Zelkova Serrata Research Articles

청도군 운문사 입구 수구막이 소나무림 식생구조 및 생육 특성

This study was designed to come up with a way of managing a cultural landscape forest by conducting research on the vegetation structure and growth characteristics. This study’s target site, which was 45,201m² in size, was <italic>Pinus densiflora</italic> forest for Sugumagi placed at the entrance of Unmun Temple, Sinwon-ri, Unmun-myeon, and Cheongdo-gun in the southernmost part of Gyeongsangbuk-do, Korea. Sugumagi means the water of the valley flows far away, and where no downstream is visible according to feng shui. The historical sources of the Sugumagi <italic>Pinus densiflora</italic> forest at the entrance of Unmun Temple isn’t clear. It waw only found at that location. The <italic>Pinus densiflora</italic> forest at the entrance of Unmun Temple is located in the waterway in terms of Feng Shui. The present condition of growth was investigated through a grid surveys of 98 trees and <italic>Pinus densiflora</italic> growth. As a result of the analysis of growth status, <italic>Pinus densiflora</italic>, <italic>Larix leptolepis, Zelkova serrata, Celtis sinensis</italic>, and <italic>Rhus javanica</italic> were distributed in the conopy layer, and 28 species including <italic>Ailanthus altissima</italic> were grown in the understroy layer, and 92 species, including <italic>Ampelopsis brevipedunculata</italic>, in the shrub layer. The plant community structure was divided into low, medium and high-density <italic>Pinus densiflora</italic> forests in the study area, based on the number in the conopy layer and the grade of and the trees analyzed. As a result of the analysis, the <italic>Pinus densiflora</italic> dominated the low, medium and high-density <italic>Pinus densiflora</italic> forests, and there were no competitive species. The relative dominance of the low-density <italic>Pinus densiflora</italic> forests was 46.9% on average, medium-density was 62.6% and 50.2% was found in high-density. The mean species diversity of Shannon in the low-density study was 0.7055, medium -density study was 0.8966 and the average species diversity of Shannon in the high-density study was 0.8317. The analysis of the age and growth of 25 sample trees in the Sugumagi <italic>Pinus densiflora</italic> forest shows that the distribution of the chest diameter (DBH) of the sample <italic>Pinus densiflora</italic> is 38 to 77cm with the average chest diameter being 61.1cm. The age was 84-161 years and the average was 114 years. In the <italic>Pinus densiflora</italic> forest, most(670,659, or 98.3%) of the tree trunk wound was collected for rosins during the Japanese colonia Era, Of the total 670, 659 were <italic>Pinus densiflora</italic>, 98.3% of the total. 394 were surgically repaired in 2005. For the preservation of the Sugumagi <italic>Pinus densiflora</italic> forest, dead trees should be replaced with substitute trees appropriate to the middle and south topography. It is demanded that foreign species such as <italic>Larix leptolepis</italic> in the research area should be removed and <italic>Pinus densiflora</italic> that underwent surgical operations should be regularly sterilized. It is also emphasized that the management of insecticide is important.

The separation of softwood and hardwood in historical wooden statues of the Nazenji-temple in Japan using NIR spectroscopy

Abstract The applicability of near-infrared (NIR) spectroscopy to the identification of wood species of archaeologically/historically valuable wooden artifacts in a non-invasive manner was investigated using reference wood samples from the xylarium of the Forestry and Forest Products Research Institute (TWTw) and applied to several wooden statues carved about 1000 years ago. Diffuse-reflectance NIR spectra were obtained from five standard wood samples each of five softwood species (Chamaecyparis obtusa, Cryptomeria japonica, Sciadopitys verticillata, Thujopsis dolabrata, Torreya nucifera) and five hardwood species (Aesculus turbinata, Cercidiphyllum japonicum, Cinnamomum camphora, Prunus jamasakura, Zelkova serrata). A principal component analysis (PCA) model was developed from the second derivative spectra. The score plot of the first two components clearly showed separation of the wood sample data into softwood and hardwood clusters. The developed PCA model was applied to 370 spectra collected from 21 wooden statues preserved in the Nazenji-temple in Shizuoka Prefecture in Japan, including 14 made from Torreya spp. and 7 made from Cinnamomum spp. In the score plot, the statue spectra were also divided into two clusters, corresponding to either softwood (Torreya spp.) or hardwood (Cinnnamomum spp.) species. These results show that NIR spectroscopy combined with PCA is a powerful technique for determining whether archaeologically/historically valuable wooden artifacts are made of softwood or hardwood.

