• The Korean Journal of Ecology
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• v.19 no.1
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• pp.71-80
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• 1996

The effects of simulated acid rain on the growth and interspecific competition of Echinochloa crus-galli and Digitaria sanguinalis were studied. Changes of growth in height and dry weight were examined and competition between the two species was investigated using the experimental model proposed by de Wit (1960). The experiments were carried out in the greenhouse, and test plants were germinated and grown for 4 weeks and then sprayed with simulated acid rain of pH 5.6, 4.2 and 2.8 for another 8 weeks. In de Wit replacement experiments, the variation of density and the treatment of simulated acid rain showed little effect on the interspecific competition between E. Crus-galli and D.sanguinalis. The ratio diagram, another method to reveal the interrelations between two competing species, always showed the predominance of E. crus-galli in competition, regardless of density and pH. The interspecific competition of the two species, represented by relative yield total (RYT), revealed that intraspecific competition was stronger than interspecific competition in both species.The treatment of simulated acid rain showed little effect on the growth of E. Crus-galli and D. sanguinalis. Height growth of both species did not differ from that of control (pH 5.6), but root/shoot ratio increased with the decrease in pH of simulated acid rain. Growth of tatal dry weight of E. crus-galli and D. sanguinalis was not influenced by the change of pH, except that D.sanguinalis showed a decrease in the total dry weight at pH 2.8 along with a visible sign of white spots on leaves. Physical environmental conditions can exert an effect on the interrelationships between the two species, but this experiment did not show the reversion of competition, and showed that E.crus-gilli was competitively dominant under any environmental conditions given in this study.

• Journal of The Korean Society of Grassland and Forage Science
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• v.15 no.4
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• pp.279-284
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• 1995

The competition relationship between orchardgrass(Docflis glomerutu L. cv; Potomac) and red clover (Trifnlium prurense L. cv; Kenland) was investigated under the pure and mixed swards. Each species were grown in intra- and interspecific competition in pots and fields for 2-years. Intra- and interspecific competition were evaluated by calculating traditional methods; expected yield, relative yield total(RYT), aggressivity and compensation index(CI), and shoot and root dry matter production in the orchadgrass(ffi) pure, red clover(RC) pure and orchardgrdss(W)-red clover(RC) mixed sward. The results obtained were summarized as follows: Compared to OG and RC pure swards, the shoot and root dry maaer(DM) yield of OG-RC mixed sward were higher and more deeply rooted under the soil than those of OG and RC pure sward. Also, the number of tillen per plant of OG in the OG-RC mixed sward was less than that of OG pure sward, but that of RC in the OGRC mixed sward was more than that of RC pure sward. OG-RC mixed sward were evaluated as a productive sward type compared to OG and RC pure swards in that actual yield was higher than expect yield and that relative yield total(RYT), and compensation index(C1) were high. As mentioned above, compared to intraspecific competition as a OG and RC pure sward, interspecific competition as a OG-RC mixed sward was evaluated to productive type under the ffi and RC species utilization

• Proceedings of the Zoological Society Korea Conference
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• 1998.10b
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• pp.105-105
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• 1998

No Abstract, See Full Text

• Proceedings of the National Institute of Ecology of the Republic of Korea
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• v.2 no.4
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• pp.219-228
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• 2021

During our observations of changes in halophyte distribution in Hampyeong Bay over a period of five years, we found that the distribution area showed a maintenance for Phragmites communis community, a tendency of gradual increase for Zoysia sinica community, gradual decrease for Suaeda maritima community, and disappearance for Limonium tetragonum community during the studied period. The Phragmites communis community stably settled in areas adjacent to land and appeared not to be significantly affected by physical factors (such as tides and waves) or disturbances caused by biological factors (such as interspecific competition). Among studied species, germination time was shown to be the fastest for Suaeda maritima. In addition, this species showed certain characteristics that allowed it to settle primarily in new habitats formed by sand deposition as its growth was not halted under conditions with high amounts of sand and high organic matter content. However, in areas where Zoysia sinica and Suaeda maritima resided together, the area inhabited by Suaeda maritima gradually decreased due to interspecific competition between the two species. This was believed to be the result of a sharp decrease in the germination of Suaeda maritima since May, while the germination of Zoysia sinica was continuously maintained, indicating that the latter had an advantage in terms of seedling competition. In the case of the Limonium tetragonum community, its habitat was found to have been completely destroyed because it was covered by sand. The study area was confirmed to have undergone a large change in topography as tides and waves resulted in sand deposition onto these lands. Hampyeong Bay is considered to have experienced changes in halophyte distribution related to certain complex factors, such as changes in physical habitats and changes in biological factors such as interspecific competition.

