Trees最新文献

Key message

Miconia predominantly accumulates Al regardless of soil saturation, though certain clades within this high-accumulating group may exhibit distinctly lower Al concentrations in their leaves.

Abstract

In acidic soils (pH < 5.0), aluminum (Al) occurs as Al³⁺, which is toxic to most plants. Tolerant species include Al avoiders and those that accumulate Al in the leaves without toxicity symptoms. The genus Miconia (Melastomataceae), mainly found in moist forests, includes Al-accumulators from the Cerrado vegetation in South America. To explore Al accumulation, we collected Miconia species in four Atlantic rainforest areas, southeastern Brazil, hypothesizing that soil Al saturation (m%) could explain the leaf Al concentration. Both parameters were measured, and a phylogenetic analysis was conducted among the species to ascertain whether Al accumulation resulted from m% or was species dependent. The 27 species found grow on dystrophic soils with m% above 70%. Despite expecting non-accumulators (reported at 15% in the genus), all 27 species were Al-accumulators, some exceeding 25,000 mg Al kg⁻¹ dry leaf, which did not cluster in any specific group in the phylogenetic analysis. Three species (M. willdenowii, M. brunnea, and M. flammea) might have lost the ability to accumulate Al above 1,500 mg kg⁻¹. When the same species occurred at different sites, m% did not drive Al accumulation. Accumulation of Al in Miconia within the Atlantic rainforest stands at a 20-fold higher accumulation range when compared to Miconia spp. from Cerrado. Leaf Al accumulation in Miconia species within the Atlantic rainforest appears to remain unaffected by m%. Within a group where a high capacity for Al accumulation seems to be prevalent, species in certain clades may exhibit distinctly lower Al concentration in their leaves.

Birches (Betula) are crucial trees in Northern Europe, enhancing forest resilience and biodiversity, and aiding in pollutant removal through phytoremediation. Industrialization and urbanization introduce polycyclic aromatic hydrocarbons (PAHs), threatening birch ecosystems and human health. This study investigated the impact of PAHs on the growth and secondary metabolite levels of silver birch (Betula pendula Roth) seedlings from four half-sib families (genetic groups). Seedlings were exposed to phenanthrene, pyrene, naphthalene, and fluoranthene at varying concentrations. Thirty-six compounds from birch leaf extracts were identified using LC–MS analysis, including catechin, quercitrin, caffeoylquinic acid. Significant findings included a reduction in shoot and root lengths, with phenanthrene at 200 µg L⁻¹ reducing shoot growth by up to 85% and root length by 69% in some families. Total phenol content increased in most families at higher pollutant concentrations, whereas total flavonoid content generally decreased. Notably, (epi)gallocatechin levels increased by up to 200% with naphthalene exposure, and catechin levels increased tenfold in some cases. The results underscore the differential responses among half-sib families to PAH exposure, with higher concentrations generally causing more pronounced negative effects on both growth and secondary metabolism. These findings emphasize the significance of secondary metabolites in plant–environment interactions, where alterations due to PAH exposure could affect birch resilience, and, consequently, the broader ecosystem functions they support.

Key message

This study focuses on poplar root's dynamic salt stress responses, finding that Hsp20s may play an important role and screening its upstream regulators.

Abstract

Populus davidiana × P. alba, an excellent tree species, which is widely planted in China, has been seriously affected by salt stress. In this study, the response of poplar roots to salt stress was deeply studied by time-course transcriptome, and a large number of differentially expressed genes (DEGs) were identified at different times. Through weighted gene co-expression network analysis (WGCNA), it was discovered that oxidative and osmotic stress regulation played a crucial role in resisting salt stress in the early salt stress response (3–6 h), and nitrogen metabolize and transport genes were identified as hub genes. At the middle stage of salt stress (12–24 h), the plants initiated extensive reprogramming to adapt to stress, and the transcription factors (TFs), WRKY53, MYB13 and NFXL1, were identified as hub genes. After 48 h of salt stress, seven PdaHsp20 genes were identified as hub genes, which may alleviate the damage of salt stress. The genome-wide analysis of Hsp20s showed that the Hsp20 proteins were divided into 11 groups. A three-layer gene regulatory network with PdaHsp20s as the underlying gene was constructed and the unique PdaERF72 was found by association analysis with the co-expression network, which may have important functions in regulating PdaHsp20s under salt stress. The expression level analysis of PdaERF72 and PdaHsp20s, which have a direct connection with it, also indicated that some of them may have a negative regulation relationship after salt stress. In a word, poplar dynamically responds to salt stress, and different hub genes play a role in different stress stages, which provided a new perspective to reveal the response mechanism of poplar to salt stress.

