Climate-smart forestry, which has emerged since 2020, is a synergistic development concept that integrates smart forestry, climate forestry, and ecological forestry. Climate-smart forestry, which is promoted by new-generation information and artificial intelligence (AI) technology, aims to change the traditional scientific research and management paradigms of forestry, and better understand and reveal the mechanisms of interactions between forest ecosystems and climate change. On this basis, nature-based climate solutions can be proposed to achieve functional efficiency, stability, and sustainability of forest ecosystem, and ultimately to achieve harmonious development between humans and nature. Similar to the conventional forestry and ecological forestry, the climate-smart forestry also requires scientific research as a fundamental support. The key science question in climate-smart forestry is the mechanisms of the interaction between forest ecosystems and climate change. The main research directions should include: 1) Monitoring, measurement, and estimation of forest ecosystem carbon sequestration, as well as the temporal effects of carbon sinks on mitigating climate change. 2) The formation of resilience (resistance, recovery, adaptability) in forest ecosystems and their response mechanisms to climate change and natural disturbances. 3) The mechanisms of carbon sequestration formation, maintenance, and enhancement in forest ecosystems, including the impact of forest management and timber production on carbon sequestration, and the balance between carbon sequestration and other functions. 4) AI and active remote sensing-driven intelligent systems for forest data collection. 5) Climate-smart forestry management system based on informatization, AI and expert decision-making. Strengthening the climate-smart forestry research is beneficial for enhancing the resilience of forest ecosystems to better adapt to climate change or mitigate the negative impacts of climate change, as well as improving the ability of forests to mitigate climate change, and promoting the multiple ecological functions of forests and the provision capacity of forest products.

Objective: This study aims to investigate the effects of nitrogen (N) and phosphorus (P) addition on soil water-stable aggregates and soil organic carbon (SOC) distribution in moso bamboo forest in subtropical China, and reveal the response of soil SOC in bamboo forest to N and P addition, providing data support for carbon sequestration and sink enhancement in bamboo forest under N deposition background. Method: In this study, NH₄NO₃ was used as N source, NaH₂PO₄ was used as P source and 4 treatments (CK: 0 kg·hm^?2a^?1N+0 kg·hm^?2a^?1P, N: 120 kg·hm^?2a^?1N, P: 120 kg·hm^?2a^?1P, NP: 120 kg·hm^?2a^?1N+120 kg·hm^?2a^?1P) were set. After N and P addition for 3 years, changes of different particle size (>2, 0.25?2, 0.053?0.25, and <0.053 mm) composition, mean weight diameter (MWD), geometric mean diameter (GMD) and SOC content were investigated. Result: 1) The content of water-stable aggregates in each soil layer was mainly macro-aggregates (>0.25 mm), and the content of macro-aggregates decreased with the increase of soil depth, while the content of micro-aggregates (<0.25 mm) increased with the increase of soil depth. In 0?20 cm soil layer, N treatment significantly increased the content of micro-aggregates, but had no significant effect on the content of macro-aggregates; P treatment had no significant effect on aggregate composition; NP treatment significantly increased the content of micro-aggregates and decreased the content of macro-aggregates; each treatment has no significant effect on MWD and GMD of water-stable aggregates. In 20?40 and 40?60 cm soil layer, the content of macro-aggregate decreased and the content of micro-aggregate increased in each treatment. In 20?40 cm soil layer, P treatment significantly reduced the MWD and GMD of water-stable aggregates, N treatment had no significant effect on MWD and GMD of water-stable aggregates, NP treatment significantly reduced the MWD of water-stable aggregates, and had no significant effect on GMD of water-stable aggregates. In 40?60 cm soil layer, each treatment significantly reduced the MWD and GMD of water-stable aggregates. 2) Compared with CK, N, and P treatment significantly reduced SOC content in each soil layer; NP treatment significantly reduced SOC content in 40?60 cm soil layer, but had no significant effect on SOC content in 0?20 and 20?40 cm soil layer. 3) N treatment only increased the SOC contribution rate of soil macro-aggregates in 20?40 cm soil layer, decreased the SOC contribution rate of soil micro-aggregates, but had no significant effect on the SOC contribution rate of soil aggregates in 0?20 and 40?60 cm soil layer; NP treatment significantly reduced the SOC contribution rate of macro-aggregates and increased the SOC contribution rate of micro-aggregates in each soil layer; the effect of P treatment on SOC contribution rate of aggregates in 20?40 and 40?60 cm soil layers was consistent with that of NP treatment, but there was no significant effect on 0?20 cm soil layer. Conclusion: NP addition could mitigate the decrease of SOC content caused by N and P addition to a certain extent. P addition could promote the transfer of SOC from macro-aggregates to micro-aggregates and increase the stability of soil carbon. Therefore, in subtropical forest soils where N is relatively rich and P is limited, P addition can alleviate the decrease of SOC content caused by N deposition and promote the sequestration of SOC to a certain extent.

