To understand how radial growth of Abies fargesii var. faxoniana on different slopes in the mid-Min mountains responds to major climatic factors, how stable these responses are under climate change, and to provide a scientific foundation for elucidating the adaptive mechanisms of subalpine coniferous forests in response to climate change, thereby informing their conservation and management strategies.

Using 48 tree-ring cores collected from the east and west slopes of the mid-Min mountains and using the dplR package in R, tree-ring chronologies were developed and growth trends were removed. Spearman correlation analysis and 21-year moving correlation analysis were applied to examine the responsiveness and stability of A. fargesii to monthly precipitation, mean temperature, mean maximum temperature, and mean minimum temperature from 1951 to 2022.

Significant differences in the statistical characteristics of the standard chronologies between the eastern and western slopes were present. A. fargesii on the east slope exhibited higher sensitivity to the key climatic factors, with divergent response relationships, response stability and temporal patterns compared to that on the west slope. The negative correlation between the eastern-slope A. fargesii chronology and previous May precipitation became significant after the beginning of the 21st century, whereas the significantly negative correlation with current September precipitation gradually weakened after 1975. Meanwhile, trees on the west slope displayed unstable correlations with current June and September precipitation, but maintained a significant and stable positive association with previous August precipitation. Radial growth on both slopes was limited by July-August air temperatures of the previous year but promoted by air temperatures during the dormant period and growing season of the current year, with trees on the western slope more sensitive to air temperature. Trees on the west slope exhibited a gradual weakening of the previously significant negative response to the previous July mean temperature, while those on the east slope showed temporal instability in the same correlation.

The response patterns of A. fargesii on the eastern and western slopes of the central Minshan mountains to precipitation and air temperature were inconsistent, and the response relationships exhibited marked non-stationarity and dynamic variability across different time scales, indicating that slope aspect is an important factor influencing the climatic response of radial growth in A. fargesii.

To explore the suitable planting density of the main varieties of Populus sect. Aigeiros in the Jianghan plain, establish a more scientific and suitable technical system for poplar afforestation in the Jianghan plain, and to provide technical support and theoretical support for efficient stand cultivation.

4 main Section Aigeiros were selected in the Jianghan plain and planted in spring in 2017. Three replicates were set up in the experiment. In each replicate, five initial planting density zones (6 m×2 m, 6 m×3 m, 6 m×4 m, 6 m×5 m, and 6 m×6 m) were designed. Different varieties were randomly arranged in the same density zone using a random block design. There were 12 plants per density, per variety, and per plot. From 2017 to 2024, the tree height and DBH were investigated after each leaf fall for eight consecutive years. Then, the changes in growth of different varieties at different densities over the years were analyzed, and multiple comparisons and analysis of variance were conducted.

Under the same density, the DBH, tree height, volume per plant, and volume per unit area of P. deltoides ‘Huashi 2’ were all optimal, while P. deltoides ‘2025’ was the worst. Compared with other species, P. deltoides ‘Danhong’ was suitable for cultivation of large-diameter wood at small density, while P. deltoides ‘Huashi 2’ was more suitable for maximizing the benefits of the accumulated volume at medium density. There were extremely significant differences in DBH, tree height, volume per plant, and volume per unit area among different densities and varieties in the 8th year after planting.

With the growth of tree age, the DBH and volume per plant of the four black poplar cultivars decreased with the increase of density, and the growth rate slowed down after 6 years. The differences in tree height growth under different initial planting densities were small, but the growth also slowed down after 6 years. At the density of 6 m×2 m, P. deltoides ‘Huashi 2’, P. deltoides ‘Danhong’ and Populus×euramericana ‘Chulin 2’ could obtain the maximum volume per unit area, while P. deltoides ‘2025’ could obtain the maximum volume per unit area at the density of 6 m×6 m. P. deltoides ‘Huashi 2’ and P. deltoides ‘Danhong’are more suitable for cultivation in the Jianghan Plain. They feature rapid growth, and can be cultivated as short-rotation stands for medium-and small-diameter timber, while also possessing great potential for targeted cultivation of large-diameter timber. The interaction effect between varieties and density began to emerge after 3 years. The interaction effect between cultivars and density began to emerge after 3 years, with growth indicators differing among the 4 poplar stands, but these differences weakened or disappeared as stand age increased.

