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19 pages, 6731 KB

Open AccessArticle

Impact of Melatonin on Antioxidant Enzymes and Soluble Metabolites in Salt–Alkali-Stressed Poplar (Populus spp.): A Comparative Study of Pretreatment and Post-Treatment Effects

by Jiefei Nai, Wanpeng He, Tieming Ma, Xidong Han, Zhenxing Luo, Xinyu Li, Jiatong Sun and Xiyang Zhao

Forests 2026, 17(3), 373; https://doi.org/10.3390/f17030373 - 16 Mar 2026

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Abstract

Melatonin plays a crucial role in modulating plant stress responses; however, its potential for mitigating salt–alkali stress remains incompletely understood. This study evaluates the efficacy of exogenous melatonin in alleviating moderate salt–alkali stress (120 mM) in poplar (Populus davidiana × P. bolleana [...] Read more.

Melatonin plays a crucial role in modulating plant stress responses; however, its potential for mitigating salt–alkali stress remains incompletely understood. This study evaluates the efficacy of exogenous melatonin in alleviating moderate salt–alkali stress (120 mM) in poplar (Populus davidiana × P. bolleana ‘Baicheng Shanxinyang No. 1’) seedlings, investigating both pre- and post-stress treatments across a concentration range of 0–1000 μM. Physiological and morphological parameters, including chlorophyll content, antioxidant enzyme activities, and osmolyte accumulation, were analyzed to assess stress responses. Under salt–alkali stress, seedlings exhibited elevated stress markers and osmolyte levels, reflecting activated stress responses. Melatonin at concentrations of 200–400 μM was the most effective in mitigating stress, significantly enhancing antioxidant enzyme activities such as superoxide dismutase (SOD) and catalase (CAT), restoring chlorophyll content, and reducing oxidative damage markers such as malondialdehyde (MDA). It also regulated osmotic balance in leaves, indicating improved cellular stability under stress. Notably, post-stress application required slightly higher melatonin concentrations to achieve comparable recovery, highlighting the critical influence of application timing. These findings provide valuable insights for optimizing melatonin use to improve poplar growth in saline–alkali environments and support molecular breeding efforts aimed at developing salt–alkali-tolerant poplar varieties. Full article

(This article belongs to the Special Issue Adaptive Physiology of Forest Plants: Mechanisms, Strategies, and Responses to Environmental Challenges)

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16 pages, 2251 KB

Open AccessArticle

Linking Leaf Angle to Physiological Responses for Drought Stress Detection: Case Study on Quercus acutissima Carruth. in Forest Nursery

by Ukhan Jeong, Dohee Kim, Sohyun Kim, Jiyeon Park, Seung Hyun Han and Eun Ju Cheong

Forests 2026, 17(3), 348; https://doi.org/10.3390/f17030348 - 10 Mar 2026

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Abstract

Due to climate change, seedling damage caused by drought stress is expected to increase in both afforestation sites and nurseries. Therefore, to ensure stable seedling production under high-temperature conditions and to cultivate seedlings with enhanced drought tolerance through hardening treatments, the development of [...] Read more.

Due to climate change, seedling damage caused by drought stress is expected to increase in both afforestation sites and nurseries. Therefore, to ensure stable seedling production under high-temperature conditions and to cultivate seedlings with enhanced drought tolerance through hardening treatments, the development of an effective irrigation system is required. Conventional physiological methods for non-destructive drought detection, such as chlorophyll fluorescence and leaf temperature measurements, require expensive and manual operation, thereby limiting their real-time applicability in forest nurseries. This study evaluated the applicability of using image-based leaf angle measurements for drought stress detection in Quercus acutissima Carruth. seedlings. One-year-old seedlings were grown under two water regimes—well-watered (CT: control) and unwatered (DT: drought)—through Day 8. Statistical analyses (RMANOVA) revealed that changes in the leaf angle parameter PMD–MD (the difference between the previous and current measurement days) showed treatment effects similar to those of the physiological responses ΦNO (quantum yield of non-regulated energy dissipation) and qL (fraction of open PSII reaction centers) to drought on Day 6. Leaf angle reflected drought stress but did not precede physiological changes, indicating its role as a complementary rather than an early indicator. Multiple regression models identified AT (air temperature), SM (soil moisture), Fm′ (maximum fluorescence in the light-adapted state), and VPD (vapor pressure deficit) as the main factors influencing leaf angle variation. Although leaf angle was affected by combined environmental stresses such as high temperature, it was less sensitive to heat stress than physiological responses based on RMANOVA results. These results indicate the potential of image-based leaf angle measurements for drought stress detection. To establish plant-based smart irrigation systems, future studies should validate and refine this approach using larger datasets. Full article

