To investigate the effects of water stress and subsequent recovery on the water potential, photosynthetic and chlorophyll fluorescence characteristics of Michelia × alba sapling, a widely utilized greening tree species in the south subtropical region.

Twelve open-topped chambers (OTCs) with isolated groundwater were utilized, each containing one Michelia × alba sapling. A randomized block design was employed to set up four water gradient treatments, incorporating both rainfall interception in the undercanopy and artificial irrigation: Over-irrigation (OW), control (CK), moderate drought (MD), and high drought (HD). The dynamic changes in instantaneous water potential, photosynthesis and chlorophyll fluorescence parameters of the Michelia × alba leaves were measured under different water stress treatments (3 consecutive months) and subsequent water recovery (2 consecutive months), and the differences between treatments were analyzed.

Compared with CK, drought stress (MD and HD) significantly reduced the leaf water potential index (midday water potential), photosynthetic indices (net photosynthetic rate, stomatal conductance, etc.), and chlorophyll fluorescence indices (maximum photochemical efficiency, electron transport rate, etc.) of Michelia × alba saplings. In contrast, excessive water irrigation had no significant effect on the leaf water potential, photosynthesis, and fluorescence indices of Michelia × alba saplings. After continuous natural atmospheric precipitation, the leaf water potential, photosynthesis, and chlorophyll fluorescence indices of Michelia × alba saplings under drought stress (MD and HD) recovered and showed no significant differences compared with those of the CK. After the soil moisture was restored, there were no significant differences in the water potential, photosynthesis, and fluorescence indices among different treatment groups.

Drought stress limits the leaf water potential, photosynthesis, and fluorescence of Michelia × alba sapling leaves, causing wilting and negatively affecting growth. Timely watering can restore the plants to normal conditions. Specifically, before the soil moisture falls below 25% of the field capacity, timely artificial watering should be applied to replenish the soil moisture. Atmospheric precipitation effectively mitigates the suppression of Michelia × alba sapling's water potential, photosynthetic fluorescence due to soil drought, promoting recovery and growth. In the maintenance and management process of urban landscaping plants like Michelia × alba, when continuous drought occurs, attention should be paid to the soil moisture index. Timely watering can help Michelia × alba recover from water stress and avoid death.

In order to explore the growth and physiological response mechanism of Gleditsia japonica var delavayi seedlings under different ratios of nitrogen, phosphorus and potassium fertilization, and to establish the best fertilization technology scheme for Gleditsia japonica var delavayi seedlings, so as to provide theoretical basis for its seedling raising.

In this study, 2-month-old Gleditsia japonica var delavayi seedlings were used as the research object, The application rates for N₀, N₁, N₂, and N₃ are 0 g/plant, 2.8 g/plant, 5.6 g/plant, and 8.4 g/plant, respectively; for P₀, P₁, P₂, and P₃ are 0 g/plant, 0.7 g/plant, 1.4 g/plant, and 2.1 g/plant, respectively; and for K₀, K₁, K₂, and K₃ are 0 g/plant, 1.4 g/plant, 2.8 g/plant, and 4.2 g/plant, respectively. The effects of different nitrogen, phosphorus and potassium ratio fertilization on six physiological indexes of superoxide dismutase (SOD), catalase (CAT), malondialdehyde (MDA), proline (Pro), soluble protein (SP) and soluble sugar (SS) and three growth indexes of plant height, ground diameter and dry weight of Gleditsia japonica var delavayi seedlings were studied.

Compared with the control group, reasonable fertilization could significantly promote the growth and physiological activity of G. yunnanensis seedlings. Under the ratio of fertilization, the overall performance is the strongest dependence on P fertilizer; in the interaction effect, the PK interaction further confirmed the promotion effect of appropriate nitrogen fertilizer on seedling growth, the NP interaction may affect root development, and P fertilizer has a significant effect on ground diameter and dry weight distribution. Under physiological stress, the contents of MDA and SS increased significantly, while the contents of SOD, CAT, Pro and SP decreased. N₂K₁ (Medium nitrogen and low potassium) fertilization combination showed good results in many physiological indexes. N fertilizer can improve the antioxidant capacity and osmotic adjustment substance content of plants, and P fertilizer has a greater impact on SP. Except MDA and SS decreased first and then increased with the increase of N, P and K fertilization, the other indexes increased first and then decreased with the increase of N, P and K fertilization. Excessive fertilization (N₃P₂K₂, N₂P₃K₂, N₂P₂K₃) significantly inhibited seedling growth.

