• Korean journal of applied entomology
• /
• v.32 no.2
• /
• pp.134-138
• /
• 1993

Larval densities and spatial distribution patterns of beet armyWorm, Spodoptera exigua, were studied in the welsh onion field located in Asan from June to November, 1991. During the period, there were two denslty-peaks;mid August and mid~late September. The larvae showed clumped distribution patterns. but the patterns changed into random as larval density decreased in Oct.ober. Each larval instar showed clumped pattern expect 6th instar surveyed on September 25, which distributed in a random pattern. The larval distribution pattern were also influenced by the host plants;clumped pattern on such host. as red pepper and welsh onion, versus random pattern on such hosts as chrysanthemum, peanut and soybean.

• Journal of Korean Society of Forest Science
• /
• v.99 no.5
• /
• pp.720-725
• /
• 2010

On the basis of vegetation data in the 9.12 ha (380 m ${\times}$ 240 m) permanent sample plot of the spruce-fir valley forest in Liangshui National Reserve of Xiaoxing'an Mountains, the study was conducted to evaluate spatial distribution pattern and spatial association by using point pattern analysis for living and dead trees of Larix gmelini by DBH size class. The number of L. gmelini were counted as 59 living stems/ha (6.42 $m^2$/ha of basal area) and 34 dead stems/ha (2.86 $m^2$/ha of basal area). The distributional curve of diameter class exhibited bimodal shape. The analysis of spatial distribution patterns of all living larch stems noted the clumped distribution on the whole. The size of larch aggregates of dead stems was decreased as diameter class was increased. The distribution of dead stems became gradually randomized with decreased clumped size as the scale increased. Living stems and dead stems of the larch had positive spatial association at most of scales, illustrating that the occurrence of mortality of the larch tree was closely related to the distribution pattern of living larch trees.

• Journal of Ecology and Environment
• /
• v.33 no.1
• /
• pp.67-77
• /
• 2010

Stand structure and spatial associations of the dominant tree species in Quercus mongolica stands were investigated to understand interspecific relationships and the persistent dominance of Q. mongolica. We examined the species composition, DBH (diameter at breast height) distribution, and spatial distribution of trees (${\geq}\;2.5\;cm$ DBH) in two permanent $100\;m\;{\times}\;100\;m$ plots in Q. mongolica-dominant stands on the western part of Mt. Jiri. Ripley's K-function was used to characterize the spatial patterns and associations of dominant tree species. Q. mongolica showed a continuous and reverse-J shaped DBH distribution with clumped spatial distribution in both study sites. Q. mongolica and Abies koreana exhibited a negative association implying potential interspecific competition. The positive spatial association between Q. mongolica and Alnus hirsuta var. sibirica and Fraxinus sieboldiana were affected by site characteristics: limited habitat conditions with a large proportion of rock surface. Our results suggest that interactions among species were complex and ranged from positive to negative. Differences in stand and site characteristics and regeneration mechanisms among the species play an important role in regulating their spatial distribution patterns, while competition between individuals also contributes to spatial patterning of these communities. The high density and the early developmental stage of spatial distribution and structural characteristics of Q. mongolica and the relatively low importance values of other species in the stands imply that Q. mongolica will remain dominant in the study sites in the near future.

• Journal of Ecology and Environment
• /
• v.37 no.2
• /
• pp.81-90
• /
• 2014

This study examined the main factors affecting the distribution of Phytolacca americana, an exotic plant species in Korea, in coastal sand dunes. The areas examined from June 2004 to February 2006 were in Sindusagu where was located on Sindu-ri, Wonbuk-myen, Taean-gun, Chungcheongnam-do. The vegetation, sediment properties, sizes and ages of Robinia pseudoacacia, P. americana and Pinus thnunbergii and spatial distribution of P. americana were assessed. Firstly, correlation coefficients (CC) between P. americana's root biomass and sediment properties were not significant. Secondly, of the four community types, P. americana was not in the mixed herbaceous community and its density was the highest in the P. thunbergii-R. pseudoacacia and R. pseudoacacia community The Poisson distribution analysis revealed the distribution of P. americana to be severely clumped. The root biomass of P. americana and the basal area of R. pseudoacacia were significantly correlated, but the CCs between P. thunbergii and other two species were not significant. The ages of P. americana and R. pseudoacacia in a quadrat were significantly correlated. Thirdly, P. americana's ages in a quadrat were mostly similar to each other. Therefore, the spatial distribution of P. americana was largely influenced by R. pseudoacacia but not by the sediment properties, and plants in a narrow area were concurrently germinated.

