinal, edible, chemical, timber, and ornamental purposes, and the genus is widely distributed in China. However, there is still a lack of understanding about the phenotypic and growth differences seen among species within the Gleditsia genus. In this study, we compared and analyzed the various species of Gleditsia seedlings in terms of their genotypes, chromosome numbers, physiological growth, photosynthesis, hormone content, and gene expression. The results showed that the genome size of the Gleditsia genus ranges from 686.08 M to 1034.24 M and that all Gleditsia species are diploid. Among the species studied, G. fera can be divided into fast-growing genotype, exhibited several advantages in terms of leaf type and photosynthetic capacity, high levels of GA₃, and fast stem growth, making it a species with the potential for promotion and application. G. delavayi exhibited high levels of auxin and cytokinin and strong photosynthetic capacity, with rapid growth in terms of plant height. G. microphylla had the lowest levels of IAA, IBA, and NAA in the apical, and showed slow growth in terms of plant height. Weighted correlation network analysis (WGCNA) identified the hub genes associated with traits. This study lays a material and theoretical foundation for the development of new resources for Gleditsia breeding and rootstock selection and provides a basis for the mechanism of rootstock–scion interaction. Full article

There is a great need to identify interactions among silvopastoral systems and microclimatic indicators that describe the effect of trees compared to conventional pasture systems without trees. The objective of this study was to evaluate thermal conditions in a silvopastoral system and a pasture area exposed to full sunlight in the eastern Amazon, Brazil. The silvopastoral system was composed of the forest tree species Bertholletia excelsa H.B.K., Dipteryx odorata (Aubl.) Willd, and Khaya grandifoliola C.DC.. During the monitoring period, a forest inventory was carried out that included 30 trees from each species for which thermal profiles were created using a high-precision thermographic camera. Near-infrared thermography showed a positive and direct correlation with dendrometric variables. Silvopastoral systems with K. grandifoliola reduced the heat profile the most compared to conditions in a pasture fully exposed to sunlight, which demonstrates the ecosystem service provided by trees for thermal regulation in these systems. The microclimatic conditions explain the greater presence of bovines in the silvopastoral system as they were most likely in search of the thermal comfort provided by the trees during the period of the highest daytime temperatures. The silvopastoral system benefits the caloric balance and thermal comfort of pasture animals. Full article

To record land cover changes over time, geographic information systems software was used for selecting and studying sampling surfaces in ortho-aerial photographs. In particular, ortho-aerial photographs of the years 1945 and 2015 were used to record changes in land cover. A total of 103 test surfaces were obtained, which consisted of 25 cells each. The results showed that the area and density of forest cover have increased significantly during the study period. Changes in land cover, and in particular forest cover, are mainly attributed to (a) the gradual decline of the population, and therefore to the decline in man-made interventions such as crops, nomadic herd grazing, and logging, and to (b) natural species competition. Moreover, the effect of climatic change and the reduction in human presence on fir treelines was examined. Based on the results, no clear evidence about treeline changes was found. Also, the effect of soil and topographic factors on land cover changes, as well as the prediction capability of land cover changes, were examined using an artificial neural network. Promising results came out that could provide substantial explanations for land cover changes and quantify the effect of environmental factors on vegetation evolution. Full article

Plant pests are a threat to biodiversity, food security, and the economy. The challenges posed by the introduction of plant pests have triggered the establishment of cooperative mechanisms such as the International Plant Protection Convention (IPPC), an international treaty to protect plant health, but also of Regional Plant Protection Organizations (RPPOs), such as the European and Mediterranean plant Protection Organizations (EPPO). RPPOs participate in activities in their regions to promote and achieve the objectives of the IPPC. Because accurate and reliable detection and identification of pests are essential in order to be able to take appropriate measures against a pest and thus avoid or reduce the economic, social, and environmental costs that it can cause, the IPPC and EPPO have established a specific program on diagnostics. The main aim of this article is to present the diagnostic activities conducted by the European and Mediterranean Plant Protection Organization and Euphresco. Some information is also presented on other initiatives in diagnostics. Full article

