Tree physiology最新文献

Pigment dynamics in temperate evergreen forests remain poorly characterized, despite their year-round photosynthetic activity and importance for carbon cycling. Developing rapid, nondestructive methods to estimate pigment composition enables high-throughput assessment of plant acclimation states. In this study, we investigate the seasonality of eight chlorophyll and carotenoid pigments and hyperspectral reflectance data collected at both the needle (400-2400 nm) and canopy (420-850 nm) scales in longleaf pine (Pinus palustris Mill.) at the Ordway Swisher Biological Station in north-central Florida, USA. Needle spectra were obtained at three distinct times throughout the year, while tower-based spectra were collected continuously over a 9-month period. Seasonal trends in photoprotective pigments (e.g. lutein and xanthophylls) and photosynthetic pigments (e.g. chlorophylls) aligned closely with seasonal changes in photosynthetically active radiation and gross primary productivity. To track inter-tree and seasonal variability in pigment pools with hyperspectral reflectance data, we used correlation analyses and ridge regression models. Ridge regression models using the full hyperspectral range outperformed predictions using standard linear regression with specific wavelengths in a normalized difference index fashion. Ridge regression successfully predicted all pigment pools (R2 > 0.5) with comparable accuracy at both the needle and canopy scales. The models performed best for lutein, neoxanthin, antheraxanthin, and chlorophyll a and b-which had greater inter-tree and seasonal variation-and achieved moderate accuracy for violaxanthin, alpha-carotene and beta-carotene. These results provide a foundation for scaling biochemical traits from ground-based sensors to airborne and satellite platforms, particularly in ecosystems with subtle changes in pigment dynamics.

Albinism is typically lethal in autotrophic plants due to the absence of photosynthetic pigments and functioning chloroplasts. Yet, rare exceptions occur where achlorophyllous individuals persist in natural ecosystems. We investigated the physiological, anatomical and isotopic characteristics of naturally occurring albino European beech (Fagus sylvatica L.) trees in the Moravian Karst, Czechia. One albino individual, estimated to be ~30 years old, represents an unprecedented case of long-term survival without photosynthesis in a woody angiosperm. Using a multi-parameter approach-including stable isotope analysis (δ13C, δ15N), pigment quantification, saccharide profiling, gas exchange, leaf anatomy, stomatal traits and microsatellite genotyping-we confirmed the absence of photosynthetic capability, explored potential mechanisms of carbon acquisition and assessed clonal affiliation of the albino to its neighbouring trees. An albino individual exhibited almost absent photosynthetic pigments and lacked differentiated thylakoids, and showed significantly reduced stomatal conductance and density. The CO2 release from albino leaves indicated predominant mitochondrial respiration even under the light conditions. Intriguingly, albino leaves accumulated higher concentrations of soluble sugars (notably glucose and fructose) and were enriched in δ13C, similar to mixotrophic orchids, suggesting heterotrophic carbon uptake. Microsatellite genotyping revealed that the albino individual is not genetically identical to any of the surrounding green trees, thus making root suckering unlikely. While partial mycoheterotrophy cannot be entirely excluded, the data strongly support a trophic strategy based on carbon translocation from an autotrophic donor through root connectivity. This study offers novel physiological insights into albino tree survival and illustrates the complexity of belowground integration in forest ecosystems.

The karst peak-cluster depression landscape is characterized by pronounced topographic and edaphic heterogeneity, resulting in a high degree of spatial variability in resource availability. Such a complex environmental mosaic influences plant functional traits and their adaptive strategies. However, the patterns of trait variation and their underlying environmental drivers in karst peak-cluster depressions remain poorly understood. In this study, we investigated a 15-ha forest dynamics plot in the Nonggang Nature Reserve, Guangxi. We used linear mixed models to partition variance, principal component analysis to examine trait covariation, and redundancy analysis combined with hierarchical partitioning to evaluate the effects of topographic and edaphic factors on leaf functional traits at the community, species and intraspecific levels. The results showed that trait variation was mainly driven by interspecific differences, with part of the variation attributable to evolutionary history. Morphological traits and physiological traits exhibited relatively higher intraspecific and interspecific variation, respectively. The trait covariation patterns revealed that several leaf chemical traits exhibited atypical modes of coordinated variation. The explanatory power of topographic and edaphic factors for trait variation differed among ecological levels, being highest at the species level, followed by the community and intraspecific levels. Among these, the soil carbon-to-nitrogen ratio and slope were identified as the main drivers of species-level variation. Overall, our findings reveal functional shifts in plant ecological strategies in complex karst landscapes and emphasize the differential influence of topographic-soil factors across hierarchical levels, providing empirical evidence for understanding plant adaptive mechanisms along multidimensional environmental gradients.