(This article belongs to the Special Issue Adaptive Physiology of Forest Plants: Mechanisms, Strategies, and Responses to Environmental Challenges)

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10 pages, 1123 KB

Open AccessArticle

Shoot Vigour, Leaf Water Status and Physiological Traits of Mature Castanea sativa Mill. Trees Along the Canopy Vertical Gradient

by Lucia Mondanelli, Claudia Cocozza, Barbara Mariotti and Alberto Maltoni

Forests 2026, 17(2), 173; https://doi.org/10.3390/f17020173 - 28 Jan 2026

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Abstract

Climate change is increasingly exposing sweet chestnut (Castanea sativa Mill.) to more frequent and prolonged drought events, which can compromise growth and nut production, particularly in Mediterranean environments. Understanding how trees respond physiologically to ecological and environmental constraints requires a detailed analysis [...] Read more.

Climate change is increasingly exposing sweet chestnut (Castanea sativa Mill.) to more frequent and prolonged drought events, which can compromise growth and nut production, particularly in Mediterranean environments. Understanding how trees respond physiologically to ecological and environmental constraints requires a detailed analysis of their architectures. The aim of this study was to investigate how the shoot vigour and leaf water status of mature chestnut trees vary with height within the canopy. Three mature chestnut trees with distinct crown architectures were selected in a traditional chestnut orchard in Central Italy; the differences in crown structure reflected individual tree development under comparable pruning practices. Morphological traits, leaf water status, and physiological parameters related to chlorophyll were measured directly within the canopy by professional tree climbers, allowing access to both lower and upper shoots during the growing season of 2020. One tree, called “Tree 1,” characterised by low bifurcation, with all epicormic shoot cluster (complexes) located on the two main branches and none on the main stem, showed partial vertical differences, mainly in water status and chlorophyll traits. “Tree 2”, characterised by high bifurcation and shoots running along the main stem, exhibited clear vertical gradients: lower-canopy shoots had larger leaf areas and more dry mass, higher relative water content, and better photosynthetic performance index e values than upper shoots. At the end, “Tree 3”, with the same architecture as Tree 1, displayed no consistent vertical trends. These findings indicate that individual tree architecture modulates hydraulic constraints and shoot vigour, even in hydraulically efficient epicormic branches. Although canopy access constraints limited the number of trees and measurements, this study—among the few to conduct in-canopy measurements on large, mature trees—provides valuable guidance for pruning and crown management, suggesting that lowering and simplifying the crown can enhance water-use efficiency, shoot vigour, and drought resilience in traditional and low-input chestnut orchards. Full article

(This article belongs to the Special Issue Adaptive Physiology of Forest Plants: Mechanisms, Strategies, and Responses to Environmental Challenges)

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17 pages, 18633 KB

Open AccessArticle

Organ-Specific Gene Expression and Metabolite Accumulation in Fargesia rufa in Response to an Altitudinal Gradient

by Qi Lin, Wanju Feng, Man Tang, Mengqiu Chen, Xun Song, Lin Wu, Xin Zhao and Zhijian Long

Forests 2026, 17(2), 167; https://doi.org/10.3390/f17020167 - 27 Jan 2026

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Abstract

Fargesia rufa, one of the main food bamboo species for giant pandas, exhibits significant changes in nutritional composition with altitudinal gradient. However, the molecular mechanisms underlying this adaptation and its impact on the foraging behavior of giant pandas remain unclear. In this [...] Read more.

