检索结果-南通市图书馆

Plant physiological changes along an encroachment gradient: an assessment of US Mid-Atlantic serpentine barrens

Journal of Plant Ecology 2018年第6期11卷 853-865页

作者： Nicole A.Havrilchak Jessica L.Schedlbauer Department of Biology West Chester University750 S.Church StreetWest ChesterPA 19383USA

Aims Serpentine barrens of the Mid-Atlantic United States are globally rare,grass-dominated ecosystems thought to exclude C3 spe-cies and characterized by unique soil ***,like many grassland ecosystems globally,these sites are presently facing encroachment by surrounding *** this ecosystem,the tendril climbing vine,Smilax rotundifolia,forms dense thickets around bar-rens that typically precede forest *** numerous factors speculatively initiate and promote encroachment in these systems,few studies have examined photosynthetic responses of serpentine grasses to changes in resource availability initiated by encroachers or physiological ability of encroaching *** to colonize high-light barren *** sought to under-stand both environmental and physiological dynamics of encroach-ment along an irradiance gradient in these *** At three serpentine barren sites in southeastern Pennsylvania,physiological responses of the native grasses Sorghastrum nutans and Schizachyrium scoparium to increased shading by ***-folia were ***,the physiological performance of *** in the forest understory was compared to that in sunlit barrens ***-saturated photosynthesis(A_(sat)),stomatal conductance(g_(s)),instantaneous transpiration efficiency(ITE),maximum efficiency of photosystem II(F_(v)/F_(m)),midday leaf water potential(ψ_(leaf))and specific leaf area(SLA)were measured for all species over the course of the 2014 growing ***-way analyses of variance were used to assess changes in these param-eters across growing environments,as well as seasonally for each *** regression analyses were also performed to inves-tigate the influence of vapor pressure deficit(D)and leaf tempera-ture(T_(leaf))on A_(sat) and *** Findings Light-saturated photosynthesis was significantly greater in ***-difolia growing in sun than in the shade(P<0.001)and early in th

关键词： encroachment photosynthesis serpentine barren Schizachyrium scoparium Smilax rotundifolia Sorghastrum nutans

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Research on the supply chain encroachment strategy of high quality manufacturer

Research on the supply chain encroachment strategy of high q...

引用

第32届中国控制与决策会议

作者： XU Qian LV Yi-fan HUANG Fu SONG Hua-ming School of Economics and Management Nanjing University of Science ＆ Technology

ISBN: (数字)9781728158556

ISBN: (纸本)9781728158563

This paper explores the best encroachment mode of entrant who produce high-quality product,and analysis the impact of encroachment on the incumbent,the impact of the service on the members of the supply *** analyzing the equilibrium solution of wholesale price,selling price and profit which between the two competing products under different *** results show that the encroachment of high-quality product will force incumbent to lower the wholesale price and selling ***,the service level of the incumbent does not *** the entrant sells product through retailer,it harms the interests of the incumbent manufacturer,but it will benefit the *** the entrant sells directly,there exists a Pareto *** best encroachment mode of entrant to encroach depends on the combined impact of the degree of the quality difference,the production cost and the direct selling cost.

关键词： supply chain encroachment quality difference service

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

encroachment of the Buriganga River in Bangladesh

引用

Journal of Minerals and Materials Characterization and Engineering 2017年第5期5卷 266-273页

作者： Swarnali Mahmood Fatema Tuz Johra Nourin Ayesha Siddika Tazeen Fatima Khan Institute of Water and Flood Management Bangladesh University of Engineering and Technology Dhaka Bangladesh Department of Soil Water and Environment University of Dhaka Dhaka Bangladesh