The production of high-quality seedlings is crucial for successful afforestation efforts, particularly in arid and semi-arid regions where drought stress is a major ecological challenge. Light and water stress are interrelated and have a major impact on seedling growth and development. The combined effects of light (25, 50, 75, and 100% of full sunlight) and water stress (field capacity of 100, 75, and 50%) on the morpho-physiological characteristics of Cercis siliquatrum seedlings were investigated in a controlled nursery experiment. Additionally, the effect of zeolite on seedling quality was evaluated. The amount of proline greatly increased with water stress, whereas light had no effect. The highest values of morphological traits were obtained in conditions without water stress and light intensity of 50% and above, whereas water deficit had the most negative effect on seedling quality in low light (L25). The use of zeolite reduced the negative effects of drought stress on seedlings and increased the seedling quality index by 15%. Additionally, zeolite increased the number of leaves (+ 13.5%), leaf dry matter (+ 7.9%), leaf area (12.1%), stem diameter (13.4%), stem length (+ 12.6%), stem dry matter (+ %), root length (+ 21.7%), and root dry matter (+ 12.3%). The results support the interplay hypothesis, which predicts stronger drought effects under both full light and heavy shade conditions compared to moderate shade. Our results also suggest that Cercis siliquastrum is a heliophyte species that thrives in moderate to high light conditions. We also recommended the application of zeolite amendment to reduce the negative effects of drought stress and promote seedling growth and quality.

Key message

Natural root grafting reduces tree uprooting likelihood and promotes stem breakage during windthrow events.

Abstract

Windthrow is a natural disturbance affecting forest dynamics, characterized by tree uprooting or stem breakage when wind forces surpass tree anchorage strength or stem resistance. Windthrow mortality has been related to several ecological biotic and abiotic factors. However, the influence of natural root grafting on windthrow mortality remains unknown. This research evaluated the influence of root grafting on windthrow mortality by excavating root systems of jack pine (Pinus banksiana) in four windthrow-affected riparian buffers and analyzing root grafts using a dendrochronological approach. Our results revealed that natural root grafting decreased the uprooting likelihood but increased the propensity for stem breakage. In addition, root grafting occurred more frequently in trees closer to one another. These results suggest that root grafting influences the windthrow mortality type, with tree proximity being a good predictor for root grafting. This study provides valuable insights into windthrow dynamics, particularly relevant for managing windthrow mortality following partial harvesting and riparian buffers, conserving soil, and mitigating the impacts of windthrow events in the face of climate change.

Key message

In Douglas-fir grown in Central Europe, growth and specific leaf area differed between coastal and interior provenances but little intra-specific variability was found for the Huber value and xylem safety.

Abstract

In Central Europe, the economically most important timber species for roundwood production, Norway spruce, has been severely affected by recent global change-type drought events. Due to its large spatial distribution, Douglas-fir (Pseudotsuga menziesii) is considered for conversion to climate-resilient forests. Specifically, provenances from moister coastal and drier and colder interior regions might differ in drought tolerance traits. Here, we characterized aboveground biomass increment as well as leaf morphological and plant hydraulic traits in mature trees of 28 Douglas-fir provenances from three climate-at-origin groups across a climatic gradient in Central Europe, covering a precipitation range of 542 mm yr⁻¹. Irrespective of the gradient, the northern interior provenances had a 5.4 kg yr⁻¹ lower aboveground biomass increment than the two coastal groups, accompanied by a 13% smaller specific leaf area. On the other hand, the Huber value, embolism resistance (P₅₀) and leaf carbon isotope signature (δ¹³C) as proxy for long-term intrinsic water use efficiency did not differ between climate-origin groups. Across the gradient and within a climate-origin-group, no effect of climatic aridity on any of the traits covered was observed. Especially P₅₀ showed very little intra-specific variability, and our observed mean of −3.5 MPa is in the same range as P₅₀-values for Douglas-fir recently reported from Europe. Our results for Douglas-fir support that xylem safety is a rather conservative and evolutionary canalized trait in conifers, while the Huber value revealed less plasticity as expected. Future studies are needed to test whether slower-growing interior provenances with thicker and smaller needles might be more drought tolerant and thus better suited for cultivation in the future climate of Central Europe although xylem safety does not differ.

Key message

Tree growth of Gmelina arborea Roxb is mainly influenced by pre-monsoon temperatures and ENSO in a moist tropical forest of Bangladesh.

Abstract

The present study was conducted to investigate the impact of climate change on tree radial growth in a moist tropical forest of Bangladesh. A standard ring-width index chronology (RWI) of Gmelina arborea Roxb. was developed spanning the 92-year period from 1929 to 2020 using the standard dendrochronological technique. The association between climate variables and RWI was determined by employing simple Pearson's correlation. Pre- and post-monsoon maximum temperature (Tmax) had a strong negative impact on tree growth. Temperatures during the monsoon period however favored tree growth. Tree growth was also influenced by previous years’ temperature providing evidence of a lag effect on radial growth. On a spatial scale, tree growth was influenced by regional climate and sea surface temperatures of Ninö 3.4 region, indicating teleconnection between tree growth and large-scale climate phenomenon. If the negative relationship between temperatures and tree growth continues in future, it will have important implications for tropical forest tree biomass, since temperature is predicted to increase in the tropics. Future global warming is thus very likely to affect the carbon sequestration potential of tropical forests in the face of climate change.

