With global climate change, traditional forest tree breeding means are facing challenges, and unable to meet the urgent demands for rapid climate adaptation and optimized resource allocation. The complex interaction between tree genotype (G) and environment (E) is central to tree growth and development research. It has become a crucial research question to elucidate the G×E interaction mechanisms to enhance breeding efficiency and precision. This review focuses on study progress of the genotype-environment interaction (G×E) algorithms in tree breeding. It analyzes the mechanisms by which genotype and environment interact to shape phenotypic traits, including the association between genomic and phenotypic characteristics, and the impact of environmental factors on phenotypic expression. Additionally, it explores the role of multi-source heterogeneous data integration in deciphering interaction mechanisms and breeding applications, covering data mining techniques, integration strategies, and real-time data processing. Furthermore, this paper elaborates on the evolution and application of G×E interaction algorithms in tree breeding, including the historical development and application in trait prediction and analysis. The review also introduces the framework for developing G×E interaction algorithms for tree breeding, encompassing data acquisition, integration, algorithm design, and model optimization. Finally, future research directions are proposed, emphasizing explainable artificial intelligence, data fusion, breeding validation, and climate adaptability prediction. These advancements aim to provide more precise predictive tools and decision support for tree breeding, ultimately enhancing the ecological adaptability and productivity of trees in the face of climate change.

Objective: A tree height sample set suitable for Grain for Green Project (GGP) stands was constructed, and the machine learning methods were integrated with remote sensing data to estimate tree height in GGP plots, in order to provide a reference basis for monitoring the effectiveness of the new round of GGP. Method: To accurately estimate the tree height of the new round of GGP stands in Inner Mongolia, this study proposed an optimized GEDI sample selection method, and constructed a high-quality tree height sample set suitable for the GGP stands in Inner Mongolia. With Sentinel-2 medium high spatial resolution remote sensing data and terrain data, the gradient boosting tree algorithm was applied to estimate the tree heights in the GGP stands, and analyze the tree height status in the GGP stands. Result: Based on the GEDI and Sentinel-2 machine learning model, the tree heights in the GGP stands were able to be accurately estimated with a coefficient of determination (R2) of 0.73, an estimation accuracy (EA) of 72%, and a root mean square error (RMSE) of 1.82 m. The optimized selection of GEDI samples improved the estimation accuracy for tree height in the GGP stands, with an increase in model estimation accuracy R2 by 0.32, a decrease in RMSE by 0.83 m, and an increase in EA by 13% compared to the unselected samples. The red-edge normalized vegetation index, difference vegetation index, and elevation, slope, and aspect variables are of high importance, with a cumulative contribution of over 50%, proving that vegetation indices and terrain information are key factors for tree height estimation. The distribution of tree height intervals in Inner Mongolia's GGP stands ranges from 2.5–20 m, with an average height of 5.5 m, mainly distributed in the 5–10 m range, which accounts for 53.51%. Conclusion: The GEDI sample optimization screening method proposed in this study can significantly improve the accuracy of tree height estimation in the GGP stands, demonstrating the effectiveness of tailoring the screening process to the specific characteristics of the GGP stands. Based on remote sensing data and machine learning, this study has achieved the estimation of tree height for the new round of GGP stands in Inner Mongolia, providing a feasible approach for tree height estimation in these regions.

Objective: The aim of this study was to investigate the changes of fuel loadings and its affecting factors of Pinus tabuliformis forest of different origins, so as to provide theoretical basis for effective management of forest fuel and prevention of forest fire. Method: The natural and planted P. tabuliformis forests of different forest districts in Shanxi Province were selected as the research objects. 53 sampling plots were set up in different forest stands with different canopy cover (0.2?0.9) and age to investigate the fuel loadings of tree layer, shrub layer, herb layer, litter layer and humus layer, and the altitude (701?1 739 m) of the plots and relevant stand factors were recorded. Firstly, the difference of various forest fuel loadings in different stand types were analyzed by multiple comparison method, and then the differences of fuel loadings at different age classes under different canopy cover were compared. Finally, the affecting factors of forest fuel loadings were determined by fitting linear regression models. Result: 1) The total fuel loadings of different stands of natural forest ranged from 44.2 to 182.18 t·hm^?2, and that of different stands of planted forest ranged from 19.28 to 214.06 t·hm^?2. 2) Multiple comparison results show that: in all kinds of natural forests of P. tabuliformis, the fuel load of the tree layer was the highest, followed by the humus layer. With the exception of the young forest with low canopy cover, other planted forests of P. tabuliformis also showed similar rules. 3) In natural forests, the fuel loads of tree layer, fine fuel and humus layer were significantly different under different canopy cover (P < 0.05), and the fuel loads in young forest was significantly different under different canopy density (P < 0.05). In planted forests, only the fuel load of the tree layer was significantly different under different canopy cover (P < 0.05), there was no significant difference in the fuel loads of other types of fuels (P > 0.05), and the fuel loads of young forest, near-mature forest, and mature forest were significantly different under different canopy cover (P < 0.05). 4) The linear regression results show that: the fuel load of natural forests of P. tabuliformis was negatively correlated to canopy cover (P < 0.05), but positively correlated to the altitude (P < 0.05) significantly. In addition, the fuel load of planted forests was positively correlated to tree height (P < 0.05) and stand density (P < 0.05) significantly. Conclusion: The variation characteristics of forest fuel loading and its influencing factors were different among P. tabuliformis forests of different origins (i.e., natural and planted forest), especially under different canopy cover conditions. Thus, it is necessary to formulate reasonable measures according to the nature of forest stand when regulating forest fuel, so as to effectively reduce forest fire risk.