Objective: This study aims to investigate the annual effects of logging disturbance on carbon storage in the canopy layer of typical natural secondary coniferous-broadleaved mixed forests in northeast China, providing a theoretical support for carbon sequestration management. Method: Four 1 hm² plots were selected in Jilin Province. The initial survey was conducted in 2011, followed by logging operations in the winter of the same year. Retention trees were re-measured in 2013, 2015, 2018, and 2021. Bivariate linear regression was used to explore the effects of logging intensity, species diversity, functional diversity, phylogenetic diversity, and community-weighted mean trait values on carbon storage and carbon increment. A multiple linear regression model was employed to compare the contribution of each variable, and a structural equation model was used to test the direct and indirect effects of each variable on carbon storage and increment. Result: 1) In the multiple linear regression model of carbon storage and increment, logging intensity accounted for 25% and 5% of the total explanatory variance, respectively. Plant species diversity (species, functional, phylogenetic diversity) contributed 67% and 58% of the total explanatory variance, respectively, for carbon storage and increment. Community-weighted mean trait values accounted for 8% and 37% of the total explanatory variance, respectively, for carbon storage and increment. 2) In the structural equation model of carbon storage, logging intensity had significant negative effects on phylogenetic diversity, functional diversity, maximum tree height weighted trait value, and carbon storage, with path coefficients of ?0.221, ?0.454, ?0.337, and ?0.229, respectively. Logging intensity had a significantly positive effect on wood density weighted trait value, with a path coefficient of 0.368. The direct effect of logging intensity on species diversity was not significant. Species diversity and functional diversity had significant positive effects on carbon storage, with path coefficients of 0.306 and 0.235, respectively. Phylogenetic diversity and community-weighted mean trait values did not have a significant direct effect on carbon storage. 3) In the structural equation model of carbon storage increase, maximum tree height weighted trait value had a significant positive effect, functional diversity was unrelated to carbon storage increase, and the relationships between other variables were the same as in the carbon storage model. Conclusion: Species diversity, functional diversity, and community weighted mean have a direct impact on carbon storage and carbon increment. During forest management, increasing plant species and promoting functional diversity can enhance the carbon sequestration capacity of forests. The cutting intensity is sufficient to directly and indirectly reduce carbon storage and carbon increment through functional diversity and community weighted mean; Therefore, in forest management, reasonable logging is of great significance for improving the carbon sequestration capacity of forests.

Objective: This study aims to predict the changes in gross primary productivity (GPP) and inherent water use efficiency (iWUE) of Pinus sylvestris var. mongolica plantations in Heishui forest station in western Liaoning Province under future different climatic conditions. Method: A sensitivity analysis was conducted on the parameters affecting GPP and evapotranspiration (ET) in the BIOME-BGC model. Parameter estimation (PEST) combined with eddy covariance data of GPP was used to adjust the model parameters, to obtain the simulated gross primary productivity (GPP_m) and simulated inherent water use efficiency (iWUE_m). The result of stable isotope measurement was compared with remote sensing data. The responses of GPP_m and iWUE_m of P. sylvestris var. mongolica in the Heishui forest station to climate change and increasing CO₂ concentration by the end of this century were also predicted. Result: The carbon allocation ratio between fine roots and leaves was a highly sensitive parameter affecting both GPP and ET in the BIOME-BGC model, while the turnover rates of leaves and fine roots were moderately sensitive parameters. After calibration of the sensitive parameters, the simulated values of GPP were closer to the observed values. The simulated iWUE_m was significantly correlated with the inherent water use efficiency (iWUE_y) obtained by remote sensing and the individual inherent water use efficiency (iWUE_d) with isotopic measurement (P<0.05). Under warming, GPP_m increased, but under reduced precipitation and increased CO₂, GPP_m did not change significantly. The iWUE_m showed similar trends in different scenarios, but with larger variations. Under the RCP2.6, RCP4.5, and RCP8.5 scenarios, GPP_m of P. sylvestris var. mongolica significantly increased compared to the baseline, with significant differences among scenarios. However, iWUE_m did not differ significantly from the baseline under RCP2.6 and RCP4.5, but increased significantly under RCP8.5 (P<0.01). Conclusion: The BIOME-BGC model, after calibration, can accurately simulate GPP_m and iWUE_m of P. sylvestris var. mongolica in the Heishui forest station. The differences in the future trends of GPP_m and iWUE_m suggest that the response mechanism of iWUE to climate change is more complex than that of GPP, and iWUE is not only influenced by climate change, but also by local site conditions.

Objective: Monitoring forest resources and its spatio-temporal changes using time-series remote sensing datasets and extracting the driving factors has a great significance in achieving scientific management and efficient utilization of regional forest land resources. Method: This study identified Feicheng City, Shandong Province as a case study, extracted the distribution information of land type from 2000 to 2020 by decision tree classification based on the 21-period Landsat remote sensing datasets, which was preprocessed by radiation calibration and atmospheric correction, and also analyzed spatio-temporal change and its driving factors of forest based on the renovated IPAT model. Result: The extracted forest land information based on decision tree classification achieved a high accuracy, which yield more than 94.7% of user’s accuracy. In the past 20 years, the area of forest land fluctuated with a net increase of 17 463.54 hm², and the increased forest land was concentrated in the central parts and northern mining area of Feicheng City, while the decreased forest land was centralized in the edge part of the central forest land, thus indicating the spatial characteristics of concentrated distribution in the central and northern parts and sporadic distribution in other areas. The renovated IPAT model showed that the endowment value of forest land was the main driving factor for the area change in Feicheng City ( the contribution larger than 80.3%), and the degree of affluence was the secondary driving factor. The contribution of both factors exceeded 92% of the total contribution of the four factors in the renovated IPAT model. In contrast, forest industry and the population posed little influence. Conclusion: Forest resources could be accurately extracted and monitored based on decision tree classification, and the endowment value of forest land has significant influences on the spatio-temporal evolution of forest land.