To investigate the key growth and physiological mechanisms underlying the adaptation of different families of Choerospondias axillaris to low phosphorus stress, so as to provide theoretical basis for the subsequent cultivation of high phosphorus efficiency and excellent varieties.

High-phosphorus-efficient families (L56, LF001) and low-phosphorus-sensitive families (L44, R27) were selected as experimental materials. A pot experiment was conducted under two phosphorus levels: normal phosphorus (16.0 mg/g, NP) and low phosphorus (0.2 mg/g, LP). Growth and physiological indices, including ground diameter, plant height, biomass, tissue phosphorus content, root activity, the activities of acid phosphatase (ACP), superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and nitrate reductase (NR) in rootswere measured to analyze the responses of morphological and physiological traits of different families to low phosphorus stress at the seedling stage.

1) Under LP stress, the growth of four families was significantly inhibited, while the root-to-shoot ratio, root activity, POD activities and phosphorus use efficiency (PUE) increased significantly. ACP and NR activities showed a decreasing trend, whereas SOD and CAT activities tended to increase. The responses of these indicators to LP stress exhibited significant variation among families; 2) Under low phosphorus stress, except for seedling height, the growth indexes such as ground diameter, root dry matter mass, total dry matter mass accumulation, root activity, ACP, SOD, NR activity and PUE of family L56 and LF001 were significantly higher than those of family L44 and R27; 3) There were obvious family differences in the response of antioxidant enzyme system (SOD, POD, CAT) to low phosphorus stress: L56 showed extremely high SOD activity and high POD and CAT activity; lF001 showed extremely high POD activity and high SOD and CAT activity. R27 showed higher POD activity, but lower SOD and CAT activity. L44 showed higher CAT activity, but lower POD and SOD activity; 4) Correlation analysis showed that there was a significant positive correlation between root-shoot ratio, root activity and antioxidant enzyme activity (SOD, POD, CAT) of Choerospondias axillaris at seedling stage. There was a significant positive correlation between NR and ACP, ground diameter, root dry weight, aboveground part dry weight and other growth indexes. The aboveground P accumulation was significantly positively correlated with aboveground part dry matter, but significantly negatively correlated with PUE.

L56 and LF001 belong to the synergistic and efficient type of high accumulation and high efficiency.

To explore the changes of growth, photosynthesis, and other physiological indices of Carya illinoinensis under drought stress and rewatering, and to provide a reference for the study of drought resistance mechanisms and breeding of drought-tolerant cultivars in C. illinoinensis.

Two-year-old grafted seedlings of 10 C. illinoinensis cultivars from southern provinces were used as test materials, with rootstocks being ‘Shaoxing’ seedlings. Drought stress and rewatering treatments were conducted through potted water control. Growth status of each cultivar was investigated on day 0 (D0), day 5 (D5), day 10 (D10) of drought stress, and day 10 after rewatering (R10). Leaf photosynthetic parameters, leaf anatomical structures, and related physiological indicators were measured. Principal component analysis and membership function analysis were used to comprehensively evaluate the drought resistance of the 10 cultivars.

