• The Korean Journal of Ecology
• /
• v.26 no.3
• /
• pp.143-150
• /
• 2003

Korea has plentiful precipitation but rainfall events concentrate on several months of rainy season in her weather condition. Korea, therefore, experiences drought for a given period every year. Moreover the soil has usually low water holding capacity, as it is composed coarse particles originated from the granite. Response of several oaks and the Korean red pine (Pinus densiflora) on water stress showed that water budget was significant factor determining vegetation distribution. In addition, dehydration level due to cold resistance mechanism of several evergreen plants during the winter season was closely related to their distribution in natural condition. Experimental result under water stress showed that the Korean red pine was very tolerant to desiccation but the seedlings showed high mortality during the dry season. The mortality tended to proportionate to soil moisture content of each site. A comparison between soil moisture content during June when it is severe dry season and moisture content of the culture soil when the pine seedlings reached the permanent wilting point due to water withheld proved that high mortality during the dry season was due to water deficit. Water potential of sample plants measured during the exposure experiment to the air pollutant showed a probability that water related factors would dominate the occurrence of visible damage and the tolerance level of sample plants. In both field survey and laboratory experiment, plants exposed to air pollution showed more rapid transpiration than those grown in the unpolluted condition. The result would due to injury of leaf surface by air pollutants. Aluminum (Al/sup 3+/) increased in the acid soil not only inhibits root growth but also leads to abnormal distribution of root system and thereby caused water stress. The water stresses due to air pollution and soil acidification showed a possibility that they play dominating roles in inducing forest decline additionally to the existing water deficit due to weather and soil conditions in Korea. Sludge, which can contribute to improve field capacity, as it is almost composed of organic matter, showed an effect ameliorating the retarded growth of plant in the acidified soil. The effect was not less than that of dolomite known in widely as such a soil ameliorator. Litter extract contributed also to mitigate the water stress due to toxic Al/sup 3+/. We prepared a model showing the potential interaction of multiple stresses, which can cause forest decline in Korea by synthesizing those results. Furthermore, we suggested restoration plans, which can mitigate such forest decline in terms of soil amelioration and vegetation restoration.

• Korean Journal of Soil Science and Fertilizer
• /
• v.40 no.6
• /
• pp.435-441
• /
• 2007

Ground-based optical sensing over the crop canopy provides information on the mass of plant body which reflects the light, as well as crop nitrogen content which is closely related to the greenness of plant leaves. This method has the merits of being non-destructive real-time based, and thus can be conveniently used for decision making on application of nitrogen fertilizers for crops standing in fields. In the present study relationships among leaf nitrogen content of rice canopy, crop growth status, and Normalized Difference Vegetation Index (NDVI) values were investigated. We measured Green normalized difference vegetation index($gNDVI=({\rho}0.80{\mu}m-{\rho}0.55{\mu}m)/({\rho}0.80{\mu}m+{\rho}0.55{\mu}m)$) and NDVI($({\rho}0.80{\mu}m-{\rho}0.68{\mu}m)/({\rho}0.80{\mu}m+{\rho}0.68{\mu}m)$) were measured by using two different active sensors (Greenseeker, NTech Inc. USA). The study was conducted in the years 2005-06 during the rice growing season at the experimental plots of National Institute of Agricultural Science and Technology located at Suwon, Korea. The experiments carried out with randomized complete block design with the application of four levels of nitrogen fertilizers (0, 70, 100, 130kg N/ha) and same amount of phosphorous and potassium content of the fertilizers. gNDVI and rNDVI increased as growth advanced and reached to maximum values at around early August, G(NDVI) were a decrease in values of observed with the crop maturation. gNDVI values and leaf nitrogen content were highly correlated at early July in 2005 and 2006. On the basis of this finding we attempted to estimate the leaf N contents using gNDVI data obtained in 2005 and 2006. The determination coefficients of the linear model by gNDVI in the years 2005 and 2006 were 0.88 and 0.94, respectively. The measured and estimated leaf N contents using gNDVI values showed good agreement ($R^2=0.86^{***}$). Results from this study show that gNDVI values represent a significant positive correlation with leaf N contents and can be used to estimate leaf N before the panicle formation stage. gNDVI appeared to be a very effective parameter to estimate leaf N content the rice canopy.