Objective: This study aims to understand the effects of propagation methods on root biomass allocation and growth of different order roots of Chinese fir seedlings, which is helpful to reveal the differences in individual root development status and growth strategies of Chinese fir seedlings. Method: One-year Chinese fir seedlings cultivated by seed germination, tissue culture and cutting were used to examine the differences in root biomass, morphological traits and tissue carbon and nitrogen content at different order levels, and analyze the relationships among the measurement indexes of root biomass at different order levels, so as to explore the differences in the influence of propagation methods on root growth strategies of Chinese fir seedlings. Result: 1) There were significantly differences (P<0.05) in the root: shoot ratio of Chinese fir seedlings cultured by different propagation methods, with the order as cutting > seedlings > tissue culture seedlings. In terms of the distribution of root biomass in the same order, the biomass [(0.68±0.13)g per plant] of the first order roots of cuttings was 4.31 times that of seedlings and 1.09 times that of tissue culture seedlings. The biomass of 2^th-4^th order roots of tissue culture seedlings was significantly greater than that of seedlings and cuttings, with values of (1.19±0.21)g per plant, (1.63±0.19)g per plant and (1.82±0.27)g per plant, respectively The biomass accumulation of different order roots of tissue culture seedlings and cuttings was greater. 2) Seedlings promoted 1-2 order root extension through 4 order root growth, and their 4-order root biomass and 1-2 order root specific surface area were significantly larger than those of tissue culture seedlings and cuttings (P<0.05). However, the root average diameter and specific root length of the 1-order roots of tissue culture seedlings and cuttings were significantly greater than those of seedlings, showing a strategy to enhance resource absorption efficiency by increasing diameter and length. 3) There were differences in the C and N contents in different order roots of seedlings, tissue culture seedlings and cuttings. The N content of 1-2 order roots of tissue culture seedlings and cuttings was significantly higher than that of seedlings (P<0.05), but the N content of 3-4 order roots was significantly lower than that of seedlings. The C content of 1-4 order roots of tissue culture seedlings was significantly lower than that of seedlings and cuttings. The C/N ratio of the 1-order roots of tissue culture seedlings and cuttings was significantly lower than that of seedlings. 4) The root biomass of seedlings was significantly correlated with tissue N content in grade 1 order roots, morphological traits of 2-3 order roots, and morphological traits and tissue C content in 4 order roots (P<0.05). For tissue culture seedlings and cuttings, there was significant correlation between root biomass and 1-2 order root morphological traits, 3-4 order root morphological traits, as well as tissue C content, reflecting that there was the ecological trade-off relationship between morphological construction and resource acquisition efficiency at different root order levels. Conclusion: There are significant differences in the root development level and growth strategy of Chinese fir seedlings cultivated by different propagation methods. The root system of seedlings shows the growth strategy of exploring and searching for soil space resources. In contrast, the root morphology construction characteristics and growth strategies of tissue culture seedlings and cuttings are more similar, showing a growth strategy to enhance the absorption and utilization efficiency of occupied space resources.

Objective: Cathaya argyrophylla is a rare and endangered plant unique to China, however it is difficult to breed. In this study, the factors influencing the induction callus of plant regeneration from mature embryo of C. argyrophylla were studied, so as to provide assistance in further elucidating the mechanisms that influence the induction of callus and adventitious buds in C. argyrophylla. Method: The mature embryos of C. argyrophylla from two provenances in Jinxiu and Guilin, Guangxi, were used as experimental materials. The media of 1/2 MS, DCR, and P6, with adding 0.5, 1.0, and 1.5 mg·L^?16-BA, 0.2, 0.4, and 0.6 mg·L^?1NAA, and 0.5, 1.0, 1.5 mg·L^?1IBA, respectively, were used to induce callus tissue, adventitious buds, and roots of C. argyrophylla, in order to obtain regenerated C. argyrophylla plants. The effects of two provenances, culture medium, plant growth regulators, etc. on the induction rate of callus, adventitious buds, adventitious roots, and proliferation rate of breeding and strengthening buds of C. argyrophylla were analyzed. Result: The callus induction rate, adventitious root induction rate, and breeding and strengthening buds rate of C. argyrophylla from Guilin provenance were significantly higher, with values of 66.48%, 21.43%, and 55.00%, respectively. The induction rate of adventitious buds in the C. argyrophylla from Jinxiu provenance was significantly higher, at 73.33%. The suitable culture medium and plant growth regulators for inducing plant regeneration from C. argyrophylla callus were: DCR+0.5 mg·L^?16-BA for callus induction, DCR+1.5 mg·L^?16-BA for adventitious bud induction, 1/2 MS+0.2 mg·L^?1NAA+0.5 mg·L^?1IBA for adventitious root induction, and DCR+1.0 mg·L^?16-BA+0.4 mg·L^?1NAA for bud proliferation and strengthening. Conclusion: The overall induction and proliferation rates of C. argyrophylla from Guilin, Guangxi are higher than those from Jinxiu, Guangxi. DCR medium has a significant promoting effect on the induction of callus and adventitious buds in C. argyrophylla, while 1/2 MS medium has a significant promoting effect on the induction of adventitious roots of C. argyrophylla. The 6-BA can induce both callus tissue and adventitious buds of C. argyrophylla. The combination of NAA and IBA can induce adventitious roots of C. argyrophylla. The combination of 6-BA and NAA can proliferate and strengthen adventitious buds of C. argyrophylla.

