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Tree regeneration in gap-understory mosaics in a subtropical Shorea robusta(Sal) forest

Journal of Forestry Research 2019年第6期30卷 2061-2068页

作者： L.N.Sharma k.b.shrestha I.E.Maren Forest Action Nepal GPO-12207 LalitpurNepal Department of biological Sciences University of BergenThormoensgate 53B5007 BergenNorway

Spatial variation in tree-regeneration density is attributed to the specialization of tree species to light availability for germination and *** availability,in turn,varies across the gap-understorey *** gaps provide an important habitat for the regeneration of tree species that would otherwise be suppressed in the *** subtropical forests,there is still a knowledge-gap relating to how canopy disturbances influence tree-regeneration patterns at local scale,and if they disproportionately favor regeneration of certain *** aim to analyze whether canopy gaps promote tree regeneration,and tree species are specialized to gaps or understory for germination and *** sampled vegetation in 128 plots(0.01 ha),equally distributed in gaps and below canopy,in two subtropical Shorea robusta Gaertn.(Sal)forests in Nepal,recording the number of tree seedlings and saplings in each *** compared the regeneration density of seedlings and saplings separately between gaps and the *** mean densities of seedlings and saplings were higher in the gaps at both sites;although there was no difference in the seedling density of the majority of the species between the *** species were confined to either gap or understorey at the seedling *** conclude that gaps are not critical for the germination of tree species in Sal forests but these are an important habitat for enabling seedlings to survive into *** classification of trees into regeneration guilds mainly based on germination does not apply to the majority of tree species in subtropical Sal *** results reaffirm that gap creation promotes tree regeneration by favouring seedling survival and growth and can influence forest management for conservation,as well as for plantations.

关键词： Canopy-gap Density Regeneration Saplings Seedlings Shade tolerance

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尼泊尔村社林业发展中的冲突

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林业与社会 1997年第5期5卷 12-13页

作者： k.b.shrestha 高发全

尼泊尔林业经历了曲折的发展过程,1989年政府制定了林业总体发展规划,村社林业项目是其六个发展项目中最大的一个。该项目依靠当地森林利用小组来保护、经营管理和利用森林。主要策略就是将便于经营管理的丘陵地带森林移交给能够、并且... 详细信息

尼泊尔林业经历了曲折的发展过程,1989年政府制定了林业总体发展规划,村社林业项目是其六个发展项目中最大的一个。该项目依靠当地森林利用小组来保护、经营管理和利用森林。主要策略就是将便于经营管理的丘陵地带森林移交给能够、并且愿意经营的当地村民管理,其面积为350万公项,占森林总面积的61％。在村社林业项目实施的初期。

关键词：村社林业森林利用尼泊尔林产品发展委员会社会地位水电站林业局林业项目发展中

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Assessment of SoilGrids data for soil erosion estimation at watershed scale: A case study in northern Thailand

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Pedosphere 2024年第4期34卷 797-813页

作者： Chike Onyeka MADUEkE Dhruba Pikha shrestha Panagiotis NYkTAS Department of Natural Resources Faculty of Geo-information Science and Earth Observation(ITC)University of TwenteEnschede 7500 AEthe Netherlands Department of Applied Earth Sciences Faculty of Geo-information Science and Earth Observation(ITC)University of TwenteEnschede 7500 AEthe Netherlands Department of Soil Science and Land Resources Management Nnamdi Azikiwe UniversityP.M.B.5025AwkaAnambra State 420110Nigeria

Soil erosion has been identified as one of the most destructive forms of land degradation,posing a threat to the sustainability of global economic,social and environmental *** underscores the need for sustainable land management that takes erosion control and prevention into *** requires the use of state-of-the-art erosion prediction *** models often require extensive input of detailed spatial and temporal data,some of which are not readily available in many developing countries,particularly detailed soil *** soil dataset Global Gridded Soil Information(SoilGrids)could potentially fill the data ***,its value and accuracy for soil erosion modelling in the humid tropics is still unknown,necessitating the need to assess its value vis-à-vis field-based *** major objective of this study was to conduct a comparative assessment of the value of SoilGrids and field-based soil data for estimating soil *** samples were collected from five physiographic positions(summit,shoulder,back slope,foot slope,and toe slope)using the soil catena *** were collected using a 5-cm steel sample ring(undisturbed)and a spade(disturbed).Data of the landform,predominant vegetation types,canopy cover,average plant height,land use,soil depth,shear strength,and soil color were recorded for each *** soil samples were subjected to laboratory analysis for saturated hydraulic conductivity,bulk density,particle size distribution,and organic matter *** functions were applied on the SoilGrids and field-based data to generate soil hydrological *** resultant field-based data were compared with the SoilGrids data for corresponding points/areas to determine the potential similarities of the two *** datasets were then used as inputs for soil erosion assessment using the revised Morgan-Morgan-Finney *** results from both datasets were again compared to determine the degree of *** r

