• 생태와환경
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• 제46권2호
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• pp.241-250
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• 2013

조성연도가 다른 일본잎갈나무조림지를 대상으로 조림 후 시간이 경과함에 따라 식생의 발달과정을 분석하였다. 일본잎갈나무의 높이와 직경은 조림 후 24년까지 빠르게 생장하였고, 그 이후 양 생장이 모두 둔화되는 경향이었다. 일본잎갈나무의 밀도는 8년생 식분과 17년생 식분에서는 유사한 밀도를 유지하였으나 24년생 식분에서 크게 감소하였고 그 이후에는 큰 변화를 보이지 않았다. 서열법을 적용하여 비교된 일본잎갈나무조림지의 종 조성은 조성연도에 따라 뚜렷한 변화경향을 나타내지 않았고, 조성연도가 다른 조림지 간의 차이가 대조구와의 차이보다 컸다. 주요 종의 직경급 별 빈도분포를 통해 분석한 결과 일본잎갈나무조림지는 신갈나무가 우점하는 자생식생으로의 천이경향을 보였다. 종 다양성은 모든 연령의 식분들이 대조구의 것보다 높았다. 이상의 결과에서 보여지듯이 일본잎갈나무조림지에서 나타난 대조지소와 유사한 종 조성, 자생식생으로의 천이 경향 그리고 높은 종 다양성은 생태적 복원의 성공을 의미하는 조건으로서 기능적 복원으로 출발한 일본잎갈나무조림지가 성공적인 복원을 이루어낸 것으로 평가할 수 있다.

• 한국산림과학회지
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• 제88권2호
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• pp.266-272
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• 1999

경기도 광릉의 중부임업시험장내 31년생 리기다소나무와 낙엽송조림지를 대상으로 임분별 3개의 $20{\times}10m$ 조사구를 선정하고 각 조사구로부터 1본씩 표본목을 선정한 후 벌도하여 지상부 현존량을 측정하고 각 부위별 양분분포를 조사하였다. 조사된 임분의 지상부 현존량은 리기다소나무의 경우 170.2ton/ha, 낙엽송은 87.2ton/ha로서 리기다소나무 임분이 낙엽송 임분에 비해 높게 나타났으며, 두 임분의 현존량의 차이는 임분 밀도의 차가 원인인 것으로 나타났다. 각 부위별 현존량 분배율은 줄기>가지>수피>잎 순이었으며, 각 부위별 조직내 양분농도는 낙엽송이 리기다소나무에 비해 높았고, 두 임분 모두 잎>가지>수피>줄기 순으로 양분농도에 차이가 있었다. 양분 축적량은 리기다소나무 임분이 질소 335.9kg/ha, 칼슘 188.6kg/ha, 칼륨 121.4kg/ha, 마그네슘 93.8kg/ha, 인산 40.4kg/ha 순이었으며 낙엽송 임분은 질소 225kg/ha, 칼슘 75.7kg/ha, 칼륨 72.9kg/ha, 마그네슘 37.1kg/ha, 인산 11.5kg/ha으로 리기다소나무 임분에서 양분 축적량이 높게 나타났다. 양분에 대한 지상부 현존량의 비로 표시되는 양분이용효율중 질소이용효율은 낙엽송 임분이 리기다소나무 임분에 비해 낮게 나타났으며 이는 리기다소나무가 낙엽송에 비해 척박지에서 더 잘 견딜 수 있는 임목의 특성을 반영하고 있다.

• Journal of Forest and Environmental Science
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• 제28권4호
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• pp.205-211
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• 2012

Yield tables are a frequently used data base for regional timber resource forecasting. A normal yield table is based on two independent variables, age and site (species constant), and applies to fully stocked (or normal) stands while empirical yield tables are based on average rather than fully stocked stands. Normal and empirical yield tables essentially have many limitations. The limitations of normal and empirical yield tables led to the development of variable density yield tables. Mathematical models for estimating timber yields are usually developed by fitting a suitable equation to observed data. The model is then used to predict yields for conditions resembling those of the original data set. It may be accurate for the specific conditions, but of unproven accuracy or even entirely useless in other circumstances. Thus, these models tend to be specific rather than general and require validation before applying to other areas. Dalbergia sissoo forms a major portion of irrigated plantations in the hot desert of India and is an important timber tree species where stem wood is primarily used as timber. Variable density yield model is not available for this species which is very crucial in long-term planning for managing the plantations on a sustained basis. Thus, the objective of this study was to develop variable density yield model based on the data collected from 30 sample plots of D. sissoo laid out in IGNP area of Rajasthan State (India) and measured annually for 5 years. The best approximating model was selected based on the fit statistics among the models tested in the study. The model develop was evaluated based on quantitative and qualitative statistical criteria which showed that the model is statistically sound in prediction. The model can be safely applied on D. sissooo plantations in the study area or areas having similar conditions.

