This study aimed to investigate the differences in growth and physiological characteristics of seedlings from five predominant Camellia oleifera cultivars in Hunan Province under acidic purple soil, alkaline purple soil, and red soil (control) conditions, so as to provide a theoretical basis for ecological adaptability evaluation, cultivar selection, and targeted soil improvement of C. oleifera in purple soil regions of Hunan.

A pot experiment was conducted using red soil as the control. Growth, physiological, and biochemical indices of three-year-old seedlings of five cultivars (‘Huashuo’@@@, ‘Huajin’@@@, ‘Huaxin’@@@, ‘Xianglin 210’@@@, and ‘Hengdong Datao No.2’@@@) were measured across three soil types. The data were comprehensively evaluated using membership function method and principal component analysis.

The acidic purple soil was more favorable for the growth of C. oleifera, with the average membership function values of growth indicators for all cultivars being higher than those in the red soil and alkaline purple soil. Under acidic soil conditions, ‘Huashuo’@@@ and ‘Hengdong Datao No.2’@@@ showed the most comprehensive performance, with generally desirable growth, physiological, and biochemical parameters, although their chlorophyll content was comparatively lower. In alkaline soil, both ‘Huashuo’@@@ and ‘Huaxin’@@@ exhibited elevated antioxidant enzyme activities; however, ‘Huashuo’@@@ displayed the highest malondialdehyde (MDA) content, indicating substantial membrane damage and poor adaptability. In contrast, ‘Huaxin’@@@ maintained lower MDA levels and achieved higher membership function rankings, reflecting superior membrane stability and stress tolerance. Principal component analysis revealed that all cultivars performed better in acidic soil than in the other soil types. ‘Hengdong Datao No. 2’@@@ and ‘Huaxin’@@@ performed well in both red soil and acidic purple soil, whereas ‘Huajin’@@@ and ‘Huaxin’@@@ demonstrated relatively better adaptability in alkaline purple soil.

Comprehensive analysis of all measured indicators revealed that acidic purple soil was the most suitable for C. oleifera growth, with cultivars grown in this soil type occupying the top five positions in the overall ranking. The order of soil adaptability was determined as: acidic purple soil>red soil>alkaline purple soil. ‘Hengdong Datao No. 2’@@@ and ‘Huaxin’@@@ exhibited the best performance in both acidic purple soil and red soil, while ‘Huajin’@@@ and ‘Huaxin’@@@ showed relatively superior adaptation in alkaline purple soil. Considering the overall performance across all three soil types, ‘Huaxin’@@@ demonstrated the strongest comprehensive adaptability.

To clarify the impact of fertilization methods on the nutrients and economic characteristics of Camellia oleifera, explore the relationship between nutrients and fruit economic characteristics, and to identify suitable fertilization methods for Camellia oleifera forests.

Using ‘Ganxing 48’@@@ Camellia oleifera as the material, three fertilization treatments were set up: hole fertilization (D), furrow fertilization (G), and no fertilization (CK). The nutrient content and fruit economic characteristics of Camellia oleifera leaves, fruits, roots, and flower buds were investigated, and a partial least squares path model was constructed to analyze the relationship between tree nutrients and fruit economic characteristics as well as the influence of fertilization methods on tree nutrients and fruit economic characteristics.

Compared with CK, the fruit shape index of the hole application treatment is closer to 1, and the quality of fresh fruits increased by 21.51% and 9.00%, respectively. The oil yield of fresh fruits increased by 22.21% and 24.67% respectively, and the oil production per plant increased by 33.12% and 41.23% respectively; With the extension of growth time, N and K nutrients gradually accumulate as a whole; P nutrients gradually transfer from leaves, fruits, and roots to flower buds. The soluble sugars in roots and flower buds gradually transfer to the fruit; The overall trend of soluble starch content is decreasing and increasing. Fertilization can promote the accumulation of N, K and soluble starch in various organs, increase P content in roots, leaves, and fruits during the growth period of spring shoots, promote the accumulation of soluble sugars in leaves and fruits, and alleviate the consumption of soluble sugars in roots and flower buds. The results of the PLS-PM show that G mainly increases fruit nutrients and reduces leaf nutrients during the oil conversion period, while D mainly reduces leaf nutrients during the rapid growth period of spring shoots and increases root nutrients during the peak fruit growth period, thereby improving fruit economic traits. The results of PCA showed that 5 fruit quality indicators, 2 moisture content indicators, fruit shape index, fresh fruit oil content, dry seed oil content, and oil production were the main indicators for evaluating the fertilization effect, with a cumulative contribution rate of 88.79%. The comprehensive score from high to low was D>G>CK.

