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Phytosociology of stratification in a lowland tropical rainforest occurring north of the Tropic of Cancer in Meghalaya, India

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Plant Diversity 2019年第5期41卷 285-299页

作者： uma shankar Department of Botany North-Eastern Hill University

Stratification in lowland rainforests of Meghalaya,India,which represent the westernmost limit of the rainforests north of the Tropic of Cancer,was studied in horizontal and vertical planes to elucidate the patterns in stacking of species diversity and community attributes,and to draw comparisons with rainforests of‘Indo-Malaya’ecozone(biogeographical realm).All individuals≥10 cm GBH(girth at breast height)were enumerated in six transects of 10 m width and up to 500 m length covering 2.45 ha area.The stratification of whole assemblage of species in vertical plane is referred to as‘storey structure’(=height class distribution),which explains structural complexity.In horizontal plane,it is typically referred to as‘stand structure’(=girth class distribution),which explains structural heterogeneity.The stratification of an individual species in vertical plane is referred to as‘loftiness’and in horizontal plane,it is frequently referred to as‘population structure’.The stand structure was characterized by a negative exponential relationship or a reverse J-shaped curve,which is typical of a well regenerating forest stand.The storey structure was characterized by the low stature of the rainforest(<30 m),subtle layering in the canopy with dearth of discrete multi-stories,narrower widths of the stories and a thick understory.The cluster analysis and‘candlestick charts’showed that the dominant species spatially segregated in canopy height to profile three strata,viz.,an understory of juveniles and shrubs below 5 m,a middle-storey of intermediate trees between 5 and 15 m,and an overstory of large trees between 15 and 25 m.Emergent trees of a few species may reach up to 30 m.The individuals tended to scatter in increasingly wider range of height classes from a lower to the next higher girth class,creating a‘torchlight scatter’pattern,with a tendency to concentrate towards smaller height classes due to stochastic factors,which potentially influence vertical growth proportionate to diametric growth.In comparison to equatorial r

关键词： Forest stratification Stand structure Storey structure Loftiness Population structure Northeast India

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Rainforests north of the Tropic of Cancer: Physiognomy, floristics and diversity in ‘lowland rainforests’ of Meghalaya, India

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Plant Diversity 2017年第1期39卷 20-36页

作者： uma shankar Amit Kumar Tripathi Department of Botany North-Eastern Hill University Shillong 793 022 India

The lowland rainforests of Meghalaya, India represent the westernmost limit of the rainforests north of the Tropic of Cancer. These forests, on the Shillong plateau, are akin to Whitmore's ‘tropical lowland evergreen rainforest' formation and exhibit striking similarities and conspicuous differences with the equatorial rainforests in Asia-Pacific as well as tropical seasonal rainforests in southwestern China near the Tropic of Cancer. We found these common attributes of the rainforests in Meghalaya: familial composition with predominance of Euphorbiaceae, Lauraceae, Meliaceae, Moraceae, Myrsiticaceae,Myrtaceae and Rubiaceae; deciduousness in evergreen physiognomy; dominance of mega-and mesophanerophytic life-forms; abundance of species with low frequency of occurrence(rare and aggregated species); low proportional abundance of the abundant species; and truncated lognormal abundance distribution. The levels of stand density and stand basal area were comparable with seasonal rainforests in southwestern China, but were lower than equatorial rainforests. Tropical Asian species predominated flora, commanding 95% of the abundance. The differences include overall low stature(height) of the forest, inconspicuous stratification in canopy, fewer species and individuals of liana, thicker understory,higher proportion of rare species, absence of locally endemic species and relatively greater dominance of Fagaceae and Theaceae. The richness of species per hectare(S) was considerably lower at higher latitudes in Meghalaya than in equatorial rainforests, but was comparable with seasonal rainforests. Shannon's diversity index(H’=4.40 nats for ≥10 cm gbh and 4.25 nats for ≥30 cm gbh) was lower on higher latitudes in Meghalaya in comparison to species-rich equatorial rainforests, but it was the highest among all lowland rainforests near the Tropic of Cancer.

关键词： Lowland rainforest Forest structure Floristics Phytosociology Species richness Life-form spectrum

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Patterns of species dominance, diversity and dispersion in ‘Khasi hill sal' forest ecosystem in northeast India

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Forest Ecosystems 2014年第4期1卷 227-246页

作者： Amit Kumar Tripathi uma shankar Department of Botany North-Eastern Hill University

