Tree Characteristics Research Articles

Mycorrhiza Better Predict Soil Fungal Community Composition and Function than Aboveground Traits in Temperate Forest Ecosystems

Forests in the northeastern US are experiencing shifts in community composition due to the northward migration of warm-adapted tree species and certain species’ declines (for example, white ash and eastern hemlock) due to invasive insects. Changes in belowground fungal communities and associated functions will inevitably follow. Therefore, we sought to investigate the relative importance of two important tree characteristics—mycorrhizal type [ectomycorrhizal (EcM) or arbuscular mycorrhizal (AM)] and leaf habit (deciduous or evergreen) on soil fungal community composition and organic matter cycling. We sampled soil in the organic and mineral horizons beneath two AM-associated (Fraxinus americana and Thuja occidentalis) and two ECM-associated tree species (Betula alleghaniensis and Tsuga canadensis), with an evergreen and deciduous species in each mycorrhizal group. To characterize fungal communities and organic matter decomposition beneath each tree species, we sequenced the ITS1 region of fungal DNA and measured the potential activity of carbon- and nitrogen-targeting extracellular enzymes. Each tree species harbored distinct fungal communities, supporting the need to consider both mycorrhizal type and leaf habit. However, between tree characteristics, mycorrhizal type better predicted fungal communities. Across fungal guilds, saprotrophic fungi were the most important group in shaping fungal community differences in soils beneath all tree species. The effect of leaf habit on carbon- and nitrogen-targeting hydrolytic enzymes depended on tree mycorrhizal association in the organic horizon, while oxidative enzyme activities were higher beneath EcM-associated trees across both soil horizons and leaf habits.

Changes over time in tree cavity availability across urban habitats

In urban ecosystems, tree cavities provide critical habitat for a variety of wildlife, and their occurrence is influenced by tree health, management, and cavity excavators. Changes over time in vegetative structure, human use patterns, and built environment affect the formation and persistence of tree cavities, and these changes may differ in various urban habitats. Trees with some decay are often associated with tree cavities, however, parks and residential habitats which are highly managed often lack highly-decayed trees, and large trees which are dead and damaged are likely to be removed and replaced with saplings. We surveyed changes over seven years (in 2013 and 2020) in the abundance of both excavated woodpecker cavities and decay cavities, in three urban habitats (forest, park, and residential) in the Chicago region, IL, USA. We observed greater stability of cavity abundance in managed park and residential habitats over time. Low numbers of highly-decayed trees in park and residential habitats were associated with reduced excavated cavity presence compared to forests. As expected, in both 2013 and 2020, the probability of cavity presence for both excavated and decay cavities was increased with greater tree size and higher levels of tree decay, though the patterns of this association varied between habitat types and years. The continued replacement and maintenance of existing trees means that managed park and residential habitats were more stable than unmanaged forest remnants, which are vulnerable to large changes in tree characteristics which could foster unpredictable booms or busts in cavity supply. A stable inventory of tree-cavities depends on preserving large trees, and decay of urban trees benefits habitat quality for cavity-nesters. Pruning of branches or removal of dead trees curtails the life-cycle of tree cavities in decayed branches, so that more highly managed habitats contain fewer cavities than the number of trees could potentially support. Cavity abundance could be improved in stable habitats through reduced intervention where safe, allowing cavity development to occur in situ.

MANGROVE PLANTING TRAINING IN KAMPOENG KEPITING TUBAN VILLAGE, KUTA SUB-DISTRICT, BADUNG DISTRICT, BALI

Tuban Village is one of the villages in Badung Regency that has the potential of coastal areas that are utilized by the community for various purposes. The high utilization of coastal areas has led to the conversion of mangrove land for various purposes, resulting in damage in the form of abrasion in several places, pollution due to industrial activities, households and aquaculture activities. Therefore, mangrove forest rehabilitation program is considered as one of the important recommendations in order to restore the condition of mangrove ecosystem in this region. The training consisted of a group of Nature Lovers Students (Mapala) which included the provision of training and socialization in the field on the introduction of mangrove tree species and characteristics and mangrove tree planting techniques in theory and application of the theory that has been obtained in the form of collecting and processing mangrove trees to be used as seeds and planting practices. The results of the training showed that all participants understood the material presented. This can be seen from the way participants apply the theory obtained by direct practice in the field.