Objective: Quantify the impacts of climate change and large-scale vegetation restoration on watershed hydrology, with the aim of achieving optimized allocation of forest and grass that balances water resource availability and ecological benefits in the watershed. Methods: Based on the semi-distributed hydrological model ( soil and water assessment tool, SWAT ) and scenario simulation, the impacts of climate change and vegetation restoration on hydrology were quantitatively evaluated in Qingshuihe watershed, a typical watershed of vegetation restoration in Haihe basin. Result: 1) From 1969 to 2015, the average annual precipitation in Qingshuihe watershed showed an insignificant decreasing trend ( P > 0.05 ), with a decrease of 1.70 mm every 10 years. The average annual air temperature showed a significantly increasing trend (P < 0.01 ), with an increase of 0.30 ℃ every 10 years. The annual potential evapotranspiration showed an insignificant increasing trend ( P > 0.05), with an increase of 7.30 mm every 10 years. The annual runoff depth showed a significant decreasing trend ( P < 0.01 ), with a decrease of 5.80 mm every 10 years. 2) Comparing landuse between 1985 and 2015, grassland to forest and cropland to grassland are the main types of vegetation restoration. 3) The calibrated SWAT model can better simulate the hydrological changes in Qingshuihe watershed. The Nash-Sutcliffe efficiency coefficients (NSE) are 0.69 and 0.77, coefficients of determination (R²) are 0.69 and 0.77, percentage bias (PBIAS) are –0.40% and –6.00%, and ratios of the root mean square error to the standard deviation (RSR) are 0.56 and 0.48 for the calibration period and validation period, respectively. 4) Compared with the base period (1984–1993), the surface runoff and lateral flow increased by 0.31 and 0.08 mm due to climate change, and decreased by 1.43 and 0.46 mm due to vegetation restoration in the scenario period (2006–2015). Climate change and vegetation restoration respectively decreased soil water content by 42.72% and 57.28%, while increasing actual evapotranspiration by 87.47% and 12.53%, respectively. 5) After grassland restoration, the actual annual evapotranspiration increased by 12.62 mm, the annual surface runoff, lateral flow and soil water content decreased by 6.47, 3.38 and 10.06 mm, respectively. After restoring cropland to grassland, the annual surface runoff decreased by 8.11 mm, and the actual annual evapotranspiration, lateral flow and soil water content increased by 7.27, 1.21 and 4.37 mm, respectively. Conclusion: Different hydrological parameters responded differently to climate change and vegetation restoration in Qingshuihe watershed. Vegetation restoration is the main driving factor for the reduction of surface runoff, lateral flow, and soil water content, and the main driving factor for the increase of actual evapotranspiration is climate change. The impacts of different vegetation restoration types on hydrology are significantly different. After the grassland was restored to forest, the water consumption increased, and more precipitation can be retained after restoring cropland to grassland. In regions with water scarcity, it is necessary to essential to carefully balance the hydrological regulation functions of different vegetation types to develop sustainable and adaptive watershed management strategies.

Objective: The aim of this study was to clarify the spatiotemporal variation characteristics of lightning in key forest areas across the country, in order to enhance the accuracy of predicting lightning-caused fires. Method: Based on the three-dimensional very low frequency/low frequency (VLF/LF) lightning monitoring data in 2023, this study analyzes the quantity, peak current intensity, cloud flash height and spatiotemporal distribution of lightning (intra-cloud lightning; cloud to ground lightning; positive lightning; negative lightning) in seven key forest areas in China, including the Liangshan forest area of Sichuan Province, Daxing?anling forest area in Heilongjiang, Daxing?anling forest area in Inner Mongolia, Saihanba forest area of Hebei Province, Altai forest area of Xinjiang, Beijing, and Fujian Wuyishan National Park. Result: 1) The Liangshan forest area of Sichuan Province experienced the highest frequency of lightning strikes, followed by the Daxing?anling forest area in Heilongjiang and Daxing?anling forest area in Inner Mongolia, with the Saihanba forest area of Hebei Province recording the lowest. The proportion of negative lightning was significantly higher than that of positive lightning in all regions. The total lightning density and cloud to ground lightning density in the liangshan forest area of Sichuan Province were the highest, reaching 9.12 and 5.03 times?km^?2a^?1, respectively, whereas the Altai forest area of Xinjiang had the lowest total lightning density and cloud to ground lightning density, with only 0.16 and 0.11 times?km^?2a^?1, respectively. 2) In Beijing, the Daxing?anling forest area in Heilongjiang, and the Daxing?anling forest area in Inner Mongolia, the distribution of current intensity for positive lightning was more concentrated, with the vast majority ranging from 0 and 40 kA, accounting for 93.91%, 91.50%, and 87.83% of the total lightning occurrences, respectively. In contrast, the other four regions were more widely distributed, particularly in Altai forest area of Xinjiang. 3) The intra-cloud lightning heights in the Daxing?anling forest area in Heilongjiang, the Daxing?anling forest area in Inner Mongolia, Beijing and the liangshan forest area of Sichuan Province were predominantly below 16 000 m. In contrast, the intra-cloud lightning heights in the Altai forest area of Xinjiang, the Saihanba forest area of Hebei Province and the Fujian Wuyishan National Park were predominantly below 22 000 m. The proportion of intra-cloud lightning at a height of 1 250 m was the highest across all forest regions. 4) The maximum number of lightning in different regions occured in various months. The Daxing?anling forest area in Heilongjiang, the Daxing?anling forest area in Inner Mongolia, Beijing and the Fujian Wuyishan National Park mainly occurred in July, the Altai forest area of Xinjiang and the Saihanba forest area of Hebei Province in August, and the Liangshan forest area of Sichuan Province peaked in September. The Daxing?anling forest area in Heilongjiang and the Daxing?anling forest area in Inner Mongolia experienced a longer period of high lightning activity within a day, with high numbers of lightning events from 12:00 and 19:00. In contrast, the Liangshan Forest Area in Sichuan showed a high concentration of lightning events from 15:00 to 24:00, indicating a greater frequency of nocturnal occurrences. Except for the Liangshan Forest Area in Sichuan, the daily distribution of lightning events in other forest regions exhibited a unimodal pattern, predominantly occurring during the daytime. 5) The lightning in the Daxing?anling forest area in Heilongjiang was mainly distributed in the northwest, central and southern parts. The lightning in the Daxing?anling forest area in Inner Mongolia was mainly concentrated in the north central areas between the Jinhe and the Khanma, as well as near the Ganhe. In Beijing, the lightning was concentrated in the Huairou District, Miyun District, Pinggu District, and Mentougou districts. In the Saihanba forest area of Hebei Province, lightning was concentrated in the area of Sandaohekou and Qaincengban. In the Liangshan forest area of Sichuan Province, lightning was mainly distributed in Yuexi County, Mianning County, and Xide County. In the Altay forest area of Xinjiang, lightning was mainly concentrated in the west of Habahe, the northwest of Burqin, and the Altay. In the Fujian Wuyishan National Park, lightning was concentrated in the southeastern and central south general control areas, as well as the southwestern core protected areas. Conclusion: Lightning occurrence in China exhibited significant spatiotemporal heterogeneity. Based on the impact of lightning on the occurrence of lightning-caused fires, more attention should be paid to lightning activities in mountainous areas from July to September. Particularly in the monitoring and early warning process of lightning-caused fire, emphasis should be placed on nocturnal lightning-caused fire events in the Sichuan area.