Background： The ＇Khasi hill sal＇ forest ecosystem in Meghalaya, India represents the easternmost limit of sal distribution. We tested if tree diversity and compositional heterogeneity of this ecosystem was higher than other sal-dominated forests due to moister environment. Methods： Vegetation was sampled in 11 transects of 10 m width and up to 500 m length covering 5.2 ha area. All stems ≥10 cm girth at breast height were enumerated. Results： We found a pattern of mixed dominance of Shored robusta （sal） and Schima wollichii and co-dominance of Pinus kesiyo and Careya arborea. The Shannon＇s diversity index （H＇） was 3.395 nats. This value is remarkably high and competitive to that of moist sal forests of eastern Himalayan foothills and sal-dominated forests of Tripura. A high value of H＇ was manifested by： a） high species richness （S = 123）, b） good equitability （70.6%）, c）＇fair＇ resource apportionment, and d） abundance of rare species （84% species with less than one per cent of total individuals, 67% species with two or less individuals ha-1 and 59% species with one or less individuals ha-1）. The compositional heterogeneity was ＇fair＇（Whittaker＇sβw = 3.15）. The presence of Fagaceae with six species commanding 4.3% of importance value （IVl） and of a pine （P. kesiya） in sal forest was remarkable. As many as 58 species showed ＇low density （〈 10 individuals ha-1）, uniform dispersion＇, five species achieved ＇higher density （〉 10 individuals ha-l）, uniform dispersion＇ and six of the top 10 species were ＇clumped＇. The forest showed an exponential demographic curve illustrating ＇good＇ regeneration of an expanding community. Vertical stratification was simple with a poor canopy and fair subcanopy, which together with low basal area （15.65 m2 . ha-1 for individuals ≥ 10 cm gbh） indicated logging of mature sal trees in the past. Conclusions： The ＇Khasi hill sal＇ forest ecosystem is richer in alpha and beta diversity than most sal-dominated forests, but past logging has reduced basal area. Selective removal of small timber

关键词： Forest structure Phytosociology Floristics Beta diversity Abundance Species dispersion Populationstructure Regeneration Shorea robusto

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Tree species diversity and stand structure along major community types in lowland primary and secondary moist deciduous forests in Tripura,Northeast India

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Journal of Forestry Research 2012年第4期23卷 553-568页

作者： Koushik Majumdar uma shankar Badal Kumar Datta Plant Taxonomy and Biodiversity Laboratory Department of BotanyTripura UniversitySuryamaninagar-799130TripuraIndia Ecosystem Research Laboratory Centre for Advanced Studies in BotanySchool of Life ScienceNorth-Eastern Hill UniversityShillong-793022MeghalayaIndia

Tree species diversity and population structure at different community types were described and analyzed for primary and secondary lowland moist deciduous forests in Tripura. Overall 10,957 individual trees belonging to 46 family, 103 genera and 144 species were counted at ≥30 cm DBH （diameter at breast height） using 28 permanent belt transects with a size of 1 ha （10 m × 1000 m）. Four different tree communities were identified. The primary forests was dominated by Shorea robusta （mean density 464.77 trees.ha^-1, 105 species） and Schima wallichii （336.25 trees.ha^-1, 82 species）, while the secondary forests was dominated by Tectona grandis （333.88 trees.ha^-1, 105 species） and Hevea brasiliensis （299.67 trees.ha^-1, 82 species）. Overall mean basal area in this study was 18.***.ha^-1; the maximum value was recorded in primary Shorea forest （26.21 m2.ha^-1）. Mean density and diversity indices were differed significantly within four different communities. No significant differences were observed in number of species, genera, family and tree basal cover area. Significant relationships were found between the species richness and different tree population groups across the communities. Results revealed that species diversity and density were increased in those forests due to past disturbances which resulted in slow accumu- lation of native oligarchic small tree species. Seventeen species were recorded with 〈2 individuals of which Saraca asoka （Roxb.） de Wilde and Entada phaseoloides （L.） Men＇. etc. extensively used in local ethnomedicinal formulations. The present S. robusta Gaertn dominated forest was recorded richer （105 species） than other reported studies. Moraceae was found more speciose family instead of Papilionaceae and Euphorbiaceae than other Indian moist deciduous forests. Seasonal phenological gap in such moist deciduous forests influenced the population of Trachypithecus pileatus and capped langur. The analysis of FIV suggested a slow trend of shifting the population of Lamiaceae group by Moraceae species

关键词： diversity and stand structure moist deciduous forest species conservation tree community types

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Finite-size-effect on a very large length scale in NBT-based lead-free piezoelectrics

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Journal of Advanced Dielectrics 2019年第5期9卷 35-41页

作者： Anupam Mishra Dipak Kumar Khatua Gobinda Das Adhikary Naveen Kumar uma shankar Rajeev Ranjany Department of Materials Engineering Indian Institute of Science Bangalore-560012 India

Na_(0.5)Bi_(0.5)TiO_(3)-based lead-free piezoelectrics are considered for potential replacement of the lead-based commercial piezoceramics in high-power transducer applications.We have examined the role of grain size in influencing the structural-polar inhomogeneity of stoichiometric and off-stoichiometric Na_(0.5)Bi_(0.5)TiO_(3)(NBT),and its morphotropic-phase-boundary(MPB)derivative 0.94Na_(0.5)Bi_(0.5)TiO_(3)-0.06BaTiO_(3)(NBT-6BT).Our study reveals that size effect comes into play in these systems on a very large length scale(on the scale of microns)considerably affecting its global structure and properties.