1) Under drought stress, all cultivars showed wilting symptoms such as leaf curling and branch drooping. Leaf thickness (LT), lower epidermal thickness (LET), palisade tissue (PT), and spongy tissue thickness (ST) decreased to varying degrees. Among them, ‘TJS’ showed the largest decline, with LT, LET, PT, and ST significantly decreasing by 27.42%, 29.96%, 32.67%, and 40.19%, respectively, compared with D0. ‘C28’ had the smallest decline, with decreases ranging from 4.73% to 13.22% for the four indicators compared with D0; 2). Compared with D0, ‘KD’ exhibited the highest net photosynthetic rate (Pn) and transpiration rate (Tr) at D10 [4.53 μmol/(m²·s) and 1.2 mmol/(m²·s), respectively], with the smallest decreases (68.01% and 83.72%, respectively). ‘MD’ showed the smallest decrease in stomatal conductance (G_s) (75.86%) ‘WQT’ exhibited relatively low P_n, G_s, and T_r values with the largest decreases, reaching 91.30%, 94.44%, and 95.35%, respectively; 3) Root activity of different pecan varieties initially increased and then decreased. At D10, although root activity decreased for all varieties, it remained significantly higher than that at D0 for all except ‘XN’ and ‘FKT’. Among these, ‘NKL’ exhibited the greatest difference, with root activity increasing by 1-fold compared with D0. Leaf relative electrical conductivity (REC) gradually increased over time, with significant differences between D10 and D0; 4) At R10, the leaf anatomical structures and photosynthetic characteristics of the 10 seedlings basically recovered to normal levels, while root activity remained at a high level. However, the recovery degrees of various indices also differed among cultivars; 5) The comprehensive evaluation scores of the cultivars were ranked as: ‘KD’, ‘C28’, ‘NKL’, ‘MD’, ‘XN’, ‘FKT’, ‘WQT’, ‘TJS’, ‘BN’, and ‘GX 5’.

Timely rewatering can alleviate the drought damage of C. illinoinensis and make the root vitality overcompensate. Therefore, when the drought time in summer and autumn is longer than 10 days, the plants should be watered in time; In addition, when planting C. illinoinensis in southern provinces with seasonal drought, it is advisable to consider drought-resistant varieties such as ‘KD’, ‘C28’ and ‘NKL’.

To screen out Camellia oleifera cultivars with strong heat tolerance and provide a theoretical basis for breeding new heat-tolerant varieties.

A pot experiment was conducted using the method of high-temperature stress in an intelligent greenhouse on seedlings of two C. oleifera cultivars, ‘Dabieshan 1’ and ‘Changlin 53’. Nine time gradients were set: 0 (CK), 4, 7, 14, 21, 28, 35, 42 and 49 d. Ten physiological and biochemical indicators were measured, including relative water content, relative electrical conductivity, malondialdehyde content, hydrogen peroxide content, superoxide dismutase activity, peroxidase activity, catalase activity, soluble sugar content, soluble protein content, and free proline content. The heat tolerance of the two C. oleifera cultivars was comprehensively evaluated using the average membership function value of each physiological indicator.

1) The leaf relative water content of both cultivars decreased continuously with the extension of high-temperature treatment, and the decline accelerated after 7 days of stress. After 49 days of high-temperature treatment, the leaf relative water content of both cultivars reached its minimum, with ‘Dabieshan 1’ at 71.40% and ‘Changlin 53’ at 63.32%. The relative electrical conductivity, malondialdehyde content, and hydrogen peroxide content increased continuously with the extension of high-temperature treatment and reached their maximum at the 49th day; 2) The activities of superoxide dismutase and peroxidase in the leaves of both cultivars first increased and then decreased. The catalase activity in ‘Dabieshan 1’ leaves showed a continuous upward trend, while that in ‘Changlin 53’ increased in the early stage of stress and began to decrease after 42 d of stress; 3) The proline, soluble sugar, and soluble protein contents in ‘Dabieshan 1’ leaves continued to increase. In ‘Changlin 53’ leaves, proline and soluble protein contents continued to increase in the early stage of stress, reached their maximum at the 42th day, and then decreased; soluble sugar content continued to increase in the early stage of stress, reached its maximum at the 35th day, and then began to decrease; 4) The average membership function value of ‘Dabieshan 1’ was 0.559, and that of ‘Changlin 53’ was 0.449, indicating that the heat tolerance of ‘Dabieshan 1’ was superior to that of ‘Changlin 53’.

Under high-temperature stress, the physiological response patterns of the two C. oleifera cultivars seedlings were different. The comprehensive membership function evaluation showed that the average membership function value of ‘Dabieshan 1’ (0.559) was higher than that of ‘Changlin 53’ (0.449). The heat tolerance of ‘Dabieshan 1’ was superior to that of ‘Changlin 53’.

