Trees最新文献

Light is a crucial environmental factor influencing plant growth and development. An efficient regeneration system is essential due to various limiting factors in the asexual reproduction of Fraxinus mandshurica. This study aimed to determine the optimal light conditions for the regeneration of adventitious buds in F. mandshurica using different red and blue light ratios. Using hypocotyls as explants, the most suitable medium for bud regeneration of F. mandshurica consisted of WPM supplemented with 1.0 mg/L Thidiazuron (TDZ), 3.0 mg/L 6-Benzylaminopurine (6-BA), 30 g/L sucrose, and 7 g/L agar (pH = 5.8-6.0). Monochromatic red light treatment effectively increased the adventitious bud induction rate to 2.25-fold of white light treatment, while the white light and B (blue): R (red) = 3:2 combination significantly promoted adventitious bud elongation. Combinations of light qualities at ratios of B: R = 2:3 and B: R = 1:4 significantly promoted root formation from seedling-derived shoots, increasing leaf area and chlorophyll content. Light conditions of B: R = 3:2 and B: R = 1:4 improved the chlorophyll a/b ratio, while a ratio of B: R = 4:1 promoted carotenoid synthesis. Furthermore, a correlation was observed between light quality and the expression of regeneration-related genes. The highest expression levels of WUSHEL (FmWUS), WUSCHEL-relatedhomeobox (FmWOX), and WOUND INDUCED DEDIFFERENTIATION1 (FmWIND1), associated with regeneration, were recorded under red light (R). Similarly, the highest expression of elongation-related genes, PHAVOLUTA (FmPHV), CUP-SHAPED COTYLEDON1 (FmCUC1), and FmWOX4, was found under blue: red (B: R) = 3:2. These gene expression results aligned with the observed phenotypes, suggesting that light quality plays a crucial role in bud regeneration and elongation. In summary, using and combining LED light sources resulted in significant improvements in the regeneration of adventitious shoots and adventitious roots for F. mandshurica.

Water-use strategies, i.e., the ratio of carbon gain to water loss, reflect how efficiently a plant assimilates carbon minimizing water loss. Leaf anatomical traits are crucial in shaping these strategies. Here, we look at evidence of water-use strategies from assessing leaf anatomical traits in two co-occurring species from the Cerrado (Brazilian savanna) and the Caatinga (a seasonally dry tropical forest in Brazil). We tested whether these species exhibit convergent anatomical adaptation or distinct structural responses, and whether individuals of the same species would exhibit distinct responses to water-use strategies between sites. We collected leaves from fully sun-exposed branches of individuals of the co-occurring species Tabebuia aurea and Tocoyena formosa, and performed light and scanning electron microscope observations of leaf anatomical traits to assess differences between sites. Leaf anatomical traits explained differences between sites only for Tabebuia aurea: individuals from the Cerrado exhibit thicker leaves and spongy and palisade parenchyma, and higher frequency of peltate trichomes, while those from the Caatinga show thicker abaxial and adaxial epidermis and a greater proportion of intercellular air space in the mesophyll. No differences are observed between individuals of T. formosa. Therefore, there is no convergent leaf anatomical response of species driven by environmental constraints. The variation in individuals of T. aurea between sites reflects contrasting functional adjustment aligning in opposite directions along the conservative-acquisitive strategy spectrum: Caatinga individuals show anatomical traits associated with an acquisitive strategy, while Cerrado individuals exhibit traits linked to a more conservative water-use strategy.