Conditions affecting ant nesting in stumps in a temperate coniferous planted forest

Dead trees are an important component of forest ecosystems as they play various roles in these ecosystems and their biodiversity. The use of dead trees as a habitat and foraging resource by various organisms affects the decomposition of the trees. Ants use dead trees as nests and slow their decomposition by weakening the function of decomposers, such as fungi and termites, through interspecific interactions. However, our understanding of the characteristics of dead trees in which ants nest and the environmental conditions under which they exist is limited. In planted forests, stumps left after harvesting account for the largest biomass of deadwood. In the present study, the characteristics of such stumps, their location, and the relationship between these factors were determined in relation to ant nesting in a warm temperate conifer planted forest (a university forest with clear past history located in central Japan). In total, 85 stands consisting of Cryptomeria japonica or Chamaecyparis obtusa were surveyed, and various environmental conditions as well as the presence or absence of ant nests in stumps logged by forestry operations were recorded. In total, 1551 stumps were surveyed, of which 113 stumps contained ant nests with 16 different ant species. Modeling and Akaike information criterion evaluation results revealed that both large and small ant species tended to nest in old stumps located in areas with an open canopy, large species tended to nest in stumps with moss or lichen cover, and small species tended to nest in stumps with bark cover. Older stumps are typically softer owing to more decomposition, and solar heat can facilitate temperature control inside the nest, which may explain why ants tended to nest under the observed conditions. Based on these findings, long-term continuous thinning rather than clearcutting, which results in excessively large canopy openings and uniformly sized stumps, is the preferred management practice for promoting ant nesting in stumps in planted forests.

Response of Date Palm Trees Phoenix dactylifera L. Khastawi Cultivar to Chemical, Organic and Biological Fertilization

The study was conducted in one of the own palm orchards located in the area of the village of Albu Assaf - Al-Dawwar, which is 10 km west of Ramadi city / Anbar Governorate, during the 2020-2021 season to know the effect of three levels of fertilizer combinations F0:0, F1: 600 g of urea (N 276) + 350 g of triple superphosphate (P2O5 168 ) + 500 g of potassium sulfate (K2O 240), 1200 g urea (552 N) + 700 g triple superphosphate (P2O5 336) + 1000 g potassium sulfate (K2O 480) and three levels of humic acid H0:0, H1:15, H2:30 ml. L-1 and two levels of a combination of biofertilizers, Trichoderma(Trichoderma harzianum) and Mycorrhizal(Glomus mosseae) B0:0, B1:300 ml Trichoderma + 400 g Mycorrhizal, with three replications for each treatment, To find out the effect of three levels of fertilizer combinations, three levels of humic acid and two levels of bio-fertilizer combination on the vegetative growth characteristics of date palm trees of the Khastawi cultivar. The results indicated the superiority of the level of F2 chemical fertilization in vegetative traits, including the dry matter of leaves, leaflet length, leaflet width, leaf length and increase in the leaves number of gave47.6372 %, 0.7128cm, 0.2436cm, 22.1039cm, 8.5000 leaves, respectively. The H2 of humic acid achieved the best values in the characteristics of the leaves dry matter percentage (%), the length and width of the leaflet, leaf length, and increased leaves number gave 48.1889 %, 0.6872cm, 0.2132cm, 21.8745cm, 8.5556 leaves, respectively, results also indicated the superiority of level B1 of the biofertilizer mixture in the characteristics of leaf dry matter percentage, leaflet width, leaf length and increase in leaf number, 45.5852%, 0.2122cm, 21.6867cm, 8.4444 leaves, respectively. The triple interaction F2H2B1 treatment achieved high averages in the characteristics of the dry matter percentage of leaves, leaflet length, leaf length and the increase in the number of leaves, 50.6900 %, 0.7400cm, 24.0662cm, 9.3333 leaves.