• Journal of Forest and Environmental Science
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• 제30권2호
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• pp.179-188
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• 2014

This research reports the effects of shifting cultivation on soil environment collecting samples from 0-5 cm soil depth from five locations viz. at Burburichhara, Maichchari, Longadu, Sukurchhari and Muralipara in Rangamati district of Chittagong Hill Tracts (CHTs). Soil analyses showed that fungal and bacterial population, microbial respiration and active microbial biomass, maximum water holding capacity, conductivity and moisture contents were significantly (at least $p{\leq}0.05$) lower in shifting cultivated soil compared to adjacent mixed tree plantations at all the sites. On an average in soils of 5 different shifting cultivated lands fungal population was $1.33{\times}10^5$ CFU/g dry soil and bacterial population $1.80{\times}10^7$ CFU/g dry soil and in mixed plantations fungal population was $1.70{\times}10^5$ and bacterial population $2.51{\times}10^7$ CFU/g dry soil. Organic matter and exchangeable Ca and Mg contents were significantly (at least $p{\leq}0.05$) lower and bulk density significantly (at least $p{\leq}0.05$) higher in shifting cultivated land in most of the locations compared to adjacent mixed tree plantations. Ratios of microbial respiration and organic carbon as well as active microbial biomass and organic carbon were distinctly lower and pH higher at 3 locations in shifting cultivated soils compared to mixed plantations. Findings of various soil properties, therefore, suggest that shifting cultivation has deteriorating effects on soil environment.

• 한국응용곤충학회지
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• 제28권4호
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• pp.201-209
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• 1989

본 실험은 나이가 다른 잣나무조림지에서의 토중 톡톡이 군집의 특성을 조사하기 위하여 수행하였다. 조림후 1~2년된 지역에서 11~12년된 지역을 1986년 7월부터 1987년 6월까지 조사한 결과는 다음과 같다. 전체적인 톡톡이군집?조는 각종에 따라 심한 집중분포현상을 나타내고 있고, 동일종도 지역에 따라 다른 분포양식을 나타낸다. 조림연도별 군집구조는 조림연도가 오랠수록 종다양도가 높아지고, 밀도와 종자도 안정되어 있었다. 조림후 2년이 지난 1985년조림지에서는 동경사면인 I구가 서면사면인 II구보다 종다양도가 높았다. 계절적 군집구조는 온도가 높은 8월과 유기물함량이 가장 많은 10월에 밀도와 종류가 높은데 이는 톡톡이군의 활동이 온도, 습도, 유기물량에 형향을 받는 것으로 생각된다.

• 농업생명과학연구
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• 제45권4호
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• pp.47-58
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• 2011

The forest of Korea had been severely degraded since early 1900s until 1950s. Korean Government has successfully accomplished the reforestation works since 1960s. However, some plantations showed poor survival and growth caused by ignoring site characteristics in selecting plantation species and lack of tending works such as thinning. The natural regeneration of indigenous species, such as Quercus species and Pinus densiflora Siebold & Zucc., were examined in the plantations of Pinus koraiensis Siebold & Zucc. and Larix kaempferi Fortune ex Gordon. Quercus species regenerated mainly by sprouting while P. densiflora regenerated naturally from a few mother trees that remained in the plantations. P. koraiensis showed poor survival ($IVI{\leq}25%$) and suppressed growth (height ${\leq}3m$ and $DBH{\leq}3cm$ at 20 year-old) by Quercus species or P. densiflora in the plantation areas, however had high survival ($IVI{\geq}70%$) and growth (8 m height and 14.1 cm DBH at 20 year-old) in areas where silvicultural practices were conducted. L. kaempferi showed good survival ($IVI{\geq}40%$) and growth (17.2 m height and 16.3 cm DBH at 30 year-old) mostly in valley areas, while it was nearly dead ($IVI{\leq}10%$) in ridge or ridge-slope areas and was replaced by indigenous species such as Quercus species ($IVI{\geq}25{\sim}55%$) or P. densiflora ($IVI{\geq}18{\sim}50%$).