Urbanization and greenhouse gas emissions have worsened the challenges of climate change, especially in densely populated semi-arid areas. Urban Green Spaces (UGSs) are essential in reducing these impacts, as they contain significant biomass and soil carbon stocks. This study aimed to enhance understanding of the role of UGSs in carbon storage by measuring the above-ground carbon stock (AGC) and below-ground carbon stock (BGC) in terms of soil organic carbon (SOC), litter carbon (LC), and understorey carbon (UC) across three selected UGSs in Delhi: a Delhi Development Authority Park (DDA park, DP), a biodiversity park (BP), and a city forest (CF), representing UGSs in Delhi. The research was carried out over two years (2022–2024). The average Above Ground Biomass (AGB) was 84.42 ± 5.92 Mg ha⁻¹, and the mean Below Ground Biomass (BGB) was 22.79 ± 9.86 Mg ha⁻¹. Similarly, the mean Above Ground Carbon (AGC) was 40.10 ± 17.36 Mg C ha⁻¹, with the mean BGC at 10.83 ± 4.68 Mg C ha⁻¹. Total biomass and carbon stock across all transects were 4074.34 Mg ha⁻¹ and 1935.31 Mg C ha⁻¹, respectively. The average Soil Organic Carbon (SOC) was 3.98 ± 1.60 Mg C ha⁻¹ across all three UGSs during the study period. The overall ecosystem carbon stock averaged 63.93 ± 23.09 Mg C ha⁻¹, ranging from 34.25 Mg C ha⁻¹ at CF in 2022 to 83.59 Mg C ha⁻¹ at BP in 2023. The total ecosystem carbon stock was 190.90 Mg C ha⁻¹ in 2022, rising to 192.71 Mg C ha⁻¹ in 2023, a 0.94% increase. Pearson’s correlation analysis indicated that structural parameters like basal area and growing stock volume density primarily influenced biomass. Meanwhile, diversity indices such as H’ and ENS significantly contributed to ecosystem diversity, complexity, and productivity. Ecologically managed UGSs amass higher carbon stocks compared to other management approaches.

Key message

Agronomic techniques effectively modified the xylem structure of Coffea arabica L., leading to both anatomical and functional changes, thereby highlighting the vascular system’s remarkable plasticity in this species.

Abstract

The cultivation of Coffea arabica L. holds significant socioeconomic and historical importance in Brazil; however, it is consistently affected by seasonal drought and limited water availability across major production regions. To mitigate the adverse effects of water availability on coffee plants, adopting agronomic practices is essential. This study aimed to evaluate the influence of different agronomic practices on the wood anatomy of C. arabica L. and their implications for water conduction. Coffee plants were cultivated under five treatments—polyethylene film (mulching), Urochloa decumbens (Stapf) R.D. Webster, agricultural gypsum, and two combined treatments—along with a control. Stem samples were collected and processed using standard methods in wood anatomy. Quantitative anatomical traits of vessel elements were measured, alongside evaluations of their functionality. Plants treated exclusively with agricultural gypsum or polyethylene film showed localized anatomical changes, with no evident effects on xylem functionality. In contrast, treatment with Urochloa decumbens alone induced more pronounced anatomical modifications, which affected xylem functionality. The most substantial anatomical and functional changes were observed in the combined treatments (gypsum + polyethylene film or U. decumbens), which enhanced characteristics associated with both hydraulic efficiency and hydraulic safety. Overall, these findings highlight the remarkable anatomical plasticity of coffee xylem in response to soil management practices, suggesting that integrated agronomic approaches may promote the development of vascular systems better adapted to water-limited conditions. Ultimately, this study emphasizes the role of agronomic strategies in enhancing water use efficiency in C. arabica cultivation.

Remote sensing technologies are valuable for effectively monitoring patterns of tree mortality; however, their integration with environmental assessments presents challenges when identifying specific stressors in forested areas. This study aimed to analyze the spatiotemporal distribution of tree dieback using UltraCam and UAV aerial imagery. Additionally, it evaluated the environmental factors influencing dieback hotspots in Daland Forest Park, located in Golestan Province, northern Iran. Images from UltraCam (2016) and UAV (2021, 2023) were analyzed using object-based classification with the Bayes algorithm to detect dead and dying trees. The generated maps were validated, and spatial patterns were assessed using Moran’s Index. The intensity of clustering was measured with the Getis-Ord General G statistic, while the Getis-Ord Gi statistic identified hot and cold spots across the study periods. A Spearman’s correlation test was applied to explore relationships between these zones and environmental factors. The results showed that UltraCam and UAV imagery achieved high accuracies (83.33%-91.2%) and Kappa coefficients (0.77–0.88). Spatial analysis using Moran’s Index revealed a clustered distribution of dieback trees. Clustering intensity analyses based on the General Getis-Ord statistic indicated low clustering in 2016 and 2021, which transitioned to high clustering by 2023. Furthermore, the investigation into hot and cold spots showed negative correlations between the prevalence of dieback and proximity to forest roads and water wells. This study demonstrated that UltraCam and UAV imagery are effective data sources for monitoring tree mortality and its spatial patterns. The findings reveal that tree mortality is predominantly concentrated near forest roads and water wells, providing a foundation for developing strategies to enhance sustainable forest management practices in these areas.

Key message

Heavy thinning from above promotes coarse root and stem diameter growth in both Scots pine and sessile oak. Coarse root-stem allometry indicates a greater allocation of resources to coarse roots relative to the stem in both species.