Effects of Gradient Magnetic Field on Electrical Tree Growth Characteristics in Silicone Rubber

In this article, the positive and inverse gradient symmetric magnetic field and the asymmetric magnetic field with different angles are constructed. The influence of the magnetic field distribution on the electrical tree characteristics is investigated. The experimental results show that both the positive and the inverse gradient magnetic fields can promote the deterioration of the electrical trees. Under the symmetrical <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Delta 1.5$ </tex-math></inline-formula> T gradient magnetic field, the tree initiation probability increases from 55% to 100%, and the breakdown time decreases by 67.5%. Under the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Delta $ </tex-math></inline-formula> -1.5 T, the tree initiation probability increases from 55% to 75%, and the breakdown time declines by 57.5%. The morphology of the electrical trees is largely affected by the distribution of the magnetic field. The dispersion of the degradation channels increases with the enhancement of the magnetic field. Under the asymmetric magnetic field, the deterioration process is also accelerated, with the increase of the magnetic field. More importantly, the growth direction of the electric trees shifts to the side with the higher magnetic flux density. The magnetic field enhances the local electric field and promotes the occurrence of partial discharge by exerting a deflection force on the charges. Consequently, the growth rate and morphology of electrical trees are affected.

Assessing Biodiversity Conditions in Cocoa Agroforests with a Rapid Assessment Method: Outcomes from a Large-Scale Application in Ghana

Cocoa fields in West Africa traditionally kept other tree species to provide shade for cocoa trees and obtain food and other products. Measuring other trees is paramount to monitoring environmental conditions in cocoa agroforests, but it has been difficult to apply at a large scale. This study presents the results of a rapid assessment method applied in Ghana, developed to measure non-cocoa tree characteristics based on easily observed parameters using sample surveys and mapping tools. We collected data from over 8700 cocoa farms and evaluated their biodiversity performance based on 6 indicators classified according to recommended thresholds to benefit biodiversity conditions. Our results show that species richness, shade cover, and potential for tree succession have the lowest proportions of fields with the recommended levels, with variations among regions and districts. The methodological procedure allowed us to identify priority areas and indicators falling behind desirable thresholds, which can inform training and management approaches regarding biodiversity-friendly practices in cocoa fields tailored to the needs of the farmers. The analysis procedure was developed with open-access automated routines, allowing for easy updates and replication to other areas, as well as for other commodities, enabling comparisons at different spatial scales and contributing to monitoring biodiversity over time.

A Review of Nano fertilization and its role on growth, yield and quality characteristics of fruit trees

Nanotechnology is one of the strategies that have the ability to achieve sustainable agriculture, and it is a promising opportunity in the field of sustainability and the provision of food security and fertilizers in general, important in terms of agricultural production, whether quantitative or qualitative. Despite the availability of various mineral, chelated or organic fertilizer sources for these nutrients and the presence of various methods of addition, the efficiency of using these fertilizers does not exceed 5% of the additive. Therefore, it is preferable to reduce the loss of nutrients through fertilization and work to increase the growth and productivity of crops through the use of nanotechnology and nano_materials through the use of alternative, environmentally friendly and very effective fertilizers called nano-fertilizers. They are materials that contain nutrients or essential and useful plant nutrients prepared in nano-sizes and loaded or coated with materials that make them more efficient, especially when added to the soil. Nanoscience is one of the modern sciences that is concerned with the study of materials on the nanoscale 10-9 meters from 1-100 nanometers and they are called nanomaterials, its physical and chemical properties are different from those when it is in conventional dimensions of more than 100 nanometers, it has physicochemical properties that are fundamentally different compared to its ordinary materials. Different types can be produced from them, and their chemical composition as well as the size and shape of the particles controls their main characteristics.&#x0D; &#x0D;