The durability against decay organisms is an essential material property for wood in outdoor use. A jack of all trades method for above-ground wood durability testing has been sought for decades, but until now no method has found its way into European standardization. The method of choice shall be applicable for untreated and treated wood—ideally also for wood composites. It shall further be reproducible, objective, fast, easy, and inexpensive. Finally, it shall provide high predictive power. This study was aimed at a review of results and practical experience with the Bundle test method which could serve as a standard procedure for above-ground field tests of wood-based materials. The method allows for water-trapping, creates a moderate moisture-induced decay risk typical for UC 3 situations, and was found applicable for a wide range of wood materials. The method allows for rapid infestation and failure of non-durable reference species within five years in Central Europe. Based on results from Bundle tests with different modifications and performed at different locations, a guideline has been developed. The method is recommended as a suitable tool for determining the durability of various wood-based materials including modified and preservative-treated wood and can provide data for durability classification. Full article

As an ornamental plant, Fatsia japonica has been widely used in gardens. From April 2021 to 2022, a disease that caused the wilting and root rot of F. japonica in a large area was observed, which eventually led to the plants wilting and dying, while the leaves did not fall off. This disease greatly reduced the landscape effect of plants. An oomycete species was isolated from the roots of the infected plants. This colony morphology was slightly radial to stellate, and the aerial mycelium was flocculent. Oval sporangia with papillae, apical chlamydospores and zoospores formed in sporangia were observed. The morphological characteristics were consistent with Phytophthora. For accurate identification, the internal transcribed spacer (ITS), cytochrome oxidase subunit II (COXII) and large ribosomal subunit (LSU) genes were amplified and sequenced. The species was identified as Phytophthora nicotianae using phylogenetic analysis. Finally, the disease was reproduced by inoculating healthy F. japonica with a zoospore suspension; the symptoms were consistent with those of natural infections, and the isolate obtained from artificially infected plants had the same morphological characteristics as the inoculated isolate. The results demonstrated that P. nicotianae is the pathogenic factor of root rot. of F. japonica. This is the first report of root rot on F. japonica caused by P. nicotianae in China. Full article

Forest fires create burned and unburned areas on a spatial scale, with the boundary between these areas known as the fire boundary. Following an analysis of forest fire boundaries in the northern region of Yangyuan County, located in the Liangshan Yi Autonomous Prefecture of Sichuan Province, China, several key factors influencing the formation of fire boundaries were identified. These factors include the topography, vegetation, climate, and human activity. To explore the impact of these factors in different spaces on potential results, we varied the distances between matched sample points and built six fire environment models with different sampling distances. We constructed a matched case-control conditional light gradient boosting machine (MCC CLightGBM) to model these environment models and analyzed the factors influencing fire boundary formation and the spatial locations of the predicted boundaries. Our results show that the MCC CLightGBM model performs better when points on the selected boundaries are paired with points within the burned areas, specifically between 120 m and 480 m away from the boundaries. By using the MCC CLightGBM model to predict the probability of boundary formation under six environmental models at different distances, we found that fire boundaries are most likely to form near roads and populated areas. Boundary formation is also influenced by areas with significant topographic relief. It should be noted explicitly that this conclusion is only applicable to this study region and has not been validated for other different regions. Finally, the matched case-control conditional random forest (MCC CRF) model was constructed for comparison experiments. The MCC CLightGBM model demonstrates potential in predicting fire boundaries and fills a gap in research on fire boundary predictions in this area which can be useful in future forest fire management, allowing for a quick and intuitive assessment of where a fire has stopped. Full article

The isolation and bottom-up assembly of nano-cellulose by using microorganisms offers unique advantages that fine-tune and meet the main key design criteria of sustainability, rapid renewability, low toxicity and scalability for several industrial applications. As a biomaterial, several properties are required to maintain the quality and functional period of any product. Thus, researchers nowadays are extensively using microorganisms to enhance the yield and properties of plant nanocellulose. A microbial process requires approximately 20%–50% less energy compared to the chemical isolation process that consumes high energy due to the need for intense mechanical processing and harsh chemical treatments. A microbial process can also reduce production costs by around 30%–50% due to the use of renewable feedstocks, fewer chemical additives, and simplified purification steps. A chemical isolation process is typically more expensive due to the extensive use of chemicals, complex processing steps, and higher energy requirements. A microbial process also offers higher yields of nanocellulose with well-defined and uniform dimensions, leading to improved mechanical properties and enhanced performance in various applications, compared with the chemical isolation process, which may result in a wider range of nanocellulose sizes, potentially leading to variations in properties and performance. The present review discusses the role of different microorganisms (bacteria, yeasts and fungi) in the isolation and production of nanocellulose. The types and properties of nanocellulose from different sources are also discussed to show the main differences among them, showing the use of microorganisms and their products to enhance the yield and properties of nanocellulose isolation. Finally, the challenges and propositions regarding the isolation, production and enhancement the quality of nanocellulose are addressed. Full article