Objective: The objective of this study is to explore the main influencing factors of forest fires in Gansu Province and the geographical division of forest fire risk in the Province. Method: Based on the historical fire data of Gansu Province from 2000 to 2021, ArcGIS 10.8 was used to extract the spatial information of topography, meteorology, vegetation, human activities, and socio-economic factors, and the Logistic regression model was used to determine the main driving factors of forest fires in Gansu Province. The standardized regression coefficient was used to test the relative importance of each driving factor to the occurrence of forest fires, and the ROC curve was used to test the fitting effect of the model. According to the prediction results of the model, the probability of forest fire occurrence was classified into hierarchical regions. Result: 1) The spatial logistic forest fire risk model established was well fitted. The AUC value of the five training samples was all greater than 0.970, and the prediction accuracy was between 89.6%?90.6%, and the AUC value of the whole sample was 0.972, and the prediction accuracy was 89.1%, indicating that the model was suitable for the predicting of forest fire occurrence in Gansu Province. 2) Elevation, slope, mean monthly temperature, vegetation coverage, and distance to the railway were positively correlated with the probability of forest fires, while mean monthly precipitation, distance to the highway, and distance to the settlement were negatively correlated with the probability of forest fires. 3) According to the standardized regression coefficients, the importance of each driving factor to the occurrence of forest fires in Gansu Province was ranked as follows: vegetation coverage (15.31) > mean monthly temperature (1.647) > slope (1.055) > distance to the railway (1.015) > elevation (1.007) > distance to the highway (0.985) > distance to the settlement (0.852) > mean monthly precipitation (0.808). 4) According to the probability of forest fires, the forest fire risk in Gansu Province was divided into five levels at equal intervals: very low fire danger area (0?0.2), low fire danger area (0.2?0.4), medium fire danger area (0.4?0.6), high fire danger area (0.6?0.8), and very high fire danger area (0.8?1), and the corresponding forest areas were 462 640, 850 160, 1 611 551, 1 715 681 and 705 050 hm², respectively. Conclusion: Vegetation coverage, mean monthly temperature, slope, distance to the railway, elevation, distance to the highway, distance to the settlement, and mean monthly precipitation are the main driving factors of forest fire occurrence in Gansu Province. The probability of forest fire occurrence is generally high in the southeast and low in the northwest, among which the extremely high fire danger areas are mainly distributed in Gannan Tibetan Autonomous Prefecture, Linxia Hui Autonomous Prefecture, Lanzhou and some areas of Longnan, and the high fire danger areas are mainly distributed in the southeast of Longnan and Tianshui, the western part of Pingliang, Lanzhou and some areas of Linxia Hui Autonomous Prefecture.

Objective: To explore the spatial distribution pattern and correlation of dominant species at different height levels in the mid-mountain evergreen broad-leaved forest of Baishanzu National Park, so as to understand the survival strategies and competition mechanisms of each level in the vertical structure of the community, and to deepen the understanding of the construction and diversity maintenance mechanisms of the regional community. Method: Based on the survey data of 1 hm² monitoring plot of mid-mountain evergreen broad-leaved forest community in Baishanzu National Park, analyze the individuals of the top three dominant species in terms of importance value at each high level by tree height division. The pair correlation function g(r) and the marked correlation function k_mm(r) based on diameter at breast height were used to analyze the spatial distribution pattern of dominant species at each height level and the correlation between the layers. Spearman rank correlation coefficient was used to analyze the correlation between population number distribution and topographic factors at each level. Result: The dominant species in the community are affected by environmental factors, and their individual number distribution is positively correlated with topographic factors; the spatial distribution pattern of dominant species in each level of the community showed a trend of changing from low-scale aggregation to high-scale random or uniform distribution, and after removing the influence of habitat heterogeneity, the scale range of aggregation distribution was reduced; the upper layer dominant species showed low-scale negative correlation with those in the intermediate and lower layers; in the marked point pattern analysis based on the diameter at breast height, there was some negative correlation among individuals within and between the intermediate and lower layers at the low scale. Conclusion: The dominant species of mid-mountain evergreen broad-leaved forest community in Baishanzu National Park exhibit a spatial pattern of aggregation at a low scale and random or uniform distribution at a high scale. The upper layer restricted the growth and development of individuals in the intermediate and lower layers at close distance, and there was resource competition between individuals in the intermediate and lower layers at low scale.

Objective: To analyze whether there are differences in the maximum light use efficiency (ε₀ ), a key parameter in the vegetation photosynthesis model (VPM), in forest ecosystems of different climatic zones and the main reasons for such differences, and to select a parameterization scheme for the maximum light use efficiency that has general applicability. In order to deepen the knowledge of uncertainty in the process of estimating vegetation productivity in forest ecosystems and to provide a reference for improving model simulation accuracy and reducing the uncertainty of model parameters. Method: The maximum light use efficiency (ε₀ ) was estimated using the four selected parameterization schemes, BPLUT look-up table method, Michealis-Menten light response curve equation fitting, maxmiun enhanced vegetation index (EVImax) of the growing season exponential fitting, and Mointeith equation estimation method. Simulation of gross primary productivity (GPP) of four forest ecosystems in China based on the estimation results of the four parameterization schemes, comparison with eddy covariance observed GPP, and evaluation of VPM simulation results by combining various model evaluation indexes (coefficient of determination R², root mean square error RMSE, the Willmott’s index of agreement d and mean relative error MRE). Result: The ε₀ values were （0.65±0.14g）, （0.47±0.10）, （0.44±0.09), and (0.69±0.12) g·mol, respectively for the Changbaishan, Qianyanzhou, Dinghushan, and Xishuangbanna. On the seasonal scale, compared with the GPP based on observation, root mean square error(RMSE) of GPP simulated by the optimal parameterization scheme for ε₀ is reduced by 55.1%(Changbaishan), 38.1%(Qianyanzhou), 48.6%(Dinghushan), and 34.3%(Xishuangbanna), respectively, than that simulated by the least applicable parameterization scheme. On the inter-annual scale, the mean relative errors (MRE) of the GPP simulated by the optimal parameterization scheme were ?7.9%, ?24.3%, ?7.4%, and ?3.0% respectively at Changbaishan, Qianyanzhou, Dinghushan, and Xishuangbanna, which were lower than that (Changbaishan: 35.8%; Qianyanzhou: ?53.4%; Dinghushan: 29.8%; Xishuangbanna: 25.4%) simulated by the least applicable parameterization scheme. Conclusion: The ε₀ values of different parameterization schemes at the same site vary greatly, and there are differences in the ε₀ values between different sites under the same parameterization scheme. The main reasons for such differences are related to the structural properties of the parameterization schemes and the differences in hydrothermal conditions in different regions. Mointeith equation estimation method was the optimal parameterization scheme for ε₀ in the Changbaishan, Qianyanzhou, and Dinghushan, and Maxmiun enhanced vegetation index (EVImax) of the growing season exponential fitting is the most applicable in the Xishuangbanna.