Mitigation of electrical treeing at high temperature in nano‐SiO2 doped epoxy resin

AbstractIn this work, electrical tree inception and ageing experiments were conducted to investigate the initiation, growth characteristics and structural characteristics of electrical trees of nano‐SiO2 doped epoxy resin at different temperatures. Electrical tree inception and ageing experiments were conducted using power frequency voltage of 15 kV at 20, 40, 60, 80 and 100°C. Electrical breakdown properties of epoxy resin were investigated by applying AC and DC voltages at 20, 40, 80 and 120°C. There are two major observations based on the experimental results. With the increase of temperature, the morphological structure of the electrical trees changes from dendritic to plexiform, the tree inception voltage decreases and the growth rate of the electrical trees increases obviously. Either under DC or AC voltage, the breakdown strength of the nano‐SiO2 doped epoxy resin decreases as the temperature increases. Finally, based on the space charge and the trap level measurement, the mechanism of the electrical tree propagation and breakdown in nano‐SiO2 doped epoxy resin was analysed.

Tree Traits and Microclimatic Conditions Determine Cooling Benefits of Urban Trees

Trees play a key role in mitigating urban heat by cooling the local environment. This study evaluated the extent to which street trees can reduce sub-canopy air temperature relative to ambient conditions (ΔT), and how ΔT relates to tree traits and microclimatic variables. Air temperature under the canopies of 10 species was recorded within residential areas in Western Sydney, Australia, during summer 2019–2020. Tree and canopy traits, namely tree height, specific leaf area, leaf dry matter content, leaf area index, crown width and the Huber value (the ratio of sapwood area to leaf area) were then measured for all species. Species differed significantly in their ΔT values, with peak cooling (maximum ΔT −3.9 °C) observed between 9–10 am and sub-canopy warming (i.e., positive ΔT values) typically occurring during afternoon and overnight. Trees with high LAI and wider canopies were associated with the greatest daytime cooling benefits and lower levels of nighttime warming. ΔT was also negatively related to windspeed and vapor pressure deficit, and positively to solar irradiance. This study provides valuable information on how tree characteristics and microclimate influence potential cooling benefits that may aid planning decisions on the use of trees to mitigate heat in urban landscapes.

Tree crown traits and planting context contribute to reducing urban heat

Urban warming affects many millions of city dwellers worldwide. The current study evaluated the extent to which trees reduce air and surface temperatures in urban settings across Greater Sydney, Australia. Summertime air and surface temperatures were measured directly in the shade of 470 individual trees planted in three contrasting contexts (parks, nature strips, asphalt) and compared with temperatures in paired adjacent areas receiving full sunlight. Differences between shade and sunlit temperatures were evaluated against measured morphological traits (leaf area index [LAI], clear stem height, crown depth, height and diameter at breast height) for all trees. On average, tree shade reduced mean and maximum air temperatures by 1.1 °C and 3.7 °C, respectively. Temperatures of standardised reference surfaces (black and white tiles and artificial grass) in tree shade were up to 45 °C lower compared to full-sun exposure, and were also lower in parks and nature strips compared to asphalt settings. The surface temperature of shaded natural grass was cooler compared to sunlit natural grass, although this difference did not vary between nature strip and park settings. The magnitude of air and surface temperature reductions due to tree shade was significantly, positively related to tree-level LAI and these relationships were stronger in asphalt and park contexts compared to nature strips. These findings can inform decisions made by urban managers and planners around the selection of tree characteristics to enhance cooling benefits in different contexts, as an important step towards more liveable and resilient cities.