Fargesia rufa, one of the main food bamboo species for giant pandas, exhibits significant changes in nutritional composition with altitudinal gradient. However, the molecular mechanisms underlying this adaptation and its impact on the foraging behavior of giant pandas remain unclear. In this study, metabolomic and transcriptomic analyses were integrated to compare gene expression and metabolite profiles in leaves and rhizomes of F. rufa collected from 1000 m and 2000 m altitudes. With increasing altitude, 710 metabolites were up-regulated and 1032 were down-regulated in the leaves of F. rufa, whereas 684 metabolites were up-regulated and 1342 were down-regulated in the rhizomes; only 629 differential metabolites were shared between the two organs. Further analyses revealed that F. rufa responds to altitudinal changes through organ-specific metabolic reprogramming: leaves adopt a “metabolic conservation” strategy, downregulating the majority of flavonoid and phenylpropanoid metabolites, while rhizomes take an “active storage” strategy, significantly enhancing secondary metabolite synthesis and starch accumulation. This functional differentiation is consistent with the biological roles of the organs: the metabolic simplification of leaves may enhance the palatability of high-altitude leaves, while the nutritional reserves in rhizomes support bamboo shoot emergence. This study reveals the molecular mechanisms of bamboo’s altitudinal adaptation at the organ level, clarifies the intrinsic link between plant metabolism and animal diet, and provides a theoretical basis for giant panda habitat conservation. Full article

(This article belongs to the Special Issue Adaptive Physiology of Forest Plants: Mechanisms, Strategies, and Responses to Environmental Challenges)

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18 pages, 4385 KB

Open AccessArticle

Transcriptomic Analysis of Anthocyanin Degradation in Salix alba Bark: Insights into Seasonal Adaptation and Forestry Applications

by Hong-Yong Wang, Xing-Ju Liu, Meng-Zhen Yin, Sheng-Jia Cui, Hai-Yong Liang and Zhen-Hua Xu

Forests 2025, 16(10), 1598; https://doi.org/10.3390/f16101598 - 17 Oct 2025

Cited by 1 | Viewed by 568

Abstract

Anthocyanins, key flavonoid-derived secondary metabolites, not only confer diverse pigmentation but also function in photoprotection, antioxidative defense, and cold acclimation. In woody species, bark anthocyanin turnover is tightly linked to environmental adaptation, stress resilience, and ornamental traits, yet its molecular regulation remains largely [...] Read more.

Anthocyanins, key flavonoid-derived secondary metabolites, not only confer diverse pigmentation but also function in photoprotection, antioxidative defense, and cold acclimation. In woody species, bark anthocyanin turnover is tightly linked to environmental adaptation, stress resilience, and ornamental traits, yet its molecular regulation remains largely unresolved. Here, we investigated Salix alba L. bark by integrating anthocyanin quantification, transcriptome profiling, and weighted gene co-expression network analysis (WGCNA) to dissect the temporal dynamics and regulatory architecture of anthocyanin degradation. Anthocyanin content peaked at D2 (late December 2024), declined through D3 (mid-January 2025) and D4 (mid-February 2025), and partially rebounded at D5 (early March 2025), coinciding with peak expression of structural genes LAC1/2, POD1/2, and BGLU10. These enzymes co-expressed with multiple transcription factors, including MYB, bHLH, and WRKY families, forming putative core modules. Functional enrichment indicated that differentially expressed genes were enriched in redox processes, glycoside hydrolysis, flavonoid metabolism, and hormone signaling, suggesting a degradation mechanism mediated by reactive oxygen species, glycosidic cleavage, and hormone–transcription factor interplay. This study provides the first comprehensive framework of bark anthocyanin degradation in white willow, advancing the understanding of pigment dynamics, gene–environment crosstalk, and breeding strategies for ornamental woody plants. Full article

(This article belongs to the Special Issue Adaptive Physiology of Forest Plants: Mechanisms, Strategies, and Responses to Environmental Challenges)

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23 pages, 3638 KB

Open AccessEditor’s ChoiceArticle

Hydro-Functional Strategies of Sixteen Tree Species in a Mexican Karstic Seasonally Dry Tropical Forest

by Jorge Palomo-Kumul, Mirna Valdez-Hernández, Gerald A. Islebe, Edith Osorio-de-la-Rosa, Gabriela Cruz-Piñon, Francisco López-Huerta and Raúl Juárez-Aguirre

Forests 2025, 16(10), 1535; https://doi.org/10.3390/f16101535 - 1 Oct 2025

Viewed by 618

Abstract

Seasonally dry tropical forests (SDTFs) are shaped by strong climatic and edaphic constraints, including pronounced rainfall seasonality, extended dry periods, and shallow karst soils with limited water retention. Understanding how tree species respond to these pressures is crucial for predicting ecosystem resilience under [...] Read more.

