Evergreen Research Articles

Multiple Phytophthora species associated with declining wild olive trees in Sardinia, Italy

AbstractWild olive represents one of the most iconic woody plants in the Mediterranean Basin. This slow‐growing evergreen tree is characteristic of sclerophyll vegetation, extremely tolerant to drought, salinity and diseases, thus is commonly used as rootstock for grafting cultivated olive varieties. Since 2022, extensive dieback and mortality of wild olive trees have been observed in Sardinia, Italy. Affected plants showed leaf chlorosis, wilting, defoliation, shoot blight and epicormic shoots, often associated with root rot and necroses on the feeder roots, initially associated with Phytophthora bilorbang and P. pseudocryptogea. A 2‐year study was thereafter conducted to clarify the aetiology of this unusual disease. Using a baiting technique, 10 Phytophthora taxa from three phylogenetic clades (2, 6, 8) were isolated from 53 of 87 rhizosphere soil samples collected, including P. asparagi, P. bilorbang, P. crassamura, P. inundata, P. kelmanii, P. oleae, P. pseudocryptogea, P. sansomeana and P. syringae. Additionally, some isolates that showed several polymorphisms in rDNA internal transcribed spacer (ITS) sequences compared with closely related known species are reported here as P. taxon paulensis. Pathogenicity tests on 1‐year‐old wild olive seedlings showed that nine out of 10 Phytophthora taxa significantly reduced root length of inoculated seedlings compared to controls. P. inundata and P. oleae caused the greatest reduction, while root length of seedlings inoculated with P. kelmanii did not differ from the controls. This study provides insights into the role of Phytophthora taxa in the wild olive decline in Sardinia, indicating the urgent need to expand monitoring and implement effective management strategies to mitigate the disease.

Mechanisms Maintaining Biomass Stability in Woody Species Communities in Evergreen Broadleaved Forests of Dong Nai Culture and Nature Reserve, Dong Nai province, Southern Vietnam

Tropical forest ecosystems experience dynamic changes in response to environmental fluctuations and disturbances. Understanding the mechanisms governing their stability is crucial for maintaining ecosystem services. Among these ecosystems, evergreen broadleaved forests play a pivotal global role. This study investigates the impacts of overyielding, stand structure, species asynchrony, and the stability of dominant species on community biomass stability (CBS) within the Dong Nai Culture and Nature Reserve's evergreen broadleaved forests. The study utilized species richness, diameter-at-breast-height (DBH) variation coefficient, species asynchrony, and stability of dominant species as explanatory variables. The response variables included CBS, mean biomass (µ), and biomass standard deviation (σ). Three structural equation models (SEMs) were constructed to assess the relative strengths of direct and indirect effects among these variables. The results indicated that: (1) The SEMs achieved a good fit, explaining 41.8% of the variance in CBS. (2) Species richness negatively correlated significantly with µ (path coefficient = -0.112) and σ (-0.056). (3) DBH variation coefficient showed significant negative correlations with CBS (-0.161) and µ (-0.087). (4) Species asynchrony exhibited significant positive correlations with CBS (0.061), µ (0.076), and σ (0.061). (5) Dominant species stability showed significant positive correlations with CBS (0.588) and µ (0.153) and a negative correlation with σ (-0.588). These findings underscore that while stand structure and species asynchrony significantly influence CBS in evergreen broadleaved forests, the stability of dominant species emerges as the primary predictor of CBS. Therefore, effective forest management strategies should prioritize conserving and enhancing conditions that support dominant species, ensuring the sustainability of forest ecosystems in the study area.

Understory Environmental Conditions Drive Leaf Level-Lipid Biosynthesis in a Deciduous and Evergreen Tree Species.