关键词： Lead-free piezoelectrics Na_(0.5)Bi_(0.5)TiO_(3) size effect crystal structure depolarization temperature

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Trusted Cluster-Based Communication for Wireless Sensor Network Using Meta-Heuristic Algorithms

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Computer Systems Science & Engineering 2023年第5期45卷 1935-1951页

作者： Pankaj Kumar Sharma uma shankar Modani Department of Computer Engineeing Mahila Engineering CollegeAjmerIndia Department of E&C Engineering Engineering CollegeAjmerIndia

The mobile transient and sensor network’s routing algorithm detects available multi-hop paths between source and destination nodes.However,some methods are not as reliable or trustworthy as expected.Therefore,finding a reliable method is an important factor in improving communication security.For further enhancement of protected communication,we suggest a trust cluster based secure routing(TCSR)framework for wireless sensor network(WSN)using optimization algorithms.First,we introduce an efficient cluster formation using a modified tug of war optimization(MTWO)algorithm,which provides loadbalanced clusters for energy-efficient data transmission.Second,we illustrate the optimal head selection using multiple design constraints received signal strength,congestion rate,data loss rate,and throughput of the node.Those parameters are optimized by a butterfly optimal deep neural network(BO-DNN),which provides first-level security towards the selection of the best head node.Third,we utilize the lightweight signcryption to encrypt the data between two nodes during data transmission,which provides second-level security.The model provides an estimation of the trust level of each route to help a source node to select the most secure one.The nodes of the network improve reliability and security by maintaining the reliability component.Simulation results showed that the proposed scheme achieved 45.6%of delivery ratio.

关键词： Trust model WSN secure routing cluster formation load-balanced clusters

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Energy Efficient Load Balancing and Routing Using Multi-Objective Based Algorithm in WSN

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Intelligent Automation & Soft Computing 2023年第3期35卷 3227-3239页

作者： Hemant Kumar Vijayvergia uma shankar Modani Department of Electronics&Communication Engineering Govt.Mahila Engineering CollegeAjmerRajasthanIndia Department of Electronics&Communication Engineering Govt.Engineering CollegeAjmerIndia

In wireless sensor network(WSN),the gateways which are placed far away from the base station(BS)forward the collected data to the BS through the gateways which are nearer to the BS.This leads to more energy consumption because the gateways nearer to the BS manages heavy trafﬁc load.So,to over-come this issue,loads around the gateways are to be balanced by presenting energy efﬁcient clustering approach.Besides,to enhance the lifetime of the net-work,optimal routing path is to be established between the source node and BS.For energy efﬁcient load balancing and routing,multi objective based beetle swarm optimization(BSO)algorithm is presented in this paper.Using this algo-rithm,optimal clustering and routing are performed depend on the objective func-tions routingﬁtness and clusteringﬁtness.This approach leads to decrease the power consumption.Simulation results show that the performance of the pro-posed BSO based clustering and routing scheme attains better results than that of the existing algorithms in terms of energy consumption,delivery ratio,through-put and network lifetime.Namely,the proposed scheme increases throughput to 72%and network lifetime to 37%as well as it reduces delay to 37%than the existing optimization algorithms based clustering and routing schemes.

关键词： Wireless sensor network(WSN) load balancing clustering routing beetle swarm optimization(BSO)

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应用电阻率和纵波速度估算印度Mahanadi盆地海洋沉积物天然气水合物饱和度

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海洋地质 2015年第3期31卷 1-17页

作者： uma shankar Michael Riedel 康冬菊不详广州海洋地质调查局矿产所

2006年，印度在国家天然气水合物计划（NGHP）第一航次钻探中于Mahanadi盆地东部大陆边缘发现了天然气水合物。对所获取的岩心进行红外成像分析证实了该区水合物主要以多层分散赋存。本文利用孔隙水化学分析、电阻率测井和声波速度测井... 详细信息