ESTIMATION OF THE OCCURRENCE TIME OF THE Δ14C PEAK IN AD 775 BASED ON THE OXIDATION TIME OF 14C IN THE ATMOSPHERE AND Δ14C VALUES IN SUBANNUAL TREE RINGS

ABSTRACTThe 14C peak in AD 775 (M12) has been measured and confirmed globally in several studies since it was first measured in annual tree rings by Miyake et al. (2012). However, M12 data measurements in early- and latewood are limited. This paper presents the Δ14C values in early- and latewood from AD 762–776 Zelkova serrata tree rings from Bangu-dong, Ulsan, South Korea (35°33′N, 129°20′E). The results indicate no early rise in Δ14C values in the latewood of AD 774 in this sample located at mid-latitude. A comparison of the results of this and previous studies suggests latitude dependence (Büntgen et al. 2018); that is, the early rise of Δ14C in AD 774 was not observed at mid-latitudes in South Korea but was observed at high latitudes in Finland. The half-oxidation time of 14C was estimated from a detailed analysis of a small bomb peak in AD 1962. Based on the half-oxidation time, the Δ14C rise in the latewood, but not in the earlywood, of AD 774 in Finland, and the absence of a Δ14C rise in both the early- and latewood of AD 774 in South Korea, the 14C spike was estimated to have been produced from late April to mid-June in AD 774.

X‐ray computed tomography of severed root wounds of Prunus serrulata and Zelkova serrata

AbstractThe performance of laboratory X‐ray computed tomography (XCT) for the non‐destructive imaging of root wood was evaluated. Lateral roots of oriental cherry (Prunus serrulata var. spontanea) and Japanese zelkova (Zelkova serrata) were severed in spring and maintained in soil for 6 months. Without sectioning, XCT revealed the phloem, xylem and vascular cambium structures in the root wood. A virtual transverse section showed a ring of woundwood covering the severed, lateral root of the two trees. Different levels of X‐ray absorption were evident around the cut surfaces of P. serrulata; however, they were rarely detected in Z. serrata. More adventitious roots were observed on Z. serrata than on P. serrulata. Distinct white spots in the rays were only detected in Z. serrata. These results suggest that XCT has potential applications in forest pathology, providing virtual sections of wound closure, wood density distribution, organ redifferentiation, and mineral deposition in root wood.

Effect of transpiration on the physiological vitality of Zelkova serrata

This study aimed to investigate the effect of suppressing transpiration on the physiological characteristics of trees and identify suitable indicators to assess tree vitality. Three seedlings of Zelkova serrata were used: a control, a unit treated on the upper sides of the leaves (TU), and a unit treated on double sides of the leaves (TD). Changes in photosynthetic rate, transpiration rate, sap velocity, and bark temperature following the suppression of transpiration were measured. The transpiration rate and other physiological characteristics of TU were not significantly different from those of the control except for photosynthetic rate. However, TD showed a significantly lower photosynthetic rate, transpiration rate, and sap velocity compared to the control. The bark temperature of TD was not significantly higher than that of the control and TU. Our findings indicate that photosynthetic rate and sap velocity were positively correlated with transpiration rate, whereas bark temperature was negatively correlated. Furthermore, photosynthetic rate showed the most significant linear relationship with transpiration rate, suggesting the photosynthetic rate is a suitable physiological indicator to evaluate the vitality of Z. serrata.