This study aims to systematically elucidate the distribution patterns and main influencing factors of fuel loads in three fuel types (herb layer, litter layer, and humus layer), construct high-precision prediction models for fuel load, and to accurately identify high-fire-risk areas in Chinese fir forest regions and develop differentiated forest fire management strategies.

Based on 702 standard sample plots of Chinese fir forests in Hunan Province, surveyed from 2020 to 2022. Fifteen factors, including aspect, slope position, slope gradient, and canopy closure were selected. One-way analysis of variance was used to examine the distribution characteristics of fuel loads among the three fuel types, and Pearson correlation analysis was applied to investigate the correlations between 15 factors and 3 types of fuel loading. Prediction models for fuel load, including linear regression, random forest, gradient boosting, and XGBoost, were developed using Python 3.8.

1) The fuel loads in the litter layer (0.615–21.110 t/hm²) and humus layer (0–44.210 t/hm²) of Cunninghamia lanceolata forests in Hunan Province exhibited extremely wide ranges. The mean fuel loads, in descending order, were: humus layer (11.647 t/hm²), litter layer (6.407 t/hm²), and herb layer (0.638 t/hm²), with significant differences among the three (P<0.01); 2) The fuel load of the herb layer was primarily driven positively by herb cover (r=0.673) and significantly suppressed by canopy closure (r=-0.290) and stand density (r=-0.240). For the litter layer, litter thickness was the core influencing factor (r=0.657), while elevation (r=0.098) and slope position (r=-0.119) indirectly regulated its accumulation by affecting decomposition rates. The fuel load of the humus layer was significantly positively correlated with humus thickness (r=0.780), elevation (r=0.167), and total growing stock (r=0.180); 3) The gradient boosting model performed best for the herb layer (R²=0.682 6) and litter layer (R²=0.751 8), while the XGBoost model achieved the best performance for predicting the humus layer fuel load (R²=0.665 5). The machine learning models (random forest, gradient boosting, and XGBoost) significantly outperformed the traditional linear regression model and demonstrated good generalization capability.

1) The extremely high fuel loads in the litter and humus layers of some C. lanceolata forest stands in Hunan Province pose a significant risk for forest fire occurrence and rapid spread; 2) Canopy closure has opposite effects on the herb layer (highly significant negative correlation) and the litter layer (highly significant positive correlation); therefore, when implementing thinning operations, managers should balance the fire risks of both layers, and promptly remove logging residues after thinning to avoid a sharp increase in litter input. In addition, litter decomposition is slower and accumulation is greater at high-elevation upper slope positions; thus, prescribed burning or mechanical removal of thick litter layers should be carried out before the dry winter-spring season. Moreover, some stands have developed deep humus layers, and areas with thick humus accumulation should be prioritized for ground-fire prevention and regularly inspected; 3) The gradient boosting and XGBoost prediction models exhibit high accuracy and strong stability, providing technical support for dynamic fuel monitoring, precise fire-risk zoning, and scientific fire prevention decision-making in C. lanceolata forest regions.

The fine root biomass and morphological characteristics of Pinus tabulaeformis plantation with different forest age and density in Daqing mountain of Hohhot City, Inner Mongolia were studied, and the relationship between forest age and density and fine roots and soil nutrients was clarified, so as to provide a theoretical basis for the scientific management of Pinus tabulaeformis plantation in Daqing mountain area.

Twenty-four plots of Pinus tabuliformis plantations were established, comprising eight treatment types with different stand age classes and densities: young stands with medium density, young stands with high density, middle-aged stands with low density, middle-aged stands with medium density, middle-aged stands with high density, mature stands with low density, mature stands with medium density, and mature stands with high density. The root coring method was employed to collect fine root and soil samples from two depth layers (0-20 cm and 20-30 cm), investigating fine root biomass, morphological characteristics, and their relationships with soil nutrients under different stand ages and densities.