• The Korean Journal of Ecology
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• v.24 no.4
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• pp.213-217
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• 2001

The purpose of this study is to investigate the effects of hardwood competitions in stand structure and dynamics by applying prediction models for unthinned loblolly pine (Pinus taeda L.) plantations. A parameter recovery procedure for the Weibull distribution function based on four percentile equations was applied to develop diameter distribution prediction models. Four percentiles of the cumulative diameter distribution prediction equations were predicted as a function of quadratic mean diameter plus competin hardwood trees perhectare varibales. According to the results of this study. it was found that as the amount of competing hardwood trees increased, diameter distributions in terms of stand structure dynamics tended to be more skewed to the right. Therefore, the influence of non-planted hardwood trees interspecific competitoin on planted loblolly pines showed negative effects on the stand structure and dynamics.

• Journal of Korean Society of Forest Science
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• v.89 no.1
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• pp.49-54
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• 2000

Stand level survival prediction model was developed that incorporated the incidence of fusiform rust(Cronartium quercuum [Berk.] Miyabe ex Shirai f. sp. fusiforme) and allowed the transition of trees from an uninfected stage to an infected stage. The influence of hardwood interspecific competition on the survival of unthinned planted stands of loblolly pine (Pinus taeda L.) was analyzed by using of information from twelve years of tracking a set of permanent plots representing a broad range of plantation parameters. Significant interaction effects between site index and hardwood basal area per acre were revealed in the survival model. Survival of the planted pines decreased with increasing density of hardwood trees per acre and site index as the productivity rating of the forest land. The effects of hardwood trees interspecific competition on loblolly pine tended to show a negative effect on predicted future number of planted pine trees.

• International Journal of Industrial Entomology and Biomaterials
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• v.18 no.1
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• pp.41-48
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• 2009

The large bumblebee, Bombus terrestris, indigenous to Europe and used extensively for high-value crop pollination, has been artificially introduced in several parts of the world. Here we show the interspecific hybridization between bumblebee species, B. terrestris and B. ignitus, under laboratory conditions. The mating and oviposition percentages of the interspecific hybridization of a B. terrestris queen with a B. ignitus male were higher than those of the intraspecific mating of B. ignitus. Furthermore, the competitive copulation experiment indicated that the mating of B. ignitus males with B. terrestris queens was 1.8-fold more frequent than with B. ignitus queens. The interspecific hybridization of a B. ignitus queen with a B. terrestris male produced either B. ignitus workers or the B. ignitus male phenotype, and the hybridization of a B. terrestris queen with a B. ignitus male produced B. terrestris males. Genetic tests using a portion of the mitochondrial COI gene for the parent and hybrid phenotypes indicated that mitochondrial DNA in the interspecific hybridization was maternally inherited. Our results indicated that interspecific hybridization occurred between B. ignitus and B. terrestris, which suggests that the hybridization will have a negative impact of competition and genetic pollution of native bumblebees.

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

• Korean Journal of Weed Science
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• v.10 no.2
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• pp.93-98
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• 1990

Interspecific competition between E. colona and rice was determined over four growth stages in replacement series. No competition between the two species as measured by plant height, leaf area and dry weight occurred by 30 days after seeding (DAS) at all the density combinations studied. At 45 DAS reductions in leaf area and dry weight of E. colons due to the competition occurred at the density combinations where number of competing E. colons plant was less than that of rice. However, there was a great increase in leaf area and dry weight of E. colons at the density combination of one E. colons competing with four rice plants at 60 DAS. As the number of E. colons plants increased, the leaf area and dry weight of E. colona decreased resulting from intraspecific competition between E. colons plants. Although rice absorbed more nitrogen than E. colons up to 30 DAS, the reverse was observed from 45 DAS. A relatively small amount of phosphorous was absorbed by both rice and E. colons, but the amount of phosphorous taken up by E. colons was greater than that taken up by rice. E. colons absorbed extremely high amount of potassium when compared to rice.

• Korean Journal of Environment and Ecology
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• v.29 no.5
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• pp.681-692
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• 2015

It is well documented that physiological and nutritional condition of wintering birds is strongly related to migration success to breeding sites, and also breeding success. However, how abiotic factors during winter affect the migration and breeding successes still remains unclear. Thus, this study developed a dynamic-state-dependent model for wintering life-history to identify the potential impact on the life-history, success to breeding site and breeding success of wintering birds, which are related to temperature fluctuation, interspecific competition and human disturbance at the wintering sites. To find the best-fit-model, we referred to the existing research data on wintering ecology of Red-crowned cranes (Grus japonensis) in Cheolwon, Korea, which is well documented as a long-term wintering study. Our model predicted that the higher temperature fluctuation and a higher rate of human disturbance are negatively related to migration success to breeding sites and their fitness, ultimately breeding success via changing of proportion in resource allocation (for e. g., lower energy compensation or higher level of stress accumulation). Particularly, the rate of body mass compensation after arrival at wintering sites may be accelerated when there are less temperature fluctuations and a lower rate of human disturbance. In addition, the rate of interspecific competition sharing the wintering foraging sites is negatively related to the rate of body mass compensation. Consequently, we discussed the conservation strategies of wintering birds based on the outcomes of the model.