• Korean Journal of Environment and Ecology
• /
• v.26 no.3
• /
• pp.437-445
• /
• 2012

The study performed the implementation monitoring of the revegetation methods applied to the test-bed of Simgok Stream in Incheon to identify the effect of water level and inundation period on the vegetation coverage of the stream bank revegetation methods. The categories of monitoring included the plant species and plant coverage for each method, physicochemical property of soil, water level and water quality. The result of monitoring revealed that plant growth conditions of all revegetation methods of each stream bank were good in the first survey as of May 2010. However, in the second survey of June 2011 when inundation period was less than a week, plant growth conditions and coverage of revegetation methods were partially bad. In the third survey as of August 2011 when inundation period was longest as 8 weeks during survey period, most vegetations did not survive except for Phragmites communis. But plant species number and plant coverage were increased gradually in the forth survey as of October 2011 when inundation period was less than 2 weeks so water level decreased more than that of third survey. Accordingly, the correlation analysis among number of plant species and plant coverage on stream bank, which applied revegetation method, water level and inundation period was performed for quantitative analysis. The result revealed that number of plant species and plant coverage has a negative correlation with water level and inundation period, but inundation period had higher correlation with plant occurrence than water level.

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.4 no.3
• /
• pp.84-95
• /
• 2001

This study was conducted to suggest the ecological restoration methods for the decomposed granite roadside cutslopes by Natural Topsoil Restoration Methods(NTRM). Four woody species, 3 shrub species, 4 native grasses, 8 wild flowers and 2 cool-season grasses were used. The experiment was conducted with the purpose of developing ecological restoration techniques by achieving following objectives for restoration by using native woody plants, shrubs, native plants and wild flowers; (1) prevention or reduction of wind and water erosion, (2) provision of food and cover for variety of animal species, (3) improvement of the visual or aesthetic quality of disturbed sites. The main results were summarized as follows. 1. Restoring naturalness to human-altered landscapes are important to protecting the worlds biodiversity. In this study, to restore or create an ecological community use as full a complement of native species as possible. Ecological restoration means returning a specific sites to its predisturbance condition. 2. Some species which are introduced first may inhibit the germination and growth of slower-growing species, or they may prevent the growth of other species whose propagules arrive later. In this study, cool season grasses was used small amount than native plants and woody species, because and Indigofera pseudo-tintoria grows well. Tall fescue and perennial ryegrass shows quick germination, but they could not inhibit the other species growing relatively slow. Pinus thunbergii used at Gonam near the ocean was suppressed by the other plants, so it can be concluded that using container seedlings is effective than seeding. 4. Ailanthus altissima, Albizzia julibrissin, Rhus chinensis Lespedeza cyrtobotrya, and Indigofera pseudo-tinctoria were germinated. In wild flowers, Coreopsis lanceolata, Dianthus sinensis, Coreopsis tinctoria, and Lotus corniculatus var. japonicus grew well and show enough plant height which will not suppressed by shrub and woody plants. After one year, native grasses such as Arundinella hirta, Miscanthus sinensis var. purpurascens and Imperata cylindrica var. koenigii cover the slopes well. 5. 25 herbaceous plants such as Trifolium repens, Arthraxon hispidus, Barbarea orthocerae, Potentilla fragarioides, Lepidium apetalum, Chenopodium album var. centrorubrum, Glycine soja, Rubus crataegifolius and 4 woody species such as Lespedeza maximowiczii, Robinia pseudoacacia, Symplocos Chinensis, Quercus acutissma were invaded. 6. Ecological restoration works by Natural Topsoil Restoration Methods for revegetation of the decomposed granite roadside cutslopes were successfully accomplished. It prevents surface water erosion and shows diverse vegetation structure. It will be successful to restore decomposed granite cutslopes.