The complete chloroplast genome of Zelkova serrata and its phylogenetic position within Ulmaceae

The complete chloroplast genome sequence of the Tertiary relict tree Zelkova serrata was reported in this study. The chloroplast genome is 158,875 bp in length with a typical angiosperm quantitative structure consisting of a large single copy (87,412 bp) and a small single copy (18,683 bp) separated by a pair of inverted repeat (26,390 bp). Genome annotation revealed a total of 129 genes comprising 84 protein-coding genes, 37 tRNA genes, and eight rRNA genes. Phylogenomic analysis based on the whole plastomes indicated that Z. serrata and Z. schneideriana formed a well-supported monophyletic clade sister to genus Ulmus in Ulmaceae.

Wood Identification of Historical Architecture in Korea by Synchrotron X-ray Microtomography-Based Three-Dimensional Microstructural Imaging

For visual inspection-based wood identification, optical microscopy techniques typically require a relatively large sample size, and a scanning electron microscope requires a clean surface. These novel techniques experience limitations for objects with highly limited sampling capabilities such as important and registered wooden cultural properties. Synchrotron X-ray microtomography (SR-μCT) has been suggested as an effective alternative to avoid such limitations and various other imaging issues. In this study, four pieces of wood fragments from wooden members used in the Manseru pavilion of Bongjeongsa temple in Andong, Korea, wereused for identification. Three-dimensional microstructural images were reconstructed from these small wood samples using SR-μCT at SPring-8. From the analysis of the reconstructed images, the samples were identified as Zelkova serrata, Quercus sect. Cerris, and Pinus koraiensis. The images displayed sufficient spatial resolution to clearly observe the anatomical features of each species. In addition, the three-dimensional imaging allowed unlimited image processing.

Comparative physiological mechanisms of arbuscular mycorrhizal fungi in mitigating salt-induced adverse effects on leaves and roots of Zelkova serrata.

Arbuscular mycorrhizal (AM) fungi enhance plant salt tolerance. However, physiological mechanisms of enhanced salt tolerance in leaves and roots of trees rarely have been compared. To reveal the different mechanisms, our study utilized comprehensive analyses of leaves and roots to examine the effects of Funneliformis mosseae on the salinity tolerance of Zelkova serrata. Seedlings of Z. serrata were exposed to four salt levels in a greenhouse with and without F. mosseae inoculation. Treatment comparisons revealed that following F. mosseae inoculation, (1) nutrient deficiency caused by osmotic stress was mitigated by the fungus enhancing nutrient contents (K, Ca, and Mg) in roots and (N, P, K, Ca, and Mg) in leaves, with Ca and K contents being higher in both leaves and roots; (2) mycorrhizas alleviated ion toxicity by maintaining a favorable ion balance (e.g., K+/Na+), and this regulatory effect was higher in leaves than that in roots; and (3) oxidative damage was reduced by an increase in the activities of antioxidant enzymes and accumulation of antioxidant compounds in mycorrhizal plants although the increase differed in leaves and roots. In particular, AM fungus-enhanced catalase activity and reduced glutathione content only occurred in leaves, whereas an enhanced content of reduced ascorbic acid was only noted in roots. Growth, root vitality, leaf photosynthetic pigments, net photosynthetic rate, and dry weight were higher in seedlings with AM fungus inoculation. These results suggest that AM fungus inoculation improved salinity tolerance of Z. serrata, but the physiological mechanisms differed between leaves and roots.