关键词： hillslope modelling pedotransfer function similarity assessment soil erosion modelling soil loss soil survey

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Aging Coefficient, Creep Coefficient and Extrapolating Aging Coefficient from Short Term Test for Sealed Concrete

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Journal of Wuhan University of Technology(Materials Science) 2011年第1期26卷 154-159页

作者： shrestha k M College of Civil Engineering Fuzhou University

Aging coefficient and creep coefficient are important parameters for creep analysis of any structure. With the aim to obtain those parameters, an experimental investigation is carried out on sealed concrete. Altogether ten specimens were tested, out of which four were for creep, two for shrinkage and remaining four for relaxation test. A year of relaxation test and two years of creep test results were analyzed to compute aging coefficient and creep coefficient. From regression analysis of observed and calculated aging coefficient using formula of bazant and kim, modification for aging coefficient is performed and extrapolation equations are generated. Instead of ACI model, b3 model has been used to obtain compliance function as the parameters of b3 model seems more relevant to creep mechanism of concrete compared to that of ACI model.

关键词： stress strength ratio creep test experimental study b3 model regression analysis

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How does the stand structure of treeline-forming species shape the treeline ecotone in different regions of the Nepal Himalayas?

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Journal of Mountain Science 2020年第10期17卷 2354-2368页

作者： Parveen k.CHHETRI Raju bISTA krishna b.shrestha Department of Earth Science and Geography California State UniversityDominguez HillsCarsonCalifornia90747USA Department of biological Sciences University of BergenPO Box 7803N-5020BergenNorway

Stand structure dynamics are considered as major happenings in any forest as a response to environmental ***,this important topic is underrepresented in the treeline studies in the Nepal *** aimed to investigate site-as well as species-specific changes in morphometric features(basal diameter,crown cover,density,and height)along the elevational gradient across treeline ecotones in response to recent environmental *** stand structure characteristics of Abies spectabilis,Pinus wallichiana,and betula utilis across the treeline ecotone of three study sites in Eastern(barun),Central(Manang),and Western(Dhorpatan)Nepal were analyzed to elucidate structural ***,eight transects(20 m×(60–250 m))across the treeline ecotone were *** of all life forms,trees(>2 m),saplings(0.5–2 m),and seedlings(basal area increment was higher in barun,but the Manang treeline,despite profound regeneration in recent years,had a low annual basal area ***,the altitudinal distribution of age and morphometry were not consistent among those ***,intra-specific competition was not *** site-specific stand structure dynamics explain why treelines do not respond uniformly to increasing *** invokes,in further studies,the incorporation of the tree’s morphometric adaptation traits,phenotypic plasticity,and interactions between species genotype and the environment.

关键词： Climate change Morphometry Nepal Himalayas Stand structure Treeline Tree-rings

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The Prevalence and Clinical Manifestations of Co-Infection in Pediatric Infectious Mononucleosis: A Single-Centered, Retrospective Study

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Open Journal of Pediatrics 2024年第3期14卷 459-475页

作者： Abdishakur Abdukadir Muse Zakaria Ahmed Mohamed Pu Yang Lihong Liao bibek Dhar shrestha Agness Nicholaus kanusya Paul Mwale Youping Deng Dongchi Zhao Department of Pediatrics Zhongnan Hospital of Wuhan University Wuhan China Department of Ophthalmology Zhongnan Hospital of Wuhan University Wuhan China