Hole fertilization is a more suitable fertilization method for Camellia oleifera forests, as it improves fruit economic characteristics by affecting the nutrients of Camellia oleifera at different stages.

To investigate the effects of two microbial fertilizers on the growth and photosynthetic characteristics of Camellia oleifera seedlings, and to provide some practical references and theoretical support for the nutrient management of Camellia oleifera.

The growth indexes, gas exchange parameters, chlorophyll fluorescence parameters and antioxidant enzyme activities of Camellia oleifera seedlings were measured after applying two kinds of microbial fertilizers, and combined with the principal component and subordinate function analysis to comprehensively evaluate the effects of different treatments and screen the optimal fertilizers and application rates.

The application of microbial fertilizer significantly promoted the growth and photosynthetic characteristics of Camellia oleifera. Compared with the control group (CK), A4 and L2 treatments increased plant height by 71.74% and 67.94%, respectively; A2 and L2 treatments increased ground diameter by 60.00% and 45.40%, respectively. Chlorophyll and carotenoid contents were significantly increased by A3 and L3 treatments, where the increase in chlorophyll a, chlorophyll b, total chlorophyll and carotenoids were 147.64%, 90.62%, 122.08%, 213.43% and 130.27%, 121.03%, 126.85% and 280.07%, respectively. The A2 treatment increased the net photosynthetic rate (P_n) compared to the 93.03% and 66.66% in the control (CK) and nitrogen fertilizer treatment (N), respectively. qP and ETR of A2-treated leaves were 31.03% and 35.95% higher than that of CK, and 46.15% and 33.75% higher than that of N group, respectively. In addition, superoxide dismutase (SOD) activities of A4 and L2 treatments were significantly higher than CK and N by 24.69%, 28.57% and 51.82%, 56.54%, respectively, while peroxidase (POD) and catalase (CAT) activities were enhanced. The comprehensive evaluation of principal component analysis and affiliation function indicated that the growth, photosynthetic characteristics and antioxidant enzyme activities of Camellia oleifera performed best under A2 treatment.

The microbial fertilizer and Randidobond significantly promoted the growth of Camellia oleifera seedlings, and enhanced the antioxidant enzyme activities by increasing the chlorophyll content, gas exchange parameters, chlorophyll fluorescence parameters of the leaves, effectively enhanced the photosynthesis of the plants, and provided a strong support for the high-efficiency cultivation of Camellia oleifera.

In order to simulate and predict the suitable habitat distribution of rare and endangered Dipterocarpaceae tree species in China, conduct conservation priority area and conservation GAP analysis, and to provide a basis for their protection and management.

Based on climate, terrain, soil, and human impact factors, MaxEnt model optimized was used with R language to simulate and predict the suitable habitats and changing trends of eight rare and endangered Dipterocarpaceae trees in China. The Marxan model was combined to identify priority areas for the protection of rare and endangered Dipterocarpaceae tree species and conducted a protection GAP analysis.

The results showed that: 1) The optimized MaxEnt model simulated the suitability zone of various tree species with high accuracy, with AUC values greater than 0.971; 2) Rare and endangered Dipterocarpaceae plants in China are mainly distributed in southern tropical regions such as Yunnan, Hainan, and Guangxi, with a relatively concentrated distribution range; 3) Annual mean temperature, isothermality, and human impact factors are the dominant factors affecting the distribution of the suitable habitat of Dipterocarpaceae tree species. Among these, annual mean temperature has the greatest impact on Dipterocarpaceae tree species, with an average contribution rate of 52.9%; 4) Under the SSPs126 and SSPs585 scenarios, the suitable areas for Dipterocarpus retusus, Hopea chinensis, Parashorea chinensis, Vatica mangachapoi decrease by 0.29% to 60.00%, and the center of gravity of the suitable areas shifts southwestward. Shorea assamica and Vatica guangxiensis expand by 8.60% to 52.22%, migrating northwest and northeast, respectively. The suitable areas for Hopea hainanensis and Hopea reticulata land decrease by 21.70% and 1.61%, respectively, under the SSPs126 scenario, and expand by 26.14% and 13.01%, respectively, under the SSPs585 scenario, with their centers of gravity shifting northeastward; 5) The priority areas for the protection of rare and endangered tree species of the Dipterocarpaceae family are mainly distributed in southern Yunnan Province and central Hainan Province. Currently, the protected area is only 0.515 6×10⁴ km².