Reasonable fertilization can enhance the growth and physiological and biochemical processes of Gleditsia japonica var delavayi seedlings, and low nitrogen, medium phosphorus and low potassium (N₁P₂K₂) treatment is the best fertilization scheme for its seedlings. According to the fitted quadratic equation, the optimum nitrogen, phosphorus and potassium application rates of Gleditsia japonica var delavayi seedlings were 3.2 g/plant, 1.6 g/plant and 2.2 g/plant, respectively.

This study aims to construct a stand-level model for estimating the carbon stock of Cunninghamia lanceolata forests applicable to Jiangxi Province based on the national standard “Tree Biomass Models and Related Parameters to Carbon Accounting for Major Tree Species” (GB/T 43648-2024), to improve the accuracy and reliability of the estimation.

Three theoretical growth equations—Logistic, Modified Weibull, and Gompertz—were used as the base models for this study. Two types of power function form, referred to as ND_g^φ and N^δD_g^φ, were introduced to reflect the density of the stand, resulting in six models for estimating carbon stock in variable-density stands. Additionally, the commonly used power-law allometric equation was included in the model comparison framework. The nonlinear weighted least squares method was employed for parameter fitting, and the optimal model was established through model evaluation and testing. To further validate the effectiveness of the constructed model, a systematic comparison was conducted between the estimates from the optimal model and those obtained using traditional methods.

1) The modified Weibull equation, incorporating the power function form ND_g^φ, achieves the highest coefficient of determination (R²=0.973) and the lowest standard error of estimate (SEE=3.004 t·hm^-2). Additionally, it demonstrates minimal values for total relative error (TRE=0.06%), mean systematic error (MSE=-0.07%), mean prediction error (MPE=1.77%), mean percent standard error (MPSE=8.99%), and Akaike Information Criterion (AIC=920.6). TRE and MSE are maintained within ±3%, while MPE and MPSE meet the general accuracy requirements of less than 3% and 15%, respectively. Furthermore, the model's residuals show significant improvements in heteroscedasticity and normality; 2) Compared with the traditional methods, the modified Weibull equation demonstrates the best performance with an R² of 0.978 and a parameter m of 0.950. The parameter n is not significantly different from 0 (P>0.1), and the absolute value of TRE is the lowest at 2.89%. Additionally, the systematic bias between the predicted values and the observed values is not significant (P>0.1). Among traditional methods, the BEF method shows an R² of 0.974 and a parameter m of 0.934. Like the modified Weibull equation, its parameter n is not significantly different from 0 (P>0.1). However, the TRE is 10.57%, indicating a significant systematic underestimation of the predicted values (P<0.001), with an average of 1.427 t·hm^-2 lower than the observed values. In contrast, the CBEF1 and CBEF2 methods yield R² of 0.792 and 0.872, respectively. Their parameter m values are 0.575 and 0.681, with parameter n values of 10.921 and 8.715. The TRE for CBEF1 and CBEF2 methods are -13.17% and -12.36%, respectively, indicating a significant systematic overestimation of the predicted values (P<0.05). On average, the predicted values exceed the observed values by 4.227 t·hm^-2 and 3.673 t·hm^-2, respectively.

The modified Weibull equation, developed according to the national standard, is optimal for estimating carbon stock in Cunninghamia lanceolata forests within the study area. Its estimation results are more accurate and reliable than those of traditional methods, offering greater practical value in application.