Plants in the understory experience climatic conditions affected by the overstory canopy that influence physiological and biochemical processes. Here, we investigate the relationships of leaf lipid molecular abundances to leaf water content, transmitted irradiance, and free-air temperature (Tair) from deciduous angiosperm (Quercus buckleyi) and evergreen gymnosperm (Juniperus ashei) understory trees across an elevation gradient in a central Texas (USA) woodland. Monthly sampling from 04/2019 to 01/2020 revealed that long-chain leaf waxes (≥ C27) accumulated with leaf water deficit over the growing season for both tree species. Higher transmitted light during the hottest, driest months was due to a decreased leaf area index (LAI) in the canopy as leaf shedding is a common drought response. Isoprenoids (sesqui-, di-terpenoids, phytosterols) in leaves changed by month with changing LAI and transmittance associated with monthly Tair changes. The chain length of n-alkanols in Q. buckleyi shifted with seasonal LAI at different topographic positions. The unsaturation of fatty acids in both tree species decreased with increased seasonal Tair but showed topography sensitivity. Leaf-level metabolites responded to understory microclimatic variables that were influenced by seasonality and topography.

Internal physiological drivers of leaf development in trees: Understanding the relationship between non‐structural carbohydrates and leaf phenology

Abstract Plant phenology is crucial for understanding plant growth and climate feedback. It affects canopy structure, surface albedo, and carbon and water fluxes. While the influence of environmental factors on phenology is well‐documented, the role of plant intrinsic factors, particularly internal physiological processes and their interaction with external conditions, has received less attention. Non‐structural carbohydrates (NSC), which include sugars and starch essential for growth, metabolism and osmotic regulation, serve as indicators of carbon availability in plants. NSC levels reflect the carbon balance between photosynthesis (source activity) and the demands of growth and respiration (sink activity), making them key physiological traits that potentially influence phenology during critical periods such as spring leaf‐out and autumn leaf senescence. However, the connections between NSC concentrations in various organs and phenological events are poorly understood. This review synthesizes current research on the relationship between leaf phenology and NSC dynamics. We qualitatively delineate seasonal NSC variations in deciduous and evergreen trees and propose testable hypotheses about how NSC may interact with phenological stages such as bud break and leaf senescence. We also discuss how seasonal variations in NSC levels, align with existing conceptual models of carbon allocation. Accurate characterization and simulation of NSC dynamics are crucial and should be incorporated into carbon allocation models. By comparing and reviewing the development of carbon allocation models, we highlight the shortcomings in current methodologies and recommend directions to address these gaps in future research. Understanding the relationship between NSC, source–sink relationships, and leaf phenology poses challenges due to the difficulty of characterizing NSC dynamics with high temporal resolution. We advocate for a multi‐scale approach that combines various methods, which include deepening our mechanistic understanding through manipulative experiments, integrating carbon sink and source data from multiple observational networks with carbon allocation models to better characterize the NSC dynamics, and quantifying the spatial pattern and temporal trends of the NSC‐phenology relationship using remote sensing and modelling. This will enhance our comprehension of how NSC dynamics impact leaf phenology across different scales and environments. Read the free Plain Language Summary for this article on the Journal blog.

The Impact of Bamboo (Phyllostachys edulis) Expansion on the Water Use Patterns of Broadleaf Trees

The expansion of bamboo (Phyllostachys edulis) affects the growth status of trees in colonized forests, but there has been insufficient research on changes in tree water physiology. In this study, we used stable δ2H, δ18O, and 13C isotope ratios to analyze the water sources and water use efficiency (WUE) of bamboo, deciduous broadleaf trees (Alniphyllum fortunei), and evergreen broadleaf trees (Machilus pauhoi and Castanopsis eyrei) in a bamboo-expended broadleaf forest (BEBF), a bamboo-absent broadleaf forest (BABF), and a bamboo forest (BF). We found that the expansion of bamboo had no significant effect on the water sources and WUE of deciduous broadleaf trees, but altered the water sources of evergreen broadleaf trees. During the growing season, evergreen broadleaf trees decrease their uptake fractions of surface soil water by 7.1% to 9.6% and increased their uptake fractions of middle soil water by 5.8%~9.4%. Conversely, during the non-growing season, they increased their uptake fractions of surface soil water by 11.9% and decreased their uptake fractions of deeper soil water by 5.6%~12.9%. Additionally, after expanding into broadleaf forests, bamboo increased its uptake proportion of surface and shallow soil water by 20.0% and 9.4% during the growing season. Its WUE also improved, increasing by 20.0 μmol/mol and 13.0 μmol/mol during the growing and non-growing seasons, respectively. These results indicate that as bamboo expands into broadleaf forests, it enhances its competitiveness for water resources by changing its water use strategy. Compared to deciduous broadleaf trees, evergreen broadleaf trees exhibit more flexible water use strategies under the conditions of bamboo expansion. Our research reveals, for the first time, how broadleaf trees adjust their water use strategies in response to bamboo expansion, and uncovers the mechanisms behind bamboo expansion into evergreen broadleaf forests from the perspective of water use strategies. This will aid future forest management under the conditions of bamboo expansion.