The optimized MaxEnt model can effectively predict the suitable habitats of various tree species in the Dipterocarpaceae. The priority suitable habitats are not sufficiently protected, so efforts should be made to strengthen their protection and expand the distribution range of each tree species.

To accurately predict the growth dynamics of Chinese fir and construct a dominant tree diameter at breast height (DBH) growth model that integrates site and climatic conditions, and to provide guidance for sustainable management and carbon sequestration assessment of Chinese fir plantations.

Utilizing 1 121 DBH-age datasets from 129 Chinese fir plantation plots, topographic, edaphic and climatic factors were incorporated. Significant environmental drivers affecting DBH growth were identified through Quantification Theory I. The optimal theoretical growth equation was selected from six candidate models. Site types and climate types were clustered into site type groups and climate type groups using the k-means algorithm. Nonlinear mixed-effects regression models were developed by incorporating site type, climate type, and their clustered groups as random effects, either individually or in combination.

Seven leading factors influencing DBH growth of dominant trees, including altitude, aspect, Climatic moisture deficit and extreme minimum temperature, were screened. Among the six basic models, the Korf model had the best fitting effect, with a determination coefficient R² of 0.782 0, 75 site types and 173 climate types clustered into 5 site type groups and 7 climate type groups, respectively, and the random effect model R² with site factor groups and climate factor groups only was 0.822 9 and 0.839 1, respectively, and the random effect model with site and climate factors was R²= 0.854 3 which was significantly better than the other models.

The nonlinear mixed-effects model developed in this study, which integrates site- and climate-effects, comprehensively incorporates environmental factors influencing the DBH growth of dominant Chinese fir trees. This model not only provides scientific guidance for predicting the DBH growth of dominant Chinese fir trees, but also establishes a generalizable modeling framework for analyzing and forecasting environmental impacts on the growth of subtropical Chinese fir plantations.

To investigate the effects of nitrogen addition on water use efficiency and related enzyme activities of P. massoniana seedlings under continuous drought and re-watering, and to provide reference for exploring whether nitrogen addition improves drought resistance of P. massoniana.

One-year-old P. massoniana seedlings were used as experimental materials, and a nitrogen application group (N) and a control group (CK, no nitrogen fertilizer applied) were set up. Continuous drought and re-watering experiments were conducted through potted plants. Samples were collected at 0, 20, 40, and 60 days during continuous drought, as well as two days after re-watering. Soil water content, physiological and biochemical indices, and water consumption were measured for drought resistance evaluation.

1) The nitrogen application group increased soil moisture content, stem water potential, amino acid content, and water consumption of seedlings during the severe extreme drought stage (20-60 days), while reducing soluble protein, superoxide anion, and malondialdehyde content during the extreme drought stage (40-60 days); 2) During 40-60 days of drought, the nitrogen application group showed a significant increase in amino acid, proline content, and CAT activity; 3) After re-watering, the soluble protein, superoxide anion, and malondialdehyde content, as well as the activities of superoxide dismutase and catalase, were significantly reduced in the nitrogen application group, while the control group maintained high levels, indicating weak recovery ability after drought; 4) The comprehensive evaluation of drought resistance was conducted on physiological and biochemical indicators using the membership function method. The results showed that during the extreme drought stage (40-60 days), the nitrogen application group exhibited strong drought resistance.

Nitrogen application can improve soil water retention during drought periods, increase the content of osmoregulatory substances in P. massoniana seedlings, and enhance antioxidant enzyme activity, thereby reducing cell dehydration and mitigating oxidative damage to seedlings, thus improving their drought resistance and post-drought recovery ability under drought stress.

In order to provide a reference for the maintenance and protection of the natural population of Picea neoveitchii, this study discussed the structure and development trend of Picea neoveitchii in the field, revealing the current situation and development trend.

This study investigated the population of Picea neoveitchii in two existing areas, Zhouqu and Tianshui, Gansu. Utilizing population ecology methods, statistical analyses are performed on aspects such as the age-class structure, population dynamics, and viability of the populations. Additionally, a time series model was employed to predict the characteristics of the population quantity structure.