Phenological synchronicity of different tree parts and habitats can provide valuable insights into the physiological relationships and regulatory factors of different phenologies. The earlywood (EW) to latewood (LW) transition of the xylem is a critical process closely related to the key functions and physiological processes of trees. This study investigated the phenology phase of the EW–LW transition in branches and stems of Smith fir (Abies forrestii var. smithii Viguié & Gaussen) along an altitude gradient (3600 m, 3800 m, and 4000 m) in Jiaozi Mountain, Yunnan, China, in 2021. The study aimed to test the hypothesis that branches transition earlier than stems, but the elevation does not affect the transition time. We monitored the EW–LW transition dates weekly using microcores and then correlated them to the climatic conditions and developmental processes. Our findings revealed that the EW–LW transition timing varied among the different parts of the tree but was synchronized across the different elevations. Furthermore, the transition always occurred earlier in branches than in the stem, but the difference narrowed with increasing altitude. The EW–LW transition was mainly influenced by photoperiod, which plays a crucial role as a signaling factor. Additionally, the tree crown was more sensitive to environmental changes than the stem. The transition time of stems was less sensitive to environmental factors than that of branches. Therefore, our results suggest that the earlywood to latewood transition is regulated by developmental factors, and the photoperiod may indirectly regulate the developmental process of trees as a signaling factor, thus regulating the earlywood to latewood transition time. Our study provides new insights into the developmental regulation and climate sensitivity of tree ring formation. Full article

Forestry workers play a crucial role in implementing forest management programs, but their outdoor work exposes them to rising temperatures caused by global climate change, which poses potential health risks related to heat. This study specifically investigates the relationship between knowledge of heat-related issues, risk perception, and precautionary behavior among Indonesian forestry workers and paddy farmers in response to the escalating workplace heat exposure. Developing effective precautionary behavior is essential for preventing heat-related health disorders and promoting health protection programs. To investigate the association of the latent variables comprehensively, structured interviews were conducted with two occupational groups of outdoor workers, comprising 210 forestry workers and 215 paddy farmers. The findings indicate that increasing knowledge about heat-related issues promotes precautionary behavior, and risk perception acts as a mediator between knowledge and behavior. Additionally, the study highlights that the emotion of “dread” intensifies the perceived risk and predicts positive behavior changes. To enhance heat-related knowledge, exploring the potential use of a “fear” tone is important. In conclusion, comprehensive strategies should be implemented to promote precautionary behavior among forestry workers, particularly manual laborers, who are more vulnerable compared to farmers. Full article

The relationship between maximizing forest revenue and reducing environmental pollution has been a challenging one. It is every country’s responsibility to protect its forest reserves and mitigate climate change. Studies on the relationship between forest economic models and climate change are limited, and most of them focus on maximizing forestry products. This study aims at filling the gaps and makes scientific contributions by providing a detailed account of various economic models and their correlations with climate change, as well as identifying the ecological footprint of forest products, fossil fuel consumption, forest cover, foreign direct investment, economic growth, and population in terms of carbon dioxide (CO₂) emissions. In this study, we observed that most forest economic models focus on forest profit maximization and disregard climate impact. The empirical results suggest that the ecological footprint of forest products increases CO₂ emissions. In addition, forest cover helps to reduce CO₂ emissions. A case study of China’s tremendous growth and the associated CO₂ emissions levels reported a recent decrease in such levels, largely due to an increase in forest cover. Although these findings are not exhaustive, they provide new insights into forestry economic models and the impact of climate change, offering theoretical and practical implications for future reference and forest governance. Full article