Populus trees are commonly used in the construction of shelter forests in water-limited areas of China; however, different poplar species are facing various levels of dieback risks under the increased drought associated with climate change. The objective of this study was to explore whether crown height affects the xylem hydraulics and to evaluate the suitability of different Populus species for constructing sustainable shelterbelt in water-limited regions. Xylem hydraulics and water relations of branches at upper and lower positions of tree crown, alongside radial growth rate, were compared between two species that are commonly used in shelterbelt construction but have contrasting crown types, i.e., Populus simonii Carrière with short oval crowns and Populus pioner Jabl. with tall columnar crowns. The results showed that as height increases, P. simonii exhibited enhanced hydraulic efficiency and safety, while no significant differences in these hydraulic traits across canopy layers were observed in P. pioner. In addition, the upper branches of P. pioner have lower water potential and longer water flow paths, resulting in lower hydraulic safety margin, which means that the species was more prone to hydraulic limitation and eventually dieback. Adjustments of vessel sizes and leaf mass per area along the crown of P. simonii contributed to the increase in xylem hydraulic capacity in upper branches and the homeostasis of leaf water potential within the crown. Although the adjustment of using water more conservatively potentially compromised the whole-tree carbon assimilation and thus growth rate, P. simonii seemingly showed stronger adaptability to projected drought intensification by shedding part of branches at the crown bottom and might thus be a more suitable species for establishing stable shelterbelt in water-limited areas. This study, from perspectives of tree physiology, provides an important reference for afforestation species optimization and thus the sustainable management of shelterbelts in water-limited areas of northern China.

Subalpine forests are one of the regions where the adjustment of fine-root water uptake becomes important for tree adaptation; however, this process has not been adequately investigated. Here, we aimed to detect species-specific elevational variation in fine-root water uptake and its relationship with the variation in fine-root functional traits in subalpine forests. Fine-root water flux (WFsoil-root) was evaluated from direct measurement of the water potential difference between the soil and fine roots, and the hydraulic conductivity of fine roots of Abies mariesii and Betula ermanii. Additionally, we measured the average diameter, specific root length, and root tissue density (RTD) as morphological traits, and nitrogen content (N) as a chemical trait. These traits were compared at different elevations (2,000, 2,300, and 2,500 m), and the relationships between WFsoil-root and root morphological and chemical traits were evaluated. The WFsoil-root of A. mariesii was highest at 2,500 m compared to the WFsoil-root value of B. ermanii at 2,300 m. These results suggest that the limiting factors of fine-root water uptake differ between A. mariesii and B. ermanii in subalpine forests. Additionally, WFsoil-root covaried with the RTD-N axis along the elevational gradient, and trees increased WFsoil-root with increasing RTD. This result brings the new insight that higher RTD of fine root could function as the acquisitive traits for water uptake in subalpine forests. However, covariation of WFsoil-root with RTD-N axis was less obvious in A. mariesii than B. ermanii indicating different driving mechanisms of WFsoil-root between the species. Trees must cope with several factors limiting their growth in subalpine forests. Adjustment of WFsoil-root may contribute to the species-specific strategy, which compensates for their physiological processes and growth, and coordination with the RTD-N axis would be important for effective water uptake in cold and carbon-limited environments.

Although the presence of methanogens in living tree trunks was reported more than 50 years ago, it has recently been suggested that trees in upland forests constitute a net sink for atmospheric CH4, which contradicts other recent or older studies. To clarify the role of tree trunks as net emitters or consumers of CH4, we measured trunk CH4 fluxes of 11 upland species, up to 12 m above ground for some trees, and estimated their ex-situ potential CH4 oxidation capacity. Trees from seven species emitted CH4 from their trunks, some at height well-above 2 m above ground, whereas little CH4 was emitted from the trunks of the other four species. The average rate of CH4 oxidation was an order of magnitude lower than the average trunk CH4 fluxes measured on the same individuals, consistent with the very weak net uptake of CH4 occasionally measured on some trees. CH4 oxidation in the bark could nevertheless mitigate CH4 emissions from tree trunks. Trees in our mountain forest were likely a net source of CH4 to the atmosphere rather than a net sink of atmospheric methane, suggesting that it is premature to conclude that tree surfaces could be a significant sink for atmospheric CH4 globally.

