• Journal of Forest and Environmental Science
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• 제29권2호
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• pp.116-124
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• 2013

Differences in rates and patterns of nitrogen cycling have been correlated with nitrogen stable isotope measurements in forest ecosystems of tropical and temperate regions, but limited similar work has been conducted in sub-tropical forests. This study investigated patterns in stable N isotopic composition in a subtropical forest in Taiwan by sampling three soil profiles and overstory and understory foliage. Soil ${\delta}^{15}N$ in the forest floor ranged from -1.8 to -1.8‰. Mineral soils had higher ${\delta}^{15}N$ (4.1 to 6.0‰). Foliage ${\delta}^{15}N$ in overstory trees ranged from -6.6 to -2.0‰, and understory foliage ${\delta}^{15}N$ ranged from -5.0 to -1.2‰. There was a weak correlation between foliar % N and ${\delta}^{15}N$ ($r^2=0.214$). Compared to results from similar surveys in tropical and temperate forests, foliar ${\delta}^{15}N$ values were generally lower. These results help highlight the need for improved knowledge regarding the relationships between patterns in N stable isotopes and processes affecting rates of N cycling, especially as related to wider scale patterns in forest ecosystems within the east-Asia region.

• Journal of Forest and Environmental Science
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• 제28권1호
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• pp.1-7
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• 2012

Tropical forests whether fragmented or undisturbed or be they equatorial or deciduous, remain the storehouse of biodiversity for hundreds of thousands of plant and animal species. This unique characteristic continues to attract a wide range of scientists and international organizations to study and attempt to understand tropical forest ecosystems. Gene flow is mediated by pollen, seed and seedling dispersal, and factors affecting this gene flow include phenology, spatial distribution, population structures, seed predation, sexual and mating systems as well as physical and biological barriers to gene flow. Two methods are used in measuring gene flow: direct method that relies on the actual observation of seed and pollen dispersal, whereas indirect methods involve the use of genetic markers such as allozymes and DNA techniques. Political strife, extreme natural and artificial disasters, the lack of a comprehensive forestry research vision, coupled with difficult socio-economic conditions in Africa have made the environment quite difficult for sustained research activities on the part of those undertaking or wishing to undertake such studies. Gene flow studies in this region are few and far between. This review elaborates on the mechanisms of gene flow mediation in Sub-Saharan Africa.

• Journal of Forest and Environmental Science
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• 제31권3호
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• pp.225-234
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• 2015

Mangroves are important coastal ecosystems and are located at the inter-tidal zones of tropical and sub-tropical belts. The global mangrove forests are declining dramatically because of the conversion of forests to shrimp farming, over-exploitation, pollution and freshwater diversion. The Bangladesh Forest Department initiated mangrove afforestation throughout the coastal belts of Bangladesh in 1966 to provide better protection for the coastal communities. Up to 1990, 120,000 ha of mangroves had been planted and it is one of the largest coastal afforestaton programs in the world. The objective of this study is to exploit the spatial extent of mangrove plantation and their dynamics of changes over the last two decades using multispectral Landsat imagery. The study area covers the coastal areas of Bangladesh that is extended over the eastern part of Sundarbans up to Teknaf, the southern tip of mainland Bangladesh. Mangrove plantations were interpreted visually on computer screen and interactive delineation of forest boundary was done. The mangrove plantation area has been estimated as 32,725, 47,636 and 43,166 ha for the year of 1989, 2000 and 2010, respectively. Mangrove deforestation by human activity has increased almost six times in the recent decade in comparison to the previous one. The mangrove forest loss due to coastal erosion has slightly declined in the 2000s. Mangroves have been lost primarily because of agricultural expansion. The result of this investigation will be helpful to understand the dynamics of mangrove plantation and the main drivers of changes in this coastal ecosystem.

• 환경생물
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• 제39권3호
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• pp.266-272
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• 2021

본 연구의 목적은 동남아시아 열대우림의 대표 산림 유형인 MDF, PSF 그리고 HF에서 지상부 바이오매스를 추정하는 것이다. 브루나이에서 MDF, PSF 그리고 HF를 대상으로 각각 3개 지역을 선정하여 20 m×20 m 조사구를 지역마다 9개씩 설치하고 흉고직경 10 cm 이상인 임목의 흉고직경을 측정하였다. 지상부 바이오매스는 측정된 흉고직경과 바이오매스 상대생장식을 활용하여 추정되었다. 지상부 바이오매스는 MDF, PSF 그리고 HF에서 각각 603.3±159.9, 305.9±23.4 그리고 284.3±19.3 Mg ha^-1 순으로 나타났다. 산림 유형에 따라 지상부 바이오매스는 유의하게 차이가 있었으며, MDF에서 가장 높게 나타났다. 이는 흉고직경이 70 cm 이상인 거대목이 MDF에서 집중되어 출현했기 때문이다. 이러한 연구 결과는 산림 유형에 따라 거대목의 출현빈도가 다르며, 나아가 거대목의 출현이 지상부 바이오매스 추정에 영향을 주는 요인 중 하나라는 의미를 가진다.