background: Recent studies indicate that the incidence of infectious mononucleosis (IM) has increased in China. Furthermore, it has been shown that children diagnosed with IM are prone to acquiring other pathogens. However, there is limited research on the prevalence of these co-infections in children with IM. Thus, we conducted this study to determine the prevalence of coinfections and common pathogens, as well as to compare clinical manifestations in children with and without coinfections. Methods: This retrospective observational study was conducted at the Department of Pediatrics Zhongnan Hospital of Wuhan University, Wuhan, China, with data from January 2018 to January 2023. Data, including demographics, symptoms, lab results, and complications, were collected from the hospital’s electronic database and analyzed. The statistical analysis included descriptive statistics, independent samples t-tests and Mann-Whitney tests to compare the means of continuous variables. Statistical significance was determined by p-values less than 0.05. Results: The study involved 216 participants diagnosed with IM, predominantly males (61.6%) aged 0 - 4 years (50.9%). Coinfection was detected in 39.8% of children, with multiple pathogens present in 33.72% of these cases. Among coinfection cases, 40% occurred in children under 5 years old, and females made up 54.2% of these cases. Mycoplasma pneumoniae (MP) was the most prevalent pathogen, accounting for 18.1% of cases. Influenza b (IFb) and Influenza A (IFA) viruses were found in 16.7% and 13.9% of participants, respectively, indicating a notable occurrence of respiratory pathogen coinfections. Male gender, fever, tonsillopharyngitis, lower HGb levels, higher ESR, CRP, and AST levels were correlated with coinfections. Conclusion: In summary, the study revealed a high prevalence of coinfections among children diagnosed with IM, particularly involving Mycoplasma pneumoniae and influenza viruses. These coinfections were notably

关键词： Prevalence Mononucleosis Coinfection Children Epstein-barr Virus Features

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Topography and human disturbances are major controlling factors in treeline pattern at barun and Manang area in the Nepal Himalaya

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Journal of Mountain Science 2017年第1期14卷 119-127页

作者： Parveen k.CHHETRI krishna b.shrestha David M.CAIRNS Department of Geography Texas A&M University College Station TX 77840 USA Uib Global Jekteviksbakken 31 PO Box 7800 5020 Bergen Norway

The alpine treeline ecotone is an important component of mountain ecosystems of the Nepal Himalaya; it plays a vital role in the livelihood of indigenous people,and provides ecosystem services. However,the region faces a problem of paucity of data on treeline characteristics at the regional and landscape scales. Therefore,we used Remote Sensing(RS),and Geographic Information Science(GIS) approaches to investigate cross-scale interactions in the treeline ecotone. Additionally,European Space Agency land cover map,International Center for Integrated Mountain Development(ICIMOD) land cover map,ecological map of Nepal,and United States Geological Survey Shuttle Radar Topography Mission-Digital Elevation Model were used to analyze treeline pattern at the regional scale. Digital Globe high-resolution satellite imagery of barun(eastern Nepal) and Manang(central Nepal) were used to study treeline patterns at the landscape scale. Treeline elevation ranges from 3300-4300 m above sea level. Abies spectabilis,betula utilis,and Pinus wallichiana are the main treeline-forming species in the Nepal Himalaya. There is an east to west treeline elevationgradient at the regional scale. No slope exposure is observed at the regional scale; however,at the landscape scale,slope exposure is present only in a disturbed area(Manang). Topography and human disturbance are the main treeline controlling factor in barun and Manang respectively.

关键词： Alpine Treeline Mountain ecosystem Himalaya Remote Sensing(RS) Geographic Information Science(GIS)

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Potential cotton aphid, Aphis gossypii, population suppression by arthropod predators in upland cotton

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Insect Science 2013年第6期20卷 778-788页

作者： Ram b. shrestha Megha N. Parajulee Texas A&M University AgriLife Research and Extension Center 1102 E. FM 1294 Lubbock TX 79403 United States

The cotton aphid, Aphis gossypii Glover, predation rate of convergent lady beetle, Hippodamia convergens Guerin-Meneville, was determined by assigning a single predator randomly to each of four prey density treatments in the laboratory. Prey densities included 25, 50, 100, and 200 aphids per Petri dish arena. Predation response was recorded at 1, 4, 8, 16, 24, and 48 h after assigning predators to their prey treatments. Rate of consumption increased through time, with all 25 aphids consumed during the first 4 h of the experiment. At the highest density, adult lady beetle consumed on average 49, 99, 131, 163, 183, and 200 aphids within 1, 4, 8, 16, 24 and 48 h, respectively. Predators showed a curvilinear feeding response in relation to total available time, indicating that convergent lady beetles have the potential to suppress larger populations of aphids through continuous feeding by regulating their predation efficiency during feeding. The analysis of age-specific mortality in absence of prey revealed that lady beetles could survive for an extended period of time （more than 2 weeks） without prey. The ability of a predator to survive without prey delays or prevents the rebound of pest populations that is a significant factor in natural biological control. A two-year field sampling of 10 cotton arthropod predator species showed that spiders （27%） were the most dominant foliage dwelling predators in the Texas High Plains cotton followed by convergent lady beetles （23.5%）, hooded beetles （13.5%）, minute pirate bugs （11%）, green lacewings （9.5%）, bigeyed bugs （7.5%）, scymnus beetles （3%）, soft-winged flower beetles （2%）, damsel bugs （1.5%）, and assassin bugs （1.5%）. A field cage study showed that one H. convergens adult per plant released at prey density of one aphid per leaf kept the aphid population below economic threshold for the entire growing season.