Objective: This study aims to investigate dynamic features of root phenotypes and photosynthetic characteristics of Corylus heterophylla × C. avellana cuttings at different growth stages. A model representing the relationship between root growth and photosynthetic indices was established and used to simulate root growth conditions of cuttings, so as to lay the foundation for future exploration of the response of mature root growth indicators to photosynthetic indicators. Method: Photosynthetic indices (net photosynthetic rate, transpiration rate, intercellular CO₂ concentration and stomatal conductance) of one-year-old C. heterophylla × C. avellana cuttings were measured at different growth periods (rooting, early growth, intermediate growth, and vigorous growth periods). A root scanner was used to scan the complete root system and determine root growth indicators such as total root length, total surface area, average root diameter, total root volume, and number of root tips. A quadratic polynomial stepwise regression method was used to construct a root growth and development evaluation model based on photosynthetic indices to clarify the relationship between photosynthetic indicators and root growth indicators. Result: 1) There were significant differences in various root growth indicators at the different growth stages. The total root length, total surface area, and total root volume during the vigorous root period were effective indices of root growth conditions and exceeded those during the rooting period by factors of 3.6, 2.8, and 2.0, respectively. 2) The maximum number of root tips occurred during the intermediate growth period and exceeded those during the rooting and vigorous growth periods by factors of 8.9 and 2, respectively. These results suggest that number of root tips is an effective index of root activity. 3) There were significant differences in photosynthetic indicators such as net photosynthetic rate, transpiration rate among the different root growth periods of the cuttings. The net photosynthetic rate and transpiration rate during rooting period exceeded those during the vigorous growth period by factors of 1.8 and 4.3, respectively. The intercellular CO₂ concentration increased with growth, and that during the vigorous growth exceeded that during the rooting period by a factor of 1.3. The stomatal conductance increased and then decreased with progressive growth periods, reaching a peak in the intermediate growth period when it exceeded that during the rooting period by a factor of 2.4, following which it decreased sharply by 75% in the vigorous growth period. 4) The total root volume, total root length, and total surface area of cuttings were positively correlated with intercellular CO₂ concentration and stomatal conductance. The net photosynthetic rate and transpiration rate were positively correlated with average root diameter, and the number of root tips was positively correlated with stomatal conductance. 5) The performance indices (R²=0.75; mean squared error MSE=0.12) confirmed the excellent performance of the proposed photosynthetic indices-based model for evaluating root growth and development. Conclusion: Root system growth indicators and photosynthetic indicators show significant differences at different growth periods. Overall, the proposed model based on photosynthetic indicators serves as a feasible and effective approach for non-destructive evaluation of root growth and development of cuttings of C. heterophylla × C. avellana. It can also lay the foundation for exploring the response of root growth indicators of mature trees to photosynthetic indicators.

Objective: This study aims to quantitatively study the transpiration of Larix gmelinii var. principis-rupprechtii plantations on different slope aspects in response of meteorological conditions, soil moisture, and forest canopy structure in the semi-arid area of Liupan Mountains in Ningxia, which is an important water source area on the Loess Plateau of China, so as to provide a theoretical basis for the integrated forest-water management in this region. Method: From May to October 2023, a fixed plot of 20 m×20 m of L. gmelinii var. principis-rupprechtii plantation was set in the middle of typical slopes with different slope aspects (northwest slope NW50°, north slope N0° and northeast slope NE30°) in the small watershed of Diediegou. The sap flow density, meteorological parameters (represented by potential evapotranspiration , PET), and the soil water content of 0–60 cm soil layer (represented by the relatively extractable soil water , REW) were monitored continuously, and the canopy leaf area index (LAI) was regularly measured, to analyze the response of stand transpiration to PET, REW, and LAI. Result: 1) During the growing season (May to October) in 2023, the average daily transpiration of the stand on the north slope was the highest (0.93 mm·d^?1), which was 0.34 and 0.2 mm·d^?1 higher than that on the northwest slope (0.59 mm·d^?1) and on the northeast slope (0.73 mm·d^?1), respectively. During the soil drought period (REW < 0.45), the stand transpiration rates on different slopes were close with each other and showed no significantly difference (P>0.05). 2) The daily stand transpiration rapidly increased first and then slowed down and gradually stabilized with rising REW and LAI, with an exponential function, while the daily transpiration rapidly increased first and then slowly increased and then decreased slightly after a certain peak with rising PET, with a binomial function. 3) The response of daily transpiration to PET was significantly stronger during non-drought periods (REW > 0.45) than that during drought periods (REW < 0.45), showing that the increasing rate of transpiration with rising PET was greater during the non-drought periods than that during the drought period, and the increasing transpiration rate on the shady slope was significantly higher than that on the half-shady slopes. During the drought period, the stand transpiration was limited by soil moisture, showing that the transpiration increased rapidly with rising REW, and the increasing rate of transpiration on the half-shady slope was significantly higher than that on the shady slope, indicating that the response of transpiration on half-shady slopes to soil drought was more sensitive than that on the shady slope. Based on the analysis of contribution ratios of various individual factors to the deviation degree of stand transpiration from the average state of the growing season, it was found that REW was the dominant factor causing the transpiration difference during the drought period, with an average contribution ratio of 10.21%, and the most obvious limitation effect on the half-shady slope (11.8%). During the non-drought periods, LAI was the dominant factor causing the transpiration difference, and the limitation effect by LAI became weaker as the slope aspect deviated more from the due north. Conclusion: During the continuous soil drought period, the transpiration of L. gmelinii var. principis-rupprechtii plantations is significantly limited by soil drought stress, and the soil drought limitation is lower on shady slope with relatively good soil moisture than that on semi-shady slope. Considering the more frequent and severe drought events in future, site-specific forest management should be carried out according to slope aspects. The result of this study can provide a theoretical basis for developing an integrated forest-water management planning with climate change adaptability.