Trunk recognition is a critical technology for Camellia oleifera fruit harvesting robots, as it enables accurate and efficient detection and localization of vibration or picking points in unstructured natural environments. Traditional trunk detection methods heavily rely on the visual judgment of robot operators, resulting in significant errors and incorrect vibration point identification. In this paper, we propose a new method based on an improved YOLOv7 network for Camellia oleifera trunk detection. Firstly, we integrate an attention mechanism into the backbone and head layers of YOLOv7, enhancing feature extraction for trunks and enabling the network to focus on relevant target objects. Secondly, we design a weighted confidence loss function based on Facol-EIoU to replace the original loss function in the improved YOLOv7 network. This modification aims to enhance the detection performance specifically for Camellia oleifera trunks. Finally, trunk detection experiments and comparative analyses were conducted with YOLOv3, YOLOv4, YOLOv5, YOLOv7 and improved YOLOv7 models. The experimental results demonstrate that our proposed method achieves an mAP of 89.2%, Recall Rate of 0.94, F1 score of 0.87 and Average Detection Speed of 0.018s/pic that surpass those of YOLOv3, YOLOv4, YOLOv5 and YOLOv7 models. The improved YOLOv7 model exhibits excellent trunk detection accuracy, enabling Camellia oleifera fruit harvesting robots to effectively detect trunks in unstructured orchards. Full article

Ginkgo leaf blight, one of the most economically important ginkgo diseases, has become very prevalent in many places in China. Flavonoids and endophytes are both considered important in ginkgo plant functioning. However, little is known about the potential relationships among ginkgo leaf blight pathogens, flavonoid accumulation profiles in infected leaves, and ginkgo leaf endophytes. In this study, the flavonoid accumulation profiles in infected leaves, pathogens of ginkgo leaf blight, and the endophytes of healthy ginkgo leaves were characterized. The levels of total flavonoids in the healthy parts of the infected leaves were significantly higher than those in the healthy leaves. Furthermore, Alternaria tenuissima, Botryosphaeria dothidea, and Dothiorella gregaria were identified as pathogens of ginkgo leaf blight; among them, A. tenuissima was the major pathogen. The in vitro experiments showed that flavonoids (apigenin, luteolin, and kaempferol) could significantly inhibit the growth of one or more pathogens at a concentration of 10 mg/L. Furthermore, fifty-six ginkgo leaf endophytic fungi (GLEF) from healthy ginkgo plants were isolated and characterized. Among them, Alternaria spp. were the most abundant, and GLEF55 shared the same ITS sequence with the pathogen Alternaria tenuissima. Thereafter, four flavonoid-producing endophytes were selected and their effects on the growth of pathogens were evaluated. The extracts of GLEF55 could significantly inhibit the growth of the pathogens B. dothidea and D. gregaria simultaneously in vitro, but not the growth of the pathogen A. tenuissima. Furthermore, the dual cultures of the candidate GLEF and ginkgo leaf blight pathogens revealed that GLEF55 had a similar growth rate to that of A. tenuissima and D. gregaria, but its growth rate was significantly slower than that of B. dothidea. Finally, the GLEF exhibited variable roles when facing pathogens in ginkgo leaves. Among them, GLEF55 showed similar pathogenicity as the pathogen A. tenuissima when they were dually cultured in ginkgo leaves. By contrast, GLEF17 (an uncultured soil fungus) could significantly counteract the pathogenic effects of A. tenuissima and D. gregaria, but it dramatically exacerbated the pathogenic effects of B. dothidea. Larger lesion areas were observed on the side of ginkgo leaves where GLEF39 (Alternaria sp.) or GLEF54 (Aspergillus ruber) and pathogens were simultaneously inoculated, which suggested that the pathogenicity of specific endophytic fungi occurred when plants were wounded. Overall, A. tenuissima, a major pathogen of ginkgo leaf blight, might lurk inside the plants as a friendly endogenous fungus and convert into a hostilely pathogenic mode at a particular time. This study proposed a possible cause of ginkgo leaf blight and provided potential theoretical guidance for its prevention. Full article