Morphological and Physiological Characteristics Influencing CO2 Assimilation Rate and Growth in Different Half-Sib Families of Quercus acuta and Q. glauca

Climate change alters vegetation patterns, pushing subtropical forests further north. These forests play a crucial role for carbon neutrality efforts due to their significant CO2 assimilation potential. This study investigated CO2 assimilation rate along with growth, morphological, and physiological traits in 23 half-sib families of Quercus acuta and 26 half-sib families of Q. glauca, two prominent East Asian evergreen broadleaf species. Q. acuta exhibited significantly higher growth rates, with diameter at breast height (DBH) and aboveground biomass exceeding those for Q. glauca by 12.1% and 69.9%, respectively (p < 0.001). Leaf traits, including leaf mass pear area (LMA), leaf nitrogen, and chlorophyll content, were also greater in Q. acuta, showing 24.5%, 45.8%, and 15.6% higher values (p < 0.001). While photosynthetic traits were similar, Q. acuta exhibited a 12.7% higher intrinsic water-use efficiency (iWUE) (p < 0.01). Among half-sib families, marginal differences were observed in growth traits (p < 0.1), and significant differences in leaf morphology and physiological traits (p < 0.05) were observed. A positive correlation was found between growth and physiological traits associated with the CO2 assimilation rate in Q. acuta, but not in Q. glauca. These findings highlight the potential of Q. acuta and Q. glauca for supporting future carbon neutrality efforts and provide traits supporting carbon uptake, valuable for selecting tree species with enhanced carbon sequestration potential.

Unveiling the antibacterial and antioxidant capabilities of Diospyros buxifolia leaf and stem extracts via GC-MS analysis

Drug-resistant microorganisms pose a significant threat to public health as they can undermine the effectiveness of existing antibiotics and other medications. Additionally, the formation of free radicals, can contribute to various health problems. Diospyros buxifolia (D. buxifolia) belonging to Ebenaceae family is a large tropical evergreen tree utilised in traditional medicine to cure several health ailments. The present study was set out to separate bioactive speciation of aqueous and methanolic extracts of stem and leaves from D. buxifolia by using Gas Chromatography-Mass Spectrometry (GC-MS) followed by evaluation of its antimicrobial and antioxidant capabilities. GC-MS identified 14 different bioactive compounds, with four compounds common for both (leaf and stem) extracts. The methanolic extracts of leaf demonstrated significant antibacterial activity) while stem extracts exhibited notable antioxidant potential. Thus, D. buxifolia is proved source of natural antimicrobial and antioxidant agent, that could address the challenges posed by drug-resistant microorganisms and oxidative stress in global health.

Xylem and Phloem in Petioles Are Coordinated With Leaf Gas Exchange in Oaks With Contrasting Anatomical Strategies Depending on Leaf Habit.

As the single link between leaves and the rest of the plant, petioles must develop conductive tissues according to the water influx and sugar outflow of the leaf lamina. A scaling relationship between leaf area and anatomical traits of xylem and phloem is expected to improve the efficiency of these tissues. However, the different constraints compromising the functionality of both tissues (e.g., risk of cavitation) must not be disregarded. Additionally, deciduous and evergreen plants may have different strategies to produce and package their petiole conduits to cope with environmental restrictions. We explored in 33 oak species the relationships between petiole anatomical traits, leaf area, stomatal conductance, and photosynthesis rate. Results showed allometric scaling between anatomical structure of xylem and phloem with leaf area. We also found correlations between photosynthesis rate, stomatal conductance, and anatomical traits in the petiole. The main novelty is how oaks present a different strategy depending on the leaf habit. Deciduous species tend to increase their diameters to achieve greater leaf-specific conductivity. By contrast, evergreen oaks develop larger xylem conductive areas for a given leaf area than deciduous ones. This trade-off between safety-efficiency in petioles has never been attributed to the leaf habit of the species.