PECULIARITIES OF INTRODUCTION OF SMALL-WIDENED DECORATIVE TYPES IN THE CONDITIONS OF THE LADYZHYN DENDROPARK

The floristic analysis of the low-frequency ornamental species of the arboretum «Ladyzhyn Dendropark» was carried out, according to which the taxonomic composition and the description of the investigated species of the arboretum were determined. Based on the results of the integrated numerical assessment of the viability of trees and shrubs based on visual observations, the prospects for the introduction of woody plants in the study region were evaluated. The species composition of the introduced ornamental plants of the arboretum is systematized, which today is more than 25 species, arranged in accordance with the formed dendroplan. The peculiarities of the introduction of low-abundant ornamental plants were investigated, and the inventories of native and introduced arboreal and shrub vegetation of the areas of the arboretum were conducted. Based on these studies, a dendroplan was developed for a dendrological park of the local importance. The age and quantitative structure of the plantations has been determined, according to which 21 composite areas have been created in the studied area of more than 10 ha. In the course of research it is determined that 9 species of plants are quite promising (Catalpa speciosa Warder., Nyssa sylvatica Marsh, Gymnocladus dioicus (L.) K.Koch, Liriodendron tulipifera L., Magnolia kobus DC., Liquidambar styraciflua L., Malus sieboldii, Pseudotsuga menziesii (Mirb.) Franco, Ginkgo biloba L. Betula nigra L); promising – 10 species (Zelkova serrata (Thunb.) Makino, Stephanandra incisa (Thunb.) Zabel, Koelreuteria bipinnata Franch., Magnolia soulangeana Soul, Rhus typhina L., Catalpa bignonioides, Chamaecyparis pisifera (Siebold &amp; Zucc.) Endl., Malus «Evereste», Malus domestica «Rajka», Diospyros virginiana L.), less promising – 5 species (Paulownia tomentosa (Thunb.) Steud., Cercis siliquastrum L., Magnolia George Henry Kern, Coffea liberica (W. Bull ex Hiern), Magnolia acuminata L.) The low adaptive index of the last 5 species is related to the inconsistency of the temperature regime in the study conditions. Inventory of the assortment of 20 shrubs and arboretum plants was made and a design decision was made to increase the species and form content of arboretum of section No. 21. The current state of compositions and flower beds of the arboretum was analyzed and recommendations for their improvement on the principle of selection and placement of species were presented. Keywords: dendropark, introduction, compositions, flower beds, integral evaluation, taxonomic composition, decorative properties, systematic principle, exotics.

Evaluation of the Importance of Some East Asian Tree Species for Refinement of Air Quality by Estimating Air Pollution Tolerance Index, Anticipated Performance Index, and Air Pollutant Uptake

Potentials of tree species as biofilters depend on appropriate selection based on their tolerance to air pollution, which is usually evaluated by the air pollution tolerance index (APTI) and anticipated performance index (API). Thus, these index values need as a means of scientific understanding to assess the role of urban trees for better greenspace planning/management to mitigate impacts of gaseous air pollution such as ozone (O3) and sulfur dioxide (SO2). O3 exposure to Chionanthus retusus, Pinus densiflora, and Ginkgo biloba showed higher stomatal O3 flux than the others, finally resulting in both favoring stomatal movement and maintaining carbon fixation. In contrast, despite the whole tree enhanced SO2 uptake under excess SO2 exposure, the carbon assimilation capacity was only found in Taxus cuspidata and Zelkova serrata as a consequence of no stomatal sluggishness. On the basis of API, P. densiflora and Prunus × yedoensis were good performers for developing greenspace, while Z. serrata and G. biloba were moderate performers; however, C. retusus and T. cuspidata were estimated to be poor and very poor performers, respectively, for reducing the air quality injury caused by air pollutants. The present study suggests that an integration of both APTI and API based on stomatal absorption flux is needed for selecting sound tree-species in greenspace planning/construction to control gaseous air pollutions.