Abstract

The effects of heavy thinning from above on stem and coarse root growth, as well as on coarse root–stem allometry, were investigated in mature Scots pine (Pinus sylvestris L.) and sessile oak (Quercus petraea (Matt.) Liebl.) growing in monospecific and mixed stands in Bavaria, Germany. Thinning was conducted in autumn 2017, and growth was analyzed over a five-year pre-thinning (2013–2017) and post-thinning (2018–2022) period using replicated thinned and unthinned plots. Thinning substantially enhanced diameter growth in both species. On average, stem increments increased by 26–61% and coarse root increments by 2–77% relative to unthinned controls, with the relative growth between stems and coarse roots varying among variants. Coarse root–stem allometry showed species-specific responses: in Scots pine, thinning intensity had the strongest effect, whereas in sessile oak, variation was more closely linked to precipitation and water availability. Across all variants, allometric exponents ranged from 1.59 to 7.14, with sessile oak exhibiting higher values than Scots pine, reflecting greater proportional investment in coarse roots among species and thinning regimes. Overall, heavy thinning from above promoted growth and altered biomass partitioning between stems and coarse roots in both species. Stimulated coarse root development likely improved anchorage, water and nutrient uptake, and resilience to climatic stress, thereby strengthening stand stability. These findings highlight the importance of adapting thinning strategies to species-specific traits and site conditions to enhance forest productivity and adaptability under changing climatic conditions.

Key message

The relict tree species Juniperus drupacea found to form in its populations in Europe, un-evened young stands of one-storey, with low tree height, and diameter growth pattern similar to other trees.

Abstract

Juniperus drupacea Labill. is a relict tree species distributed in west Asia (Turkey, Syria, Lebanon and Israel), while in Europe it is only found in southern Greece, Peloponnese. It appears in patches and its habitat, in many cases, appeared fragmented. This study aims to provide a detailed account of the forest stand structure of J. drupacea in the two unique populations of Europe, on Mount Parnon, south Greece, along with a comprehensive analysis of the species’ growth pattern based on tree-ring analysis. The results analysis indicated that J. drupacea within two populations (northern and southern - at local scale) comprises uneven aged stands, which probably were established progressively in successive waves. The majority of the sampled trees are between 30 and 60 years old, while there are some individuals elder or younger. However, only a few individuals exceed 60 years of age, clearly suggesting that stand establishment occurred predominantly after 1960. This variation in age does not lead to significant differences in height, as most plots exhibit a single-storey stand with only minor fluctuations in tree height; in most plots, trees are ranging between 4 and 8 m in height, while a small proportion of trees in some north and south plots reach greater heights, up to 10 m. These findings confirm that the species is morphologically characterized as a small tree, which reaches at a height up to 12 m in the mature stage (100–120 years old). Annual pattern growth shows that this depends on the tree age classes, and it is significantly higher in the trees of northern population origin. Special silvicultural measures, e.g. stand tending aiming at favoring the best trees, by removing their most competitive individual, are suggested for improving species populations’ conservation.

Key message

Salvadora species demonstrate pronounced intra- and interspecific adaptations along an aridity gradient, underscoring their high ecological plasticity. These adaptive variations reveal substantial resilience potential, emphasizing their importance for sustaining dryland ecosystems and guiding conservation strategies under future climate change scenarios.

Abstract

Aridity acts as a strong ecological filter, shaping plant functional strategies in arid and semi-arid regions. Salvadora oleoides Decne. and Salvadora persica L., two dominant mesomorphic facultative halophytes, occur across diverse ecozones of Pakistan, where they are exposed to varying degrees of climatic and edaphic stress. Understanding their adaptive responses along an aridity gradient is critical for predicting species resilience under climate change. We investigated intra- and interspecific variation in growth, physiological, and anatomical traits of Salvadora species collected from ten populations distributed along an aridity gradient, quantified using the De Martonne Aridity Index (IDM). Substantial intraspecific variation was observed in both species across the gradient. Certain populations, such as AL in S. oleoides and SA and MP in S. persica, exhibited enhanced growth performance, greater biomass accumulation, and elevated concentrations of osmoprotectants, including proline, soluble sugars, and free amino acids. Anatomical adaptations also varied markedly across populations in response to aridity. In S. oleoides, populations such as AL and SP exhibited well-developed vascular tissues in both root and stem, alongside increased lamina and midrib thickness—features likely contributing to efficient water conduction and structural support under drought stress. In S. persica, notable anatomical enhancements were observed in the SA and RY populations, characterized by pronounced cortical development, thicker sclerenchymatous layers, and enlarged stomatal dimensions. These traits collectively suggest divergent anatomical strategies between the two species, with S. oleoides favouring vascular robustness and S. persica exhibiting cortical reinforcement and stomatal plasticity to maintain physiological function under arid conditions. Interspecific comparisons revealed that S. persica demonstrated stronger structural adaptations under arid conditions, while S. oleoides exhibited greater physiological plasticity. Correlation analysis revealed significant associations between soil properties and plant traits; for instance, soil electrical conductivity and phosphate levels showed strong influences on biomass and anatomical development. These findings underscore the adaptive plasticity of Salvadora species and highlight their potential for ecological restoration in arid and semi-arid regions.

