30권 4호
초록
Abstract
We conducted research to determine the effects of forest tending works (FTW) on forest carbon(C) storage in Korean red pine forests by estimating changes in the quantity and distribution of stored organic C in an approximately 40-year-old red pine stand after FTW. We measured organic C storage (above- and belowground biomass C, forest floor C, and soil C at 50 cm depth) in the Hwangmaesan Soopkakkugi model trees/ha to 367 trees/ha. The total C stored in tree biomass was 69.5 Mg C/ha before FTW and 38.6 Mg C/ha after FTW. The change in total C storage in tree biomass primarily resulted from the loss of 19.9 Mg C/ha stored in stem biomass after FTW. The total C pool in this red pine stand was 276 Mg C/ha before FTW and 245.1 Mg C/ha after FTW. Prior to FTW, 71.5% of the total C pool was stored in mineral soil, 25.2% in tree biomass, and 3.3% in the forest floor, where as after FTW 80.5% of the total C pool was stored in mineral soil, 15.7% in tree biomass and 3.7% in the forest flor. These results suggest that the development of site-specific tending techniques may be required to minimize the loss of tree biomass C storage capacity in red pine stands from FTW.
초록
Abstract
We monitored a breeding population of the Asian toad (Bufo gargarizans), in the Wonheunge pond at Sannamdong, Chungju, from 5 March to 11 April, 2006 and 14 February to 31 March, 2007 to investigate their movement patterns, breeding population sizes, and physical characteristics. Terrestrial migration to the pond started on 5 March in 2006 and 14 February in 2007. We captured a total of 266 immigrating individuals (213 males, 53 females) in 2006 and 307 (222 males, 85 females) in 2007, and found 50 adults apparently killed by motor vehicles while migrating to the pond in 2007. Emigration from the pond to terrestrial sites started on 15 March 2006 and 5 March 2007. We captured a total of 245 emigrating toads (181 males, 65 females) in 2006 and 99 (92 males, 7 females) in 2007. An additional 10 emigrating adults were found dead on the road. During both the immigration and emigration periods, two peaks in capture frequency appeared for each sex in each breeding season. The immigration peaks corresponded with higher temperatures, while the emigration peaks corresponded with high humidity. Migrating Asian toads showed sexual size dimorphism and a malebiased sex ratio. Body weights and SVL (snout-vent length) of immigrating and emigrating individuals were negatively related with migration dates.
초록
Abstract
This study examined the distribution, population and vegetation structure of Corylopsis coreana in South Korea. C. coreana is distributed around the Suncheon area, Jeollanam-do, on the southern part of the Korean Peninsula, but the species is also found in Pocheon and Gangneung, on the central and central east parts of the peninsula. This discontinuous pattern of distribution is coupled with the unusual feature of only growing on northern exposed slopes. The mean density of C. coreana populations is 35 individuals per 100 m2, ranging up to a maximum of 92 individuals per 100 m2. Cut specimens sprouted a maximum of 38 stems per plant. Based on DCA analysis, the species' habitats was divided into three types by species composition and stratification structure. These types include: habitats affected strongly by human activities, valley and mantle communities which are affected relatively little by human activities, and stable forests. Populations affected by artificial intervention have actually flourished, while some populations in the stable forest system have declined. We conclude that the species, now endangered, should be maintained by means of specific external interventions such as cutting or removal of the canopy. To this end, further ecological data should be collected through monitoring and research to identify appropriate interventions to support threatened C. coreana populations
초록
Abstract
(superoxide dismutase, catalase and peroxidase) activity in leaves and roots of rice (Oryza sativa L.) plants ex-posed to high salinity. Under salt stress, the reduction in RWC (relative water content) in leaves was relatively severe in comparison with that of roots. The proline content was also significantly higher in leaves of rice plants following salt treatment. The activities of CAT and POX in roots increased with increasing NaCl concentration, but the activity of SOD decreased. These results suggest that the increase of endogenous proline is closely associated with the increase of CAT and POX activities, which may play important roles in salt tolerance. Therefore, we conclude that the alleviation of oxidative damage and increased resistance to salinity may result from the presence of efficient antioxidative systems.