• Journal of Forest and Environmental Science
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• 제25권1호
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• pp.1-24
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• 2009

Teak (Tectona grandis) is one of the most valuable timber yielding species in the world, with predominant distribution in tropical or sub-tropical countries. However, natural teak available only in few countries like India, Myanmar, Laos People's Democratic Republic and Thailand. Teak grows well in deep, well-drained alluvial soils, fairly moist, warm, tropical climate with pH ranges from 6.5-7.5. Teak is cultivated in many Asian, African and South American countries for timber production. The global teak plantations are estimated to be three million hectare with major share in India (44%) followed by Indonesia (33%). India is considered as richest genetic resources of teak with large areas of natural teak bearing forests (8.9 million ha), plantations (1.5 million ha), clonal seed orchards (1000 ha) and seed production areas (5000 ha). The studies on diversity of teak populations showed that teak is an out crossing species with major portion of diversity present within the populations. The productivity and quality of teak timber varies depending upon the site and environmental conditions. Teak wood is moderately heavy, strong and tough,straight grained, coarse textured and ring porous with specific gravity varies from 0.55 to 0.70. The sapwood is white to pale yellow in colour and clearly demarcated while heartwood is dark brown or dark golden yellow in colour. Teak is one of the most durable timbers in the world, practically, impervious to fungus and white ant attack and resistant to decay. Teak wood is used in ship and boat constructions, furnitures and aesthetic needs. Genetic improvement programmes have been undertaken in countries like Thailand, India, Malaysia and Indonesia. The programme includes provenance identification and testing, plus tree selection and clonal multiplication, establishment of seed orchards and controlled hybridization. Several aspects like phenology, reproductive biology, fruit characteristics, silvicultural practices for cultivation, pest and diseases problems, production of improved planting stock, harvesting and marketing, wood properties and future tree improvement strategy to enhance productivity have been discussed in this paper.

• Journal of Forest and Environmental Science
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• 제35권4호
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• pp.213-222
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• 2019

Climate change has been intensifying and affecting forest ecosystems. Over the years, the intensity and frequency of climate change have increased and the effects of climate change have been aggravating due to cumulative greenhouse gases such as CO₂, which has resulted in several negative consequences, drought being the main threat among all. Drought affects forest ecosystems directly and indirectly. Insufficient soil moisture, due to drought, may affect the growth of plants and soil respiration (SR), and soil temperature may increase because of desiccated soil. In addition, the mortality rate of plants and soil microorganisms increases. As a result, these effects could reduce forest productivity. Thus, in this article, we have presented various research studies on artificial drought using throughfall exclusion, and we have mainly focused on SR, which is significantly related to forest productivity. The research studies done worldwide were sorted as per the main groups of Köppen-Geiger climate classification and intensively reviewed, especially in tropical climates and temperate climates. We briefly reviewed the properties among the exclusion experiments about the temperate climate, which mostly includes Korean forests. Our review is not a proof of concept, but an assumption for adequate investigation of drought effects in the Korean forest.

• 대한원격탐사학회지
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• 제31권2호
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• pp.127-136
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• 2015

본 연구는 항공 LiDAR 자료를 이용하여 열대원시림인 브루나이 지역의 지상부 생체량을 정량화하기 위하여 수행되었다. 25ha 크기의 연구대상지에 0.09ha ($30m{\times}30m$) 크기의 24개의 표본구 내에서 조사된 각 표본점 내 개체목의 흉고직경 및 위치자료를 활용하였다. 또한, 항공 LiDAR 자료를 이용하여 수치표면모델(Digital Surface Model), 수치지형모델(Digital Terrain Model), 수고모델(Canopy Height Model)을 구축하였다. 수고모델을 표본구단위로 분할하고 총 12개의 LiDAR 높이변수를 구축하였다. 표본구별로 상대생장식을 이용하여 계산된 생체량과 LiDAR 자료로부터 추출된 변수간의 다중회귀분석을 통해 LiDAR 자료로부터 생체량을 추정할 수 있는 식을 도출하였다. 표본구의 생체량은 평균 366.48 Mg/ha였으며, 155.81 Mg/ha부터 597.21 Mg/ha까지 분포하였다. LiDAR로부터 생체량을 추정하는 식의 검증 결과, 결정계수 값은 0.84로 나타났다.