The results showed that: 1) The population in Zhouqu had a relatively abundant number of seedlings and saplings, with an age structure approximating a bell shape, indicating a stable population. The population in Tianshui was in a remnant state, with fewer than 10 individuals and scarce seedlings, suggesting insufficient potential for regeneration and classifying it as a declining population. Both populations were highly sensitive to external disturbances and had weak anti-disturbance capabilities; 2) The survival curve of the Picea neoveitchii population followed Deevey-Ⅱ, with equal mortality rates at all age groups. The population was in a relatively stable state, and the survival curve showed two peaks of extinction occurring in the Ⅱ and Ⅵ age groups; 3) The survival analysis function indicated that the survival rate (S_t) decreased with increasing age, while the cumulative mortality rate (F_t) increased with increasing age. After diameter class IV, the survival rate of the Picea neoveitchii population balances with its cumulative mortality rate, and the changes in the mortality density curve (f_ti) and hazard rate curve (λ_ti) were basically consistent, showing an overall upward trend, the upward trend slowed down in age groups II to IV, and the increase was more significant after age group IV; 4) The analysis based on the time series prediction model revealed that after undergoing periods of 2, 3, 4, 5, 6, and 7 diameter classes in the future, the number of individuals across all diameter classes of the Picea neoveitchii population was projected to show an overall upward trend. Moreover, the longer the time span within the same diameter class, the more significant the increase in the number of individuals becomes. The population was a growth population, but normal updates were difficult to maintain in the long term without considering external factors.

This study suggested that the population stability of Picea neoveitchii was poor, it was highly sensitive to the environment, and its ability to resist external interference was weak. It is recommended that the species be included in conservation programs for extremely small populations, with protected areas established. Increased investment in scientific research is needed to enable long-term, systematic monitoring and evaluation of population dynamics. Explore the research and development of artificially modified and intervention-applicable technologies to construct suitable habitats that align with the characteristics of Picea neoveitchii; establish in-situ conservation demonstration zones and conduct research and demonstration of key techniques for wild reintroduction.

To explore the changing patterns of carbon storage at different development stages of forest stands, identify the factors influencing carbon storage, and to provide a theoretical foundation for the scientific management, operation, and enhancement of forest carbon storage.

Focusing on Quercus mongolica forests in the east of Liaoning mountainous area, the carbon storage in the arboreal layer was estimated using the anisotropic growth equation. Additionally, the carbon stocks of shrubs, herbs, litter, and soil within representative sample plots were measured utilizing the sampling method. Our analysis of these data elucidated the characteristics of ecosystem carbon storage across different developmental stages of Q. mongolica forests. Moreover, redundancy analysis was employed to identify the key environmental factors influencing variations in carbon storage.

1) The ecosystem carbon storage of Q. mongolica forests in the east of Liaoning mountainous area is 296.13, 332.65, 300.72, and 503.55 t·hm^-2 for young, half-mature, mature, and overmature forests, respectively. Notably, overmature forests exhibit the highest carbon stocks, significantly surpassing those of the other developmental stages. (P<0.05); 2) Among the ecosystem components, the carbon stock in the soil layer (0-30 cm) accounted for the largest proportion. As the forest progresses through its developmental stages, carbon storage in the vegetation layer gradually increases, while the proportion of soil carbon stock decreases; however, it consistently remains above 50%; 3) The proportion of carbon storage in the vegetation layer exhibits a trend of initially increasing and then decreasing with forest age, reaching its maximum of 48% in mature forests; 4) Elevation, aspect, and soil total phosphorus content are the primary environmental factors influencing variations in carbon storage, collectively accounting for 20.5%, 12.1%, and 3.6% of the total variation in ecosystem carbon storage, respectively.

Among the various development stages of Q. mongolica forests in the east of Liaoning mountainous area, carbon storage remains relatively stable from the young to mature stages, while overmature forests exhibit the highest ecosystem carbon stocks. The soil layer constitutes the primary component of carbon storage within the ecosystem, followed by the vegetation layer. Elevation is the most significant factor influencing changes in ecosystem carbon storage, followed by aspect and total phosphorus content in the soil.

The restoration and improvement of the degraded natural grassland ecosystem in the Qilian mountains rely heavily on the strong support of composite measures. This study aims to enhance grassland productivity and forage quality in the Qilian mountains, providing technical references for ecological restoration.

Compound measures for grassland improvement, including grass seed combination reseeding, reseeding with grass seed mixtures + compound fertilizer + pest control, were adopted to investigate their effects on species diversity, grassland productivity, and forage nutritional value in the grassland ecosystem.