A Novel 3D Tree-Modeling Method of Incorporating Small-Scale Spatial Structure Parameters in a Heterogeneous Forest Environment

Currently, 3D tree modeling in a highly heterogeneous forest environment remains a significant challenge for the modeler. Previous research has only focused on morphological characteristics and parameters, overlooking the impact of micro-environmental factors (e.g., spatial-structural diversification and habitat heterogeneity) and providing less structural information about the individual tree and decreasing the applicability and authenticity of 3D tree models in a virtual forest. In this paper, we chose a mixed-forest conversion of Chinese fir (Cunninghamia lanceolata) plantations in a subtropical region of China as our study subject and proposed a novel 3D tree-modeling method based on a structural unit (TMSU). Our approach modified traditional rule-based tree modeling (RTM) by introducing a nonlinear mixed-effect model (NLME) to study the coupling response between the spatial structures and morphological characteristics (e.g., tree height (H), height-to-crown base (HCB), and crown width (CW)) of three dominant trees (e.g., Cunninghamia lanceolata (SM), Machilus pauhoi (BHN), and Schima superba (MH)) and develop a prediction model of the morphological characteristic by incorporating forest-based structural parameters. The results showed that: (1) The NLME model in TMSU was found to better fit the data and predict the morphological characteristics than the OLS model in RTM. As compared to the RTM morphological model, the prediction accuracy of the TMSU model of morphological features was improved by 10.4%, 3.02%, and 17.8%, for SM’s H, HCB, and CW, respectively; 6.5%, 7.6%, and 8.9% for BHN’s H, HCB, and CW, respectively; and 13.3%, 15.7%, and 13.4% for MH’s H, HCB, and CW, respectively. (2) The spatial-structural parameters of crowding (Ci), mingling (Mi), and dominance (Ui) had a significant impact on the morphological characteristics of SM, BHN, and MH in TMSU. The degree of crowding, for example, had a positive relationship with tree height, height-to-crown base, and crown width in SM, BHN, and MH; under the same crowding conditions, mingling was positively correlated with tree crown width in SM, and dominance was positively correlated with tree height but negatively correlated with height-to-crown base in BHN; under the same crowding and mingling, dominance was positively correlated with height-to-crown base in MH. (3) Using 25 scenes based on the value class of Ci,Mi for SM, 25 scenes based on the value class of Ci,Ui for BHN, and 125 scenes based on the value class of Ci,Mi,Ui for MH, we generated the model libraries for the three dominating species based on TMSU. As a result, our TSMU method outperformed the traditional 3D tree-modeling method RTM in a complex and highly heterogeneous spatial structure of a forest stand, and it provided more information concerning the spatial structure based on the neighborhood relationships than the simple morphological characteristics; a higher morphological prediction accuracy with fewer parameters; and the relationship between the spatial-structural parameters and the morphological characteristics of a reference tree.

A multiscale framework for defining homeostasis in distal vascular trees: applications to the pulmonary circulation.

Pulmonary arteries constitute a low-pressure network of vessels, often characterized as a bifurcating tree with heterogeneous vessel mechanics. Understanding the vascular complexity and establishing homeostasis is important to study diseases such as pulmonary arterial hypertension (PAH). The onset and early progression of PAH can be traced to changes in the morphometry and structure of the distal vasculature. Coupling hemodynamics with vessel wall growth and remodeling (G&R) is crucial for understanding pathology at distal vasculature. Accordingly, the goal of this study is to provide a multiscale modeling framework that embeds the essential features of arterial wall constituents coupled with the hemodynamics within an arterial network characterized by an extension of Murray's law. This framework will be used to establish the homeostatic baseline characteristics of a pulmonary arterial tree, including important parameters such as vessel radius, wall thickness and shear stress. To define the vascular homeostasis and hemodynamics in the tree, we consider two timescales: a cardiac cycle and a longer period of vascular adaptations. An iterative homeostatic optimization, which integrates a metabolic cost function minimization, the stress equilibrium, and hemodynamics, is performed at the slow timescale. In the fast timescale, the pulsatile blood flow dynamics is described by a Womersley's deformable wall analytical solution. Illustrative examples for symmetric and asymmetric trees are presented that provide baseline characteristics for the normal pulmonary arterial vasculature. The results are compared with diverse literature data on morphometry, structure, and mechanics of pulmonary arteries. The developed framework demonstrates a potential for advanced parametric studies and future G&R and hemodynamics modeling of PAH.