Objective: This article aims to reveal the biological function of cysteine protease CfAtg4 in Colletotrichum fructicola on Camellia oleifera, so as to provide a candidate target site for the development of new prevention and control agents for anthracnose in C. oleifera. Method: The CfATG4 gene knockout fragment was constructed by Overlap PCR, and the knockout mutants and complemented strains were obtained by homologous recombination and PEG-mediated protoplast transformation. The sensitivity of wild-type, mutant and complemented strains to rapamycin was measured. The degree of autophagy was evaluated by observing the number of autophagosomes before and after starvation induction under an inverted fluorescent microscopy, and validating the microscopic observation results using the Western blot assays. The growth rate, conidia number, pathogenicity, spore germination rate, appressoria formation rate and response to external stresses were measured in the wild type, mutant and complemented strains. Result: 1) The CfATG4 knockout mutant, ΔCfatg4, was more sensitive to rapamycin and showed significantly fewer autophagosomes than wild-type CFLH16. The ΔCfatg4 mutant was not able to degrade the autophagy marker protein, GFP-CfAtg8, before and after starvation induction, exhibiting autophagy abolishment. 2) The biological phenotypic analysis revealed that ΔCfatg4 mutant grew slowly, and the aerial hyphae decreased on different nutrient media. ΔCfatg4 mutant significantly reduced conidiation, and lost pathogenicity on tea oil leave. 3) The spore germination rate and appressoria formation rate of ΔCfatg4 mutant were significantly reduced. 4) ΔCfatg4 mutant showed stronger tolerance to salt stresses (NaCl, KCl), and a cell wall integrity stress agent, Congo red (CR), but it was more sensitive to sodium dodecyl sulfate (SDS), another cell wall integrity stress agent. Furthermore, ΔCfatg4 mutant was more sensitive to oxidizing environment (H₂O₂), and however, more tolerant to reducing environment (dithiothreitol, DTT). Conclusion: The cysteine protease CfAtg4 is involved in regulating the growth and development, conidiation, appressoria formation, external stress responses, and pathogenicity through mediated autophagy. In this study, we have first elucidated that the CfAtg4-mediated autophagy regulates the pathogenicity of C. fructicola, which provides potential target sites for the development of novel fungicides.

Objective: This study aims to determine the azimuthal variations of water transport in the sapwoods of the trees under special site conditions, so as to provide a scientific basis for improving the accuracy in estimating tree transpiration by sap flow through observing and comparing the sap flow velocity of sapwoods facing and backing to an irrigation channel in the oasis farmland protection forest trees planted alongside the channel. Method: Three typical poplar species (Populus×popularis, P. alba var. pyramidalis and P. deltoides cl. Beikang) in the oasis farmland shelterbelt in Ulan Buh Desert were selected as the research objects. The heat field deformation (HFD) method was used to synchronously monitor the sap flow velocity of the trunk that was either face to or back to the irrigation channel in eight measuring sites. Result: Sap flow velocity of sapwood facing to the irrigation channel (J_Q-side) was significantly higher than that of sapwood backing to the irrigation channel (J_NQ-side) in each tree species (P<0.01). J_Q-side values of P.×popularis, P. alba var. pyramidalis and P. deltoides cl. Beikang were 1.83 (R² = 0.90), 1.40 (R² = 0.71) and 3.55 (R² = 0.71) times of corresponding J_NQ-side values, respectively. On sunny days, the average J_Q-side peak values of the three tree species were 3.38, 2.47, and 5.35 cm·h^?1, respectively. The differences in sapwood sap flow velocity between the two sides reached the maximum around noon. Both J_Q-side and J_NQ-side showed a decreasing trend with the increase of sapwood depth, and the sap flow velocity at each point (1.5?7.5 cm) of sapwood facing to the irrigation channel was significantly higher than that of sapwood backing to the irrigation channel (P<0.01). The radial variation pattern of sap flow velocity in different azimuths in each poplar specie was consistent, which could be well fitted by the negative exponential function (R²>0.98). Conclusion: The irrigation channel causes significant differences in the sapwood water transport between facing side and backing side to the channel, but does not change the radial variation pattern of sap flow of the trees in farmland shelterbelt.

