Abstract:Frequent extreme high temperature and heat waves seriously threaten the growth and survival of urban plants. The heat resistance of leaves can reflect the tolerance and adaptability of plants to heat stress. Exploring the relationship between leaf heat tolerance and their structural traits in urban garden tree species can reveal the ecological adaptation strategies of urban plants under heat stress, thereby enhancing the predictive ability of their responses and adaptations to high temperatures. This study took 10 common urban garden tree species in Chongqing (3 species of Ficus from Moraceae, 4 species of Magnolia from Magnoliaceae, and 3 species from Rosaceae) as research subjects, comparing their leaf damage rates, heat tolerance, and structural traits during the 2022 heatwave event, and analyzing their different heat adaptation strategies. The results showed that there was a significant negative correlation between leaf damage rate and heat tolerance under natural heatwaves. The leaves of Ficus species from Moraceae had higher heat tolerance, resulting in lower leaf damage rates; while Magnolia species and Rosaceae species had lower heat tolerance, but they might avoid heat stress through adaptation strategies such as changing leaf inclination angles and shedding leaves during heatwaves. Additionally, heat tolerance was significantly negatively correlated with leaf area, upper epidermis thickness, and the ratio of palisade to spongy tissue thickness. These traits can predict leaf heat tolerance relatively well. Therefore, the study of heat adaptation strategies of three typical urban garden woody plants under heatwaves is of great significance for the selection of heat-tolerant tree species in cities and the prediction of damage risks to trees under heat stress.

Abstract:Polygonatum kingianum, as one of the important traditional Chinese medicinal materials in Yunnan, has seen a decline in its wild resources due to over-harvesting, and the research on its artificial cultivation is relatively insufficient, which has seriously affected the protection and utilization of its resources. Therefore, predicting the spatial changes of its potential suitable habitat is of great significance. The potential suitable habitat of P. kingianum in China was predicted by using Maxent model and geographic information system, combined with 63 valid distribution records in China and 15 environmental variables. The results showed that the area under the receiver operating characteristic curve was 0.971, indicating that the model had good predictive ability; the suitable habitat of P. kingianum was mainly concentrated in the southwest region of China, including Yunnan, Guizhou, Guangxi, Sichuan and Chongqing; annual precipitation, precipitation in the driest quarter, altitude and the lowest temperature in the coldest month played a key role in the geographical distribution of P. kingianum; in the future, the center of the suitable habitat of P. kingianum will gradually shift towards Guizhou. This would be provided a theoretical basis for the in-situ and ex-situ conservation of P. kingianum and the selection of artificial high-efficiency and high-quality cultivation bases, and has important practical significance for the protection and utilization of its germplasm resources.

Abstract:To explore the significance of Casuarina equisetifolia as a major tree species in coastal protective forests for improving and maintaining the water conservation function of the ecosystem, this study took the litter and soil of four types of forests, namely pure C. equisetifolia forests, pure Eucalyptus urophylla forests, mixed coniferous and broad-leaved forests, and natural forests, as the research objects, and measured their hydrological characteristics and related physical and chemical properties. The results showed that pure C. equisetifolia forests could accumulate significantly more litter than other forests in a short period of time [(36.83±1.11) t/hm²], which was 2 to 3 times that of other forests; they could absorb more water in the same period of time, and their saturated water holding capacity could reach 2 to 3 times that of other forests [(102±2.15) t/hm²]. At the same time, the average water loss rates of the litter of the four types of forests in each time period were similar, indicating that forests with higher water absorption capacity could have better water retention effects. In addition, soil moisture content was significantly positively correlated with the saturated water holding capacity, effective water retention rate, maximum water retention rate and carbon-nitrogen ratio of the litter, indicating that the hydrological characteristics and chemical properties of the litter had a significant impact on soil moisture retention. Pure C. equisetifolia forests showed significant advantages in water retention capacity and ecosystem water conservation function improvement in sandy coastal areas, which was of great significance for improving the hydrological function of the ecosystem. This study provided important theoretical basis and practical reference for the ecological restoration and sustainable management of sandy coastal areas, and at the same time provided scientific guidance for the future management strategies of coastal protective forests and the optimization of ecosystem service functions.