Seasonally dry tropical forests (SDTFs) are shaped by strong climatic and edaphic constraints, including pronounced rainfall seasonality, extended dry periods, and shallow karst soils with limited water retention. Understanding how tree species respond to these pressures is crucial for predicting ecosystem resilience under climate change. In the Yucatán Peninsula, we characterized sixteen tree species along a spatial and seasonal precipitation gradient, quantifying wood density, predawn and midday water potential, saturated and relative water content, and specific leaf area. Across sites, diameter classes, and seasons, we measured ≈4 individuals per species (n = 319), ensuring replication despite natural heterogeneity. Using a principal component analysis (PCA) based on individual-level data collected during the dry season, we identified five functional groups spanning a continuum from conservative hard-wood species, with high hydraulic safety and access to deep water sources, to acquisitive light-wood species that rely on stem water storage and drought avoidance. Intermediate-density species diverged into subgroups that employed contrasting strategies such as anisohydric tolerance, high leaf area efficiency, or strict stomatal regulation to maintain performance during the dry season. Functional traits were strongly associated with precipitation regimes, with wood density emerging as a key predictor of water storage capacity and specific leaf area responding plastically to spatial and seasonal variability. These findings refine functional group classifications in heterogeneous karst landscapes and highlight the value of trait-based approaches for predicting drought resilience and informing restoration strategies under climate change. Full article

(This article belongs to the Special Issue Adaptive Physiology of Forest Plants: Mechanisms, Strategies, and Responses to Environmental Challenges)

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14 pages, 1594 KB

Open AccessArticle

Effect of Lead on the Physiological Parameters and Elemental Composition of Pinus sylvestris L. and Picea abies (L.) H. Karst Seedlings

by Andrea Pogányová, Djordje P. Božović, Martin Bačkor, Michal Goga, Marián Tomka and Marko S. Sabovljević

Forests 2025, 16(6), 990; https://doi.org/10.3390/f16060990 - 11 Jun 2025

Viewed by 727

Abstract

Lead (Pb) pollution poses a long-term threat to forest ecosystems, particularly in mountainous areas affected by atmospheric deposition. This study examined the physiological and biochemical responses of juvenile Pinus sylvestris L. and Picea abies (L.) H. Karst seedlings to low concentrations of lead [...] Read more.

Lead (Pb) pollution poses a long-term threat to forest ecosystems, particularly in mountainous areas affected by atmospheric deposition. This study examined the physiological and biochemical responses of juvenile Pinus sylvestris L. and Picea abies (L.) H. Karst seedlings to low concentrations of lead nitrate during early development. Treatments simulated environmentally relevant Pb exposure and focused on pigment composition, oxidative stress markers, soluble protein and proline levels, and elemental content. Both species exhibited hormetic stimulation of photosynthetic pigments at lower Pb concentrations. In P. sylvestris, this effect declined at the highest dose, whereas P. abies maintained pigment levels, suggesting stronger regulatory control. Pb exposure reduced soluble proteins and induced species-specific alterations in MDA and proline levels. Correlation analysis revealed a well-integrated stress response in P. abies, while P. sylvestris showed a more fragmented pattern. Elemental analysis confirmed Pb accumulation primarily in roots, with higher levels in P. sylvestris. Both species experienced reduced root Mg, K, and Mn, indicating ionic imbalance due to Pb²⁺ interference. Zn content increased in P. sylvestris but decreased in P. abies, possibly reflecting differences in uptake regulation. These species-specific responses support the hypothesis that P. abies activates more effective defense mechanisms against Pb toxicity, while P. sylvestris exhibits a stronger physiological stress response. Full article

(This article belongs to the Special Issue Adaptive Physiology of Forest Plants: Mechanisms, Strategies, and Responses to Environmental Challenges)

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22 pages, 4319 KB

Open AccessArticle

Functional Traits Associated with Drought Tolerance Exhibit Low Variability in 21 Provenances of a Montane Tree Species—Eucalyptus delegatensis

by Anita Gurung, Benjamin Wagner, Elizabeth C. Pryde, Craig R. Nitschke and Stefan K. Arndt

Forests 2025, 16(6), 898; https://doi.org/10.3390/f16060898 - 27 May 2025

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Abstract

Elevated temperatures and extended drought periods are driving significant changes in the structure and function of forest ecosystems. High-elevation alpine ash forests (Eucalyptus delegatensis R.T. Baker) in Australia are an example of forests that are already impacted by climate change. These obligate [...] Read more.