Objective: It is clear whether China’s “forest fire in 1987”, a major historical event, has caused changes in the probability and driving factors of forest fires in Inner Mongolia’s Daxing’an Mountains. Method: Based on historical fire data (1980—2018), taking the“forest fire in 1987”in China as the dividing line, two models, Logistic regression (LR) and boosted regression tree (BRT), were used to analyze and compare the occurrence probability and driving factors of forest fires in Daxing’an Mountains in Inner Mongolia before, after, and throughout the“forest fire in 1987”. Meanwhile, the areas of low, medium, and high fire risk grades in each banner and county were calculated, and the differences in forest fire driving factors and fire risk changes in different periods were interpreted. Result: 1) Whether using all years or data before and after 1987 for modeling, both BRT and LR models demonstrated higher forecasting accuracy compared to each other. Although the accuracy of LR model is slightly lower, it can still meet the prediction requirements. 2) The accuracy of both models in predicting at three different periods was observed to be: all years > post-1987 > before-1987, indicating that with sufficient sample data, the prediction models based on major historical events such as the forest fire in 1987 did not improve the forecasting accuracy. This finding suggests that the model built using all years of data has a higher degree of reliability in terms of accuracy. 3) Climate factors have been the dominant factors influencing forest fires throughout all periods, contrary to previous studies. This study found that it is particularly important to pay attention to relevant meteorological indicators such as average/maximum temperature, average/maximum surface temperature, and sunshine duration during the pre-fire season one year prior to the occurrence of a fire. 4) Obvious changes have occurred in the medium- and high-risk areas of forest fires in three different periods. The eastern part of Daxing’an Mountains in Inner Mongolia (the southeast of Elunchun Autonomous Banner, most of Morin Dawa Daur Autonomous Banner and the central of Arug Banner) have relatively high risks of forest fires in all three periods. In the northern virgin forest areas (the northern part of Argun City), there were few medium- and high-risk areas before 1987, but the number of such areas increased significantly after 1987. Conclusion: The occurrence of the major historical event“forest fire in 1987”led to a significant change in China’s forest fire prevention policies, resulting in the transformation of the dominant factor affecting the probability and driving factors of forest fires in Daxing’an Mountains, Inner Mongolia from human factors to natural factors (lightning fire).

Objective: Great Gobi A Strictly Protected Area of Mongolia is a refuge for many endangered species distributed in border areas between China and Mongolia. Especially the Gobi Bear, which is a subspecies of the brown bear, holds the distinction of being the sole bear globally residing in the Gobi and desert region, and is revered as a“national mammal”in Mongolia. In response to the request by the Mongolian government, diversities and distribution patterns of the dominant mammals were investigated in this protected area. We aim to provide data support for Gobi Bear management and scientific research of wildlife in the Great Gobi A Strictly Protected Area. Method: From April 2019 to March 2021, a total of 118 infrared cameras were set up at Gobi Bear feeding stations, water source sites and animal trails in the protected area. A list of mammal and bird species was compiled according to the camera trapping data. The distribution index and relative abundance index were used to compare the distribution intensity and abundance of Gobi Bear and its Sympatric wild animals and to compare the distribution patterns of the main animal speceis. Relationships between their distribution patterns and species interaction or environmental factors were analyzed and discussed. Result: In total, 13 mammal animal species which belong to 6 orders, and 48 bird species, which belong to 10 orders, were identified with a total of 59 271 camera days and 23 312 independent detections of the dominant mammals during the survey. Among the mammal species, the top three were Asiatic Wild Ass, Wild Camel, and Gobi Bear. The distribution index of the Gobi Bear was gradually decreasing from east to west in the Protected Area. It was the highest in the Tsagaan Bogd region, the Shar Khuls region was the second, and the Atas Inges region was the lowest. Most of the ungulate species showed a decreasing trend from west to east in distribution index. While carnivore species showed different distribution patterns among different oases. As the survey focus on Gobi Bear, the relative abundance index of Gobi Bear was the highest (20.61) among the carnivore species. The relative abundance index of Asiatic Wild Ass was the highest (17.26) in ungulates. Conclusion: The distribution index of the dominant mammals were different in different oases. It may be related to their habitat selection preferences and the distribution of predators/prey. Most species have different relative abundance index among the feeding stations, water source sites and animal trails. Especially in ungulates, the relative abundance index at the water source sites were significantly higher than that at the other habitats. It is recommended that continuing investigation around the water source sites is important to further find out the animal diversity in the Great Gobi A Strictly Protected Area and to understand the distribution dynamics of the endangered species such as Gobi Bear and the sympatric animals.