• Journal of Ecology and Environment
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• 제44권4호
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• pp.264-274
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• 2020

Background: Climate change has altered the various ecosystem processes including forest ecosystem in Himalayan region. Although the high mountain natural forests including treelines in the Himalayan region are mainly reported to be temperature sensitive, the temperature-related water stress in an important growth-limiting factor for middle elevation mountains. And there are very few evidences on growth performance of planted forest in changing climate in the Himalayan region. A dendrochronological study was carried out to verify and record the impact of warming temperature tree growth by using the tree cores of Pinus roxburghii from Batase village of Dhulikhel in Central Nepal with sub-tropical climatic zone. For this total, 29 tree cores from 25 trees of P. roxburghii were measured and analyzed. Result: A 44-year long tree ring width chronology was constructed from the cores. The result showed that the radial growth of P. roxburghii was positively correlated with pre-monsoon (April) rainfall, although the correlation was not significant and negatively correlated with summer rainfall. The strongest negative correlation was found between radial growth and rainfall of June followed by the rainfall of January. Also, the radial growth showed significant positive correlation with that previous year August mean temperature and maximum temperature, and significant negative correlation between radial growth and maximum temperature (Tmax) of May and of spring season (March-May), indicating moisture as the key factor for radial growth. Despite the overall positive trend in the basal area increment (BAI), we have found the abrupt decline between 1995 and 2005 AD. Conclusion: The results indicated that chir pine planted population was moisture sensitive, and the negative impact of higher temperature during early growth season (March-May) was clearly seen on the radial growth. We emphasize that the forest would experience further moisture stress if the trend of warming temperatures continues. The unusual decreasing BAI trend might be associated with forest management processes including resin collection and other disturbances. Our results showed that the planted pine forest stand is sub-healthy due to major human intervention at times. Further exploration of growth climate response from different climatic zones and management regimes is important to improve our understanding on the growth performance of mid-hill pine forests in Nepal.

• Journal of Ecology and Environment
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• 제38권4호
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• pp.485-491
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• 2015

This study was conducted to develop stem volume models for the volume estimation of Quercus glauca Thunb. in Jeju Island, Republic of Korea. Furthermore, this study validated the developed stem volume models using an independent dataset. A total of 167 trees were measured for their diameter at breast height (DBH), total height and stem volume using non-destructive sampling methods. Eighty percent of the dataset was used for the initial model development while the remaining 20% was used for model validation. The performance of the different models was evaluated using the following fit statistics: standard error of estimate (SEE), mean bias absolute mean deviation (AMD), coefficient of determination (R²), and root mean square error (RMSE). The AMD of the five models from the different DBH classes were determined using the validation dataset. Model 5 (V = aD^bH^c), which estimates volume using DBH and total height as predicting variables, had the best SEE (0.02745), AMD (0.01538), R² (0.97603) and RMSE (0.02746). Overall, volume models with two independent variables (DBH and total height) performed better than those with only one (DBH) based on the model evaluation and validation. The models developed in this study can provide forest managers with accurate estimations for the stem volumes of Quercus glauca in the subtropical forests of Jeju Island, Korea.

• Animal Bioscience
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• 제34권11호
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• pp.1727-1738
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• 2021

Objective: This review consolidates the available information on the socio-economic and ecological significance of Mithun in the lives of ethnic communities in the Eastern Himalaya. Methods: Standard guidelines were followed for the review and data collection was carried out at three stages; literature search, literature screening, and literature review and analysis. Results: Records indicate a long association of Mithun with the ethnic groups. Mithun serves as a symbol of pride and local currency for barter trade in the ethnic society. Its utilities range from being used as a bride price to settling legal disputes. Several cultural festivals and local ceremonies are celebrated around this bovine. Due to its semi-wild nature, this animal also has an ecological role to conserve broad leaf sub-tropical forests. However, it remains neglected and has not received policy attention, leading to a stagnated growth. The institutions for Mithun research and development are also weak. Furthermore, the species is under threat from new diseases and habitat alteration triggered by climate change. Conclusion: Founded on the current state of knowledge, there is a need for institutional development, strengthening institutional linkages, and promoting regional cooperation among Mithun rearing countries for further research and development of this unique cattle.