Elevated temperatures and extended drought periods are driving significant changes in the structure and function of forest ecosystems. High-elevation alpine ash forests (Eucalyptus delegatensis R.T. Baker) in Australia are an example of forests that are already impacted by climate change. These obligate seeder forests can shift to non-forest ecosystems following extreme drought and altered fire regimes, raising concern about their adaptation to a rapidly changing environment and long-term forest persistence. Plant functional traits play a major role in determining adaptive mechanisms to environmental conditions. While alpine ash forests are vulnerable to climate change, it is unclear if different provenances have adapted to the climatic conditions in which they grow. We therefore studied the variation in expression of functional traits related to drought tolerance in 21 provenances of alpine ash distributed across an environmental gradient. We investigated if functional traits varied between the provenances and were related to climate of origin in order to identify provenances that may be better adapted to drought. We measured the following traits in a common garden experiment under well-watered conditions: stomatal density, specific leaf area, minimum stomatal conductance and osmotic potential at full turgor. There was very little variation in trait expression between the 21 provenances for all functional traits related to drought tolerance. All provenances had medium-range stomatal density (170–300 stomata mm²) and specific leaf area (SLA, 50–70 cm² g⁻¹), a very low minimum stomatal conductance (2–4 mmol m² s⁻¹) and a high osmotic potential at full turgor (−0.6–0.7 MPa). There was no statistically significant correlation of trait expression with the climate of origin. Thus, there is very little evidence for genetically controlled differences in trait expression of drought tolerance traits in this species. It is likely that the high elevation and high rainfall environment of the species’ ecological niche has not been subjected to frequent and extensive drought periods that would elicit an evolutionary pressure selecting for drought-tolerant traits. We could not identify provenances that would have different drought-tolerant functional trait responses than others, potentially conferring an adaptive advantage under climate change. This has implications for using climate-adjusted provenancing to improve resilience in alpine ash forests predicted to experience more frequent and severe droughts in the future. Full article

(This article belongs to the Special Issue Adaptive Physiology of Forest Plants: Mechanisms, Strategies, and Responses to Environmental Challenges)

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15 pages, 5288 KB

Open AccessArticle

Seasonal Variations in the Relationship Between Canopy Solar-Induced Chlorophyll Fluorescence and Gross Primary Production in a Temperate Evergreen Needleleaf Forest

by Kaijie Yang, Yifei Cai, Xiaoya Li, Weiwei Cong, Yiming Feng and Feng Wang

Forests 2025, 16(6), 893; https://doi.org/10.3390/f16060893 - 26 May 2025

Viewed by 841

Abstract

The temperate evergreen needleleaf forest (ENF), primarily composed of Mongolian Scots pine (Pinus sylvestris var. mongolica), plays a pivotal role in the “The Great Green Wall” Shelterbelt Project in northern China as a major species for windbreak and sand fixation. Solar-induced [...] Read more.

The temperate evergreen needleleaf forest (ENF), primarily composed of Mongolian Scots pine (Pinus sylvestris var. mongolica), plays a pivotal role in the “The Great Green Wall” Shelterbelt Project in northern China as a major species for windbreak and sand fixation. Solar-induced chlorophyll fluorescence (SIF) has emerged as a revolutionary remote sensing signal for quantifying photosynthetic activity and gross primary production (GPP) at the ecosystem scale. Meanwhile, eddy covariance (EC) technology has been widely employed to obtain in situ GPP estimates. Although a linear relationship between SIF and GPP has been reported in various ecosystems, it is mainly derived from satellite SIF products and flux-tower GPP observations, which are often difficult to align due to mismatches in spatial and temporal resolution. In this study, we analyzed synchronous high-frequency SIF and EC-derived GPP measurements from a Mongolian Scots pine plantation during the seasonal transition (August–December). The results revealed the following. (1) The ENF acted as a net carbon sink during the observation period, with a total carbon uptake of 100.875 gC·m⁻². The diurnal dynamics of net ecosystem exchange (NEE) exhibited a “U”-shaped pattern, with peak carbon uptake occurring around midday. As the growing season progressed toward dormancy, the timing of CO₂ uptake and release gradually shifted. (2) Both GPP and SIF peaked in September and declined thereafter. A strong linear relationship between SIF and GPP (R² = 0.678) was observed, consistent across both diurnal and sub-daily scales. SIF demonstrated higher sensitivity to light and environmental changes, particularly during the autumn–winter transition. Cloudy and rainy conditions significantly affect the relationship between SIF and GPP. These findings highlight the potential of canopy SIF observations to capture seasonal photosynthesis dynamics accurately and provide a methodological foundation for regional GPP estimation using remote sensing. This work also contributes scientific insights toward achieving China’s carbon neutrality goals. Full article