• Korean Journal of Agricultural and Forest Meteorology
• /
• v.20 no.1
• /
• pp.135-143
• /
• 2018

The effect of elevated temperature on temperate paddy rice will be significant for dependable food supply in East Asia. Using temperature gradient field chamber (TGFC), which was designed to make the horizontal air temperature gradient by $0^{\circ}C$ to $3^{\circ}C$ higher than outside, we examined the measurement to understand the effects of extremely high temperature on paddy rice. In particular, the data of the year 2016, the worst heat wave in over 22 years, was analyzed in this study. The rice height in the relatively warmed condition was rapidly increased during early growth stage. However, the average grain weight and number of spikelet per panicle in the warmed chamber condition were gradually declined with increasing air temperature averaged for 40 days after first heading in each chamber. In particular, the grain yield was more dramatically decreased by the raising temperature because the percent ripened grain was quickly dropped as getting over the threshold temperature for pollination. Therefore, the surplus photosynthetic product by such lower grain filling rate may disturbed the decreases of the NDVI (Normalized Difference Vegetation Index) and SPAD chlorophyll values after first (normal) heading. In addition, the late-emerging head grain were appeared. However, this yield was too small to recover the normal yields decreased by extremely high temperature condition. Our result represented that the warmed condition in 2016 would be the critical limit for the stable yield of temperate paddy rice.

• Korean Journal of Environment and Ecology
• /
• v.30 no.6
• /
• pp.929-938
• /
• 2016

This study reviewed the external morphological characteristics of a rare species, Exochorda serratifolia S.Moore, in South Korea through a comparison of its previous records. Also, a distribution map of this species was made using previous data on flora and voucher specimens. Furthermore, the soil characteristics of Exochorda serratifolia S.Moore was analysed in order to determine the correlation between external morphological features and soil characteristics. At the study sites, soil organic matter, total nitrogen, available phosphates, exchangeable potassium, exchangeable calcium, exchangeable magnesium, cation exchange capacity and soil pH were found to be in the ranges of 3.25-29.83%, 0.15-1.14%, 3.0-156 mg/kg, $0.39-1.49cmol^+/kg$, $2.48-38.07cmol^+/kg$, $0.77-18.29cmol^+/kg$, $7.3-23.0cmol^+/kg$ and 4.6-7.1 respectively. The soil condition surrounding the population of Exochorda serratifolia S.Moore in Mt. Ap-san (Daegu) was found to have higher percentages of organic matter, total nitrogen, and cation exchange capacity than the soil condition of other populations. Moreover, the length of inflorescence and the number of flowers in this population were significantly higher than the populations studied in other areas (P < 0.001). We also identified a significant correlation between genetic, geographic distance and several morphological characteristics. A comprehensive review of various data on Exochorda serratifolia S.Moore such as external morphological characteristics, genetic structure, growth conditions, vegetation properties, and environmental characteristics is required to understand its growth characteristics and conserve this rare species.

• Journal of Korean Society of Forest Science
• /
• v.30 no.1
• /
• pp.50-60
• /
• 1976

For finding out the proper method of developing Buxus koreana var. insularis, this study was carried out in Pokil-Do, Wan-Do, Chonnam, in 1975. The ecology, morphology and characteristics of the plant were mainly investigated and analyzed. The results are summarized as follows; 1. The small islands of the southern sea of Korea; Pokil-Do, Chin-Do and So-Huk-San-Do, turn out to be the site of the natural communities of B. koreana var. insularis. 2. The growth of the plant is fairly good in the acid soil of these islands. 3. This vegetation of composed as the three-layered communities, these communities consit of Camellia, Buxus and Cares. 4. The plant is a board leaved evergreen shrub that is tolerant to shade and native to the temperate zone. 5. The size of the leaves, fruits and seeds is slightly larger than those of B. koreans. 6. As fruiting and germination of the seeds are favorable. it is easy for us to make a number of seedlings. 7. The proper times for sowing and harvesting the seeds are around the middle of July and August, respectively. 8. The seedlings is difficult to grow in the naked ground because the germinated seeds are seriously damaged by frost. 9. The plant growth per annum is about 8 to 10cm in height, 1.5mm in diameter. It is graceful looking as the branches and leaves as of the dense foliage type 10. It is possible to develop the plant in many ways, such as; ornamental plant, bee plant, sculptural and industrial materials.