Objective: The adsorption-desorption isotherms and wood fiber tissue, wood ray and vessel dimension of change ratio of Catalpa bungei earlywood and latewood were real-timely and synchronously documented. This work aimed to reveal the pattern and interaction between the dimensional changes of different tissues of the earlywood and latewood. Method: The earlywood and latewood of the same growth ring in the heartwood of Catalpa bungei were studied using a dynamic vapor sorption analyzer combined with a video Dino X Lite Digital Microscope. The measurements were taken at a constant temperature of (25±0.1)℃, starting at 0% relative humidity (RH) and increasing in increments of 10% RH up to 95% RH, and then decreasing back to 0% RH also in 10% RH decrements. The each RH process was divided into the water vapor sorption period and equilibrium moisture content (EMC) constant period. During the water vapor sorption period, wood fiber tissue, wood ray and vessel dimensional change ratio and the sorption isotherm were synchronously measured. During the EMC constant period, whether there was hysteresis between“dimensional change behavior”and“EMC”or not was investigated. Result: 1) Throughout the moisture sorption process, both earlywood and latewood existed a significant hygroscopic hysteresis. The absolute hysteresis increased and then decreased with the increasing RH, reaching a maximum at the 70% RH level. Compare with earlywood, the absolute hysteresis of latewood was smaller. 2) The change ratio of wood fiber tissue dimension and wood ray dimension for both earlywood and latewood increased with increasing RH, while the change ratio of tangential diameter follow the opposite pattern of change with RH. The change ratio in tangential of earlywood and latewood at 95% RH was 0.945 and 0.918, respectively. 3) As the linear length (L) between the wood ray and the vessel increased, the change ratio of tangential dimension of wood ray decreased, and ceased to change after L≥200 μm, while the change ratio of longitudinal dimension of wood ray remained unchanged or changed minimally. At 95% RH, the maximum values of the change ratio in the tangential dimension of earlywood and latewood rays were 1.051 and 1.038, respectively. 4) In the process of moisture sorption cycle, the change ratio of three tissues dimension in both earlywood and latewood showed a significant swelling hysteresis, which increased first and then decreased with increasing RH, reached the maximum at 70% RH. 5) In the process of moisture adsorption-desorption, the dimensional change ratio of earlywood and latewood tissues“just reached the moisture content equilibrium state”was considered equivalent to the dimensional change ratio after“keeping the moisture content equilibrium state for 180 min”. Conclusion: The effect of lignin on absolute hysteresis was greater than that of hemicellulose. In the process of moisture adsorption, the swelling behavior of wood fiber tissue and wood rays compressed the vessel causing them to contrast, similarly, the vessel expanded due to the pull of wood fiber tissue and wood rays shrinkage during moisture desorption. The compressive and tensile forces exerted on the vessels by latewood tissue are greater than those exerted by earlywood tissue. Wood fiber tissue inhibited the swelling and shrinkage behavior of wood rays, with latewood wood fiber tissue inhibiting the tangential swelling and shrinkage behavior of wood rays more significantly than earlywood wood fiber tissue. The hygroscopic hysteresis behavior of wood is the one reason of the swelling hysteresis phenomenon. “EMC”and“the equilibrium of dimensional change”of the earlywood and latewood tissues were reached synchronously. It meant that there was not hysteresis between“dimensional change behavior”and“EMC”.

Objective: The lateral performance of cross-laminated timber (CLT) shear wall made of domestic fast-growing poplar wood （Populus spp.） was investigated under cyclic load. The effects of wood thermal pretreatment and wall accelerated weathering on the lateral performance of CLT shear wall were determined. The results might serve as a valuable reference for thermal modification and effective use of low-value fast-growing wood in buildings. Method: The CLT wall made of fast-growing poplar wood was taken as the research object, and its lateral performance was compared to that of commonly-used spruce (Picea abies) CLT wall in timber structures. According to previous studies, poplar wood was thermally treated at 180 ℃, and a total of five full-scaled CLT shear walls were prepared and tested in this study. The lateral performance tests of CLT shear walls with the absence and presence of accelerated weathering were performed under cyclic load. Result: The peak load, elastic lateral stiffness, and energy dissipation of the untreated poplar CLT shear wall under cyclic load decreased by 5.8%, 12.9% and 8.0%, respectively, as compared to those of spruce CLT shear wall with the same laminate strength class. The characteristics of lateral performance of poplar CLT shear walls reduced to varied degrees, after thermal pretreatment of wood, accelerated weathering treatment of walls, or a combination of the two treatments. Compared with the untreated poplar CLT walls, the ultimate bearing capacity, elastic lateral stiffness, and energy-consuming capacity of the CLT shear wall, after accelerated wall weathering treatment, reduced by 9.4%, 9.7%, and 11.2%, respectively; and the wood was treated with high temperature. After accelerated weathering, the ultimate bearing capacity, elastic lateral stiffness, and energy consumption capacity of the CLT shear wall changed less, decreasing by 2.9%, 2.4%, and 5.0%, respectively. Conclusion: The lateral performance of the fast-growing poplar CLT shear wall under cyclic load was slightly lower than that of the spruce CLT shear wall with the same laminate strength class. The poplar CLT shear wall failed in a manner similar to the spruce wall. The damage to spruce and poplar CLT walls under lateral load conditions was mostly caused by screw breakage. The failure mode of poplar CLT shear wall made of thermally-treated poplar was wood fracture or split at the connection, which was identical to the failure mode of the accelerated weathering CLT wall and accelerated weathering wall manufactured using heated wood. Thermal pretreatment of wood can reduce the influence of accelerated weathering on the lateral performance of shear walls, resulting in comparatively strong resilience to wall degradation. The theoretical lateral peak load of CLT shear walls was established, and the error between the theoretical and test value was less than 10%.