Impact of urbanization on soapnut Sapindus trifoliatus L. tree cover and the need for community involvement: a case study from Kochi, Kerala, India

ABSTRACT The South Indian soapnut tree, Sapindus trifoliatus L, is a midsized evergreen tree from the Indian subcontinent whose fruit can produce natural detergents, biodiesel, and biopesticides. In this study, we document the systematic destruction of soapnut trees through a citizen-supported tree census in an emerging Tier 2 city, Kochi, in South India. In the study, 3580 respondents allowed us to find and map 210 locations of soapnut trees across 411.57 km2. Kochi expanded suddenly in the early 2000s, with a drastic increase in built-up area (126%) and a steady decline in wetlands (57.6%) and croplands (15%). Habitat loss and removal from home gardens has quartered soapnut tree density, to 0.11 km−2. With only 50 trees remaining, the population of the South Indian soapnut will reach the brink of local extinction by 2080.

Seed Regeneration in Taxus baccata: Unveiling Ecological Restrictions and Paving the Way for Future Studies.

Taxus baccata, commonly known as English yew, is an evergreen tree native to regions ranging from Ireland and Sweden to Morocco, Algeria, and northern Iran. This species is of special concern due to habitat loss from human activities, including forest management, leading to declining populations. A 4-year monitoring study was conducted to investigate the factors behind the poor seed regeneration of yew. We examined seed germination, dormancy, desiccation tolerance, and seed predation as potential contributors to this issue. Our study proposed potential seed predation by frugivores and granivores, along with morphophysiological dormancy, as primary reasons for poor regeneration. Despite high seed production and seed availability in certain years, germination did not improve, likely due to the small size of the yew seed embryos, which prolongs dormancy. Yew seeds are desiccation-tolerant, water-permeable, and lack physical germination barriers, making seed predation a significant limiting factor. In conclusion, the natural regeneration of yew is hampered by potential seed predation, morphophysiological dormancy, and environmental factors such as altered temperature and rainfall patterns, which change the dormancy-breaking process. Further research is needed to quantify seed predation and explore its impact on seedling survival.

In Vitro vs. In Vivo Transcriptomic Approach Revealed Core Pathways of Nitrogen Deficiency Response in Tea Plant (Camellia sinensis (L.) Kuntze).

For the first time, we used an in vitro vs. in vivo experimental design to reveal core pathways under nitrogen deficiency (ND) in an evergreen tree crop. These pathways were related to lignin biosynthesis, cell redox homeostasis, the defense response to fungus, the response to Karrikin, amino acid transmembrane transport, the extracellular region, the cellular protein catabolic process, and aspartic-type endopeptidase activity. In addition, the mitogen-activated protein kinase pathway and ATP synthase (ATP)-binding cassette transporters were significantly upregulated under nitrogen deficiency in vitro and in vivo. Most of the MAPK downstream genes were related to calcium signaling (818 genes) rather than hormone signaling (157 genes). Moreover, the hormone signaling pathway predominantly contained auxin- and abscisic acid-related genes, indicating the crucial role of these hormones in ND response. Overall, 45 transcription factors were upregulated in both experiments, 5 WRKYs, 3 NACs, 2 MYBs, 2 ERFs, HD-Zip, RLP12, bHLH25, RADIALIS-like, and others, suggesting their ND regulation is independent from the presence of a root system. Gene network reconstruction displayed that these transcription factors participate in response to fungus/chitin, suggesting that nitrogen response and pathogen response have common regulation. The upregulation of lignin biosynthesis genes, cytochrome genes, and strigalactone response genes was much more pronounced under in vitro ND as compared to in vivo ND. Several cell wall-related genes were closely associated with cytochromes, indicating their important role in flavanols biosynthesis in tea plant. These results clarify the signaling mechanisms and regulation of the response to nitrogen deficiency in evergreen tree crops.

