Trees最新文献

Key message

Visual inspection parameters for predicting the risk of urban trees falling match the actual internal condition of the stem, as well as the results of tomograms (SoT and ERT).

Abstract

Eliminating the risk of tree falls in urban areas is economically and technically unfeasible. Effective management requires reliable tools to guide interventions and maximize urban forest benefits. This study examined the relationship between visual analysis and the internal condition of Spathodea campanulata trunks, using sonic (SoT) and electrical resistance (ERT) tomograms. The trunk sections from 30 removed trees at UFV (Viçosa-MG) were analyzed. The cavities appeared in 26.7% of cases, cracks in 20%, and wood deterioration in 10%. Tomograms aligned with cutting results in 70% of cases, with sonic tomography being easier for cavity detection and electrical tomography more accurate for wood deterioration. It was not possible to define a visual analysis methodology with association with the problems evidenced in the section. Combining tomographic and visual inspections enhances tree fall risk assessments.

Key message

A multi-parameter-study of quantitative wood anatomy of oak reveals site-dependent climate-growth relations. Many of these are unstable, making climate reconstructions based on oak questionable. Winter temperatures may be an exception.

Abstract

In Europe, oak tree-ring chronologies spanning millennia offer considerable potential for dendroclimatology. However, site conditions might influence the climate-growth relationships, particularly for species such as lowland European oak (Quercus robur/petraea) that grow under a range of soil moisture conditions. The inclusion of sub-fossil or archaeological samples in chronologies often introduces uncertainty regarding the soil moisture regime in which the trees grew, potentially impacting the contained signal and the suitability of millennia-long oak chronologies as paleoclimate proxies. Here, we present a rare example of a multi-parameter study on the quantitative wood anatomy of oak. We analysed the climate-growth relationships of earlywood vessel sizes, earlywood width and latewood width in trees from five nearby stands situated on wet and dry soils in north-eastern Switzerland that experienced the same atmospheric conditions. We observed a large variety of climate-growth relationships. And we observed both signal plasticity (variability of climate growth relationships between site categories) and classical signal instability over time. In fact, the only stable relationships are between earlywood vessel sizes in trees on wet soils and winter/early spring temperatures. The relationship between late spring/early summer precipitation and latewood width on dry soils is probably stable as well but less reliable. In both cases, the correlation coefficient reaches values as high as r = 0.6. We suggest that signal instability needs to be explored with further and larger datasets before oak can be reliably used as a paleoclimate proxy.

Key message

Provenances show a high phenotypic plasticity and the ability to grow beyond the cold treeline. Local is best can still be applied.

Abstract

Boreal forests situated in high latitudes face heightened susceptibility to climate extremes and global warming. Understanding the relative influence of adaptation mechanisms like phenotypic plasticity or local adaptation on key traits is crucial to better understand and project species distribution, forest growth and vitality. To address this, we conducted a reciprocal transplant experiment featuring two white spruce (Picea glauca [Moench] Voss) provenances in Alaska, representing cold and dry treelines. Trees from each provenance were reciprocally transplanted across a gradient spanning from dry bluff sites, dry treelines via old-growth forests to cold-limited treelines and beyond. From 2015 to 2022, we monitored survival, vitality, growth, and various needle morphology traits. Results showed that the dry provenance had a superior performance in its home environment. Whereas both provenances performed similarly at the cold site. Survival and vitality rates indicated that elevated temperatures favoured tree growth. Seedling survival and growth are possible beyond the current cold treeline. Further, needle morphology traits were more influenced by the current environment than by origin, thus showing a high phenotypic plasticity. Nevertheless, significant differences in needle morphology among provenances hinted at a genetic base of these traits. Results suggested that local is best can still be applied.

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.