A survey on different aspects of Buriganga River encroachment was conducted in a 300 meter long encroached part of the river located in Dhaka, Bangladesh. A total of 100 respondents were surveyed and three Focus Group Discussions (FGDs) were arranged prior to the semi-structured questionnaire survey. It was observed that almost all of the respondents migrated to the study area. The majority of the respondents had better business opportunity (69.23%) as the cause of encroachment. Significant portions of the respondents occupying the encroached area were found to be landless (36.84%), small businessmen (31.58%) and people with political affluence (26.32%). Major portions (23.33%) of the encroached land were used for industrial development as well as housing and developmental projects. Negative health impact (40%) was found to be the main adverse effect of encroachment of the river. Other adverse effects included economic loss through obliteration of fisheries (35.71%), scarcity of clean water (32.14%), reduction of aesthetic value of the surroundings (25%) etc. For the protection of the river, the majority of the respondents opted for relocation of the industries (46.15%) and enforcement of strict rules and regulations (38.46%).

关键词： Buriganga River encroachment Respondents Questionnaire Survey

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

The Impact of encroachment on the Distribution of Tree Species in Cross River National Park, Oban Division, Nigeria

引用

Journal of Environmental Protection 2015年第7期6卷 744-754页

作者： Margaret A. Yaro Department of Urban and Regional Planning Cross River University of Technology Calabar Nigeria

Increasing human activities around protected area pinpoint to looming degradation and alteration of the component of such areas, especially where adequate measures are not taken to forestall encroachment. The Oban division of the Cross River National Park is one of the oldest rainforests and has been identified as a biodiversity hotspot. However, communities settling around the park have been involved in some economic activities for their livelihood. Resource utilization at the edge of the park may alter the components of the park such as species diversity. Therefore this study is geared towards assessing the impact of human encroachment and the concomitant impact on the distribution of species within the park. The study adopted participatory research methods which included Focus Group Discussion and participatory mapping as well as a plot based survey which involved the laying of sample plots within two zones of the park designated as areas bounded by cultivated land and areas bounded by fallow. Three 40 m × 40 m square plots are laid along a 320 meter transect measured from the boundary of the park at each buffer zone. The plots are separated by 100 m gap. From the result obtained, it is discovered that Musanga cercropoides dominates the outer plots of the cultivated zones and fallow zones comprising 20.2 and 21.5 percent respectively while Terminalia ivorensis dominates the middle and inner areas of the park. Moreover the composition of species decreases inward to the inner part of the park. Diversity index decreases in the order of 2.566 < 2.348 < 2.163 at the cultivated zones and 2.443 < 2.376 < 2.366 at the fallow zones. It is concluded that human activities close to the park alters the species composition of the park. Hence, it’s recommended that adequate alternatives livelihood and incentive be provided to support zone communities to reduce their dependents on the edge of the park.

关键词： Park encroachment Impact Diversity Colonizers Zones

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Modeling and Mapping Sand encroachment Risk as an Aid for Urban Planning in the United Arab Emirates (UAE)

引用

Journal of Geographic Information System 2018年第6期10卷 699-717页

作者： Naeema Alhosani Department of Geography and Urban Planning College of Humanities and Social Sciences United Arab Emirates University Al Ain UAE

Sand encroachment into urban areas represents a high risk factor for transportation infrastructural and urban development in the United Arab Emirates. The UAE is located in one of the world’s largest arid regions with a strong prevalence of sand movement and encroachment into urban areas, particularly in the last few years. The objective of this research is to develop a land surface process platform that models sand movements and further generates an encroachment risk index map of potential encroachment risk areas season-wise in the UAE. To achieve this objective, this research used elevation and land cover maps generated from Lands at 8 Operational Land Imager (OLI) data which represent the topography of the study area coupled with meteorological information on wind speed, temperature and precipitation. Furthermore, the study considered the vegetation cover as a major contribution factor to reduce sand encroachment. Using developed sand movement model for this research, sand encroachment risk maps were generated to help urban planners in cities making informed decisions of future urban protection structures and transportation networks that mitigate the effects of sand dunes encroachments in the UAE. A major finding of this research results conclude that during the summer season encroachment risk reaches 30% higher compared to the winter season due to the extremely high temperature which leads to reduced vegetation in the country. Urban planning decision maker may consider the finding of this research for future infrastructural adjustments.