Impression of streetscape from evaluation of landscape elements in &lt;i&gt;Oike-dori&lt;/i&gt; street, Kyoto City

This study investigated rating of a streetscape maintained by a local administrative ordinance. A questionnaire survey was conducted to examine frequency of use and purpose of use on target respondents. The results of the survey were analyzed against the street impression goals set by Kyoto City. We considered whether the landscape elements of the streetscape as desired by the ordinance of the city stimulated intentional application and whether it had an influence on resident perception of the streetscape. The area of study was the Oike-dori street which is also a recommended walk space to town. From the results, the scene component of authority for Oike-dori street was found to be elements of Japanese zelkova row of trees and a flower bed, natural items such as shrubs and the artifact-like thing such as building. Harmony of features in the landscape scenery of Oike-dori street was the man reasons that contributed to strong identity of the study area. It is thought that sense of unity, at such a location within the streetscape will become important in future. The scene component of Japanese zelkova row of trees was the most preferable in this investigation. Through text mining, sense of seasonal changes such as fresh green was found to be critical. Therefore, it is necessary to perform investigation throughout the year. It is important to put into consideration problems associated with high stratification of buildings. The results of current analysis and the new knowledge generated can help towards maintaining space quality and identity of the streetscape.

Macrofungal diversity of urbanized areas in southern part of Korea

Most macrofungi are cosmopolitan, occurring in both tropical and temperate regions. Studies on diversity and distribution of the mushroom flora in Korea are mainly conducted in major national parks and forest, but there are few studies on species distributed in urbanized areas. As part of the Korea National Arboretum project, we investigated the diversity of mushrooms through examining the distribution of mushrooms in Gyeongsang Province from May to September in 2017. In this province, we surveyed urbanized areas comprising three cultural heritage protection zones (Salix chaenomeloides forest, Tongdo Temple, Placenta Chamber of King Sejong's Princes), two urban parks (Duryu and Amnam parks), and 20 legally protected trees (such as Ginko biloba, Pinus densiflora, Quercus acutissima, Salix hallaisanensis, Zelkova serrata and so on). Consequently, 37 species on legally protected trees, 48 species in urban parks, and 84 species in cultural heritage protection zones were confirmed. A total of 37 families, 90 genera, and 139 species were identified. Of those, three species were confirmed for the first time in Korea. This study provides the basic data for the preparation of protection management protocols for macrofungal flora on legally protected trees and in cultural property protection areas.

Growth characteristics and growth equations of the diameter at breast height using tree ring measurements of street trees in Kyoto City, Japan

Tree growth equations are indispensable for modeling tree functions for ecosystem services. However, knowledge about the growth rates of street trees in Japan remains limited. This study aimed to examine the growth characteristics of street trees (Zelkova serrata, Platanus orientalis, and Prunus yedoensis) in Japan to generate growth equations of the diameter at breast height (DBH) based on measurements of tree rings. Specifically, diameter growth was used and compared against nursery-grown trees used in previous studies in Japan and street trees in the USA. The diameter growth rate per year of Z. serrata ranged from 0.43 cm to 1.12 cm, with peak growth occurring at 17.8 years of age. For P. orientalis, the diameter growth rate per year ranged from 0.25 cm to 1.59 cm, with peak growth occurring at 7.4 years of age. For P. yedoensis, the diameter growth rate per year ranged from 0.68 cm to 1.65 cm, with no apparent peak growth. The Chapman-Richards growth function generated the best fit as a diameter growth equation for all three species out of three tested theoretical growth equations (Chapman-Richards, Gompertz, and Logistic function). For 25-year old trees, the estimated DBH of Z. serrata and P. orientalis grown as street trees was 68 % and 84 % of that of nursery-grown trees, respectively. For street trees 25 years after planting, the estimated DBH of Z. serrata, P. orientalis, and P. yedoensis in Kyoto City was 62 %, 63 %, and 56 % of that of street trees in the USA. The diameter growth of street trees in Kyoto was substantially lower than that of nursery-grown trees and street trees in the USA. Therefore, region-specific growth equations must be developed for street trees when the planting environment and management approaches are different.