Global Temperature Dependency of Biogenic HCHO Columns Observed From Space: Interpretation of TROPOMI Results Using GEOS‐Chem Model

AbstractTemperature is the principal driver of global atmospheric formaldehyde (HCHO) and its primary oxidation precursor biogenic volatile organic compounds (BVOCs). We revisit such a temperature (T‐) dependency globally, leveraging TROPOMI HCHO column data. We find substantial variations in the T‐dependency of biogenic HCHO across plant functional types (PFTs), with the highest over Broadleaf Evergreen Tropical Trees (doubling every 6.0 K ± 4.1 K) and lowest over Arctic C3 Grass (doubling every 30.8 K ± 9.6 K). The GEOS‐Chem model interprets HCHO columns' T‐dependency at the PFT level (r = 0.87), with a 16% discrepancy on average. The discrepancy can be explained by BVOC emissions T‐dependency for Broadleaf Evergreen Tropical Trees and Warm C4 Grass and can be attributed to the insensitivity of HCHO columns to BVOC emissions for other PFTs. Our findings underscore a potentially magnified variation of BVOC emissions by GEOS‐Chem and MEGAN therein, particularly in regions experiencing greater temperature variations.

Formulation and evaluation of herbal face scrub

Herbal face scrubs have become increasingly popular in recent years due to their ability to improve skin health and are available at a low cost. These scrubs contain natural ingredients such as rice powder and orange peel powder, ficus riligiosa etc. Which work to exfoliate, whiten, and prevent free radical damage. Vitamin E, rose Oil, and almonds are used to hydrate and exfoliate the skin. Neutralizers and herbal preservatives like neem, and rosemary are used in the variuos formulations. The preparation was evaluated for various parameters, such as colour, odour consistency, pH, spreadability, viscosity, and foamability. The results from the evaluation indicated that the scrub was satisfactory after application and was non-irritating to the skin. Ficus religiosa L., commonly known as Peepal tree known to be a native Indian is a medicinally important tree species belonging to the Moraceae family. It is a large evergreen tree found throughout the India. This tree is popular indigenous system of medicine like Ayurveda, Siddha, Unani, and Homeopathy. Ficus religiosa is sacred tree, which is having great traditional uses as well as pharmacological activities. Almost all parts of the tree are useful in traditional system. The various parts like leaf, bark, fruit, and seeds are beneficial in treatment of gastrointestinal diseases, healing and curative, heart diseases, constipation, mumps and boils, gynaecological problems, fever and joint pains, respiratory problems, skin diseases orodental and ear problems. Ficus religiosa tree shows pharmacological activities analgesic, antioxidant, anticonvulsant, antimicrobial, wound healing, ant amnesic, anti-acetyl cholinesterase, proteolytic activity. The present review is hence an effort to give detailed survey of the literature on its pharmacognosy, photochemistry and medicinal applications.

Evaluation of African Neem Plant (Dogon Yaro) antibacterial activity against certain pathogenic organisms

The neem plant is a tropical evergreen plant native to the Indian sub-continent. It has been used in ayurvedic medicine for more than 4000 years due to its medicinal properties. The phytochemical screening carried out on the extract of Neem plant revealed the presence of some active ingredients such as alkaloids, tannins, saponins, and phenols also glycosides, steroids, Terpenoids, flavonoids, and phlobatanins are present in this extract. It was observed that alkanoids has a concentration of 0.52g/ml, tannins has a concentration of 9.00g/ml, saponins has a concentration of 1.99g/ml, flavonoid has a concentration of 0.62g/ml and phenol has a concentration of 0.024g/ml. The antimicrobial activity of the Leaf, Stem, Stem-bark and Root extract of Neem plant (Azadirachta indica) against some of the pathogenic bacteria such as E. coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Staphylococcus epidermidis, was determined. This was done by using alcoholic and water extracts of Neem leaves, stem, stem bark and roots. Varying concentration of each extracts 200mg/ml, 150mg/ml and 100mg/ml were prepared and tested. When compared with Gentamycin 10mg, the Ethanol Extract of Neem Root shows maximum inhibition on Pseudomonas aeruginosa, Staphylococcus epidermidis, Staphylococcus aureus and E. coli in an ascending order, followed by the ethanol extract of Neem Leaf which shows maximum inhibition on Pseudomonas aeruginosa, Staphylococcus aureus, E. coli and Staphylococcus epidermidis in an ascending order. Conclusively, this can explain the rationale for the use of the plant in treating infections in traditional medicine. The plant could be a veritable and cheaper substitute for conventional antibiotics since it is easily obtainable and the extract can easily be made via a simple process of maceration or infusion. However, further research is necessary to determine and purify the active components against micro-organisms.