초록
Abstract
Cooperative or non-territorial permanently social spiders are believed to have evolved from speciesshowing subsocial maternal care. The transition from subsocial to cooperative social groups probably involved a transition from an outbreeding breeding system to one with inbreeding. Nepotistic recognition among siblings should facilitate the evolution of social cooperation through avoidance of inbreeding and maintenance of mutual tolerance between siblings. We conducted experiments to determine whether a mechanism for sibling recognition is present in the subsocial spider, Clotes terrestrisprovisioning. The numbers of surviving individuals within unfed groups were observed and compared between non-sibling groups of ten spiderlings and groups of ten siblings. The number of survivors differed significantly between groups, with consistently fewer spiderlings surviving in the non-sibling groups than the sibling groups over the study period. This result suggests that sibling recognition and nepotism do occur in this subsocial species. The nepotism involved in the maternal social organization of the Clotes might be an example of a preadaptation facilitating the evolution of permanent social life.
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Abstract
To investigate the impacts of transgenic rice on freshwater organisms, we conducted two life table experiments using Daphnia magna for fifteen and twenty days, respectively. We examined life history traits such as population growth rates (r), reproductive rates (R0), generation times, and survivorship. In the first experiment, we used non-drought-stressed transgenic and non-transgenic rice harvested in 2005. In the second study, we used non-transgenic and transgenic rice harvested in 2006 following drought stress. Each experiment involved three treatments in which D. magna neonates were fed with Selenastrum capricornutum (control treatment) and S. capricornutum with 5% aqueous extracts of non-transgenic rice (N-T) and transgenic rice (T). In the first experiment, D. magna showed reduced population growth rates and lowered fecundity in the N-T and T treatments. In the second experiment, D. magna receiving both transgenic and non-transgenic rice extracts showed very high mortality, low population growth rates and reproduction rates. We could not detect any significant negative effects of extracts from transgenic rice on D. magna life history traits at 95%.
초록
Abstract
Recognizing the ecological importance of forest gap formation for forest community structure, we examined the differences in species diversity between forest gaps and closed canopy areas for trees and shrubs in three developmental stages (seedling, saplingⅠ, and saplingⅡ) in a typical mixed broadleaved-Korean pine forest. We randomly placed 100 sample plots (2×2 m for seedling and saplingⅠ, and 5×5 m for saplingⅡ) in forest gap and closed canopy areas of a 9 ha permanent sample plot for vegetation surveys of plants of each developmental stage in each habitat type. Even though the formation of forest gaps encouraged the occurrence of gap-dependent species and increased overall species diversity, there were no significant differences in species richness among the three developmental stages for both tree and shrub species (p>0.05). Comparing the two types of sites, statistical tests revealed no difference in species richness for trees, but highly significant differences (p<0.01) between forest types for shrubs for seedlings and saplingⅠ, but not saplingⅡ. Analysis of variance test indicated that there were no significant differences in species diversity among the three developmental stages of tree species (p>0.05) for both Simpson and Shannon indices. The variance for shrub seedlings was significantly different between forest gaps and closed canopy areas, but not for saplingⅠ and saplingⅡ. The analysis showed that the species diversity in forest gaps was significantly different from that of closed canopy areas for seedling and saplingⅠ (p<0.01), but not for saplingⅡ (p>0.05).