• Journal of the Korean Society for Marine Environment & Energy
• /
• v.11 no.2
• /
• pp.63-69
• /
• 2008

As a basic study on the creation of artificial tidal flats using dredged sediments, the pilot-scale artificial tidal flats with 4 different mixing ratio of ocean dredged sediment were constructed in Nakdong river estuary. The phragmites australis was transplanted from the adjacent phragmites australis community after construction, and then the survival and growth rate of the planted phragmites australis were measured. Also the changes of soil chemical oxygen demand (COD), ignition loss (IL), and the heterotrophic microbial numbers were monitored. The survival rate of the planted phragmites australis decreased as the mixing ratio of dredged sediment increased but there was little difference of length and diameter of the shoots. 30% of COD and 9% of IL in the tidal flat with 100% dredged sediment decreased after 202 day, however, fluctuations of COD and IL concentrations were also observed possibly due to the open system. It was suggested that the construction of tidal flats using ocean dredged sediment and biological remediation of contaminated ocean dredged sediment can be possible considering the growth rate of transplanted phragmites australis, decrease of organic matter and increased heterotrophic microbial number in the pilot plant with 100% dredged sediment. However, the continuous monitoring on the vegetation and various environmental factors in the artificial tidal flat should be necessary to evaluate the success of creation of artificial flats using dredged sediments.

• Korean Journal of Remote Sensing
• /
• v.34 no.5
• /
• pp.709-720
• /
• 2018

In order to optimize the evaluation of biomass in crop monitoring, accurate and timely data of the crop-field are required. Evaluating above-ground biomass helps to monitor crop vitality and to predict yield. Unmanned Aerial Vehicle (UAV) imagery are being assessed for analyzing within field spatial variability for agricultural precision management, because UAV imagery may be acquired quickly during critical periods of rapid crop growth. This study reports on the development of remote sensing techniques for evaluating the biomass of winter crop. Specific objective was to develop statistical models for estimating the dry weight of barley and wheat using a Excess Green index ($E{\times}G$) based Vegetation Fraction (VF) and a Crop Surface Model (CSM) based Plant Height (PH) value. As a result, the multiple linear regression equations consisting of three independent variables (VF, PH, and $VF{\times}PH$) and above-ground dry weight provided good fits with coefficients of determination ($R^2$) ranging from 0.86 to 0.99 with 5 cultivars. In the case of the barley, the coefficient of determination was 0.91 and the root mean squared error of measurement was $102.09g/m^2$. And for the wheat, the coefficient of determination was 0.90 and the root mean squared error of measurement was $110.87g/m^2$. Therefore, it will be possible to evaluate the biomass of winter crop through the UAV image for the crop growth monitoring.

• Ecology and Resilient Infrastructure
• /
• v.4 no.3
• /
• pp.149-155
• /
• 2017

Willow plants are representative biomaterials used in river restoration and main target trees in stream managements. In order to understand the changes in the growth of Salix subfragilis and S. chaenomeloides with their stand ages, we investigated the density, height and basal area of stems and biomass at their different aged stands of the riparian zone of the sand-bed stream, the Nakdong River, Korea. We also developed allometric equations for estimating the biomass of these two species by establishing the relationship between diameter at breadth height and tree height with above-ground biomass. The stem density showed a sharp decrease for 3 years after germination for S. subfragilis and 6 years for S. chaenomeloides, resulting in strong self-thinning. The stem height of the two species increased to 7.5 m in 15 years for S. subfragilis, and to 14 m in 13 years for S. chaenomeloides. Aboveground biomass also increased rapidly at the early stage of growth. The biomass increased to 17 ton DM/ha in 13 years for S. subfragilis and to 1,110 ton DM / ha in 13 years for S. chaenomeloides. It is expected that the allometric equations of two Salix species derived from this study will be applied to the objectively estimating the biomass of willow plants for the management of floodplain trees in streams.