Objective: In this study, the responses of vegetation productivity and carbon use efficiency of different forest ecosystems to climate factors were investigated, which is of great significance for revealing the changes of carbon balance in terrestrial ecosystem and providing scientific basis for the protection and management of subtropical forest ecosystems. Method: Four typical forests, namely evergreen coniferous forest, evergreen broadleaf forest, evergreen conifer-broadleaf mixed forest, and bamboo forest, in the Ganjiang River Basin were targeted. The parameters localized Biome BGC model was used to simulate the gross primary productivity (GPP) and net primary productivity (NPP) from 1970 to 2021, revealing the response of productivity and carbon use efficiency of the four typical forest vegetation to climate factors at interannual and inter-monthly scales. Result: 1) The annual GPP (g·m^–2a^–1) was ranked as evergreen coniferous forest (2 514.6) > evergreen broadleaf forest (2 467.9) > evergreen conifer-broadleaf mixed forest (2 285.0) > bamboo forest (2 040.1). At the interannual scale, bamboo forest GPP was positively correlated with accumulated temperature (r = 0.41, P<0.01). At the inter-monthly scale, the GPP of the four typical forests was positively driven by accumulated temperature (r > 0.99, P<0.01). 2) The annual NPP (g·m^–2a^–1) was ranked as evergreen broadleaf forest (862.4) > bamboo forest (739.2) > evergreen conifer-broadleaf mixed forest (721.1) > evergreen coniferous forest (681.3). At the interannual scale, the NPP of evergreen coniferous forest, evergreen broadleaf forest and evergreen conifer-broadleaf mixed forest was positively driven by precipitation (r > 0.32, P<0.05). At the inter-monthly scale, there was a significant positive correlation between the NPP of evergreen coniferous forest and precipitation (r = 0.59, P<0.05). The NPP of evergreen broadleaf forest was mainly driven by accumulated temperature (r = 0.93, P<0.01). 3) The order of carbon use efficiency at the interannual and inter-monthly scales was sorted as bamboo forest > evergreen broadleaf forest > evergreen conifer-broadleaf mixed forest > evergreen coniferous forest. Compared to NPP, the carbon use efficiency had stronger response to climate change. The carbon use efficiency was negatively driven by accumulated temperature at both interannual and inter-monthly scales (r > 0.51, P<0.01). Conclusion: In summary, accumulated temperature is the main factor driving the productivity and carbon use efficiency of subtropical forest ecosystems. Compared to evergreen coniferous forest and evergreen conifer-broadleaf mixed forest, evergreen broadleaf forest and bamboo forest have stronger carbon sequestration capacity and greater carbon sink potential under the background of climate change.

Objective: This study aims to analyze the dynamic changes of morphological structure and physiological characteristics of Cinnamomum migao seed embryos during germination to reveal the mechanism of natural regeneration barrier, so as to provide a theoretical basis and technical support for the breeding and application. Method: In this study, the naturally germinating C. migao seeds were used as test materials. The morphological changes of embryo and microscopic changes of cotyledon cells, and physiological changes such as the contents of endogenous hormones and storage substances, and antioxidant enzyme activities in C. migao seeds at four different germination stages of dry seed (GZ, seeds without absorbing water), imbibed seed (XS, absorb water to full imbibition), fissure seed (LK, seed coat fissure after imbibition), and germinated seed (MF, radicle protruding the seed coat after imbibition). Result: At the dry seed stage, there were abundant oil bodies in the cotyledon cells of C. migao seeds. The oil bodies began to be consumed at the stage of XS, decreased significantly at the stage of MF, and subsequently, the oil structure disappeared. With seed germination, starch and lipid gradually degraded to supply energy. There was no significant difference in starch content between the stage XS and stage GZ. The starch content decreased significantly in the stage LK and stage MF, while the fat content decreased rapidly after the seed water absorption stage. On the contrary, the soluble protein content and POD activity significantly increased, while the soluble sugar content first decreased and then increased during the germination process of seeds. MDA content and SOD activity first increased and then decreased, reaching a peak at the stage LK, while CAT activity maintained a stable status after a sharp increase at stage XS. ABA and JA contents showed a decreasing trend, and IAA、GA₃、CTK and BR contents showed an increasing trend during the germination process. At the same time, the ratios of ABA/GA₃ and ABA/IAA significantly decreased, while ETH and SA contents increased significantly at stage LK. From stage GZ to stage MF, starch content was highly significantly negatively correlated with soluble sugar content, and highly significantly positively correlated with fat content. The content of soluble protein was highly significantly positively correlated with the activities of SOD and POD, and significantly positively correlated with CAT activity. ABA content was highly significantly negatively correlated with GA₃, IAA, CTK and BR content, significantly negatively correlated with ETH content, but significantly positively correlated with JA content. Conclusion: Starch and lipid are important storage substances which provide essential material and energy during the germination of C. migao. CAT and SOD play a key role in balancing MDA contents, while POD significantly promotes seed germination. The growth of radicle, hypocotyl and germ is mainly affected by endogenous hormones ETH and SA. The increase of GA₃ content and the decrease of ABA content are the critical to promote the germination of C. migao seeds.