关键词： Aphis gossypii biological control cotton IPM functional response Hippo-damia convergens natural suppression

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Recent treeline dynamics are similar between dry and mesic areas of Nepal, central Himalaya

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Journal of Plant Ecology 2015年第4期8卷 347-358页

作者： krishna b.shrestha Annika Hofgaard Vigdis Vandvik Department of biology University of BergenPO Box 7803NO-5020BergenNorway Uib Global University of BergenJekteviksbakken 31PO Box 7800NO-5020BergenNorway Norwegian Institute for Nature Research PO Box 5685 SluppenNO-7485TrondheimNorway

Aims We investigated the treeline dynamics of two environmentally con-trasting areas in the Nepalese Himalaya to address the following questions:(i)Does the timing of establishment of the current tree-line differ between the two study areas,and can area-specific tree-line developments be identified?(ii)Do recruitment patterns and height growth indicate recent climate-driven treeline advance,fol-lowing the general prediction for the central Himalayan region,in the two study areas?Methods a dry-climate treeline dominated by Pinus wallichiana and a mesic-climate treeline with Abies spectabilis were selected for *** each area,we sampled the size and age structure of the study spe-cies along three elevational transects(20-m wide)from the forest line to the tree species line crossing the *** also sampled treeline trees from within and outside transects to reconstruct past treeline establishment *** Findings Despite differences in moisture regimes,tree species and recent climate trends,our two study areas showed very similar treeline dynamics over the past six *** both areas,the recruitment of treeline trees indicates stationary treelines over the past six decades with the current treelines being dominated by trees that were established around *** mesic area has experienced an overall climatic warming trend,and the stationary Abies treeline is hypothesized to be regulated by non-climatic factors,notably *** dry area has not experienced warming but increased climatic variability and some very cool summers in the recent dec-ades may explain the stationary to weakly receding Pinus treeline,which appears more climatically controlled with decreased recruit-ment over the past decades and decreased growth towards higher *** both areas,there is a potential for treeline advance,depending on future land use and climate *** results highlight the importance of conducting treeline ecotone analyses for several sites or are

关键词： Abies spectabilis Himalaya Pinus wallichiana slope aspect treeline ecotone dynamics

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Metapopulation approach for landscape level management of western tarnished plant bug,Lygus hesperus,in Texas( Hemiptera,Miridae)

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植物保护学报 2014年第6期41卷 761-768页

作者： Parajulee Megha N shrestha Ram b Texas A & M University System AgriLife Research and Extension Center

Insect source-sink dynamics are vital to ecologically intensive pest management. Maintaining sink plant hosts,or "trap crops",and destroying alternate hosts or breeding places adjacent to the field crop are effective pest management strategies for some arthropods. However,determining whether a host acts as a source or a sink is challenging, especially when the pest species is highly mobile and polyphagous. The western tarnished plant bug,Lygus hesperus,is highly polyphagous,and can utilize >300 hosts. Its presence has been documented in 26 roadside weed hosts in the Texas High *** studies demonstrated that L. hesperus prefer alfalfa over cotton and several alternate weed hosts.A four-year project involved surveying and sampling for L. hesperus in the agricultural landscapes of several sub-regions of the southwestern United States,including the Texas High Plains. In Texas,geographic information of the landscape vegetation complex was compiled from a 150 km radius in the Texas High Plains. In one study,fifty irrigated cotton fields representing the crop diversity within this region were sampled via sweep-net for 10 weeks. This effort also included sampling of up to six noncotton insect habitats within a 3 km radius of each field. Seasonal average L. hesperus abundance data were regressed with 27 field characteristics( variables),including habitat-specific land cover,distance between focal cotton fields and non-cotton habitats,longitude,latitude,elevation,habitat heterogeneity index,and several environmental / ecological variables. Significant variables were selected using a stepwise regression at 15% probability rate. A 10-parameter linear model explained 93% of the variation in the data. Major parameters contributing significantly to variation in L. hesperus abundance in cotton were corn and sunflower acreages,focal cotton field distances from several non-cotton hosts,and habitat heterogeneity index. In addition,field marking-and-capture studies were cond

关键词： western tarnished plant bug cotton IPM ecological pest management alternate host management

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