Trees最新文献

Key message

A scaling exponent numerically less than unity for the scaling of flower versus pedicel fresh mass was observed across seven Magnoliaceae species, indicating a disproportionate pedicel investment with increasing total flower mass.

Abstract

Although biomass allocation between vegetative organs (e.g., laminae and petioles) has been extensively studied, the quantitative patterns among floral organs, particularly between floral parts (i.e., the perianth, androecium, and gynoecium) and their supporting pedicels, remain largely unexplored. To address this gap, we analyzed flower versus pedicel biomass allocation patterns across seven Magnoliaceae species using a total of 2012 flowers. Flower fresh mass (FM_F) and pedicel fresh mass (FM_P: the internode between the uppermost annular stipular scar and perianth base) were measured. Reduced major axis regression signifies a statistically significant scaling relationship for FM_F versus FM_P (r² = 0.92). The scaling exponent for this relationship (α = 0.923 with its 95% confidence interval: 0.912 − 0.935) confirms the phenomenon called “diminishing returns” (i.e., increasing flower mass requires a disproportionately larger pedicel investment), which suggests prioritized biomass investing for mechanical or hydraulic support with increasing reproductive display. These findings provide additional insights into functional constraints in floral architecture. Future studies should expand taxonomic samplings to test the generality of FM_F versus FM_P scaling and compare functional investments in floral support structures (e.g., pedicels versus receptacles) across pollination syndromes to elucidate structural constraints in floral evolution.

Fungi are considered to be an important cause of agarwood formation. However, most of the fungal species used to artificially induce agarwood formation are fungi that are pathogenic on trees. Their improper selection can cause the tree to rot, which seriously affects the yield of agarwood and causes significant economic losses. Research on the production of agarwood induce by fungi antiseptically is highly significant for the innovation and optimization of the techniques to induced agarwood, as well as for the enhancement of its yield and quality. In this study, the existing difference between the anatomical structure of xylem tissues, physiological characteristics, and major aromatic components in agarwood formation was compared using an induction treatment of the Aquilaria sinensis (Lour.) Spreng test with Melanotus flavolivens (M₁, decay fungus), Muscodor sp. (M₂, nonpathogenic fungus) and a mixed solution of both (M₃). After the induction, the M₃ treatment showed the largest area of xylem tissue discoloration and the highest contents of oleaginous substances in month 12. The treatments of M₁, M₂, and M₃ tended to increase and then decrease the activities of superoxide dismutase(SOD), peroxidase (POD) (except for M₁), and catalase(CAT) and the content of malondialdehyde(MDA), as well as the significant enhancement of the activities of terpene synthases(TPS) and polyketide synthases(PKS). M₁, M₂, and M₃ agarwood yield and alcohol-soluble extract reached their maximum values at 27.12%, 22.35%, and 30.08% for the former and 13.46%, 9.02%, and 16.82% for the latter, respectively. The results of gas chromatography–mass spectrometry showed that 58 major aromatic components were identified in the agarwood samples. The total relative contents of aromatic components, M₃ (90.88%) > M₁ (83.39%) > M₂ (76.21%) > CK (33.51%). The terpenes primarily included ( +)-α-longipinene, α-muurolene, and santalol among others. The most common chromones were 2-(2-phenylethyl)chromone, and the aromatics were benzaldehyde and benzylacetone. The alkanes were hexadecane and 5-(2,3-dimethyltricyclo[2.2.1.02, 6]heptan-3-yl) and pentan-2-one among others. A Mantel’s r analysis indicated a significant positive correlation between the terpenes, chromones, aromatics, and alkanes with both the content of alcohol-soluble extracts and the POD activity (P < 0.05), and no significant correlation existed between them and the other physiological indicators (P > 0.05).Briefly, the M₃ induction treatment resulted in a relatively strong response and longer duration of A. sinensis to stress injury, which was the primary reason for the higher production and better quality of agarwood.

Light drives mortality, growth, and functional strategies of Pericopsis elata, guiding optimal silvicultural practices from early shading to timely thinning.

The low natural regeneration of many exploited tree species in Central Africa highlights the need to more precisely define appropriate silvicultural practices. Understanding how seedlings adjust their functional traits and growth in full sunlight and under the shade of other trees is essential to optimise enrichment planting protocols. To address this topic on Pericopsis elata, an important light-demanding timber species exploited in Central Africa, 230 seedlings were transplanted between 2022 and 2024 in the buffer zone of the Yangambi Biosphere Reserve, Democratic Republic of Congo, either in full sunlight or shaded environments (under Acacia auriculiformis). Twenty-three morpho-physiological and chemical traits were measured, alongside growth dynamics. Mortality was higher in full sunlight (10.7%) during the first ten months after transplantation, but converged to similar rates (about 13%) in both environments after three years in the field. Diameters were higher in full sunlight after 310 days, and heights were greater after 600 days of planting. Seedlings in full sunlight exhibited a conservative resource-use strategy contrasting with a more acquisitive strategy under shade. Light environment explained over 58% of the variation in key traits such as specific leaf area, stomatal density, and maximum stomatal conductance. Trait correlations were stronger and more coordinated in full sunlight, while they weakened or disappeared under shade, reflecting a shift along the resource acquisition-conservation continuum in response to light availability. These results provide one of the first experimental insights into how light influences growth and functional strategies in juvenile P. elata. We conclude that shading with a canopy openness of about 20–65% promotes early establishment after transplanting seedlings, but a gradual thinning of shade trees is needed from the second year to enhance growth and survival.