Objective: Pinus massoniana is an important afforestation tree species in southern China. Asexual rapid propagation technology is one of the effective ways to solve the problem of high genetic differentiation and low stand productivity of forest trees. Adventitious root induction is the key technical bottleneck to cultivating asexual seedlings of P. massoniana. Endogenous gibberellins (GAs) have dual effects in the formation of adventitious roots of P. massoniana. High levels of GAs are not conducive to the rooting of P. massoniana. In this study, the metabolism of endogenous GAs in the rooting process of P. massoniana under the treatment of GAs biosynthesis inhibitors such as paclobutrazol (PBZ) and mepiquat chloride (DPC) was investigated, in order to reveal the rooting-active GAs and the mechanism, and to provide reference for improving the effectiveness of cultivating asexual seedlings of P. massoniana. Method: An elite tree, GLM-3, selected from over 15-year-old P. massoniana var. ‘Tongmiansong’ stand was used as the propagation object, and the rejuvenated branches obtained by micro-continuous grafting technology were used as the experimental materials. Cutting propagation under the conditions of 200 mg·L^?1 NAA (control), 200 mg·L^?1 NAA+100 mg·L^?1 PBZ (PBZ), and 200 mg·L^?1 NAA+100 mg·L^?1 DPC (DPC) treatment was carried out respectively. Liquid chromatography-tandem quadrupole mass spectrometry (LC-MS/MS) technology was used to detect the variation characteristics of GAs at 0 (rooting initial stage), 10 (root formation stage), 20 (root development stage) and 35 days (root formation stage). With 200 mg·L^?1 NAA as the control, the effects of rooting-active GAs in 200 mg·L^?1 NAA+100 mg·L^?1 GA₃ (GA₃) and 200 mg·L^?1 NAA+100 mg·L^?1 GA₄ (GA₄) on rooting ability, endogenous IAA level, rhizome anatomical structure and small molecules of lignin pathway were analyzed. Result: 1) Both PBZ and DPC were able to improve the rooting ability of P. massoniana, but the rooting time and rooting rate were different under the treatment of the two GAs inhibitors. Compared to the control, the rooting time under PBZ treatment was shorter, while the rooting rate under DPC treatment was higher, but there were not significant differences in root number and survival rate between the treatments and the control (P>0.05), with the overall at a low level. At 10 days of cutting, PBZ/DPC reduced the GA₃ level in the cuttings, while at 20 days of cutting, the GA₄ level under PBZ treatment was significantly increased. 2) GA₃ and GA₄ had inhibitory effect on rooting of cuttings, and the rooting rate, root number and survival rate were significantly lower than those of the control (P<0.05). The endogenous IAA content was lower than that of the control at 10–35 days under GA₃ treatment, but there was no significant difference in IAA content between the GA₄ treatment and the control at 20–35 days (P>0.05). Under GA₄ treatment, the suberization was aggravated, the suberin was increased, the level of small molecule caffeol in lignin was decreased, and the levels of caffeic acid and ferulic acid were both increased in the root and stem tissues of cuttings at 20–35 days of cutting. Conclusion: In the process of P. massoniana cutting, different inhibitors of GAs synthesis have different root-promoting effects and mechanisms. The root-inducing effect of PBZ is stronger than that of DPC, but the rooting stability is less than that of DPC. Both PBZ and DPC lead to a decrease in GA₃ level that inhibites IAA level during adventitious root formation. However PBZ causes an increase in GA₄ level that can induce increased cell suberization during adventitious root development. This study reveals that GA₃ and GA₄ are related to the difficulty of adventitious root formation in P. massoniana.

Objective: The development of bamboo culm has always been a research hotspot. This study aims to reveal the physiological mechanism of culm lodging, by exploring the dynamic changes in the morphological, anatomical, and cell wall composition characteristics of the culm of the somatic clone variant strain of Pseudosasa japonica f. akebonosuji. Method: The dwarf and lodging mutant (DWF) of P. japonica f. akebonosuji with somaclonal variation was used as the research object, and the normal tissue-cultured P. japonica f. akebonosuji (WT) served as the control. After 90, 180, 270, and 360 days of transplanting, the phenotype, cross-sectional anatomical structure, and changes in cell wall component content of the newly-grown bamboo culm were investigated. Result: There were significant differences in culm morphology, anatomical structure, and cell wall component content between DWF and WT at different transplanting stages. 1) Compared to WT, DWF culms experienced varying degrees of lodging during all four transplanting periods. At 90 days after transplanting, the angle between the stem and the ground was 35.27°, indicating the greatest degree of culm lodging. At 360 days after transplanting, the angle between the culm and the ground was 73.13°, indicating the least degree of culm lodging. 2) The stem diameter, stem height, and basal internode length of DWF were extremely significantly lower than those of WT, with the largest difference occurring at 360 days after transplanting. DWF grew slowly, and the height increase of new culms from 270 to 360 days after transplanting was only 21.41% of that of WT, and the diameter increase of new culms was only 17.49% of that of WT. 3) The number and area of vascular bundles in DWF were significantly lower than those in WT. At 360 days after transplanting, the number and area of large vascular bundles in DWF were 65.71% and 55.35% lower than those in WT, respectively, while the number and area of small vascular bundles were 75.44% and 55.51% lower than those in WT, respectively. When the number and area of vascular bundles of the new culms of WT increased rapidly, the increase in DWF was slow. The thickness of the DWF sclerenchyma decreased, and there were significant differences in sclerenchyma thickness between WT and DWF in all four periods, with DWF being 50.21%, 55.77%, 54.59%, and 45.41% smaller than WT, respectively. The development of the DWF pith cavity was slow, and the pith cavity appeared at 270 days and 360 days after transplanting, with a significantly smaller diameter than that of WT. 4) With the extension of transplanting time, though the lignin and cellulose content of the new culms of DWF increased, their content in DWF was significantly lower than that in WT. The degree of lignin and cellulose deposition in the internodes was also lower than that of WT, however there was no significant difference in hemicellulose content between WT and DWF. 5) There was a significant negative correlation between the degree of DWF stem lodging and its stem diameter, and there were highly significantly negative correlations between the degree of DWF stem lodging and the number and area of large and small vascular bundles, the thickness of sclerenchyma, as well as the content of lignin and cellulose. Conclusion: Compared to WT, DWF shows stunted growth and dwarfism in the development process, with weak culm strength and lodging. DWF stem diameter is smaller, the number and area of large and small vascular bundles are smaller, and the thickness of the sclerenchyma is also smaller, which all are the reason for its lodging. The low content of lignin and cellulose in the cell wall of DWF results in weak stem strength, which is another reason for its lodging.