Study the phytochemical, Biological and pharmacological aspects of Azadirachta indica: A review

Neem (Azadirachta indica) is a fast-growing tropical evergreen plant that belongs to the Meliaceae family. Its compounds have been shown to be effective against illnesses and insect pests that are significant economic concerns. The plant's whole body has biopesticidal properties, especially in the form of extracts from the leaves, bark, and roots. Every part of the plant has been utilized medicinally and is now considered a treasure in contemporary medicine. Salannin, quercetin, nimbolinin, nimbin, nimbidin, nimbidol, and azadirachtin are among the beneficial active compounds that have been isolated from several plant sections. This review article's primary goal is to provide information on a range of pharmacological activities, including anti-inflammatory, anti-cancer, anti-bacterial, antiviral, antifungal, antihelmethic, antidiabetic, wound-healing, and ulcer-preventing properties. activity hepatoprotective, Effects on Immunomodulation and Antinephrotoxicity.

Exploring the inhibitory activity and mechanism on lipid production in 3T3-L1 cells by hot water extract derived from Acacia confusa flowers.

Acacia confusa Merr. (Fabaceae) (A. confusa) is a native tree species of Taiwan, commonly found in the low-altitude mountains and hilly areas of the Hengchun Peninsula. This evergreen, perennial, and large-sized tree was the focus of a study that employed various chromatographic and spectroscopic methods to analyze the hot water extract of its flowers. The analysis revealed that the major components of the extract were myricitrin, quercitrin, europetin-3-O-rhamnoside, and chalconaringenin-2'-xyloside, with respective concentrations of approximately 0.22, 0.02, 0.26, and 0.10mg/g of the flowers. Subsequent cell assays were conducted to assess the inhibitory effect of the extract on lipid synthesis in fat cells. Oil Red O staining results indicated that the extract significantly suppressed fatty acid accumulation in 3T3-L1 cells, with the most pronounced effect observed at a concentration of 180μg/ml. Furthermore, the hot water extract of A. confusa flowers was found to increase the phosphorylation of AMP-activated protein kinase (AMPK), decrease the phosphorylation of cAMP response element-binding protein (CREB), and reduce the expression of glucocorticoid receptor (GR) protein. This, in turn, inhibited the expression of downstream transcription factors such as CCAT/ehancer binding proteins α (C/EBPα), CCAT/ehancer binding proteins β (C/EBPβ), CCAT/ehancer binding proteins δ (C/EBPδ), peroxisome proliferation-actived receptor γ (PPARγ), and sterol regulatory element binding proteins-1 (SREBP-1). Consequently, the expression of lipid synthesis-related proteins acetyl-CoA carboxylase (ACC), fatty acid synthase (FAS), and fatty acid translocase (CD36) was reduced, ultimately inhibiting lipid generation. Therefore, the hot water extract of A. confusa flowers shows potential for development as a weight-loss tea.

Leaf nutrient basis for the differentiation of photosynthetic traits between subtropical evergreen and deciduous trees.

Compared to evergreens, deciduous tree species usually have higher photosynthetic efficiency to complete vegetative and reproductive growth in a shorter growing season. However, the nutrient basis for the differentiation of photosynthesis functional traits between evergreen and deciduous tree species has not yet been clarified. Thirty evergreen and twenty deciduous angiosperm tree species from a subtropical common garden were compared in terms of photosynthetic traits and leaf nutrients. Generally, their differences in area-based photosynthetic capacity were uncorrelated with area-based leaf nutrient content but were caused by the fraction of nitrogen allocated to photosynthetic components. By comparison, the differences in mass-based photosynthetic capacity were more correlated with leaf nitrogen content than leaf phosphorus and potassium content. Convergence in phosphorus and potassium constraints to photosynthesis occurred in deciduous tree species but not in evergreen tree species. Furthermore, leaf C/N ratio played a more significant role than leaf mass per area in determining the differentiation of photosynthetic traits between evergreen and deciduous groups. Our findings provide insight into the nutrient basis for photosynthetic carbon gain and functional strategies across trees species.