Key message

Development of de novo SSR markers in jamun with high PIC and high cross-species transferability provide a valuable resource for genetic diversity analysis, conservation, and molecular breeding in S. cumini.

Abstract

Syzygium cumini (Jamun) is an underutilized tropical fruit tree valued for its nutritional and therapeutic properties, particularly high content of antioxidants, flavonoids, and phenolic compounds. Despite its economic and medicinal potential, genomic resources for jamun remain limited. In this study, partial genome sequencing of the cultivar ‘Dupdal’ was done using the Illumina HiSeq 2500 platform, yielding a 432 Mb assembly and identifying 72,464 simple sequence repeats (SSRs), with predominant di-nucleotide motifs. Thirty polymorphic SSR primers were utilized to genotype 254 jamun accessions. The markers exhibited high informativeness, with polymorphic information content (PIC) values ranging from 0.80 to 0.94 (mean: 0.88). Observed and expected heterozygosity ranged from 0.33 to 0.84 and 0.62–0.94, respectively. Population structure analyses using neighbor-joining dendrogram, STRUCTURE, and principal component analysis (PCA) revealed two distinct genetic clusters, generally corresponding to geographic origin. Analysis of molecular variance (AMOVA) indicated that 21.54% of the total genetic variation resided among populations, while 78.44% was within populations, with a significant fixation index (FST = 0.2159; p = 0.001) suggesting high genetic differentiation. The newly developed genome-wide SSR markers demonstrated high cross-species transferability and also provide a valuable resource for genetic diversity analysis, conservation, and molecular breeding in S. cumini and related Syzygium species.

Key message

Nutrient utilization strategies of three alpine plants were less affected by elevation, exhibited different N or P limitation types and change with growing season stages.

Abstract

Alpine plants in high mountain regions have to cope with challenging cold climate, and potential nutrient limitations induced by low temperature. The historic large-scale volcanic eruption in 946 A.D. on Changbai Mountain, Northeast China, dramatically altered its natural soil and vegetation, making it a unique area to investigate nutrients constrains on alpine plants growth. This study examined carbon (C), nitrogen (N), phosphorus (P) and potassium (K) utilization strategies in three dominant alpine plant species (Betula ermanii, Vaccinium uliginosum and Rhododendron aureum) across five elevations and three growing season stages. The results showed that the nutrient concentrations (C, N, P and K) in leaves and shoots varied significantly with species and seasonal stages, but were less influenced by elevation. Stoichiometric ratios indicated initial N limited (N: P < 14) in all species. Subsequently, B. ermanii showed balanced N and P requirements (N: P, 14.42 to 15.98), V. uliginosum shifted to P limitation by senescence (8.81 to 19.54), while R. aureum remained N limitation (8.71 to 9.47). Deciduous species (B. ermanii and V. uliginosum) exhibited higher N and P resorption efficiencies, whereas the evergreen R. aureum experienced higher K limitation (N: K > 1, P: K > 1). With their different biogeochemical ecological niches, the findings revealed that interspecific differences and seasonal dynamics are key drivers of nutrient strategies in alpine plants. The study highlights the complexity of nutrient limitations and resorption in a warming-sensitive treeline ecotone, offering insights into alpine plant adaptation and ecosystem conservation.

Elucidating the underlying mechanisms driving the geographic and niche differentiation of forest tree species is amongst the key issues in studies of phytogeography as well as for determination of the climate-forest structure relationships. However, an explicit knowledge on the controls of the spatial displacement of congenic tree species by climatic factors is still lacking. Here we investigated changes in the radial growth of three deciduous oak species (Quercus variabilis, Quercus aliena var. acuteserrata, and Quercus wutaishanica) occurring sequentially along an altitudinal gradient on Mt. Taibai of the Qinling Mountains. We found that changes in moisture conditions with altitude, inferred by the standardized precipitation-evapotranspiration index (SPEI), dominated the influences on the radial growth of the three oak species. While an increase in temperature appeared to favor the radial growth in both Q. aliena var. acuteserrata and Q. variabilis across their altitudinal range, the association between rising temperature and drought (decreasing SPEI value) suppressed the radial growth of the high-altitude oak species Q. wutaishanica. Moreover, although three oak species exhibited comparable levels of drought resistance, the growth performance of Q. aliena var. acuteserrata and Q. variabilis demonstrated greater resilience, with more effective recovery from extreme drought compared to Q. wutaishanica. Our findings suggest that with projected future warming and more frequent and severe drought events, a range contraction would likely occur in Q.wutaishanica at its upper limit, whereas the distributional range of Q. aliena var. acuteserrata and Q. variabilis would possibly shift upwards or remain unchanged due to their higher plasticity to environmental changes.