2006年，印度在国家天然气水合物计划（NGHP）第一航次钻探中于Mahanadi盆地东部大陆边缘发现了天然气水合物。对所获取的岩心进行红外成像分析证实了该区水合物主要以多层分散赋存。本文利用孔隙水化学分析、电阻率测井和声波速度测井来估算Mahanadi盆地三个站位（NGHP-01—08，NGHP-01—09和NGHP-01—19）的天然气水合物饱和度。利用孔隙水氯离子浓度异常估计位于天然气水合物稳定带底界（BGHSZ）之上海底200m以下的水合物饱和度最高为10％，利用电阻率测井和声波速度测井建模这两种方法估算的水合物饱和度值之间具有可比性，估算的值均在10％～15％之间变化。本文还对研究区的地震反射数据进行了分析，以识别天然气水合物存在的证据。该地区的BSR深度变化范围在海底以下200~300m之间，这取决于Mahanadi盆地的水深。基于区域地震资料发现天然气水合物存在与否与深水水道堤坝沉积复合体有关（尤其是在NGHP—01—19站位）。但是每个站位的取心或录井剖面都显示砂组分稀少，这就造成了水合物饱和度不会很高。从地震振幅时间切片来看，Mahanadi盆地所有钻孔均分布在河道体系陡坡地段中，而砂体绕过该地段沉积，所以推断重要的砂体沉积很可能出现在滑坡较远的地段，而从地震数据中可以推断出该较远地段沉积体系为典型的扇形沉积，因此可以预想在该较远地区可能存在更多的天然气水合物。

关键词：天然气水合物 Mahanadi盆地电阻率测井 Archie分析 P波速度测井岩石物理模型天然气水合物饱和度

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Lithospheric Structure Model of Central Indian Ocean Basin Using Ocean Bottom Seismometer Data

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Journal of Earth Science and Engineering 2012年第6期2卷 344-359页

作者： Pasupuleti Prasada Rao Sanjeev Rajput Bhaskarbhatla Ashalatha uma shankar Kalachand Sain Maradani Simhadri Naidu Vuyyuru Triveni Naresh Kumar Thakur CSIR-National Geophysical Research Institute Hyderabad 500007 lndia Commonwealth Scientific and Industrial Research Organization Perth 6151 Australia

The intense deformation zone in the central Indian Ocean, south of Indian continent is one of the most complex regions in terms of its structure and geodynamics. The deformation zone has been studied and debated in 1990s for its genesis. It was argued that deformation is mainly confined to sedimentary and oceanic crustal layers, while the large wave length geoidal anomalies, on which the deformation region lies, called for deeper sources. The inter connection between deeper and the shallower sources is found missing. The current study focuses on the complexities of this region by analyzing OBS (ocean bottom seismometer) data. The data acquired by five OBS systems along a 300 km long south-north profile in the CIOB (central Indian Ocean basin) have been modeled and the crustal and sub-crustal structure has been determined using 2-D tomographic inversion. Four subsurface layers are identified representing the sediment column, upper crustal layer, lower crustal layer and a sub-crustal layer (upper mantle layer). A considerable variation in thickness as well as velocity at all interfaces from sedimentary column to upper mantle is observed which indicates that the tectonic forces have affected the entire crust and sub-crustal configuration. The sediments are characterized by higher velocities (2.1 km/s) due to the increased confining pressure. Modeling results indicated that the velocity in upper crust is in the range of 5.7-6.2 km/s and the velocity of the lower crust varies from 7.0-7.6 km/s. The velocity of the sub-crustal layer is in the range of 7.8-8.4 km/s. This high-velocity layer is interpreted as magmatic under-plating with strong lateral variations. The base of the 7.0 km/s layer at 12-15 km depth is interpreted as the Moho.

关键词：岩石圈结构模型海底地震仪印度洋盆地大地水准面异常复杂性分析上地壳变形区

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Effect of Digital and Financial Awareness of Household Womens on the Use of Fin-Tech in India: Observing the Relation with (Utaut) Model

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Journal of Sustainable Business and Economics 2022年第3期5卷 18-26页

作者： uma shankar Yadav Ravindra Tripathi Mano Ashish Tripathi Department of Humanities and Social Sciences Motilal Nehru National Institute of Technology AllahabadPrayagrajIndia

Era of COVID-19 resulted in contactless transactions and extensive use of technological applications.Similar was the case of Fin-Tech which has extensively been used by consumers all around the globe for making transactions and other financial and economic needs.Although there is a lack of research to reflect these forms of evidence from the developing as well as Indian sides of the globe.On the other side,some studies indicated the Unified Household Acceptance and Use of Technology(UTAUT)model as the base to prefer mobile methods of transaction and Fin-Tech use.Hence this paper has been developed systematically to relate the financial literacy of household females from Generation Y with the use of Fin-Tech during the eve of COVID-19.For devising this relationship research has been induced with the UTAUT model and data have been collected from married household females between twenty-four to thirty-five years of age.Results were analyzed through SMART-PLS which highlighted the financial literacy of Indian household females has a significant association with UTAUT model.However,the entire UTAUT model does not have a significant relationship with the use of Fin-Tech.

关键词： SMART-PLS Fin-Tech COVID-19 Household females UTAUT model&financial awareness

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