Objective: Agarwood extract is one of the main applications. According to the problem that there are significant differences in the demand for agarwood ingredients in different application fields, this work focused on the main components of agarwood by crude separation during the extraction process, and clarified the incense release behavior of different extracts, aiming to provide references for the directional and efficient utilization of agarwood in specific fields. Method: Taking the traditional agarwood (CX) and new variety Qinan agarwood (QN) as the research objects, three extracts of essential oil, extractum, and alcohol precipitation were obtained by the steam-solvent multi-stage extraction. The main chemical components of CX and QN’s multi-stage extracts were studied by gas chromatography-mass spectrometry (GC-MS) combined with high performance liquid chromatography (HPLC). Headspace-gas chromatography (HS-GC-MS) was used to analyze the aroma release rules of CX and QN’s multi-stage extracts at 40?160 ℃. Result: The crude separation of CX and QN sesquiterpenoids and chromones was achieved by the steam and solvent multi-stage extraction. There is little effect on the components of the essential oil obtained by distillation in water and out of water. The relative peak areas of sesquiterpenoids and other small molecules were ≥99%. After distillation, solvent extraction was carried out and the extractum mainly contained chromone, and the relative peak area was ≥90%. The alcohol precipitation method was suitable for CX extract extractum to effectively separate impurities. There were significant differences in the main components and aroma release components between CX and QN. The elemenol and α-santalol were the main component from CX and QN essential oil, respectively. Both of CX and QN had good aroma release ability at low temperatures. The main aroma releasing substances of CX and QN were eucalyptol and (1R,3aR,5aR,9aS)-1,4,4, 7-tetramethyl-1,2,3,3a,4,5a,8, 9-Octahydrocyclopenta [c]benzofuran at 40 ℃, respectively. The types of chromones in CX extractum were relatively richer. The chromone could be dissociated to form small molecule volatile substances at 160 ℃. Both of the number and intensity of CX’s pyrolysis products were significantly higher than those of QN. Conclusion: By multi-stage extraction method, agarwood essential oil rich in sesquiterpenoids, agarwood extract rich in chromones and alcohol precipitation with high impurities were obtained. Essential oil has a good aroma release ability at low temperature, which is suitable for the development of perfumes, daily chemicals and other room temperature fragrance release products. Extractum is suitable for high temperature incense release, and can be developed incense, burning incense and other products. QN extract mainly contains 2-(2-phenylethyl) chromone and 2-[2-(4-methoxyphenyl) ethyl] chromone, which can be used for monomer separation of the chromone. The active substance of agarwood in alcohol deposition is obviously reduced, and low value products can be developed.

Objective: In order to explore the effect of lignin on enzyme adsorption in substrate enzyme hydrolysis, using the proto lignin as material, isolated from different species of poplar, eucalyptus and acacia wood, and the adsorption behavior of cellulase on lignin films was studied by quartz crystal microbalance with dissipation (QCM-D) technology. Method: The structures of isolated lignins were characterized by 2D NMR. The lignin/cellulose biosensor was prepared by spin coating method and characterized by the surface morphology before and after enzyme adsorption, and the QCM-D technology was used to explore the influence of lignin with different structural unit on cellulase adsorption in situ and in real time. Result: Lignins from poplar, eucalyptus and acacia were GS lignin, and the main connection mode between structural units was β—O—4, and their S/G ratios were 1.09, 1.73 and 1.22, respectively. After the injection of the cellulase, the cellulase was evenly distributed on the surface of the lignin film, and they were bound tightly. The roughness of the lignin film of eucalyptus was higher than that of poplar and acacia at the end of injection. By QCM-D analysis, the poplar lignin film had minimal capacity to adsorb cellulase while eucalyptus lignin largest capacity. Conclusion: Different structural unit types in lignin structure also show different adsorption capacity to cellulase. The enzymatic hydrolysis process of composite film can be divided into four stages: adsorption, rapid hydrolysis, slow hydrolysis and hydrolysis equilibrium. Combined with the kinetic parameters of enzymatic hydrolysis, eucalyptus lignin with higher S/G ratio takes longer time to reach the maximum enzymatic hydrolysis conversion and lower hydrolysis degree.

Objective: Bending mechanical test and theoretical analysis of bamboo scrimber were carried out, as well as the suggestions on the characteristic values of bending strength and bending modulus of elasticity (MOE) of bamboo scrimber were put forward. The correlation was fitted to provide technical reference for engineering application. Method: The bending mechanical properties of 40 bamboo scrimber specimens were tested as referred to ASTM D143—14 and other specifications, and their mechanical properties were analyzed in combination with the mid-span displacement curve and the failure modes of each stage. Using statistical theory, the characteristic values of bending strength and bending MOE were obtained by using parametric method, non-parametric method and relevant standard calculation methods respectively. Result: According to the mid-span displacement curve of the specimens, the bending failure of bamboo scrimber occurs in three stages: at the initial stage, the deformation was linear with the load. With the increase of load, the stress of the outermost bamboo fiber in the tensile area reaches the maximum strength and fracture occurs, and the section stiffness decreases. At this time, the specimens are in the elastic-plastic stage. After continuous loading, the cracks developed along the longitudinal and neutral axis of the specimen, and finally the specimen failed after reaching the ultimate load, and no obvious damage was found in the compression area of the specimen. The characteristic values of bending strength calculated using the parametric method are all greater than those calculated using the non-parametric method, and the characteristic values of bending strength calculated using the normal and log-normal distributions are very close, and are all greater than those calculated using the Weibull distribution. For the bending MOE, the characteristic values calculated by the parametric, non-parametric method, and relevant standard are relatively close. Conclusion: From the perspective of accuracy, take the 5% percentile value of non-parametric calculation as the characteristic value of bending strength, and take the 5% percentile of parametric calculation value as the characteristic value of bending MOE. On this basis, the suggested values for bending strength corresponding to different levels of bending MOE of bamboo scrimber were proposed.