Forest fire video monitoring is the key means of forest fire monitoring in forest management agencies. Reasonable spatial distribution pattern can improve monitoring efficiency, reduce monitoring blind spots, detect fires in time, and reduce losses from forest fires.

Taking 216 state-owned forest fire video monitoring points in Hunan Province as study objects, the spatial distribution type, spatial distribution density and spatial distribution direction of forest fire video monitoring points were analyzed by using the nearest neighbor index, kernel density estimation method and standard deviation ellipse, respectively. The spatial distribution pattern of forest fire video monitoring points in state-owned forest farms in Hunan Province was studied, and the influencing factors of site selection of forest fire video monitoring points were discussed from four aspects: topography, traffic, fire risk and social economy.

There are 645 forest fire video monitoring points in the state-owned forest farms in Hunan Province, showing a significant agglomeration pattern in space. From the distribution of forest fire video monitoring points in various cities and prefectures of Hunan Province, Shaoyang City has the largest number of forest fire video monitoring points, and Xiangtan City has the least, accounting for 17.36% and 0.31% of the total number of the provinces, respectively. From the perspective of distribution density, the spatial distribution shows a regional difference of ‘less in the north and more in the south’. There are four high-density area centers, located in Changsha City, Zhuzhou City, Yongzhou City and Shaoyang City; in addition, there is a sub-intensive area center located in Xiangxi Tujia and Miao Autonomous Prefecture. The numerical difference between the long and short axes is large, indicating that the spatial distribution of forest fire video monitoring points has a strong directionality, and presents a northwest-southeast distribution trend.

The spatial distribution of forest fire video monitoring points in state-owned forest farms in Hunan Province is significantly affected by factors such as elevation, slope, traffic accessibility, number of graves, operating area of state-owned forest farms, and number of tourist attractions. It provides a reference for strengthening the construction of forest fire prevention and extinguishing capacity in Hunan Province and the rational layout of forest fire video monitoring points.

This study aims to investigate the effects of growth regulators and medium on cuttage adventitious root occurrence of Alniphyllum fortunei, and to provide theoretical for A. fortunei propagation by cutting.

Using lignified branches of 2-year-old A. fortunei as the cuttings, an orthogonal experimental design with four factors and three levels was employed to investigate the effects of growth regulator type, concentration, treatment duration, and medium composition on adventitious root formation. Combined with anatomical observations, a total of twelve cuttings growth indices were measured and statistically analyzed to clarify the regulatory effects of each factor on cutting rooting and seedling growth.

The soluble sugar content, PPO, and IAAO in the A. fortunei growth regulator treatment group were higher than those in the control group during both the adventitious root formation stage and the adventitious root growth stage. The average root length, average root diameter, root volume, fine root specific root length and fine root specific root area of NAA treatment group were significantly higher than those of other treatments; regulator type × concentration, regulator type × treatment time mean analysis showed that the rooting effect of high concentration (1 500 mg·L^-1) and low treatment time (10 min) of NAA treatment was better. Four principal components were extracted by principal component analysis, which were the comprehensive growth status of aboveground and underground parts, root coarseness index, root length index, and comprehensive growth status of root system. The highest comprehensive score was T13, that is, 75% vermiculite+25% perlite was selected as the matrix, and 1 500 mg·L^-1 IAA was used for 10 min. the rooting rate was 71.87%, and the rooting index was 147.19.

The root system growth of A. fortunei cuttings belongs to the callus rooting type, with adventitious roots emerging around 56 days. Through growth regulator treatment, the dynamic changes in soluble sugar content and oxidase activity (PPO、POD、IAAO) in A. fortunei cuttings can be accelerated, thereby promoting rooting. Cuttings of Alniphyllum fortunei exhibited optimal growth under the T13 treatment, offering a reference for large-scale clonal propagation.

The aim of this study is to understand the effects of thinning intensity on the growth and plant species diversity of Pinus sylvestris var. mongholica plantation in Saihanba area, and provide scientific basis for the scientific and reasonable management of the plantations.

Based on the on long-term monitoring plots, the DBH, volume, stand stock and species diversity of Pinus sylvestris var. mongholica plantations under different thinning intensities were studied.