Abstract:To explore the effects of leaf position and leaf order on the photosynthesis and inorganic carbon utilization of tropical seagrasses, the light response curves, photosynthetic fluorescence, pH drift and HCO₃^– utilization of different parts of the leaves of Thalassia hemprichii and Cymodocea rotunda in the same habitat were studied. The results showed that the middle part of the seagrass leaves had a higher net photosynthetic rate (P_n), the base was higher than the top, and the young leaves were higher than the mature leaves; the maximum photosynthetic efficiency (F_v/F_m) of the leaf top was lower than that of other parts; the photosynthetic pigment content in the middle part of the leaves was higher than that in the top and base, and the photosynthetic pigment content in the young leaves was higher than that in the mature leaves. Both seagrass species could effectively utilize HCO₃^– in seawater as a carbon source, but the mature leaves had a better ability to utilize HCO₃^– than the young leaves, and the middle part of the leaves had a better ability to utilize HCO₃^– than the top and base. Therefore, although the two seagrass species have developed similar strategies for light energy and HCO₃^– utilization in the same habitat, their photosynthesis and inorganic carbon utilization capabilities vary with leaf position and leaf order.

Abstract:To promote the application of Araucariaceae plants, the salt tolerance of four Araucariaceae species, such as Araucaria cunninghamii, A. heterophylla, A. bidwillii and Agathis dammara, was compared. After 28 days of salt stress, the salt damage of the four species was statistically analyzed, the related physiological indicators were measured, and their salt tolerance was comprehensively evaluated by the membership function method. The results showed that under 500 mmol/L NaCl stress for 28 days, the salt damage rate of the four species was all 100%; the salt damage index was in the order of Araucaria cunninghamii>Agathis dammara>　Araucaria heterophylla>A. bidwillii; the chlorophyll content, F_v/F_m, q_p and K⁺/Na⁺ of the four species were significantly lower than those of the control; the soluble sugar content was significantly higher than that of the control; the proline content of A. bidwillii was significantly lower than that of the control, while that of the other three species was significantly higher than that of the control; the POD activity in the leaves of A. cunninghamii and A. heterophylla significantly increased, while that of the other two species did not change significantly; the MDA content and SOD activity in the leaves of the four plants did not change significantly. Based on the comprehensive evaluation of 11 salt tolerance indicators, the salt tolerance of the four speciess was in the order of A. heterophylla > Agathis dammara > Araucaria bidwillii > A. cunninghamii.

Abstract:In order to explore the tolerance mechanism and dynamic migration of Zn in torpedograss (Panicum repens), the accumulation and transport capacity of Zn in roots, stems and leaves, as well as the distribution characteristics of Zn subcellular and chemical states were studied by hydroponic pot experiment. The results showed that the maximum Zn contents in roots, stems, and leaves were 2 728.38, 388.63 and 1 199.07 mg/kg, respectively, and their enrichment factors (with a maximum of 3.11) all exceeded the international limit for super-accumulating plants. The average migration rate from root to leaf (264.99%) was much higher than that from stem to leaf (14.16%). With the extension of stress time and the increase of Zn concentration, the Zn contents in stems and leaves significantly increased (P<0.05). However, the change in Zn content of root showed a “Λ” type, reaching the highest value at 21 days. The roots and leaves were detoxicated mainly by cell wall fixation (more than 58%), while the stems were detoxicated mainly by vacuole compartments. The Zn in the roots and leaves mainly exists in the NaCl extraction state, with the highest proportions of 75.40% and 61.05%, respectively, followed by organic state (HAc and HCl), which mainly reduces the damage by allocating more Zn to the less active chemical state storage. The Zn in stems is mainly in the form of ethanol and d-H₂O with high activity, and the higher fluidity of Zn ions enhances the transport from stem to leaf, resulting in higher Zn content in leaves. Therefore, Panicum repens exhibits strong Zn tolerance and accumulation capacity, and has the potential and advantage of ecological remediation of heaviy Zn-contaminated water-level-fluctuation zones in tropical and subtropical regions.