The fine root biomass, root length density and root surface area density were concentrated in the 0-20 cm layer. In young forests, with the increase of density, fine roots showed an increasing trend. From middle-aged forest to mature forest, the fine roots showed a trend of increasing first and then decreasing with the increase of density. The total biomass, root length density and root surface area density of fine roots reached the maximum of 411.60 g/m², 830.87 m/m² and 224.05 m²/m³ at medium density in middle-aged forest. Soil organic matter, total nitrogen, total carbon, available nitrogen and available phosphorus content were positively correlated with fine root biomass, root length density and root surface area density, but negatively correlated with fine root specific root length and specific surface area.

In the scientific management of Pinus tabulaeformis plantation in Daqing mountain, combined with the synergistic effect of forest age and density, high-density planting mode should be adopted in the young forest stage, and medium-density planting mode should be adopted in the middle-aged forest and mature forest stage, which is more conducive to promoting the growth and development of trees.

To provide theoretical and technical support for the sustainable management and soil fertility maintenance of larch plantations.

Larix olgensis plantations with basically the same site conditions were selected. In 2018, selective cutting operations with different intensities (25%, 35% and 45%) were carried out according to the stock volume, and non-selective cutting was set as the control. Subsequently, three fixed sample plots were set up in the stands with different selective cutting intensities. In August 2023, after five years of selective cutting operation, the coverage thickness, standing stock, soil physical and chemical properties of litters were measured in each plot. Through single factor analysis of variance, Mantel analysis and structural equation modeling, the changes of litter cover thickness, standing stock and soil physical and chemical properties under different selective cutting intensities and their relationships were studied.

After 5 years of selective cutting, the litter cover thickness decreased by 17.4%, 30.3%, and 31.0% at 25%, 35% and 45% selective cutting intensities, respectively, compared to the control stand. The undecomposed litter layer thickness decreased by 32.7% and 36.1% at 35% and 45% selective cutting intensities, respectively, compared to the control stand. The semi-decomposed litter layer thickness decreased by 25.7%,44.2%, and 43.4% at 25%,35%, and 45% selective cutting intensities, respectively, compared to the control stand. High-intensity selective cutting (45%) significantly reduced soil bulk density in the 0-10 cm layer by 17.7% compared to the control. Moderate-intensity selective cutting (35% and 25%) also reduced soil bulk density in the 20-40 cm layer, with reductions of 15.0% and 11.0% respectively. Soil moisture content increased by 40.8% (0-10 cm), 21.8% (10-20 cm), and 18.7% (20-40 cm) after high-intensity selective cutting compared to the control. The maximum soil compaction degree in 0-40 cm soil layer was 785.0 kPa in control forest,724.4 kPa in 25% selective cutting forest, 525.6 kPa in 45% selective cutting forest and 503.9 kPa in 35% selective cutting forest. Under the moderate selective cutting (35%), the soil pH, total nitrogen, total phosphorus, organic carbon and hydrolyzable nitrogen in the 0-10 cm soil layer increased by 5.5%, 21.7%, 39.8%, 45.4% and 51.3% respectively compared with the control. Under the high intensity (45%) selective cutting, the contents of available potassium and available phosphorus in the 0-10 cm soil layer increased by 30.0% and 60.4% respectively compared with the control. The results of structural equation modeling showed that selective cutting had a significant positive effect on soil moisture content and soil chemical properties, and a significant negative effect on soil bulk density, litter cover and litter stock, and also had a significant negative effect on soil chemical properties through changing litter cover and litter stock.

Selective cutting management can significantly reduce the accumulation of litter on the surface of forest land, improve the microenvironment in the stand, and be beneficial to the decomposition of litter such as larch needles on the surface. After selective cutting with medium and high intensity (35%, 45%), it can accelerate the decomposition of litter, effectively promote the circulation of soil nutrients, and play an important role in maintaining soil fertility and preventing soil acidification.