Comparison of four decay diagnostic instruments on artificial cavities in woods of Japanese zelkova (Zelkova serrata)

Comparison of four decay diagnostic instruments on artificial cavities in woods of Japanese zelkova (<i>Zelkova serrata</i>)

Dynamics of xylem and phloem sap flow in an outdoor zelkova tree visualized by magnetic resonance imaging.

Xylem and phloem sap flows in an intact, young Japanese zelkova tree (Zelkova serrata (Thunb.) Makino) growing outdoors were measured using magnetic resonance imaging (MRI). Two propagator-based sequences were developed for q-space imaging: pulse field gradient (PFG) with spin echo (PFG-SE) and stimulated echo (PFG-STE), which were used for xylem and phloem flow measurements, respectively. The data evaluation methods were improved to image fast xylem flow and slow phloem flow. Measurements were taken every 2-3h for several consecutive days in August 2016, and diurnal changes in xylem and phloem sap flows in a cross-section of the trunk were quantified at a resolution of 1mm2. During the day, apparent xylem flow volume exhibited a typical diurnal pattern following a vapor pressure deficit. The velocity mapping of xylem sap flow across the trunk cross section revealed that the greatest flow volume was found in current-year earlywood that had differentiated in April-May. The combined xylem flow in the 1- and 2-year-old annual rings also contributed to one-third of total sap flow. In the phloem, downward sap flow did not exhibit diurnal changes. This novel application of MRI in visualization of xylem and phloem sap flow by MRI is a promising tool for in vivo study of water transport in mature trees.

Investigating the Effect of Weather and Seasonal Factors on Root Stability Using Dynamic Measurements

The dynamic tree stability assessment technique allows trees to be measured efficiently, under realistic weather conditions. In this study, the stability of four trees, including two conifers and two broad-leaved species was assessed in the Botanical Gardens of the University of Sopron, Hungary. The examined trees included Horse chestnut, Japanese zelkova, Douglas fir and Giant sequoia. Each tree was measured in various weather and seasonal conditions. Results show that the seasons affected the stability of broadleaved trees significantly, due to considerable changes in the crown surface area, while this difference was much lower in softwoods. Rainy weather loosens the topsoil, which adversely affects the stability of trees with relatively shallow roots. Lower layers take longer to saturate, and therefore trees with very deep roots are usually unaffected by the looser topsoil, while the increased weight of the top layer compacts the lower layers and improves stability, as evidenced by results measured on Sequoia. Snow accumulation on the branches increases the inertia of the tree, which imposes higher torque on the root collar, decreasing stability. In the meantime, the increased resistance offered by frozen ground stabilizes the tree, which more-or-less counterbalances this effect. A more extensive database of tree stability under different conditions is being built to allow for more comprehensive analysis of various factors, like wind direction, tree health and morphology, shading, etc.

Wood identification of Japanese Shinto deity statues in Matsunoo-taisha Shrine in Kyoto by synchrotron X-ray microtomography and conventional microscopy methods

Research on the wood species of Japanese Buddhist statues has an over 60 years’ history and recently many Buddhist “Ichiboku” statues carved out of a single bole made from the Nara to Heian periods were scientifically revealed to be made of Torreya nucifera. Shinto deity statues in Japan, however, have not yet been investigated scientifically. Because many Shinto deity statues are enshrined behind closed doors, there are fewer opportunities to investigate them. To examine the differences and similarities in wood selection between Buddhist and Shinto deity statues, wood identification was conducted on the 11 Shinto deity statues of Matsunoo-taisha Shrine, Kyoto, Japan, using synchrotron X-ray microtomography and conventional microscopy methods. The results indicated two female deity statues with the ink inscriptions indicating the production year of 1143 were of Torreya nucifera, one female deity statue of Zelkova serrata, and the other eight statues, i.e., two female deity statues, four male deity statues and two priestly attire deity statues of Prunus s.l. spp.