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Abstract
We examined the evolutionary and ecological pr ocesses shaping current geographical distributionsof a Korean wood-eating cockroach species, Cryptocercus kyebangensis. Our research aims were to understand evolutionary pattern of DNA sequences, to construct genetic network of Cryptocercus kyebangensis local popu-lations and to understand evolutionary and ecological processes shaping their current geographical distribution patterns via DNA sequence information and genetic networks, using sequence data of two genes (ITS-2 and AT region) from local populations of C. kyebangensisappropriate molecular markers for elucidating C. kyebangensis geographic patterns at the population level. The MSN-A based on the ITS-2 showed two possible routes, the Hwak-san and Myeongji-san route and the Seorak- san and Gyebang-san route, for migration of ancestral C. kyebangensis into South Korea. The MSNs (MSN-A and -B) elucidate migration routes well within South Korea, especially the route of Group Ⅰ and Group Ⅱ.
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Abstract
Nest density was determined and tree and soil characteristics around Nycticorax nycticorax breeding sites and non-breeding sites on Bamsum Island in Seoul were analyzed from May 2005 to October 2006 to identify breeding site preferences of N. nycticorax and the effects of N. nycticorax nesting density on nesting tree structure and soil characteristics. N. nycticorax preferred trees of low height (3.5～6 m) and small diameter at breast height in high density Salix communities. Excrement of heron juveniles was dropped on the soil under the nests. The soil nutrient content under nests (P: 126.0 mg/kg, N: 202.8 mg/kg, EC: 549 μS/cm, pH 4.7) was much higher than that of control soils from Bamsum Island not enriched by heron excrement (P: 41.5 mg/kg, N: 42.0 mg/kg, EC: 342 μS/cm, pH 5.1). Formation of Salix communities on the shores of Bamsum Island is ongoing, and their structure has been directly influenced by annual flooding. After flooding, the nutrient content differences between heron-affected soils and control soils were not significant. This might be the reason that Salix communities on Bamsum were not affected by nesting herons as in other terrestrial communities where herons nest. This result indicates that flooding plays an important role in sustaining Salix communities on Bamsum Island where herons nest. The results of this study may increase understanding of N. nycticorax breeding behavior which may be useful for conservation planning.
초록
Abstract
The structure and dynamics of Korean red pine stands established in the riparian zone werestudied in the Tsang stream in Mt. Seorak National Park, in east-central Korea. Pine stands were classified into four successional stages, the initial, establishing, competitive, and stabilizing stages, based on the age distri-bution of a dominant tree, Pinus densiflora, the vegetation stratification, and the microtopography of the riverine environment. The stages usually corresponded to disturbance frequencies, depending on the horizontal and vertical distances from the watercourse. Stands of the initial and establishing stages lacked tree or subtree layers, or both. As stands progressed through the developmental stages, soil particle size became finer and species ordination differentiated species specializing in relatively dry and wet habitats. The results of the analysis of vegetation dynamics provided ecological information which will be useful for understanding the developmental processes of vegetation established in riparian zones. Species diversity indices usually increased acros develop-mental stages, following the typical pattern for sucesional proceses. We discus the importance and necesity of riparian vegetation in Korea, where most riparian forests have disappeared due to excessive human land use.
초록
Abstract
To determine the feeding sites preferred by adult gold-spotted pond frogs, Rana plancyi chosenica, and the foods that induce favorable growth of the frogs in the laboratory, we conducted two separate experiments between 27 May and 12 July 2007 in a vivarium. In the first experiment, we counted the number of crickets eaten by four gold-spotted pond frogs in a 60 min period at four different feeding sites within the experimental arenas: on the water surface, at the edge of a pond, and at two terrestrial sites. Adult gold-spotted pond frogs ate more crickets on the water surface and at the edge of the pond than the terrestrial sites. In the second experiment, we measured the growth of SVL (snout-vent length) and body mass of adult gold-spotted pond frogs fed crickets, mealworms, maggots, or earthworms in individual experimental boxes over a one month period. The SVL and body mass of the adult gold-spotted pond frogs fed crickets, mealworms, or maggots were greater than those of the frogs that were fed earthworms. These results indicate that providing crickets, mealworms, or maggots on the water or at the edge of a pond should induce favorable growth of captive-reared adult goldspotted pond frogs.