Key Message

Machine learning models accurately predict F. orientalis stand basal area in the Hyrcanian forest using environmental variables, with the RF model performing best. Elevation is the most important predictor.

Abstract

Accurate prediction of tree basal area (BA) as an important forest stand structural characteristic is essential for sustainable forest management. The aim of this study was to use four machine learning methods, including generalized linear model (GLM), k-nearest neighbors (KNN), support vector machine (SVM), and random forest (RF), to predict and assess the stand BA of Fagus orientalis Lipsky using national forest inventory data and a comprehensive set environmental variables. Modeling was performed using a 10-fold spatial cross-validation technique to counteract the effect of spatial auto-correlation in predictor and response data, as well as to reduce the dependency between training and test data. The RF model outperformed the others by having the best match between measured and predicted stand BA values, with the highest squared correlation coefficient (({R}_{text{Train}}^{2}) = 0.77; ({R}_{text{Test}}^{2})= 0.76) and the lowest root mean square error (({text{RMSE}}_{text{Train}})= 2.70; ({text{RMSE}}_{text{Test}})= 2.90) and mean absolute error (({text{MAE}}_{text{Train}})= 1.74; ({text{MAE}}_{text{Test}})=1.76). Among all investigated variables, elevation showed the highest correlation with stand BA of F. orientalis in the Hyrcanian forest. The relation was positive and restricted to the range of approximately 700 to 1200 m. The RF and GLM models indicated the bulk density as the second-most important variable, whereas the SVM and kNN models indicated the air temperature as the second important variable. In general, this research identifies key variables influencing the stand BA of F. orientalis, providing valuable insights for forest management and conservation efforts. These findings contribute to a better understanding of forest dynamics in the Hyrcanian region and can inform targeted management strategies.

Key message

Nitrogen deposition and precipitation analyzed along independent gradients did not cause major foliar nutrient imbalances that affected tree health in temperate tree regeneration of Fagus sylvatica, Pseudotsuga menziesii and Abies alba.

Abstract

While drought tolerance receives great attention in the scope of climate change research, the response of trees to high N deposition, which is also part of global change, has remained less studied. We investigated 45 temperate forest stands across Germany along a gradient of atmospheric N deposition of 22 kg N ha⁻¹ a⁻¹ (range 10–32 kg N ha⁻¹ a⁻¹) and analyzed foliar nutrient concentrations and ratios in saplings of European beech, Douglas fir, and silver fir. We also measured relative shoot length increment and (as a proxy for intrinsic water use efficiency, WUEi, and stomatal conductance, g_s) foliar δ¹³C signatures to detect potential effects of nutrient imbalances on productivity and plant water relations. Although all species responded on deposition with increased foliar N concentrations, reduced foliar nutrient concentrations were only observed for P, but not K, Ca, Mg, and Fe. The effect on foliar P concentrations was only observed at sites with low mean annual precipitation (range 565–1690 mm). Reduced growth was not observed. Low foliar P concentrations were associated with high g_s in Douglas fir, which poses a potential risk under dry conditions and is consistent with the literature, but lacks a mechanistic explanation. The lack of nutrient imbalance at high N supply can at least partly be explained by the relatively low absolute amounts of nutrients needed by the small-sized tree regeneration.

Key Message

The de novo genome sequencing of Dalbergia latifolia (Indian rosewood) reveals crucial genetic insights, aiding conservation, sustainable timber production, and scientific research. The high-quality draft genome identifies key pathways and markers for improving disease resistance and timber quality, supporting the protection and sustainable use of this important species.

Abstract

Wood, as a natural and sustainable energy source, serves as an eco-efficient alternative to fossil fuels, and is playing a vital role in stabilizing woody plants and transporting water to all plant parts. Over the last few decades, our knowledge of cellular wood formation (xylogenesis) has significantly increased. Dalbergia latifolia, commonly known as ‘Indian rosewood’, emerges as a premier timber species from the Indo-Malaysian region. This slow-growing tree is prized for its durable timber, which is stronger and harder than teak, and for its natural resistance to pests and fungal attacks. However, escalating demand for rosewood, particularly from China, has led to increased illegal exploitation and listing under CITES Appendix 2. By the end of 2020, D. latifolia was assessed as globally vulnerable by the IUCN Red List of Threatened Species under criteria A1cd. Key threats in India include inadequate regeneration and slow growth rates due to rising commercial demand. In response, India has banned the export of logs and sawn wood from this species. Despite its ecological and economic significance, genome-level information for D. latifolia has been lacking, hindering scientific research and conservation efforts. This study presents a comprehensive de novo genome sequencing and assembly of D. latifolia, providing valuable insights into its genetic makeup and potential applications. We generated 22,319 contigs totaling 613.95 Mb with high completeness (95%) and an identification rate of 92% for single-copy BUSCO genes.