(This article belongs to the Special Issue Adaptive Physiology of Forest Plants: Mechanisms, Strategies, and Responses to Environmental Challenges)

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17 pages, 4170 KB

Open AccessArticle

The Effects of Inoculation with Rhizosphere Phosphate-Solubilizing Bacteria on the Growth and Physiology of Reaumuria soongorica Seedlings Under NaCl Stress

by Xueying Wang, Peifang Chong, Xinguang Bao and Feng Zhang

Forests 2025, 16(4), 591; https://doi.org/10.3390/f16040591 - 28 Mar 2025

Viewed by 831

Abstract

Soil salinization significantly exacerbates the deficiency in plant-available phosphorus in the soil, thereby adversely affecting plant growth and development. Through various processes, phosphate-solubilizing bacteria in the rhizosphere significantly increase soil-soluble phosphorus content, boosting plant development and stress resistance. This study focused on annual [...] Read more.

Soil salinization significantly exacerbates the deficiency in plant-available phosphorus in the soil, thereby adversely affecting plant growth and development. Through various processes, phosphate-solubilizing bacteria in the rhizosphere significantly increase soil-soluble phosphorus content, boosting plant development and stress resistance. This study focused on annual R. soongorica seedlings to examine how rhizosphere phosphate-solubilizing bacteria enhance growth under NaCl-induced stress conditions. This study isolated and characterized rhizosphere phosphate-solubilizing bacteria, evaluating their phosphate solubilization capacity and effects on R. soongorica seedling growth and physiology under NaCl stress through pot experiments, with potential applications in saline soil improvement and desert ecosystem restoration. This study used four treatment groups (control group, NaCl treatment group, bacterial inoculation treatment group, and bacterial and NaCl mixed-treatment group) with twelve treatments and four replicates per treatment. The experimental results demonstrated that five phosphate-solubilizing bacterial strains exhibited a significant phosphate solubilization capacity, accompanied by a notable reduction in pH within the inorganic phosphorus medium. Compared to the NaCl treatment, the net growth of the plant height of R. soongorica seedlings inoculated with strains J23, J24, and M1 under NaCl stress increased significantly (p < 0.05), and all of them more than doubled, and the net growth of the stem diameter of R. soongorica seedlings inoculated with strain J24 increased significantly by 144.17%. The physiological characteristics of R. soongorica seedlings demonstrated significant alterations following inoculation with the five phosphate-solubilizing bacterial strains. The inoculation of R. soongorica seedlings with the five phosphate-solubilizing bacterial resulted in a statistically significant increase in both foliar total phosphorus content and available phosphorus levels within the rhizosphere soil (p < 0.05). Additionally, under NaCl stress conditions, R. soongorica seedlings inoculated with the five phosphate-solubilizing bacterial strains exhibited varying degrees of salt tolerance, with the following descending order of effectiveness: J24 > P2 > J23 > P3 > M1. In conclusion, the rhizosphere phosphate-solubilizing bacteria J24 represents a potentially valuable microbial resource for saline soil amelioration, demonstrating the most pronounced enhancement in both the growth parameters and salt tolerance of R. soongorica seedlings under 300 mmol·L⁻¹ NaCl stress. Full article

(This article belongs to the Special Issue Adaptive Physiology of Forest Plants: Mechanisms, Strategies, and Responses to Environmental Challenges)

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19 pages, 4421 KB

Open AccessArticle

Variations in Leaf Photosynthesis and Its Limitations at Different Canopy Positions in Mature Camphor Trees

by Hanbing Leng, Lingyan Zhou and Wei Yan

Forests 2025, 16(4), 581; https://doi.org/10.3390/f16040581 - 27 Mar 2025

Cited by 1 | Viewed by 1046

Abstract

Urban forests play important roles in carbon sequestration and climate change mitigation. However, their adaptive mechanisms and limitations on photosynthesis throughout the canopy are poorly understood. This study takes the most widely distributed 50-year-old camphor plantations (Cinnamomum camphora) in Shanghai as [...] Read more.