After 3 years of tending thinning, the average annual growth of DBH (Diameter at breast height) and volume of each tree was significantly higher than that of CK, and the average annual growth of DBH of low (LT, 2 000 plant/hm²), medium (MT, 1 667 plant/hm²) and high (HT, 1 333 plant/hm²) thinning intensity increased by 22.22%, 48.15% and 81.48%, respectively, compared with CK (3 200-3 425 plant/hm²). The annual growth of volume was increased by 58.00%, 72.00% and 130.00%, respectively. Thinning changed the DBH class distribution of the stand, which changed from normal to lognormal. The annual growth of stock of the thinning forests was lower than that of CK, but did not reach a significant level (P>0.05), and there was a significant level between HT, MT and the control (P<0.05) in the annual growth rate, which were increased by 38.02%, 23.37% and 2.97% for HT, MT and LT respectively, compared with CK. The biomass of HT, MT and LT increased by 123.53%, 94.12% and 35.29% compared with CK, and the species number increased by 46.67%, 70.00% and 36.67%, respectively. The Simpson index, Shannon index and Margalef index increased with the increase of thinning intensity, but the differences among them did not reach a significant level; the biomass of understory plants was more sensitive to tending thinning than species diversity.

Thinning obviously promotes the growth of DBH, individual tree volume, growth rate of forest stock, as well as the biomass and species number of understory plants; considering the impact on the growth and diversity of the stand, the current suitable tending intensity is HT, under which the density is about 1 333 trees/hm².

This study aims to evaluate the distribution of the potential suitable habitats of eight ancient tree species on Hainan island under climate change and their responses to environmental factors, and to provide a reference for the management and protection of ancient trees on Hainan island.

Taking eight ancient tree species with a tree age of≥300 years on Hainan Island as the research objects, relevant environmental variables were screened out. The MaxEnt model was used to predict the changes in the potential suitable habitats and the key influencing factors of these eight ancient tree species under current and future climate conditions.

1) The average training AUC values of the eight ancient tree species are all above 0.9, indicating extremely high prediction accuracy. 2) Population density is an important influencing factor for the suitable distribution of many ancient tree species, and the contribution rate and permutation importance value of this factor are relatively high. Different ancient tree species are also jointly affected by their respective specific climate, soil and other factors; 3) Under the current climate conditions, Ficus virens and Bischofia javanica have the widest suitable habitat ranges on Hainan island, approximately 20 248.36 km² and 16 367.39 km² respectively. The suitable habitat areas of Mangifera indica and Tamarindus indica are relatively narrow among the eight ancient tree species; 4) Under the future climate scenarios, the areas of potential suitable habitat change for ancient trees are basically centred on the edges of the original suitable habitat areas. Areas of high loss, gain and turnover of ancient trees are mainly concentrated in coastal cities and counties in the northeast and southwest of Hainan island.

The response of eight species of ancient trees on Hainan island to climate change can be better simulated using the optimized MaxEnt model. Human activities and the natural environment have a combined effect on the long-term survival of ancient trees. The results can provide scientific reference for the sustainable conservation of Hainan's ancient tree resources.

This study systematically analyzed the adaptability, growth performance, and plant diversity of different tree species allocation modes during vegetation restoration in China's south subtropical region. The findings aim to provide a theoretical basis and practical support for understanding community succession mechanisms in vegetation reconstruction and restoration, and for scientifically guiding tree species selection and optimal allocation.

Multiple suitable tree species were introduced to establish four allocation modes: species selection mode (Tree allocation I), multi-species mixed forest with precious tree species (Tree allocation II), conifer-broadleaf mixed forest (Tree allocation III), and a control mode (CK) planted with Liquidambar formosana and Schima superba. Permanent plots were established, and continuous vegetation surveys were conducted in 2012 (pre-afforestation), 2016 (4 years after afforestation), and 2024 (12 years after afforestation), comprehensively recording vegetation growth, species composition, and community structure changes.