Determinate the Number of Growth Rings Using Resistograph with Tree-Ring Chronology to Investigate Ages of Big Old Trees

To verify the possibility of using resistograph to estimate the age of big old living trees, we selected three Zelkova serrata and seven Pinus densiflora in Goesan. The mean diameters at breast height of Z. serrata and P. densiflora were 102 (92-116) cm and 80 (65-110) cm, respectively. The heights measured from the ground using a resistograph ranged at 1.2-4.3 m and 0.6-1.1 m for Z. serrata and P. Densiflora, respectively. The most appropriate needle speed to determine tree-ring boundaries for measuring ring width was 1500 r/min for both tree species. Alternatively, the suitable feed speeds for Z. serrata and P. densiflora were 50 cm/min and 150 cm/min, respectively. From the measured data, the mean numbers of tree rings of Z. serrata and P. densiflora were 57 (43-68) and 104 (93-124), respectively, and the mean tree-ring widths were 4.27 mm (3.18-5.09 mm) and 2.93 mm (2.32-3.34 mm), respectively. A comparison between the time series of tree-ring widths by resistograph and that from the local master chronologies tallied for the heartwood part. Finally, this study showed that resistograph can be used to estimate tree ages when a local master chronology is available.

The Removal Efficiencies of Several Temperate Tree Species at Adsorbing Airborne Particulate Matter in Urban Forests and Roadsides

Although urban trees are proposed as comparatively economical and eco-efficient biofilters for treating atmospheric particulate matter (PM) by the temporary capture and retention of PM particles, the PM removal effect and its main mechanism still remain largely uncertain. Thus, an understanding of the removal efficiencies of individual leaves that adsorb and retain airborne PM, particularly in the sustainable planning of multifunctional green infrastructure, should be preceded by an assessment of the leaf microstructures of widespread species in urban forests. We determined the differences between trees in regard to their ability to adsorb PM based on the unique leaf microstructures and leaf area index (LAI) reflecting their overall ability by upscaling from leaf scale to canopy scale. The micro-morphological characteristics of adaxial and abaxial leaf surfaces directly affected the PM trapping efficiency. Specifically, leaf surfaces with grooves and trichomes showed a higher ability to retain PM as compared to leaves without epidermal hairs or with dynamic water repellency. Zelkova serrata (Thunb.) Makino was found to have significantly higher benefits with regard to adsorbing and retaining PM compared to other species. Evergreen needle-leaved species could be a more sustainable manner to retain PM in winter and spring. The interspecies variability of the PM adsorption efficiency was upscaled from leaf scale to canopy scale based on the LAI, showing that tree species with higher canopy density were more effective in removing PM. In conclusion, if urban trees are used as a means to improve air quality in limited open spaces for urban greening programs, it is important to predominantly select a tree species that can maximize the ability to capture PM by having higher canopy density and leaf grooves or trichomes.

Period-3 dominant phase synchronisation of Zelkova serrata: border-collision bifurcation observed in a plant population

The population synchrony of tree seed production has attracted widespread attention in agriculture, forestry and ecosystem management. Oaks usually show synchronisation of irregular or intermittent sequences of acorn production, which is termed ‘masting’. Tree crops such as citrus and pistachio show a clear two-year cycle (period-2) termed ‘alternate bearing’. We identified period-3 dominant phase synchronisation in a population of Zelkova serrata. As ‘period-3’ is known to provide evidence to imply chaos in nonlinear science, the observed period-3 phase synchronisation of Zelkova serrata is an attractive real-world phenomenon that warrants investigation in terms of nonlinear dynamics. Using the Hilbert transform, we proposed a procedure to determine the fractions of periods underlying the survey data and distinguished the on-year (high yield year) and the off-year (low yield year) of the masting. We quantified the effects of pollen coupling, common environmental noise and individual variability on the phase synchronisation and demonstrated how the period-3 synchronisation emerges through a border-collision bifurcation process. In this paper, we propose a model that can describe diverse behaviours of seed production observed in many different tree species by changing its parameters.