The Impact of Different Types of Trees on Annual Thermal Comfort in Hot Summer and Cold Winter Areas

Trees positively improve the annual thermal comfort of the built environment in tropical areas, where climate change is slight throughout the year. However, for areas with high changes in climate all year, the current studies have only explored the summer cooling performance of trees without the impact of different types of trees on annual thermal comfort, especially in cold seasons. Therefore, to quantify the impacts and scientifically guide the optimization of green space layout in hot summer and cold winter areas, this study selected Changsha City as the study area and analyzed how the annual thermal comfort is affected by evergreen trees and deciduous trees, which are two common types of trees in hot summer and cold winter areas. The analytical results indicated that the difference in the effect of deciduous and evergreen trees on outdoor thermal comfort was insignificant in summer, where the difference in the monthly mean PET for the three summer months was slight, being 0.28 °C, 0.14 °C, and 0.29 °C, respectively. However, evergreen trees greatly exacerbated winter cold compared to deciduous trees, with a monthly mean PET decrease by nearly 1.0 °C and an hourly PET reduced by up to 3.57 °C. The difference is mainly attributed to the absorption and reflection of solar radiation by the tree canopy, as well as the cooling and humidifying effect of the tree leaf. In hot summer and cold winter areas, outdoor thermal comfort is still in the “comfortable” and “slightly warm” acceptable stage despite the warming effect of deciduous trees in the spring and autumn seasons. Planting evergreen trees is an inevitable thermal mitigation choice for tropical areas. However, for the areas with high annual climate change, such as hot summer and cold winter areas in China, a change in empirical tree planting patterns and selecting deciduous trees where appropriate will improve year-round outdoor thermal comfort.

The heterogeneous response in leaf traits among seasons and plant types of an evergreen broadleaf forest in western China to nitrogen addition was regulated by fertilization intensity

The heterogeneous response in leaf traits among seasons and plant types of an evergreen broadleaf forest in western China to nitrogen addition was regulated by fertilization intensity

Influence of Terrain on MODIS and GLASS Leaf Area Index (LAI) Products in Qinling Mountains Forests

Leaf Area Index (LAI), as a pivotal parameter in characterizing the structural properties of vegetation ecosystems, holds significant importance in assessing the carbon sink function. Given the availability of multiple long-term LAI products, validating these LAI products with consideration of topographic factors is a prerequisite for enhancing the quality of LAI products in mountainous areas. Therefore, this study aims to evaluate the performance of MODIS LAI and GLASS LAI products from 2001 to 2021 by comparing and validating them with ground-measured LAI data, focusing on the spatio-temporal and topographic aspects in the Qinling Mountains. The results show that the GLASS LAI product is a better choice for estimating LAI in the Qinling Mountains. The GLASS LAI product has better completeness and generally higher values compared to the MODIS LAI product. The time-series curve of the GLASS LAI product is more continuous and smoother than the MODIS LAI product. Both products, however, face challenges in quantifying LAI values of evergreen vegetation during winter. The MODIS and GLASS LAI products exhibit differences between sunny and shady slopes, with mean LAI values peaking on sunny slopes and reaching their lowest on shady slopes. When the slope ranges from 0 to 10°, the mean values of GLASS LAI product show a higher increasing trend compared to the MODIS LAI product. At elevations between 1450 and 2450 m, the mean LAI values of the GLASS LAI product are higher than the MODIS LAI product, primarily in the southern Qinling Mountains. Compared to ground-measured LAI data, the GLASS LAI product (R² = 0.33, RMSE = 1.62, MAE = 0.61) shows a stronger correlation and higher accuracy than the MODIS LAI product (R² = 0.24, RMSE = 1.61, MAE = 0.68).