Objective: The aim of this study was to understand the prevelance and incidence of Juglans leaf necrosis (JLN) in Xinjiang, investigate the disease dynamics and its correlation with phyllosphere microbiome and mineral elements, and determine the key precipitating factors of JLN in walnut in Xinjiang, which could provide information for its monitoring, forecasting, and prevention. Method: We selected 291 walnut orchards from 17 counties in the main planting areas of walnut in South of Xinjiang. Conducted on-site investigations on the current situationof JLN. The disease rating scale of the leaf necrosis was established based on severity. The structure and composition of microbial communities inhabiting the phyllosphere, root endosphere and rhizosphere soil of healthy walnuts and the ones suffered from leaf necrosis were analyzed, and the pathogenicity of walnut-associated fungi was performed. Linear regression analysis was used to reveal the correlation between the content of mineral elements in leaves and the severity of leaf necrosis. Result: The results showed that the JLN occurred approximately in the stop-growing period of the new shoots and reached the peak before the germination of the secondary shoots, where the leaf margins or tips initially appeared withered and yellow (or necrosis). This symptom then gradually spread towards the leaf core. Leaves with mild necrosis showed, the symptom manifested as the scorch of leaf edge or tip, while on the leaves of severe necrosis, the whole leaf was scorched and the plant was damaged heavily. No wilted leaves can be observed before occurrence of leaf necrosis, while fallen leaves were rarely detected after the symptom showed up. Juglans leaf necrosis had no obvious disease center or infectivity. The symptom can be rated on a five-level scale based on the incidence and severity. The results of microbiome analysis showed that Halomonas, Pseudomonas and Haliangium were significantly enriched that could tolerate high salt stress in the phyllosphere, root and rhizosphere soils with pyrophyllosis. Leaf fungi, including Alternaria, Colletotrichum and those belonging to Didymellaceae were significantly enriched in the phyllosphere. The results of leaf pathogenicity detection showed that these three types of leaf fungi were not the key biological factors causing leaf necrosis. The contents of O₂^? and H₂O₂ in the leaves of walnut suffered from leaf necrosis were significantly increased, furthermore, the quantities of Cl^?, Na and B elements in the diseased leaves rose significantly with the increasement of severity of leaf necrosis, but the contents of N, K and Fe elements in these leaves were remarkably decreased. Conclusion: Bacterial communities tolerant to high salt stress were significantly enriched in the phyllosphere, root and rhizosphere soil where leaf necrosis occurred. Pathogenic fungi were not the main biological factors causing scorchleaf disease. We speculate that toxicity of Cl^?, Na, B and insufficient of N, K, Fe in leaves might be the key cause of the Juglans leaf necrosis. Our results demonstrated that Juglans leaf necrosis may be a physiological disease caused by abiotic factors.

Objective: A three-dimensional grid format sequential dissection method is proposed to improve common defects of existing wood-based reconstituted materials such as wood-based panels. This method offers a new theoretical approach for wood processing and unit preparation in engineered wood and provides a foundational raw material for the development of novel wood-based reconstituted materials. Method: Based on the main characteristics of wood microscopic structure, a technical approach is established involving the setup of a three-dimensional grid of logs, followed by longitudinal scoring and slicing. This process, combined with the design of composite tool structures and the functional roles of various tool components, explains the forming process of wood rod lumber units. Taking small-diameter wood as the research object, a three-dimensional rectangular coordinate system in a stereoscopic grid is established for the wood. The main cutting motion of the tool and the feeding motion of the wood segments are designed accordingly; combined with the division of the small-diameter wood processing area and the layout of the combined cutting tools on the transfer chain and the corresponding allocation of the small-diameter wood processing area, a new method for preparing wood-based panel units is proposed, namely the three-dimensional grid format sequential dissection method. The relationship between the cutting tool and the wood in the three aspects of speed, time and distance in the three-dimensional grid format sequential dissection method is analyzed, and the speed relationship formula for the main cutting motion and the feed motion is derived. Based on the three-dimensional grid format sequential dissection method, an experimental machine for processing wood rod lumber units is developed and processing experiments are conducted for verification. Result: The relationship between the speed of the main motion and the feed motion is v=[(N×H)/S]×V (where N is the number of combined cutting tools in each processing area and S is the circumference of the transmission chain); The main motion speed is V=2.49 m·s^?1, and the feed motion speed is v=0.0053 m·s^?1 or 0.0057 m·s^?1, successfully achieving continuous automatic processing and forming of wood rod units. The produced wood rod units are non adhesive, undamaged, and have the same shape, with dimensions of length (L) ×width (B)×height (H) = 90.0 mm×1.5 mm×(1.1?1.5) mm. Conclusion: 1) A novel method for preparing engineered wood units, namely the three-dimensional grid format sequential dissection method, is originally proposed, demonstrating technical feasibility. 2) The speed relationship formula for the main cutting motion and feed motion is given by v=[(N×H)/S]×V. This formula provides a theoretical basis for calculating the relevant motion parameters in unit processing experiments and for selecting equipment for unit preparation. 3) The validity of the speed relationship formula for the main cutting motion and feed motion is confirmed. The height (or thickness) (H) of the wood rod lumber units depends on the transmission system of the main and feed motions and their speed ratios. The length (L) of wood rod lumber units is equal to the length of the log segment, and the width (B) is determined by the combined cutting tools.