• Asian-Australasian Journal of Animal Sciences
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• 제8권1호
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• pp.67-73
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• 1995

This study showed that models of energy utilization(EU) developed for grazing cattle in oil palm plantations is valid as the simulated results shows an agreement with actual data of calves and cows body weight changes collected from Brahman x Kedah-Kelantan herd on Pengeli Timor Plantation. Simulation runs on EU models demonstrated that the growth pattern of male and female calves and the weight changes of cows are similar and showed slight variation from the actual data but with no significant difference (p > 0.05). Parameter values such as metabolizability (q), dry matter digestibility(DMD) of herbage and voluntary intake of grazing cattle (VIG) and faecal output/body weight ratio (F) of the animals which were collected from the field are essential in bearing the pattern of body weight changes of the calves and cows in relation to increase in time, physiological status and quality of herbage grazed by these animals in the production system. The EU models is suitable for determining the metabolizable energy requirements and to predict the production of grazing cattle according to quality of the feed on offer.

• Asian-Australasian Journal of Animal Sciences
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• 제8권1호
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• pp.59-66
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• 1995

Energy obtained by grazing cattle in oil palm plantations is usually used for maintenance of body functions, the construction of body tissues and pregnancy, the synthesis of milk and the conversion to mechanical energy used for activities such as walking, eating and others. In this study, attempt was made to estimate metabolizable energy (ME) requirement of grazing cattle. Models of ME requirement (MER) for maintenance, gain, pregnancy, lactation and activities were developed. ME system and units were used because of wide recognition. Estimation of ME intake in grazing cattle was expressed as MEVI = $14.58{\times}VI{\times}DMD$, and under grazing condition MEVI = $MER_i$. MER was expressed as a function of net energy(NER, MJ) required for the i'th body function. Coefficient of efficiency for conversion of ME into net energy(ki) was adopted from literatures. Quantifying of ME requirement for Kedah-Kelantan cattle under grazing condition was made by using equation MERM = NEM / kn. The estimated values of MER for Kedah-Kelantan cattle is quite reasonable if compared with other estimates as reported in literatures from stall-fed animals. Dynamic MER models for grazing herd was developed in order to estimate ME requirement for maintenance and productions. These ME requirement models can be used for prediction of energy utilization pattern of the herd in the grazing systems.

• The Korean Journal of Ecology
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• 제18권3호
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• pp.385-395
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• 1995

Species effects on soil nitrogen mineralization and nitrification in the top 15 cm of soil were evaluated using the buried-bag incubation method in three coniferous plantations in the Kwangneung Experimental Forest, Kyonggi Province. The plantations were established on a similar soil in 1927, and included Larix decidua, Pinus strobus, and Thuja occidentalis. Ten soil samples within each plantation were taken during an entire growing season (May 2~Oct. 30, 1994). Mean daily nitrogen mineralization rates during 45-day in situ soil incubations were significantly different among species and incubation dates. Growing season nitrogen mineralization also differed significantly among species and ranged from 47.7 mg N/kg soil for Larix decidua to 21.5 ma N/kg soil for Thuja occidentalis. Growing season nitrification differed significantly among species and comprised from 93% to 100% of the total growing season nitrogen mineralized. We speculated that organic matter contents and quality might control nitrogen mineralization and nitrification in these soils.

• 한국잡초학회지
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• 제30권3호
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• pp.206-214
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• 2010

The laboratory and green house studies evaluated the effect of three different environmental factors on the seed germination, seedling emergence and survival of four major weed species in coconut plantations, Mimosa pudica, Ureana lobata, Panicum maximum and Pennisetum polystachyon. Germination percentage of all the weed species was significantly reduced with increasing soil moisture stress, no germination was observed at -0.9 MPa. Germination of both grass seeds ranged from 8% to 25% and 10% to 45% as moisture stress decreased from -0.4 MPa to 0 MPa, respectively. In contrast, seeds of M. pudica, and U. lobata were moderately tolerant to soil moisture stress and best adapted to moist environment. All the weed species seeds germinated over a wide range of soil pH values with the highest germination occurring at pH 6. In all the species, seedling emergence was declined rapidly with increasing depth with the exception of U. lobata. Seedling emergence significantly declined when the duration of flooding was three days or longer in dicotyledonous weed species and two days or longer in monocotyledonous weeds. This study illustrates the adaptability of these weeds to different environmental conditions which would enable the development of management strategies to reduce their populations below economic threshold levels in coconut plantations.