1) After adopting composite measures, the species composition of the temperate grassland plant community in the northern foothills of the Qilian mountains significantly improved compared to the control grassland; the average vegetation height and grass yield also significantly increased by 20.9% and 56.8%, respectively. 2) After adopting the combined measures of “Poa pratensis + Elymus nutans + Dongnong 1 alfalfa” plus “Agropyron cristatum” or “Bromus inermis”, the Shannon-Wiener diversity index of the community significantly increased compared to the control. The combined measures of “Poa pratensis + Elymus nutans” plus “Dongnong 1 alfalfa + Agropyron cristatum” or “Elymus sibiricus + Bromus inermis” followed by the application of nitrogen, phosphorus, potassium compound fertilizer and nicotine-matrine insect control measures significantly increased the Pielou evenness index and Margalef richness index. The Simpson ecological dominance index and Simpson diversity index of the community in the experimental area showed no significant difference compared to the control; 3) After adopting the combined measures of “Poa pratensis + Elymus nutans” plus “Dongnong 1 alfalfa + Elymus sibiricus” or “Dongnong 1 alfalfa + Agropyron cristatum” or “Agropyron cristatum + Ganyin 1 rye”, the crude protein content of the grassland forage significantly increased compared to the control, by 30.2%, 19.8% and 32.7%, respectively. After adopting the combined measures of “Poa pratensis + Elymus nutans + Dongnong 1 alfalfa” plus “Ganyin 1 rye” or “Elymus sibiricus” or “Agropyron cristatum” followed by the application of nitrogen, phosphorus, potassium compound fertilizer and nicotine-matrine insect control measures, the crude protein content of the grassland forage significantly increased compared to the control, by 19.8%, 47.7% and 18.0%, respectively.

The combination of “Kentucky bluegrass + Elymus nutans + Dongnong No.1 alfalfa + Agropyron cristatum” and the application of nitrogen, phosphorus, and potassium compound fertilizer and nicotine-matrine insect control measures performed optimally, significantly enhancing grassland productivity and improving grassland quality, greatly increasing grassland carrying capacity, and providing a scientific basis for the restoration and management of the Qilian mountain grassland ecosystem.

The middle section of the Yinshan mountains in Inner Mongolia, as a representative area of the Three-North Shelter Forest Program, faces critical challenges in enhancing ecosystem carbon sequestration functions. This study aims to investigate the diurnal variation characteristics of photosynthesis and water use efficiency (WUE) in arbor and shrub species in the Middle Section of the Yinshan Mountains, analyze the influence of environmental factors on photosynthetic regulation, and comprehensively evaluate the ecological adaptability and carbon sequestration functions of different tree species. For the first time, a combination of random forest regression models and cluster analysis is applied to provide scientific insights for improving shelter forest ecosystem functions.

Seven arbor species and five shrub species were selected in the middle section of the Yinshan mountains, Inner Mongolia. Photosynthetic parameters were measured using a CI-340 portable photosynthesis system. Spearman's correlation analysis, principal component analysis (PCA), random forest regression modeling, and hierarchical cluster analysis were employed to explore the photosynthetic mechanisms and ecological adaptability of the species.

The study revealed distinct diurnal variation patterns in photosynthetic activity among arbor and shrub species. Net photosynthetic rate (P_n) and WUE exhibited significant interspecific differences, with single-peak and double-peak patterns observed. Temperature, stomatal conductance, and transpiration rate were identified as key regulators of photosynthesis, particularly in coniferous species, which demonstrated higher WUE. Random forest regression analysis highlighted the critical roles of temperature and water management in photosynthetic processes. Cluster analysis further revealed marked differences in carbon sequestration capacity and ecological adaptability among species, offering critical guidance for species selection and carbon sequestration assessments.

This study underscores the significant differences in photosynthesis and WUE between arbor and shrub species in the middle section of the Yinshan mountains. Temperature, stomatal conductance, and transpiration rate were pivotal in photosynthetic regulation. Unlike traditional linear regression methods, the random forest model effectively captured the nonlinear relationships between environmental variables and photosynthetic rates. The hierarchical cluster analysis, applied for the first time in this context, identified distinct functional groups of species based on their carbon sequestration potential and ecological adaptability. These findings fill a critical gap in understanding photosynthetic mechanisms and carbon sequestration capacity within the Three-North Shelter forest program, providing a novel framework for quantitative carbon sequestration assessment and informing future afforestation and restoration strategies.