Accelerated drought stress along with global warming has significantly impacted high-elevation ecosystems, causing a massive decline of conifers worldwide, including Korean fir (Abies koreana E.H.Wilson). However, studies on the climate adaptability and underlying physiological mechanisms of coexisting species remain limited, despite their importance for understanding future species composition. To investigate species-specific responses to climate change, a rainfall reduction and heat experiment was implemented by blocking precipitation by 33% and 67% and increasing temperature by 1.5°C for three coexisting high-elevation tree species: Korean fir, Korean pine (Pinus koraiensis Siebold & Zucc.), and Manchurian ash (Fraxinus mandshurica Rupr.). Korean fir exhibited the most sensitive stomatal control to conserve its hydraulic status, which significantly suppressed photosynthesis, depleted root starch reserves, and ultimately reduced growth. In contrast, Manchurian ash showed the highest resistance, with stable stomatal response through active leaf osmoregulation and increased chlorophyll content, which supported the maintenance of photosynthesis and root nonstructural carbohydrate (NSC) reserves. Korean pine exhibited intermediate responses, with the second-most sensitive stomatal and photosynthetic regulation, along with temporarily tolerant traits such as increased leaf sugar and chlorophyll content, while allocating relatively more carbon to growth than to storage. This resulted in the highest mortality in Korean fir, followed by Korean pine and Manchurian ash. This study enhances our understanding of the early stress responses of high-elevation species and provides insights into predicting future forest dynamics.

Woody plants have garnered significant attention in recent years for their essential ecological and economic contributions. Protoplasts, isolated from plant cells, have exhibited remarkable totipotency and offered immense potential in a broad array of biological and biotechnological fields. These include, but are not limited to, protein gene expression regulation, functional gene analysis, subcellular localization, interaction studies, gene editing and single-cell sequencing. This review offers a comprehensive overview of protoplast isolation methods, key influencing factors, purification techniques and viability assessment. It further explores the use of protoplast transient expression systems for gene function characterization, while highlighting the diverse applications of protoplast-based technologies, such as fusion, regeneration, genome editing and single-cell sequencing. With technological advancements, future breakthroughs in these areas will be poised to create new avenues for research, genetic improvement and biotechnological innovations in woody plants.

Fine root carbon (C), nitrogen (N) and phosphorus (P) stoichiometric characteristics are key indicators of plant nutrient acquisition strategies and environmental adaptation. Yet, their responses to long-term N deposition, especially the hierarchical variations across root orders, remain unclear, hindering a mechanistic understanding of root system plasticity. To assess root-order-specific responses of fine root C, N and P concentrations and stoichiometric ratios to long-term N fertilization, a field experiment was initiated in 2014 in coastal Metasequoia glyptostroboides Hu & W.C. Cheng plantations in Jiangsu Province, eastern China, involving five N fertilization levels (0, 56, 168, 280 and 336 kg ha-1 year-1). The results showed that N fertilization generally increased fine root N concentration, C/P and N/P ratios, and decreased P concentration and C/N ratio across root orders. Except for fine root C concentration, the absolute response ratios of fine root stoichiometric traits to N fertilization exhibited an increasing trend across root orders. The direct effects of N fertilization on the fine root stoichiometric characteristics were obviously higher than the indirect effects whether at the scale of the entire root system, functional module or individual root order. Significant associations between fine root functional traits and stoichiometric characteristics were observed at the scale of the entire root system, whereas such relationships were not evident at the scale of individual root order or functional module. Overall, the fine root stoichiometric characteristics responded more strongly with increasing root order under N fertilization, and interpretations of the drivers of these characteristics should be scale-explicit.

Understanding the factors and processes of tree water use at night is critical for sustainable fruit production and ecological protection within the context of increasing global climate extremes. A long-term experiment was set up in China's Loess Plateau region on rainfed fruit trees-jujube (grown under arid, semi-arid conditions) and apple (grown under semi-humid, drought-prone conditions). Data were collected under both wet and dry conditions and then analyzed for total sap flow (Q), daytime sap flow (Qd), nighttime sap flow (Qn) and the related components of nighttime canopy transpiration (QTn) and nighttime water recharge (QRn). The results showed that the percentage fraction of Qn to Q was 27.6% for jujube and 20.9% for apple. For jujube, QTn/Qn was 67.5%, which was higher than that of apple (56.9%), a species that was under relatively humid conditions. At annual scale, higher annual precipitation (P) resulted in higher Qd but lower Qn. At the daily scale, the components of Qn were positively correlated with leaf area index (LAI) but negatively correlated with solar radiation (Rs) and vapor pressure deficit (VPDn) for jujube at Mizhi Station. Under low LAI/Rs conditions, Qn components of jujube trees had negative correlation with soil water content (SWC). The components of Qn are positively correlated with SWC for apple at Luochuan Station. Under adequate SWC, QRn increased with increasing Qd for apples. Structural equation modeling suggested that the main drivers of nighttime water use were similar for the two fruit trees, but with stronger direct effect of LAI on Qn for jujube. Moreover, Rs mainly affected Qn/Q and QTn/Q through an indirect pathway in jujube, while both its direct and indirect effects were strong and almost equivalent in apple. The findings are critical for the management of fruit trees in ecological environments under worsening environmental conditions.