Plants exposed to salinity and drought often employ distinct adaptive strategies, which can influence their energy metabolism and overall physiological responses. This study investigated the morphological, biochemical, and physiological responses of two-year-old grafted carob (Ceratonia siliqua (L.)) plants to salt and drought stresses, along with an analysis of their cost-benefit ratios. Two sets of plants were grown under field conditions: for salt stress, plants were irrigated with saline water at concentrations of 0, 30, 60, 120, and 240 mM NaCl; for drought stress, irrigation was 100%, 75%, 50%, and 25% of the plants’ water requirements. Results showed that salt stress significantly inhibited growth, particularly reducing collar diameter (gain of severe salt stress 35.81%; control 122.11%). Higher salt concentrations decreased the membrane stability index (61.67%; control, 76.69%) and increased electrolyte leakage (up to 44%), while levels of proline and soluble sugars rose (up to 5.79 µmol. g^− 1 FW and 10.78 mg. g^− 1 FW, respectively). Severe drought stress, on the other hand, enhanced the activities of phenol oxidase (up to 50 UE/mg of protein), polyphenol oxidase (up to 131.51 UE/mg of protein), catalase (up to 239.83 µmol/min/mg of protein), and increased hydrogen peroxide levels (up to 1.95 µmol/g FW). Both primary and secondary metabolites, especially under moderate to severe stress conditions, were significantly elevated. Severe drought also resulted in higher osmolyte levels, particularly proteins (up to 12.73 mg.g^− 1 FW) and soluble sugars (up to 8.55 mg.g^− 1 FW), while total nitrogen content decreased (0.0746% DW). Both stressors triggered increased antioxidant defense mechanisms and the accumulation of osmotic regulators, highlighting the carob plant’s adaptive responses to these environmental challenges. While drought stress reduced irrigation costs, the reduction was insufficient to fully offset the negative effects of drought. According to our cost-benefit analysis, the most favorable treatment was the 25% drought stress level (i.e., 75% of the plant’s water requirements).

Key message

Picea crassifolia shows varying growth patterns, climate-growth relationships, and ecological resilience across climatic habitats.

Abstract

Significant unknowns persist concerning how forest ecosystems globally react to climate change. Dryland trees exhibit increased sensitivity to rising temperatures, threatening the survival of regional forest ecosystems. Therefore, understanding growth patterns of trees and assessing their ecological resilience to extreme drought events are of critical environmental importance. Dendrochronological samples of Picea crassifolia were obtained across elevational gradients in both humid and arid regions of the Qilian Mountains, positioned within northwestern China’s arid and semiarid belt. We evaluated tree growth patterns, their climatic sensitivity, and key indicators of ecological resilience to drought using tree-ring data. Our findings were as follows: (1) Trees at three elevations in the arid region demonstrated uniform growth trajectories: initial augmentation, intermediate suppression, and terminal resurgence. Tree growth at high elevation in the humid region exhibited a continuous upward trend, whereas trees at mid and low elevations initially increased before declining. (2) Drought imposed limitations on arboreal development across tripartite elevational tiers in the arid region. High temperatures had suppressive effects on arboreal development within middle and low elevational belts in the humid region, while low temperatures limited tree growth at high elevation. (3) Trees in the humid region exhibited greater drought resistance, while those in the arid region demonstrated higher recovery. Drought resistance increased with increasing elevation, whereas recovery decreased. Consequently, developing and implementing adaptive silvicultural strategies is imperative for proactive climate response.

Key message

The Montgomery equation accurately estimates leaf area in two Quercus species using either midrib-based or conventional leaf length measurements, even under bilateral asymmetry.

Abstract

Estimation of leaf area is crucial for assessing photosynthetic potential and light interception in plants. The Montgomery equation (ME), which assumes a proportional relationship between leaf area (A) and the product of leaf length (L) and width (W), i.e., A ∝ LW, is widely used, but its validity under leaf bilateral asymmetry requires further testing, particularly when using a midrib-based length definition. Using over 300 leaves each from Quercus acutissima and Q. chenii, we compared a midrib-based approach (curvilinear midrib length as L, and maximum width perpendicular to the midrib tangent as W) with the conventional approach (straight-line distance from leaf apex to base as L). Leaf asymmetry was quantified using two indices. Quercus chenii exhibited significantly greater bilateral asymmetry than Q. acutissima (p < 0.05). Both methods predicted leaf area accurately, with mean absolute percent errors (MAPE) below 5%. The midrib-based approach showed slightly better statistical performance, but the conventional approach remained highly accurate. The ME is valid for estimating leaf area in asymmetric leaves. The conventional approach is recommended for its practicality and sufficient accuracy in field applications.