Urban forests play important roles in carbon sequestration and climate change mitigation. However, their adaptive mechanisms and limitations on photosynthesis throughout the canopy are poorly understood. This study takes the most widely distributed 50-year-old camphor plantations (Cinnamomum camphora) in Shanghai as the research objects. We investigated the variations in leaf morphology and photosynthetic physiology and biochemistry at six different canopy positions during a summer and an autumn period. We discovered that on account of leaf nitrogen loss and water deficit, light-saturated photosynthesis (A_max) declined in upper sunlit leaves despite being exposed to high sunlight in the same fashion as stomatal and mesophyll conductance (g_sw, g_m), photochemical quenching coefficient and actual photochemical efficiency of PSII (Φ_PSII, q_P), and maximum rate of electron transport and carboxylation (J_max, V_cmax) during the growing season. Although seasonal change had little effect on A_max, the relative importance of limitations varied temporally. Mesophyll and biochemical limitation were the major contributors to the decline in the A_max in upper sunlit leaves between summer and autumn, respectively. Our study highlights the constraints of carbon fixation capacity in dense stands of mature camphor trees and offers technical support for the accurate prediction of canopy photosynthesis and the enhancement of carbon sequestration management in urban forests. Full article

(This article belongs to the Special Issue Adaptive Physiology of Forest Plants: Mechanisms, Strategies, and Responses to Environmental Challenges)

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23 pages, 14226 KB

Open AccessArticle

Mycorrhization of Quercus dentata Seedlings with Laccaria bicolor Enhances Salt Tolerance of Plants Only Under Relatively Moderate Soil Salinity Level

by Wenlong Sun, Luyu Qi, Haonan Chen, Yixin Song, Jiaqi Jiang, Puyi Zhang, Bojian Wang, Qiang Wang, Gaode Meng, Tianyu Ji, Xinke Sun, Weihua Guo, Ning Du and Janusz J. Zwiazek

Forests 2025, 16(3), 413; https://doi.org/10.3390/f16030413 - 25 Feb 2025

Cited by 2 | Viewed by 1110

Abstract

Soil salinization is a growing global concern in many ecosystems. Although ectomycorrhizal fungi have been shown to alleviate the effects of salinity in some tree species, uncertainties persist concerning their effectiveness when plants are exposed to different salinity levels that are commonly present [...] Read more.

Soil salinization is a growing global concern in many ecosystems. Although ectomycorrhizal fungi have been shown to alleviate the effects of salinity in some tree species, uncertainties persist concerning their effectiveness when plants are exposed to different salinity levels that are commonly present in salt-affected soils. Quercus dentata seedlings either non-inoculated (mycorrhizal control) or inoculated with the ectomycorrhizal fungus Laccaria bicolor were then treated with three NaCl concentrations (0, 0.4%, and 0.8%). The physiological, stoichiometric, and growth characteristics of the plants were examined. NaCl significantly affected seedling growth and physiology. However, the impact of L. bicolor on Q. dentata seedlings could shift in response to varying salt concentrations. Under moderate salinity, inoculation of L. bicolor increased root biomass by 4.55% and leaf chlorophyll concentrations by 46.8%, and decreased leaf Na⁺ concentrations and the Na⁺/K⁺ ratios. Under high salinity, L. bicolor decreased leaf water content and fluorescence parameters, and increased leaf Na⁺ concentrations. The effect of ectomycorrhizal fungus L. bicolor on Q. dentata seedlings was dependent on NaCl concentration, and our results indicate that the use of L. bicolor in afforestation efforts with Q. dentata would only be effective under relatively low soil salinity levels. Full article

(This article belongs to the Special Issue Adaptive Physiology of Forest Plants: Mechanisms, Strategies, and Responses to Environmental Challenges)

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