• Journal of Korean Society of Forest Science
• /
• v.98 no.2
• /
• pp.189-196
• /
• 2009

This study was conducted to evaluate spatial distribution pattern and spatial association of crowns (${\geq}10m$ of height) and saplings (<10 m of height and ${\geq}2cm$ of DBH) for four major tree species (Pinus koraiensis, Abies nephrolepis, Acer mono, and Tilia amurensis) in the mixed broadleaved-Korean pine forest of Xiaoxing'an Mts. Vegetation data were collected in the 9 ha permanent sample plot, and the analysis adopted the point pattern analysis method. Main results are as follows; 1) crowns and saplings of major species showed clumped distribution pattern in small scale, became random distribution as the scale was increased. 2) Saplings of Pinus koraiensis performed poor regeneration under the crowns of Pinus koraiensis and Abies nephrolepis; Saplings of Abies nephrolepis did good regeneration under the crowns of Pinus koraiensis and Abies nephrolepis; and crowns of Acer mono and Tilia amurensis had little effect on the distribution of saplings of Pinus koraiensis and Abies nephrolepis. Saplings of Acer mono and Tilia amurensis made good regeneration under the crowns of Pinus koraiensis and Tilia amurensis; and the crowns of Acer mono and Abies nephrolepis had little effect on the distribution of saplings of Acer mono.

• Korean journal of applied entomology
• /
• v.32 no.1
• /
• pp.61-67
• /
• 1993

Experiments were conducted to study the functional response of Amblyseius longispinosus Evans to egg densities (10-80) of Tetranychus urtica Koch under different egg distributions (clumped & uniform) and arena sizes (3, 9 & 16 $cm^2$). The searching success of A. longispinosus was affected by the spatial distribution and density of the prey but not by the arena size. there was a highly significant negative correlation (r=-0.85; p=0.0001) between predation amount and distances between preys. The predation response showed a type III functional response. The random predator equation satisfactorily described A. longispinosus predation. The search rate ranged from 0.1030 to 0.1504 under distribution of the prey while it ranged from 0.0546 to 0.276 under uniform distribution.

• Korean Journal of Ecology and Environment
• /
• v.37 no.3 s.108
• /
• pp.297-303
• /
• 2004

Two dimensional cellular automaton (CA) models were developed to investigate growth of biofilms in aquatic ecosystems. Simple local rules on CA were applied to governing growth of bacterial populations in relation to different nutrient concentrations. Initial bacterial distribution played an important role in determining population size and morphology of biofilm at low concentrations of nutrition. With clumped distribution, population size increased slowly compared with uniform and random distributions, while the porosity tented to be higher with uniform distribution compared with other initial distributions.

• Korean journal of applied entomology
• /
• v.33 no.1
• /
• pp.6-11
• /
• 1994

The Spatial distribution pattems of the oriental tobacco budworm (OTB), Helicoverpa assuita, eggs w were studied in red pepper and tobacco fields. With a plant as a sample Unit. Taylor's power law analyses indicated that om egg spatial patterns were clumped in red pepper fields (a=1.3914, b = 1.1648) and were unifom in tobacco fields (a = 1.6035, b = 0.6880). In red peppers om eggs w were found in leaves (76.2%), fruits (16.8%), stems (6.5%), and flowers (0.4%). The upper leaf surface ( (70.1 %) contained sianificantly more eggs than the lower surface (25.2%). In tobaccos most eggs were also found in leaves. However, the lower surface (66.3%) contained significantly more eggs t th

• The Bulletin of The Korean Astronomical Society
• /
• v.43 no.2
• /
• pp.47.1-47.1
• /
• 2018

Solar cycles are inherent to the Sun, which experiences temporal changes in its magnetic activity via the surface distribution of the solar magnetic field. This raises a fundamental question of how to derive the distribution characteristics of a solar-surface magnetic field that are responsible for individual solar cycles. We present a new approach to deriving as long-term and large-scale distribution characteristics of this quantity as was ever obtained; that is, we conducted a population ecological analysis of Wilcox Solar Observatory (WSO) Synoptic Charts which provide a more than 40-year time series of latitude-longitude maps of solar-surface magnetic fields. In this approach, solar-surface magnetic fields are assumed as hypothetical trees with magnetic polarities (magnetic trees) distributed on the Sun. Accordingly, we identified a peculiarity of cycle 23 with a longer period than an average period of 11 years; specifically we found that the negative surface magnetic field had much more clumped distributions than the positive surface magnetic field during the first one-third of this cycle, while the latter was dominant over the former. The Sun eventually spent more than one-third of cycle 23 recovering from these imbalances.

• Journal of Apiculture
• /
• v.32 no.3
• /
• pp.163-170
• /
• 2017

Small hive beetle (SHB, Aethina tumida Murray (Coleoptera: Nitidulidae) is a honeybee pest infesting combs and stores inside the hive. Contamination of the SHB on Apis mellifera colonies were firstly noticed on September 23, 2016, in Miryang City, Gyeongnam Province in Korea. After that, on October 5, 2016, we investigated the spatial distribution of SHB inside the hive and outside soil within the apiary. Total of 169 beehives were observed. We found all stages of SHB inside or outside of hives. 61% of hives infested with the adult SHB still had live honeybees whereas hives containing larval SHB did not have bees, implying colony destruction In hives with live bees, infestation density was higher as bee population became higher. Coefficient of dispersions (CD) showed significant clumped distribution of infestation among hives. CDs were much higher inside hive than outside soil. Our results indicates SHB could result in honeybee colony collapse it not managed properly. Also even during October, there are new infestation into honeybee colonies and every stage of SHB could still be able to develop. Further detailed analysis of this insect' adaptation in Koran environment could help guide the management strategies of the invaded new pest of honeybee.