Abstract:To explore the eco-physiological adaptation strategies of mangrove plants to light intensity and guide the species configuration of different layers in artificial mangrove communities, eight common mangrove species, including Sonneratia apetala, Kandelia obovata, Bruguiera gymnorhiza, Aegiceras corniculatum, Acanthus ilicifolius, Acrostichum aureum, Heritiera littoralis, and Talipariti tiliaceum, were selected as research subjects. Through shading control experiments, the leaf gas exchange parameters, water use efficiency (WUE), and photosynthetic nitrogen use efficiency (PNUE) of one-year-old seedlings under different growth light intensities (100%, 45%, 30%, and 10% of natural light intensity) were compared. The results showed that the net photosynthetic rate (P_n) of B. gymnorhiza, Aegiceras corniculatum, and Acanthus ilicifolius did not show statistical differences under different light intensities, while K. obovata, Acrostichum aureum, H. littoralis, and T. tiliaceum exhibited higher P_n under 45% or 30% light conditions, indicating that B. gymnorhiza, Aegiceras corniculatum, and Acanthus ilicifolius showed better adaptability to different light intensities in terms of P_n. The stomatal conductance (g_s) and intercellular CO₂ concentration (C_i) of K. obovata, Aegiceras corniculatum, H. littoralis, and T. tiliaceum under 100% light intensity were significantly lower than those under shading treatments. The WUE of Aegiceras corniculatum and Acrostichum aureum under shading conditions was significantly higher than that under full light conditions, indicating that the WUE of Aegiceras corniculatum and Acrostichum aureum showed adaptability to low light. The PNUE of the seven mangrove species except Aegiceras corniculatum increased under shading conditions. The chlorophyll content of the eight mangrove species increased with the increase of light intensity, but their trends in chlorophyll a/b were different. Therefore, Bruguiera gymnorhiza, Aegiceras corniculatum, Acanthus ilicifolius, and Acrostichum aureum are more shade- tolerant and suitable for planting under the forest canopy, while K. obovata, H. littoralis, and T. tiliaceum are more suitable as middle and upper layer tree species or for planting under a less dense canopy.

Abstract:To understand the physiological response mechanisms and post-drought recovery capabilities of different tree species to drought stress, a pot experiment was conducted on the seedlings of Michelia maudiae and Elaeocarpus decipiens, which have both ornamental and ecological values. Gas exchange parameters, leaf water status, superoxide dismutase (SOD) activity, and osmotic adjustment substances were measured during the drought and rewatering processes. The results showed that under drought stress, the leaf water potential and photosynthetic parameters of E. decipiens seedlings decreased more rapidly than those of M. maudiae, with a 99.1% decrease compared to the control after only 6 days. Before rewatering, the SOD activity in the leaves of M. maudiae and E. decipiens seedlings was 36.1% and 33.4% of the control, respectively; the proline content in the leaves of the two tree species was 2.1 and 5.5 times that of the control, respectively; however, the soluble sugar content of E. decipiens seedlings was not significantly different from that of the control. Seven days after rewatering, the net photosynthetic rate, stomatal conductance, and transpiration rate of M. maudiae seedlings did not yet recover to the control level, while those of E. decipiens seedlings fully recovered. The SOD activity and osmotic adjustment substances of the two tree species gradually returned to the control level after rewatering. Therefore, there are differences in the response to drought stress and post-drought recovery capabilities between M. maudiae and E. decipiens seedlings. Elaeocarpus decipiens is more sensitive to drought but has a stronger recovery ability after rewatering than M. maudiae. This study clarifies the physiological response mechanisms of M. maudiae and E. decipiens to drought and rewatering from the perspective of plant physiology, providing a reference basis for practical applications such as seedling cultivation management, landscaping, and tree species selection.