This study explored the soil arbuscular mycorrhizal (AM) fungal communities in park green spaces under the context of urbanization, aimed to provide foundational data support for the soil microbial diversity and ecological conservation of parks in Nanchang City.

In this study, three urbanization gradient levels (high, medium, and low) were divided according to the proportion of impervious surface area in the built-up area of Nanchang City, and 63 sample plots of park green space soil were sampled and investigated. High-throughput sequencing technology was used to detect the community characteristics of arbuscular mycorrhizal (AM) fungi in the soil, analyze the differences in the structural composition, Alpha diversity and Beta diversity of AM fungal communities, and reveal the correlation between AM fungal communities and soil physicochemical properties through RDA analysis.

The AM fungal communities in the park green spaces of Nanchang City were predominantly composed of dominant genera such as Glomus and Paraglomus. The Shannon and Simpson indices exhibited a significant logarithmic increase with rising urbanization intensity by 3.89% and 1.90%, whereas the Dominance index showed a significant logarithmic decrease by 44.36%. Soil pH value, electrical conductivity, soil organic carbon content and total nitrogen content were positively correlated with the abundance of genera such as Glomus, Claroideoglomus, Scutellospora and Gigaspora; total potassium content, moisture content and soil bulk density were positively correlated with the abundance of genera such as Archaeospora and Diversispora, and soil total phosphorus content was positively correlated with the abundance of genera such as Paraglomus.

With the increase in urbanization intensity, species diversity and community evenness of AM fungi communities increased, while the dominance of the dominant genera weakened. Soil physicochemical factors such as soil organic carbon, pH value, total phosphorus content, and total potassium content play a key role in influencing the composition of AM fungal communities.

By analyzing the quantitative changes in land use types, identifying driving mechanisms, and examining land cover transition patterns along with spatial proximity relationships in Changsha from 2000 to 2020, this study aims to reveal the underlying trends of land-use transformation in the city.

Using a PLUS model-based mask extraction approach on raster datasets, this study examined the correlations and underlying mechanisms of various driving factors influencing land use change patterns in Changsha from 2000 to 2020. The land-use expansion module employs adaptive relationships to simulate spatial evolution, enabling analysis of dynamic processes within the study area. Based on the land-use spatiotemporal change data of Changsha from 2000 to 2020, a linear regression model was fitted to investigate the temporal and quantitative relationships among different land use types. The optimal fitting line was obtained by minimizing the sum of squared residuals between observed values and model predictions. The 12 selected driving factors were normalized to generate raster spatial distribution maps, contribution rates, and root mean square errors. Using the random forest algorithm, development probabilities for various land types were calculated. Based on three research objectives-natural development, ecological benefit maximization, and urban economic growth-three future scenarios (natural development, ecological conservation, and urban expansion) were established to simulate future land changes.

Changes in land use categories showed a high correlation with time sequences, with linear regression coefficients averaging over 0.85. The main driving factors and their contributions vary among different land categories. The expansion area of urban land was mainly affected by elevation. The contribution rate of elevation reached 0.16 during the period from 2000 to 2010, and the RMSE value was 0.23. During the period from 2010 to 2020, the contribution rate of elevation decreased to 0.15, and the RMSE value was 0.24. Future land use simulations under the ND (Natural development), EP (Ecological protection), and US (Urban spread) scenarios predict urban expansion areas of 145.22 km², 46.93 km², and 317.64 km², respectively, highlighting the significant role of government policies and measures in influencing the spatiotemporal evolution of urban land use.

From 2000 to 2010, urban expansion demonstrated a steady growth trend in both scale and duration, while the decline rates of arable land and forest land accelerated during the same period. From 2010 to 2020, the expansion rate of construction land slowed down and stabilized, effectively mitigating the reduction trends of ecological lands such as arable land and forest land. In the influence mechanism, elevation is the primary factor; during this period, number of soil types exhibited the lowest impact intensity. The temporal variation patterns of these driving factors align closely with Changsha's actual development trajectory: extensive and rapid urban expansion from 2000 to 2010, followed by controlled expansion scale and slower growth rates from 2010 to 2020.