Objective: Hot-pressed peanut meal (HPM) and cold-pressed peanut meal (CPM) were used as raw materials to improve the bonding performance and water resistance through denaturation and crosslinking. Method: HPM and CPM protein-based adhesives were prepared by two-step method of urea (U) denaturation and polyamide polyamine epichlorohydrin (PAE) resin crosslinking, and their differences in bonding strength, viscosity, functional groups, thermal properties and micro morphology were compared. Result: Compared with the pure HPM adhesive and CPM adhesive, the dry shear strength of poplar plywood prepared by the denatured and crosslinked HPM and CPM adhesive was increased by 134.1% and 111.4% respectively. The wet shear strength reached the national class I poplar plywood standard and class II poplar plywood. After denaturation crosslinking, the viscosity was increased by 101.5% and 70.5%, the thermal decomposition temperature was increased to 316.44 ℃ and 307.57 ℃, respectively. And the adhesive prepared by HPM had the most compact surface. Conclusion: The adhesive prepared by HPM has better bonding strength and water resistance than CPM adhesive, and HPM is more suitable as adhesive raw material than CPM.

The earth critical zone (ECZ) is situated at the intersection of atmosphere, water, pedosphere, microsphere and lithosphere. Soil microbes play an important role in the carbon cycle processes of the ECZ. It is one of the current hotspots in key zone research to understand the structure and functions of the ECZ, and elucidate the carbon transformation process mediated by soil microorganisms in the key zone. On the basis of summarizing domestic and international progress, this review first introduces the structural connotation of the ECZ, and the characteristics of soil microbial structure and the research progress of the microbial-driven soil carbon cycle. Then it is pointed out that the current work is still limited to understanding the basic structure of the ECZ and describing the soil carbon storage characteristics. It is suggested to systematically explore the carbon cycling process from plant canopy to bedrock by the framework system of the ECZ. In the future, a variety of techniques and methods are integrated in the research, and the short-term and high-frequency observations and the long-term positioning observations are combined. An attention should be paid to the response and feedback mechanisms of soil organic carbon cycling to global changes and human activities at a long-term scale. Special attention should be paid to the microbial driving processes and the migration and transformation patterns of soil carbon within each sphere and at various interfaces of the ECZ. According to the background of time factors such as earth’s big data science project and global carbon emission pathways, we should carry out synchronous observation and systematic research on multi-interfaces, multi-processes and multi-time scales of atmosphere, vegetation, soil, microorganisms, bedrock, and groundwater, which would provide scientific basis for carbon cycle model optimization and climate change prediction, and also provide important theoretical reference for China’s terrestrial ecosystem to achieve the goal of carbon peaking and carbon neutrality.

Green plants absorb CO₂ from the atmosphere through photosynthesis, which is the main source of carbon (C) in terrestrial ecosystems. Quantifying the allocation of photosynthetic C between plants and soil systems is of great significance for clarifying the turnover and retention of C, and predicting the potential of vegetation and soil C pools in the context of climate change. The ¹³C stable isotope technology, with its accuracy and ease of operation, is widely used in C cycle research, and provides important technical support for exploring the characteristics of C allocation, soil microbial community structure, C utilization efficiency, and changes in CO₂ flux from soil C mineralization in plant soil systems. This article first introduces the development and labeling methods of ¹³C stable isotopes, mainly including ¹³C pulse (single and multiple) labeling, ¹³C continuous labeling, and how to determine of ¹³C abundance by planting C₃ plants in C₄ soil, and how to identify natural ¹³C abundance without changing vegetation conditions. Secondly, the application of this technology in C cycling in the plant microbial soil system is summarized, including the application of ¹³C isotope labeling in C allocation in the plant-soil system, the application of ¹³C natural abundance technology in tree growth rings and plant community level C cycling, and the formation and decomposition process of soil organic C. In terms of soil microorganisms, the application of ¹³C stable isotopes in microbial biomarkers such as phospholipid fatty acids, amino sugars, chip stable isotope probes, nano secondary ion mass spectrometry isotope imaging, fluorescence in situ hybridization nano secondary ion mass spectrometry technology is summarized. Then, the shortcomings of the ¹³C stable isotope method are summarized, namely, the high cost of ¹³C sample detection, inaccurate ¹³C abundance detection due to ¹³C fractionation, and high requirements for ¹³C abundance in combination with microbial marker technology. Finally, prospects for future research on ¹³C isotope tracing technology are proposed: in theory, it is necessary to explore the mechanisms of action and influence of ¹³C labeled substrates in C allocation, transformation, and fixation in the plant soil microbial system, and construct statistical and validation models; in terms of application, emphasis should be placed on interdisciplinary applications, combining geographic information systems, remote sensing and other geoscience technologies with ¹³C stable isotopes to promote research on the C cycle in terrestrial ecosystems from a broader and more comprehensive perspective.