Abstract:Manglietia longipedunculata, an evergreen broad-leaved plant belonging to the genus Manglietia of the Magnoliaceae family, has only been found in one population in the Nankunshan Provincial Nature Reserve in Longmen City, Guangdong Province. It was currently classified as critically endangered (CR). In this study, the petroleum ether fraction, ethyl acetate fraction, n-butanol fraction and water fraction from stems and leaves were obtained by solvent extraction. The anti-tumor, antioxidant and anti-inflammatory activities of different fractions were evaluated using multiple biological activity test models. The results showed that the petroleum ether fraction of the stems and leaves had the best anti-tumor activity, followed by the ethyl acetate fraction, while the n-butanol and water fractions had almost no anti-tumor activity. The petroleum ether fraction of the stems and leaves had the best anti-inflammatory activity, with IC₅₀ values of (7.20±0.22) and (14.96±0.61) µg/mL, respectively. The ethyl acetate fraction of the stems and leaves had the best antioxidant activity, with IC₅₀ values of (5.12±0.13) and (0.46±0.09) µg/mL, respectively. The functions of its stem and leaf extracts were evaluated at the first time, which could provide a material basis and theoretical support for its later development and utilization.

Abstract:To understand the antioxidant active components in fruits of Amalocalyx yunnanensis, the antioxidant activity and cytotoxicity of different polar fractions of the fruit’s ethanol extract were evaluated through in vitro antioxidant experiments and the MTT colorimetric method. Meanwhile, the total acid and total phenol contents of each fraction were determined, and their correlations with antioxidant activity were analyzed. The chemical components of the fraction with the best antioxidant activity were analyzed by ultra-high performance liquid chromatography coupled with Q-Exactive Orbitrap mass spectrometry (UHPLC-QE-MS) to identify the anti- oxidant active components. The results showed that the ethanol extract of A. yunnanensis fruits and its different polar fractions all had certain antioxidant activities and were non-toxic to LO₂ cells. The total acid and total phenol contents were positively correlated with antioxidant activity. Among them, the ethyl acetate fraction had the strongest antioxidant activity and the highest total acid and total phenol contents, which were 835 g/kg and 14.49%, respectively. Through UHPLC-QE-MS analysis, a total of 98 compounds were identified, among which flavonoids and phenolic acids accounted for 30.21% and 14.58%, respectively, which might be the main active components of the ethyl acetate fraction. Therefore, it could provide a basis for the development of A. yunnanensis fruits as natural and safe antioxidants.

Abstract:Fulvic acid is a key component of humic acid, which plays an important role in enhancing soil property, improving plant growth, and promoting plant stress resistance. The physiological functions of fulvic acid were reviewed from the aspects of promoting seed germination, enhancing root growth, promoting nutrient absorption, and improving crop yield and quality, etc. The possible mechanism of fulvic acid promoting crop growth was systematically summarized, and the key factors of fulvic acid research and the internal relationship with systemization of root-soil was further looked forward. These would provide theoretical basis for further understanding of the functional diversity of fulvic acid, which is of great significance for ecological and sustainable agriculture development.

Abstract:Wetland ecosystems play crucial roles in water regulation, water purification, and biodiversity conservation. However, the conflict between human development and ecological protection is becoming increasingly prominent. Wetland parks can effectively balance biodiversity conservation with the creation of habitable environments for humans, promoting harmonious coexistence between humanity and nature. This paper reviews the conceptual classification, policy evolution, construction achievements, existing challenges, and potential solutions for wetland parks in China, aiming to provide insights for future planning. Research indicates that studies on wetland parks in China have rapidly expanded, with a shift in focus from social service functions to mechanisms sustaining natural biodiversity. Current classification systems are primarily based on composition, conservation type, and area, while future management could be refined according to functional service differentiation. In recent years, China has strengthened wetland protection through legislation, emphasizing the “ecological, scenic, and service-oriented” characteristics of wetland parks. However, improvements in planning and management remain necessary. Future efforts should include: coordinating local livelihoods with wetland park construction to minimize conflicts; Enhancing ecological prioritization and reducing artificial interventions; Implementing scientific zoning to highlight wetland-specific features; Optimizing management systems and improving interdepartmental collaboration; Increasing public participation and enhancing professional management capacity; Refining legal frameworks and enforcement mechanisms; Strengthening technological support for dynamic monitoring and ecological restoration. These efforts will help fight climate change, support national priorities, and unlock wetland parks’ full potential for ecology and local economies.