Objective: This study aims to explore the enhancement mechanism of the interface modified by biomimetic mineralization of nano-SiO₂ and dopamine/polyethylenimine, so as to provide a basis for the modification of bamboo fiber by biomimetic mineralization of nano-SiO₂ and improve the interface compatibility of bamboo plastic composites. Method: Using polylactic acid resin as matrix and bamboo fiber as reinforcement material, functional coating was constructed on the surface of bamboo fiber by dopamine-polyethylenimine hybrid polymerization, and nano SiO₂ was prepared by“sol-gel”. Through electrostatic interaction, nano SiO₂ was induced to accumulate and grow on the surface of bamboo fiber, and then to improve the interface properties. Fourier infrared spectroscopy, X-ray photoelectron spectroscopy and X-ray diffraction were used to analyze the changes of fiber surface elements and fiber crystal structure after modification. The mechanism of bionic mineralization modification of nano-SiO₂ to improve the interface compatibility of bamboo plastic composite was comprehensively discussed through mechanical property testing and analysis, thermogravimetric analysis, scanning electron microscopy and dynamic thermomechanical property analysis. Result: The nano-SiO₂ was attached to the fiber surface, and the content of Si element on the surface of bamboo fiber was significantly increased, and the modification did not cause the change of fiber crystal structure. The test of mechanical properties showed that the bending strength, tensile strength and impact strength of the composite modified by nano-SiO₂ bionic mineralization are increased by 18.99%, 15.91% and 34.34%, respectively. SEM analysis showed that the fiber pulling out at the interface of the modified composite was reduced, the fiber surface was coarser, and the interface bond between the fiber and the matrix was closer. The thermogravimetric analysis showed that the introduction of nano-SiO₂ improved the thermal stability of the composite, and the thermal degradation temperature of the fiber moved to the high temperature region, and the initial degradation temperature and maximum thermal degradation rate temperature of the composite increased by 22.81 ℃ and 11.54 ℃, respectively. The results of differential scanning calorimetry showed that the interaction between the modified fiber and the matrix increases the molecular movement resistance of polylactic acid, decreased the crystallinity of the composite and increased the melting temperature of the composite. The dynamic thermal mechanical properties analysis shows that the energy storage modulus of the modified composite increased and the loss modulus decreased, which indicated that the internal defects of the composite are reduced and the interface properties of the composite are improved. Conclusion: The biomimetic mineralization modification of nano-SiO₂ formed an organic-inorganic hybrid modified network of SiO₂ on the surface of bamboo fiber, which enhanced the mechanical anchoring and chemical bonding cooperation between fiber and matrix, improved the interface bonding force between fiber and matrix, improves the interface performance of the composites, and thus enhanced the interface compatibility.

Objective: Based on the logic of the formation of new quality productive forces in forestry, this study constructs an evaluation system for China’s forestry new quality productive forces and captures the spatiotemporal evolution process. It explores how to alleviate the main constraints currently faced by the development of forestry new quality productive forces, providing a reference and decision-making basis for the targeted development of China’s forestry new quality productive forces. Method: First, based on panel data from 31 provinces (municipalities and autonomous regions) in China from 2012 to 2020, the entropy weighting method was applied to assign weights to tertiary indicators, calculating the comprehensive and dimensional development levels of new quality productivity in forestry across regions. Second, kernel density estimation was used to capture the temporal and spatial evolution characteristics of forestry productivity at the national and regional levels. Third, the Dagum Gini coefficient method was employed to calculate and decompose regional disparities in forestry productivity and assess spatial autocorrelation among provinces using Moran’s I. Lastly, obstacle factor identification was utilized to pinpoint the top three factors hindering the development of new-quality productivity in forestry. Result: First, China’s forestry new quality productive forces exhibited an overall upward trend during the sample period, yet the phenomenon of unbalanced and insufficient development was quite evident. Second, the Gini coefficient of forestry new quality productive forces, both within and between regions, has fluctuated and increased, with spatial autocorrelation and clustering characteristics evident among the development levels of forestry new quality productive forces in each province. Third, the study indicates that the development of forestry new quality productive forces is primarily constrained by the unit forestry labor productivity, the proportion of the output value of emerging and new forestry industries, and the value of forest ecosystem services. Conclusion: In the future, First, to enhance the training system required for new forestry workers and strengthen the extension of forestry science and technology. Second, to adjust the industrial structure required for new forestry labor materials and promote the upgrading of the forestry industry. Third, to optimize the policy system required for new forestry labor objects and facilitate the channels of value transformation.

Objective: Horizontal ecological compensation is an important initiative to guide multiple subjects to participate in regional ecological environment governance. It is important to study the choice of governmental subject behavior in the process of forest horizontal compensation to promote forest ecological protection and coordinate equitable regional development. Method: This paper constructs a tripartite evolutionary game model involving forest ecological protection areas, beneficial areas, and the central government. It explores the decision-making and evolutionary paths of the three parties at different stages. Based on the actual data of Chongqing in 2020, this paper conducts a simulation analysis to examine the progress of Chongqing’s forest horizontal ecological compensation mechanism and the impact of changes in key parameters on the game system. Result: The results show that the players of the game will reach different stable equilibrium points in different development stages. In the initial period, the cooperation between local governments cannot be reached spontaneously, which requires the supervision of the central government. When the forest horizontal ecological compensation enters the mature period, the cooperation between local governments can still be achieved without the supervision of the central government. Chongqing is currently in the early stage of the developmental period, and the optimal strategy of the tripartite game players is“protection, compensation and supervision”. The grassroots governments in forest ecological protection areas and beneficial areas have different sensitivity to the rewards and punishments of the the superior government (Chongqing), and the grassroots governments in forest ecological beneficial areas have higher sensitivity to the reward amount. The amount of compensation fees can affect the time and decision making of the local government to reach the stable state. The degree of public media participation is directly proportional to the speed at which the three parties of the game reach a stable equilibrium state. Conclusion: There are stage characteristics in the development process of forest horizontal ecological compensation. Chongqing is currently in the early stage of development, and the amount of reward and punishment of the higher government, compensation amount and the participation degree of the public media will affect the strategy selection of the main body of the tripartite game. Based on this, this paper puts forward relevant suggestions from the perspectives of the superior government, the grass-roots government of the forest ecological protection areas, and the grassroots government of the forest ecological beneficial areas, respectively: 1) The superior government should lead the establishment of a consultation mechanism for forest horizontal ecological compensation, promote the conclusion of the agreement, and dynamically adjust the reward and punishment intensity by improving the supervision system and formulating differentiated reward and punishment mechanisms to ensure the compensation effectiveness and financial efficiency. 2) The government of forest ecological protection areas should leverage local resources to develop ecological forestry industries, expand new business models such as under-forest economy, health and wellness tourism, and cultural and creative trade, thereby enhancing comprehensive benefits. 3) Based on the level of economic development, the ecological cost and service value of the forest ecological beneficial areas should be calculated, and the quality of forest species and ecological location should be combined to formulate scientific compensation standards. 4) It is advocated that the public and media actively participate in the process of forest ecological compensation, guiding society to foster a collective atmosphere of supervision.