The tree cooling pond effect and its influential factors: A pilot study in Gold Coast, Australia

Residents were suffering from climatic issues resulting from global warming and urban heat islands (UHI). Researchers have explored ways of mitigating these issues. They have discovered several factors that adjust microclimate, including vegetation. Vegetation, especially trees, can significantly mitigate heat stress, often by providing canopied spaces. However, the temperature differences between various points under individual trees have rarely been investigated. The present study aimed to determine these temperature distribution patterns. A new concept, the tree cooling pond effect (TCP), was proposed and defined in a similar way to UHI. The level of TCP was represented by the mean radiant temperature (MRT) difference between four points in line with the direction of tree shade (A, next to the trunk; B, the midpoint between A & C; C, the margin of the shade; and D, 1 m away from C and in the sunshine). The MRT was measured and shown to increase slightly when moving from A to C, with a sharp increase between C and D. Physical characteristics of the trees, especially the tree crown diameter (TCD), impacted the incremental change (∆MRT) significantly. Through linear regression, it was found that ∆MRT was polynomially correlated with tree characteristics; e.g., TCD and distance from the trunk. For a tree with a TCD of 16.6 m, the ∆MRT between Point A and Point D was up to 18 °C; this result indicates that trees had insignificant cooling effects on the unshaded area (in the sunshine) despite neighbouring it. This study represents an initial effort; it visually illustrate tree cooling by identifying several critical points to delineate the pond, which has rarely been considered in previous studies.

Phytodiversity, structure and carbon sequestered by avenue trees in the Municipality of Sèmè-Podji, Southern Benin

The importance of plants in the urban environment is sufficiently demonstrated by their potential and the ecosystem services they generate for the environment and populations. The present work aimed at assessing the contribution of avenue trees to carbon sequestration in the municipality of Sèmè-Podji in Benin. The methodological approach used has allowed making the inventory of trees along 26 kilometers of managed roadways. The diversity and structure parameters were computed to assess the floristic potential, the diameter and height structure of the trees, then the sequestered carbon from the allometric equations established for urban environments. The results revealed 19 species grouped into 12 families and 17 genus along the explored streets. Shannon's average diversity index (3.25±0.13 bits) and Pielou's equitability (0.76±0.04) explain the dominance of a few species, among which the most representative are Terminalia catappa (33.79%), Delonix regia (12.5%), and Khaya senegalensis (9.72%). The diameter and height structures are irregular, with average of 46.75 ± 33.46 cm and 10.35 ± 5.33 m respectively. The aerial biomass for the inventoried streets is 756.16 t/ha, corresponding to a carbon stock of 378.17 t/ha, that is the equivalent of 102.09 t of CO2 per hectare. It appeared from this study that the floristic procession and the structural characteristics of the avenue trees are limited to ensure the socio-ecological functions in the municipality of Sèmè-Podji. However, this information could encourage decision-makers to take reforestation measures to increase the vegetation cover of the streets and for better management of the city's urban forestry.

Rapid Assessment of Architectural Traits in Pear Rootstock Breeding Program Using Remote Sensing Techniques

Over the decades in the US, the introduction of rootstocks with precocity, stress tolerance, and dwarfing has increased significantly to improve the advancement in modern orchard systems for high production of tree fruits. In pear, it is difficult to establish modern high-density orchard systems due to the lack of appropriate vigor-controlling rootstocks. The measurement of traits using unmanned aerial vehicle (UAV) sensing techniques can help in identifying rootstocks suitable for higher-density plantings. The overall goal of this study is to optimize UAV flight parameters (sensor angles and direction) and preprocessing approaches to identify ideal flying parameters for data extraction and achieving maximum accuracy. In this study, five UAV missions were conducted to acquire high-resolution RGB imagery at different sensor inclination angles (90°, 65°, and 45°) and directions (forward and backward) from the pear rootstock breeding plot located at a research orchard belonging to the Washington State University (WSU) Tree Fruit Research and Extension Center in Wenatchee, WA, USA. The study evaluated the tree height and canopy volume extracted from four different integrated datasets and validated the accuracy with the ground reference data (n = 504). The results indicated that the 3D point cloud precisely measured the traits (0.89 &lt; r &lt; 0.92) compared to 2D datasets (0.51 &lt; r &lt; 0.75), especially with 95th percentile height measure. The integration of data acquired at different angles could be used to estimate the tree height and canopy volume. The integration of sensor angles during UAV flight is therefore critical for improving the accuracy of extracting architecture to account for varying tree characteristics and orchard settings and may be useful to further precision orchard management.