Key message

The proposed methodology represents the first work to estimate the AGB of hazelnut trees by TLS and for representing the different woody structures. Potential application for carbon credit certification.

Abstract

Accurate estimation of Aboveground Biomass (AGB) in tree orchards is essential for assessing productivity and carbon sequestration. The objective of this research was to develop a method for estimating the total AGB of hazelnut trees (Corylus avellana L.) of different ages, based on TLS technology integrated with the MATLAB TreeQSM algorithm combined with destructive measurements of coarse (Ø ≥ 4 mm) and fine (Ø ≤ 4 mm) structures in order to overcome the estimation limitations of the algorithm. This study, the first contribution on hazelnuts, proposed an integrated approach for estimating AGB, combining Laser Imaging Detection and Ranging (LiDAR) based on TLS, computational analysis in MATLAB^®, and targeted destructive and manual measurements to derive key dendrometric parameters. Results revealed statistically significant differences in fine structure biomass between 15-year-old (22.56 ± 4.15 kg) and 20-year-old trees (34.69 ± 10.80 kg), confirming the use of TLS, combined with MATLAB processing and limited destructive measurements, as an appropriate technology for biomass estimation and for representing the different structures. TreeQSM algorithm was found to be highly reliable in estimating the length of branches with Ø ≤ 4 mm (R² = 0.95) and in estimating the volume of woody structures Ø ≥ 4 mm. The proposed methodology provides valuable support for AGB estimation in tree crops by integrating TLS-based modelling with empirical measurements. A key outcome of this study is the potential application of the proposed methodology for carbon credit certification. Future research should extend to the different stages of tree growth to consider the growth dynamics induced by agronomic management.

Key message

Differentially expressed genes involved in tension wood in ‘Shanxin’ poplar have been identified, and gene expression regulatory network has been established, laying the foundation for research on the molecular mechanisms.

Abstract

Tension wood (TW), a specialized wood structure, forms in woody angiosperms under mechanical force or gravity. Studying the transcriptional regulation of genes during TW formation is valuable for molecular biology research and the genetic improvement of wood properties. In this study, TW xylem cell walls in ‘Shanxin’ poplar (Populus davidiana × P. alba var. pyramidalis) exhibited a relatively higher cellulose content and a distinct gelatinous layer (G-layer), as identified by safranin-fast green staining, compared to opposite wood (OW) and normal wood (NW). Transcriptome analysis of TW, OW, and NW yielded 52,697 unigenes. Differential expression analysis identified 2,321, 462, and 2,683 differentially expressed genes(DEGs)in TW_NW, OW_NW, and TW_OW comparisons, respectively. GO enrichment analysis of DEGs highlighted their involvement in secondary processes including cell wall organization, response to stimulus, hormone-mediated signaling pathway, cell wall, transcription regulator activity and oxidoreductase activity. KEGG enrichment analysis revealed significant pathways including phenylpropanoid biosynthesis, flavone and flavonol biosynthesis, plant hormone signal transduction, and starch and sucrose metabolism. Specifically, 13 out of 16 DEGs were noted in the glucose synthesis pathway within the starch and sucrose metabolism. A two-layer gene expression regulatory network (GRN) was constructed, involving 6 transcription factors (TFs) and 37 functional genes, totaling 181 interactions. Validation using ChIP-PCR and RT-qPCR for a total of 35 interactions involving PdaMYB52, PdaERF6, and PdaERF17 demonstrated a 91% accuracy rate, with 57% direct interactions and 34% indirect interactions. These results lay the foundation for further exploration of the molecular mechanisms driving TW formation in ‘Shanxin’ poplar.