• Journal of Plant Biology
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• v.34 no.1
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• pp.9-18
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• 1991

This study deals with the effect of dwarf growth on xylem structure, especially on the dimension of xylem elements described for 12 species of naturally occuring dwarf trees. The length and tangential diameter of tracheary elements and fibers in dwarf trees appear to be shorter and narrower than those in normal trees. Radial width and cell number of the same annual rings are narrower and smaller in dwarf trees than those in normal trees. Height of rays in dwarf trees is lower than that in normal trees. Dwarf conifers appear to have higher ratio, of latewood to earlywood than that in normal trees. In the hardwood species studied, mesomorphy of vessel elements is lower in dwarfs than that in normal trees. It can be concluded that this dwarf growth occurs as a result of extremely slow growth by environmental stress such as water deficiency.ciency.

• Journal of People, Plants, and Environment
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• v.22 no.5
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• pp.481-488
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• 2019

The purpose of this study is to suggest how to manage healing forests. Field investigation and surveys were conducted to produce results and 313 questionnaires collected from workers in the forestry sector and ordinary people were analyzed. The results were as follows: it is required to preserve flowering plants, scenic trees, and ecological trees in the understory vegetation, and to remove trees that block the forest landscape, leaving about 50 to 60 percent of the understory vegetation. The preferred density order of broadleaf trees was analyzed as follows: Betula platyphylla > Liriodendron tulipifera > Quercus acutissima. The preferred density order of coniferous trees was analyzed as follows: Abies holophylla > Cryptomerias japonica and Chameacyparis obtusa > Larix kaempferi > Pinus densiflora > Pinus koraiensis. The preferred density in healing forests was 81-89% compared to the number of residual trees for quantitative thinning. Specifically, the preferred density were 87% for P. koraiensis, 86% for L. kaempferi, 81% for P. densiflora, 83% for C. japonica, 84% for C. obtusa and 89% for Q. acutissima. In the case of healing forests, it is recommended to periodically conduct a small-scale thinning with different densities according to the species and diameter of trees based on the results of this study.

• The Plant Pathology Journal
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• v.40 no.3
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• pp.282-289
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• 2024

Fire blight is a bacterial disease caused by Erwinia amylovora. In Korea, fire blight was first reported in 2015 in an orchard. If the infection is confirmed, all trees in the orchard must be removed and the orchard must remain closed for 3 years. Since 2020, if the number of trees infected with fire blight is less than 5% of the total trees in the orchard, only the infected tree and adjacent trees are removed in Korea. Three years after removal, the trees can be replanted after confirming that the orchard soil is free from E. amylovora. In this study, a protocol was established for detecting E. amylovora in soil via selective enrichment, using tryptic soy broth with 0.05% bile salts and 50 ㎍/ml cycloheximide, and real-time polymerase chain reaction. This protocol resulted in a 1,000-times improved detection limit for E. amylovora in soil samples compared to that in unenriched samples. Soil monitoring was performed for orchards where fire blight-infected trees had been removed 3-27 months prior; the selected orchards were monitored every 3 months. Monitoring confirmed that E. amylovora was not present in the soil at any site in any of the orchards. A new detection protocol facilitates the monitoring of E. amylovora in soil and could help permit the replanting of trees in orchards. Also monitoring results provide evidence that trees can be planted earlier.

• Journal of People, Plants, and Environment
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• v.23 no.3
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• pp.333-345
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• 2020

Background and objective: The purpose of this study was to provide basic data on trees that can be used for planting design and construction for permanently shaded areas by grasping the growth status of trees according to the daylight conditions of the outdoor spaces of apartment complexes. Methods: On the recently completed apartment complexes, daylight conditions were analyzed by using daylight simulations utilizing Solar Access Analysis of Ecotect Analysis. With a criteria for assessment of tree condition, the defect rate of trees planted in permanently shaded areas and green spaces with good daylight conditions was analyzed to suggest trees applicable to permanently shaded areas. The first tree survey was conducted from November 18, 2019 to February 15, 2020, focusing on trees planted in permanently shaded areas, and the second tree survey of all the trees planted on the study sites including permanently shaded areas was conducted from March 16 to March 30, 2020. Results: Evergreen trees which are classified as shade intolerant trees including Pinus densiflora, Thuja occidentalis, and Abies holophylla showed a higher defect rate of trees among the trees planted in permanently shaded areas. Taxus cuspidata, Zelkova serrata, Cornus kousa, Chionanthus retusus and Acer palmatum which are classified as shade tolerant trees and shade moderate tolerance trees seemed to be able to be used in the plant design of permanently shaded areas in apartment complexes because the trees showed good growth and a low tree defect rate. In addition, although it was excluded from the analysis due to a small number of samples, Sorbus commixta and Prunus cerasifera var. atropurpurea also can be used for planting in permanently shaded areas. Conclusion: The daylight simulation technique used to analyze permanent shaded areas in this study can be used as an analysis tool considering the daylight environment at the stages of design and construction, and additional research will be required to analyze tree growth according to daylight conditions through data accumulation and monitoring by managing records throughout the entire life cycle of trees in the process of planting and maintenance.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.24 no.4
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• pp.15-29
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• 2021