The study of the characteristics of the secondary flowering of Cerasus subhirtella 'Autumnalis'.

The short flowering period of ornamental cherry trees is the main factor limiting their use in gardens. Determining the secondary flowering characteristics of ornamental cherry trees is required to prolong their flowering period. In this experiment, Cerasus subhirtella 'Autumnalis' was used as the experimental material. The phenological differences in their annual growth cycle were observed using the BBCH coding system. The cooling requirements of the flower buds were evaluated by the chilling hours model (temperature between 0 and 7.2 °C) and the Utah model. The expression of the core gene involved in bud dormancy regulation DAM (dormancy-associated MADS-box) from the completion of flower bud differentiation in one year until the following year was measured by performing real-time fluorescence-based quantitative PCR. The results showed that the flowering duration of C. subhirtella 'Autumnalis' from November to December was longer than that of C. yedoensis 'Somei Yoshino', which was from March to April. The progress from seed bud-break to flower bud opening took about 10 days for C. subhirtella 'Autumnalis', while the same stage for C. yedoensis 'Somei Yoshino' took around 20 days. Additionally, the flower buds of C. subhirtella 'Autumnalis' needed only the chilling temperature unit of 54.08 to satisfy the chilling requirement, while C. yedoensis 'Somei Yoshino' required a chilling temperature unit of 596.75. After the completion of flower bud differentiation, during low-temperature storage, the expression of DAM4 and DAM5 genes first increased and then decreased, whereas, the expression of the DAM6 gene continued to decrease, and the expression of DAM4, DAM5, and DAM6 in C. yedoensis 'Somei Yoshino' increased rapidly and was maintained at a high level. This showed that the upregulation of the expression of the DAM4, DAM5, and DAM6 genes can inhibit the flower bud germination of Cherry Blossom. The relative expression of the DAM gene of C. subhirtella 'Autumnalis' was significantly lower than that of the DAM gene of C. yedoensis 'Somei Yoshino' from the end of October to the beginning of December, leading to its secondary flowering in autumn. These results might elucidate why the flower buds of C. subhirtella 'Autumnalis' can break their internal dormancy and bloom in the autumn and then again in the following year. Our findings might provide a reference for conducting further studies on the mechanisms of secondary flowering and bud dormancy in cherries.

Spatial patterns and determinants of nitrogen composition in the trunk xylem sap of tree species from tropical to temperate forests

Trunk xylem sap nitrogen (N) composition can provide key information for interpreting tree N transport strategies in a changing environment. However, there remains poorly explored to properly depict the spatial patterns and determinants of the xylem sap N composition in different tree species across climate zones. Here, we analyzed the trunk xylem sap N of dominant tree species from tropical to temperate forests in eastern China. The random forest (RF) approach was used to quantify the relative importance of biotic and abiotic variables in driving the spatial patterns of the trunk xylem sap N composition. The concentration ranges of total N (TN), ammonium (NH4+) and nitrate (NO3−) in the trunk xylem sap were 0.37–37.23, 0.01–2.60 and 0.01–0.49 mM, respectively. Dissolved organic nitrogen (DON) was the main component of TN in the xylem sap of forest trees, accounting for 83.4 ± 3.6%, followed by NH4+ (11.8 ± 3.2%) and NO3− (4.8 ± 1.3%). In addition, the TN and NH4+ concentrations increased from the tropical rainforest and then decreased to the northern temperate forest, with a peak in the subtropical deciduous forest in the middle-latitude climatic transition zone. The NO3− concentration in the temperate forest was higher than that in other forests, regardless of coniferous and broad-leaf forests. Tree species was the key factor affecting the spatial TN patterns, whereas soil pH primarily and conversely determined the spatial NH4+ and NO3− patterns. Together, tree characteristics and soil properties were the most important factors affecting the spatial patterns of xylem sap N composition. These findings provide new insights into N cycling within forest trees and have implications for better understanding the adaptation to global changes in forest ecosystems.