1) After nearly 12 years of vegetation restoration, 35 of the 63 initially planted tree species survived. Among them, 17 species, including Phoebe zhennan, Aquilaria sinensis, and Michelia macclurei, exhibited high survival rates and good adaptability. Among all surviving species, Pinus massoniana showed the fastest growth, with an average height of 8.7 m and average DBH of 17.1 cm. Tree Allocation III (conifer-broadleaf mixed forest), dominated by P. massoniana, performed outstandingly, with the basal area of planted trees being 5.2 times that of the control mode (CK), and the average tree height (7.4 m) and average DBH (12.6 cm) significantly higher than those of other allocation modes. 2) After 12 years of restoration, species composition was rich, including 77 woody plant species and 30 herb and shrub species. P. massoniana had the highest importance value (48.89), indicating its absolute dominance in the community as the dominant and constructive species, followed by S. superba, Castanopsis hystrix, and others. Among wild tree species, Rhodomyrtus tomentosa had the highest importance value (21.60), followed by Pinus elliottii, Cratoxylum cochinchinense, and others. In the herb-shrub layer, Dicranopteris dichotoma accounted for 78.0% of the total importance value of shrubs and herbs. 3) The Simpson diversity index (D), Shannon-Wiener diversity index (H′), and evenness index (J) for tree species were 0.942 9, 4.841 1, and 1.121 3, respectively, while for herbaceous species they were 0.154 5, 0.706 8, and 0.207 8, indicating a relatively high level of plant diversity.

In the selection of tree species for vegetation restoration in south subtropical regions, garden species and introduced species should be used with caution. If economic tree species are randomly mixed with other species for restoration without proper management, expected economic returns are unlikely to be achieved. For severely degraded ecosystems, selecting the pioneer species P. massoniana and mixing it with native broadleaf species can effectively accelerate vegetation reconstruction and restoration. After 12 years of restoration, a species-rich and structurally stable forest community of trees, shrubs, and herbs has initially formed.

To investigate the effects of mushroom residue (SMC) addition on the improvement of gold tailings substrate and plant growth, and to screen plant species with good adaptability and tolerance to gold tailings.

In view of the problems existing in gold tailings, such as extreme nutrient deficiency, poor water and fertilizer retention capacity, unsatisfactory physical structure, excessive accumulation of heavy metals, and the dominance of herbs in existing remediation plants, Koelreuteria paniculata, Nerium oleander, Paulownia fortunei, Rhus typhina, Syringa vulgaris and Acacia podalyriifolia were selected as test plants, and mushroom residue (SMC) was used as the amendment. The physical and chemical properties of three substrates (100% gold tailings as control (CK), 90% tailings + 10% SMC (S1), 80% tailings + 20% SMC (S2)), as well as the differences in physiological and biochemical characteristics, heavy metal uptake and translocation of plants in different substrates were compared.

1) After adding SMC to tailings, the water content increased by 4.21-16.53 percentage points, total porosity increased by 12.39-25.44 percentage points, and organic matter content and cation exchange capacity increased by 66.55%-100.35% and 36.71%-63.24% respectively compared with the control.; 2) Compared with the control group, plants in the amended groups showed better overall performance in growth vigor, biomass, height increment, chlorophyll content, heavy metal uptake and translocation factor; however, there were interspecific differences among plant species within the amended groups; 3) Overall, Paulownia fortunei, Nerium oleander and Koelreuteria paniculata exhibited strong heavy metal tolerance, especially Nerium oleander, which had the best comprehensive performance under S2 treatment. The TOPSIS comprehensive evaluation method was used to comprehensively assess various physiological and biochemical indicators, and it obtained the highest score.

The addition of SMC makes the tailings structure looser and more porous, enhances water permeability and aeration, and effectively improves soil fertility. The growth and development of plants in the amended groups are generally better than those in the control group. Based on comprehensive growth and physiological indicators, Nerium oleander performs the best under S2 treatment (80% tailings + 20% SMC), and can be used as a dominant remediation plant for improved gold tailings.