Urban green spaces offer a variety of benefits to living things and humans. However, existing green spaces have been reduced and fragmented due to urbanization, and there is a limit to creating new large green spaces in densely developed cities. Street trees have fewer restrictions on land use, which can be a measure to secure green areas in cities. In Korea, excessive pruning is being done on some street trees for reasons such as blocking of building signboards, contact with electric wires, and restrictions on sidewalk widths. Therefore, it is necessary to quantitatively understand the relationship between the benefits provided by street trees and their structures to come up with an efficient and systematic planning and management plan for urban street trees. In this study, we quantitatively analyzed the relationship between the thermal comfort improvement by the shades of street trees and the vertical structure, planting environment, and types of street trees. To calculate the thermal comfort felt by human body, we calculated UTCI (Universal Thermal Climate Index) of each street tree. For the vertical structure of street trees, we used Terrestrial LiDAR and the point clouds of street tree's crown was sliced vertically at 1m intervals. We conducted a multiple regression analysis on the thermal comfort improvement using the variables we obtained from fields. As a result, in the case of a street tree's vertical structure, the lager the volume of tree's crown located 3-4m (β=0.298, p<.05) and 6-7m (β=0.568, p<.001) above clear length, the better the cooling effect. In addition, the thermal comfort improvement was assessed to decrease as the DBH increased (β=-0.435, p<.001). In general, the crown diameter and DBH are positively correlated, with a cooling effect occurring as crown diameter increases. In this study, the opposite result was obtained due to the small number of trees measured, so additional research is needed by increasing the number of tree samples. In the case of the planting environment, the effect of improving thermal comfort was higher in the shaded area of trees planted to the south (β=-0.541, p<.001). Since unsystematic management of street trees can deteriorate the function of them, quantitative evaluations of the vertical structure of street trees are required, which can provide specific measures for planning and management of urban street trees with thermal comfort effect.

• Journal of Korean Society of Forest Science
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• v.103 no.3
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• pp.510-518
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• 2014

Conflicts between humans and wild boars (Sus scrofa) have increased because of causing crop damage and appearing in downtown. Management to reduce population size has mostly been implemented on pests, but knowledges about ecological values are very rare. Rubbing trees by wild boar was investigated to figure out characteristics and for management ecologically from July to October 2013 in a mixed forest, Geochang, Gyeongnam Province, Korea. Pinus rigida was most frequently founded, and rubbing trees, both conifers and deciduous, were mainly located in 200~600 m above sea level. DBH was no significant difference between rubbing and control trees. The use intensity of conifers was higher than that of deciduous. The coverage of foliage layers and the number of woody plants within a radius of 2.5 m of trees (rubbing and control) were also investigated and compared to determine ecological characteristics. There were 1,332 individuals founded from 25 families. In the coverage of foliage layers, the understory and midstory showed statistically significant, but not in the subover and overstory. The number of Shrubs and saplings are higher in rubbing trees than those of control, but no difference in stems. Total individuals, the number of species, species diversity index(H') within a radius 2.5 m is considerably higher in rubbing trees with high intensity than those of low intensity and control. Our results show that wild boar mainly selected and used conifers more frequently as rubbing trees. Wild boar also modified the physical environments around rubbing trees. Consequently, the positive effects such as species diversity is increase. Thus the conservation policies is required after the intensive population reduction every 3-4 years for forest ecological management rather than annual sustainable hunting.