Drought survival strategies differ between coastal and montane conifers in northern California

AbstractIncreasingly severe and prolonged droughts are contributing to tree stress and forest mortality across western North America. However, in many cases, we currently have poor information concerning how drought responses in forests vary in relation to competition, climate, and site and tree characteristics. We used annual tree ring evidence of 13C discrimination (Δ13C) and growth metrics to assess drought resistance and resilience for six conifer species at the intersection of several bioregions in northern California. Within each species' range in northern California, we collected competition and tree characteristics from 270 focal trees across sites that varied from wetter to drier habitat conditions (54 sites). Across sites, all six conifer species weathered the severe 2013–2015 drought with reasonably high resistance and post‐drought resilience. However, we found important differences in drought responses between coastal and montane species based on annual growth and Δ13C metrics. Broadly, the two coastal species showed consistent declines in drought resistance across successive drought years, whereas the four montane species maintained high drought resistance across drought years. More specifically, we found lower Δ13C and growth during drought years in coastal species, suggesting stomatal closure during drought with the potential for vulnerability to carbon depletion during long‐term drought. Conversely, Δ13C and growth were stable in montane species throughout the drought, which may contribute to hydraulic failure under increased drought frequency and/or severity. We also evaluated environmental factors that affect Δ13C using data from before and during the drought. These physiological models were consistent for the two coastal species, with a positive relationship between annual precipitation and Δ13C and a negative relationship between tree density and Δ13C. Conversely, the four montane models illustrated a greater importance of site conditions on drought responses for these species. Our findings show differential risk for drought stress across diverse conifers during severe drought. This work highlights the importance of site and tree characteristics in determining drought responses across cool, annually humid coastal habitats to seasonally dry montane habitats.

The load-bearing mechanism of plant wings: A multiscale structural and mechanical analysis of the T. tipu samara.

Spinning winged fruits ("helicopter" samaras) generate significant lift forces at relatively low velocities, which enable the wind to disperse them across long distances. The biological material of the samara sustains the aerodynamic loadings and maintains the physical shape of the samara in the air via a yet unknown load-bearing mechanism. Here, positing that this mechanism fundamentally originates from the macro-to-microscale structural and mechanical characteristics of the samara, we use sub-micron computer tomography, electron microscopy, and multi-scale mechanical experiments to map the structural and mechanical characteristics of the tipu tree (Tipuana tipu) samara down to the micrometer length scale. Then, using theoretical models, we characterize the multiscale structural-mechanical principles of the samara and use these principles to disclose the underlying load-bearing mechanism. We found that the structural motifs of the tipu tree samara are closely analogous to various other types and forms of winged fruits, suggesting that this load-bearing mechanism is widespread in plant wings. The structural-mechanical principles governing the samara bear unconventional design concepts, which pave the way toward the development and engineering of small-scale wing elements for miniature aviation platforms with specialized mechanical capabilities. STATEMENT OF SIGNIFICANCE: The biomaterial of plant wings grants them mechanical resistance to flight forces during wind dispersal. "Helicopter seeds" demonstrate an intricate load-bearing mechanism that spans three structure-functional scales of their biomaterial. This mechanism appears widespread in plant wings and may promote novel micro-engineering design guidelines for futuristic flight materials and small-scale aviation platforms.