This study aimed to investigate the effects of growth ring width, height from the tree base, and loading direction on the transverse compressive strength of Japanese larch wood, which is commonly used in wood structures in China. Plantation wood is often used to replace natural forest woods for reconstruction purposes, despite significant differences in properties (e.g., growth rings, density, strength) between them. The ends of transversely compressed wood members in such structures are prone to damage by breaking or crushing. A transverse compressive test was conducted following Chinese national standards, which revealed the following key findings. (1) There was a significant difference in the transverse compressive strength of wood with different growth ring widths (p < 0.05). The radial and slant compressive strength of wood increases with growth ring width, while the tangential compressive strength decreases as growth ring width increases. (2) The transverse compressive strength of wood decreases as the height from the tree base increases. The radial, tangential, and slant compressive strength at a lower height were 18.39%, 22.58%, and 18% higher than those at a greater height in the stem, respectively, with significant differences at the 0.05 level. (3) The load–displacement curve of Japanese larch wood under radial and slant compression follows a “three-segment” form. In contrast, the load–displacement curve of tangential compression is a continuous curve that drops sharply upon reaching its highest point. (4) There is a significant difference in the transverse compressive strength of Japanese larch wood in different loading directions when growth ring width and height from the tree base are constant (p < 0.05), which fall into order as tangential > radial > slant. Full article

Bamboo has great potential in restoring degraded lands while providing multiple environmental benefits and harvestable products at regular intervals due to its unique characteristics of rapid growth. However, a comprehensive and species-specific knowledge of biomass productivity, nutrient dynamics, and potential harvest-induced nutrient losses is lacking. This study compared the biomass and nutrient dynamics of four bamboo species Bambusa oldhamii Munro, Dendrocalamus latiflorus Munro, Bambusa tulda Roxburgh, and Dendrocalamus brandisii (Munro) Kurz in Northern Thailand. Field measurements, laboratory analyses, and statistical modeling were used to estimate their aboveground biomass (AGB), nutrient use efficiency (NUE), and nutrient stocks. Culm diameter at breast height (DBH) and age were identified as the most reliable predictors of AGB. The study revealed that D. brandisii had superior productivity and NUE compared to the other species, particularly the introduced non-native bamboo species. These findings emphasize the need for species-specific strategies that consider both biomass productivity and nutrient dynamics. Furthermore, D. brandisii can be suggested as a native candidate for bamboo plantations in Northern Thailand and similar environments, given its high productivity and efficient nutrient use, underpinning its potential contribution to environmental rehabilitation and rural livelihoods. However, more research is required to minimize nutrient losses and maintain a productive age structure. Full article

Natural World Heritage properties provide humanity with a rich and diverse range of ecological products, and the realization of their economic value is related to heritage protection and the improvement of community residents’ well-being. In this study, the equivalent factor method was used to calculate the ecological product value (EPV), and the fishnet tool in ArcGIS was used for spatial zoning. The main land use type of the study area is forest land, accounting for over 82% of the total area. The conversion of land use types is weak in the property and strong in the buffer zone. The EPV of the study area was about USD 172.41 million, showing a downward trend before World Heritage inscription but an upward trend after the inscription, with forests as the main contributor. The spatial distribution of the ecosystem service value of the study area has obvious hierarchical characteristics. World Heritage inscription is beneficial for maintaining the stability of land use and for the improvement of the EPV of the property. The high- and low-EPV areas, respectively, are related to the distribution of forests and agricultural land. The dominant models of EPV in the study area are ecological forestry economy, water economy, and ecological agricultural economy and forestry economy. Full article

Earth’s forests are increasingly exposed to climate risks through climate change-related drought and heat waves. Here, we review the climate vulnerability of European beech (Fagus sylvatica), the most abundant tree species of Central Europe’s temperate forests, and its adaptation potential to a hotter and drier climate in northern Germany, close to the center of the species’ distribution range. About two-thirds of the studied beech forests show persistent negative growth trends of their dominant trees since the onset of rapid warming in the early 1980s, driven primarily by long-term deterioration of the climatic water balance (CWB) in summer and, locally, long-term decrease in June precipitation. Lower water storage capacity of the soil increases the climate sensitivity of growth. Even though beech populations of drier sub-regions reveal some acclimation to drought (reduced stomatal conductance, turgor loss point reduction, higher C allocation to roots), they are more climate-vulnerable than populations at moister sites, visible in larger growth decreases and greater CWB sensitivity of growth. Even though beech mortality is still lower in the study region than in other parts of Central Europe, our results identify beech forest regions with <350 mm growing-season precipitation as vulnerable to recent climate conditions, which refers to half of the study region. With further climate warming and aridification, most of northern Germany likely will become unfavorable for beech growth within the next tree generation, which suggests choosing in many production forests alternative, more drought- and heat-resistant timber species. Full article