• Journal of Ecology and Environment
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• v.43 no.3
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• pp.320-331
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• 2019

Background: Dioecious plant species having both male and female plants have been investigated regarding sex-related characteristics such as sex ratio, sex-differential resource requirements, and spatial segregation of the sexes. Habitat loss and fragmentation are major threats to the survival of plant populations, but dioecious species are particularly more prone to such habitat degradation than non-dioecious species because of their dimorphic sexual system. We examined the sex-related demographics of two Ilex cornuta populations being different regarding land use history. Methods: During 2016-2017, we examined I. cornuta trees with a basal diameter ${\geq}1.5cm$ in the Yongsu-ri population (YS population) and the Gotjawal Provincial Park population (GP population). Plant sex (male, female, or unsexed) was identified. The tree size (basal diameter and height of the main stem), clonal production (the ramet numbers per genet), and vitality for each clone were measured. The associations between population, sex, tree size, clonal production, and vitality were examined using ANOVAs and contingency table analyses. Finally, point pattern analyses using O-ring statistics were conducted to assess spatial patterns. Results: Upon excluding unsexed trees, the YS population with 74 trees was significantly male-biased (0.66), while the GP population with only 26 trees had a 1:1 sex ratio. In both populations, males and females did not differ in tree size. Although the mean number of ramets differed significantly between populations, females tended to produce more ramets than males. The proportion of weak trees was significantly higher in the YS than in the GP population. Neither population showed evidence of spatial segregation of the sexes. Conclusions: The two populations of dioecious I. cornuta are characterized by the small number of trees and relatively high frequencies of non-reproductive trees. Both indicate that these populations are quite susceptible to environmental and genetic stochasticity. On the other hand, the differences between populations in sex ratio, clonal production, and vitality suggest that conservation efforts for I. cornuta need to be population-specific. In order to help recover and enable this vulnerable species to persist, it is necessary to find ways to enhance their sexual reproduction and simultaneously reduce habitat disturbances due to anthropogenic activities.

• Bulletin of the Korean Mathematical Society
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• v.44 no.2
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• pp.259-263
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• 2007

Which spheres are shellable?[2]. We present one of them which is the k-tree with n-labeled vertices. We found that the number of ways to shell the k-dimensional trees on n-labeled vertices is $$\frac{n!}{(k+1)!}(nk-k^2-k+1)!k$$.

• Journal of Forest and Environmental Science
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• v.35 no.1
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• pp.1-5
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• 2019

Species diversity is one of the most important indices that used to evaluate the sustainability of forest communities. In the present study, three variables including number of individuals (frequency of species), basal area and volume of tree species were compared to estimate tree species diversity in broadleaves forests of Iran. Based on systematic random design, 30 plots (circle plot, $1000m^2$) was selected. Type of species, number of species, DBH and height of trees were measured. Simpson (1-D), Hill ($N_2$), Shannon-Wiener (H'), Mc Arthur ($N_1$), Smith-Wilson ($E_{var}$) and Margalef ($R_1$) indices used to estimate tree species diversity. Species diversity was calculated in each plot. ANOVA test showed that there was a significant difference between of three variables used for estimation of species diversity. Number of trees variable has more precision than basal area and volume variables to estimate of species diversity. But Duncan test revealed that there were significant difference between of basal area and volume variables with number of trees. Therefore, basal area and volume variables were selected as more suitable variables in order to estimate of biodiversity indices in northern forests of Iran.

• Journal of Sericultural and Entomological Science
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• no.12
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• pp.13-16
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• 1970

The studies were intended to clarify the correlations between the characters and the influences upon yield of mulberry trees. The analysis of covariance was used to obtain the genotypic correlations and phenotypic correlations among the eight characters namely branch length, node number, branch diameter, branch number per stock, total branch weight, old branch weight, new shoot and leaf weight, etc., and path-coefficients were calculated by Dewey's method (5). The results obtained are summarized as follows： 1. Genotypic correlations were slightly higher than the corresponding phenotypic correlations between tile characters as shown in Table 1. It could be indicated that hight leaf yield was genetically correlated with almost all characters studied except branch diameter. 2. Leaf yield of mulberry trees was mainly associated with the characters such as node number per branch, total branch weight and old branch weight, etc. 3. Branch length, branch diameter, branch number per stock and new shoot weight had little direct influence upon yield but it had rather considerable indirect in fluence upon yield by increasing the node number and total branch weight per stock. As a result, it can be concluded that total branch weight is primarily determined by branch number per stock and old branch weight, and in turn the leaf yield of mulberry trees is secondary determined by the node number by increasing the branch diameter and length which are positively correlated with branch number per stock and new shoot weight of mulberry trees.