关键词： Aeolian Sand Lands at 8 OLI Sand encroachment Transportation Vegetation Temperature

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Gas Exchange Rates of Texas Persimmon (Diospyros texana) in Central Texas Woodlands

引用

American Journal of Plant Sciences 2024年第5期15卷 329-348页

作者： Matthew B. Grunstra Oscar W. Van Auken Department of Integrative Biology University of Texas at San Antonio San Antonio TX USA

Diospyros texana (Texas persimmon) is a secondary species in most Juniperus ashei/Quercus fusiformis woodlands in central Texas. It has high density, but plants are mostly in the community understory. Light response curves at ambient and elevated levels of CO2 and temperature were measured for D. texana. The Anet (photosynthetic rate) increased significantly as both light level and CO2 levels increased but not temperature. The Amax (maximum photosynthetic rate) of D. texana in full sun at elevated levels of CO2 was increased for all treatments. Stomatal conductance increased with levels of CO2 but only if the interaction was removed from the model. Intercellular levels of CO2 increased with both temperature and CO2 treatments as did water use efficiency (WUE). Furthermore, light saturation (Lsat) increased with CO2 treatments and light compensation (Lcp) increased with temperature. The dark respiration (Rd) increased with both temperature and CO2 treatments. Markov population models suggested D. texana populations would remain ecologically similar in the future. However, sub-canopy light levels and herbivory should be considered when examining population projections. For example, Juniperus ashei juveniles are not recruited into any canopy unless there are high light levels. Herbivory reduces the success of Quercus juveniles from reaching the canopy. These factors do not seem to be a problem for D. texana juveniles which would allow them to reach the canopy without need of a high light gap and are not prevented by herbivory. Thus, Juniperus/Quercus woodlands will change in the future to woodlands with D. texana a more common species.

关键词： Replacement Dynamics Ecological Succession CO2 Concentrations Temperature Levels Photosynthetic Rates Drought Tolerance Herbivory Species Replacement encroachment Juniper

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Variations in soil properties and native woody plant species abundance under Prosopis juliflora invasion in Afar grazing lands, Ethiopia

引用

Ecological Processes 2020年第1期9卷 411-422页

作者： Abeje Eshete Anna C.Treydte Mengsteab Hailemariam Negasi Solomon Tatek Dejene Zewdu Yilma Emiru Birhane Central Ethiopia Environment and forestry Research Center(CEEFRC) Ethiopian Environment and Forestry Research Institute(EEFRI)P.O.Box 30708Addis AbabaEthiopia Agroecology in the Tropics and Subtropics University of HohenheimStuttgartGermany Biodiversity Conservation and Ecosystem Management Nelson Mandela African Institution of Science and TechnologyArushaTanzania School of Life Sciences and Bioengineering Nelson Mandela African Institution of Science and TechnologyArushaTanzania Department of Land Resources Management and Environmental Protection Mekelle UniversityP.O.Box 231MekelleEthiopia

Introduction:Pastoralism and agro-pastoralism are the major modes of life in arid and semi-arid ***,rangeland quality and quantity are rapidly deteriorating due to a number of natural and human-induced factors,one of which is bush *** is known on how bush encroachment affects the ecosystem functions and services expressed in terms of the native vegetation composition and structure,status of the soil seed bank,soil chemical and physical properties,and the abundance of mycorrhiza ***:We assessed woody species in 64 plots distributed across four levels of Prosopis juliflora invasion(high,medium,low,and none)at two sites,Amibara and Gewane,in the Afar Region,*** collected composite soil samples to investigate the soil seed bank,mycorrhizal associations,and spore ***:Plant biodiversity was generally low,with eight and four woody species in Gewane and Amibara,*** juliflora was dominant in highly,moderately,and lowly invaded areas while Acacia senegal dominated the non-invaded *** average number of *** individuals ranged from 3/ha at non-invaded areas in Gewane to 4200/ha at highly invaded areas in Amibara while the total individual number of native woody species ranged from 0 to 88/ha at highly and lowly invaded areas,*** population structure of trees/shrubs in all invasion areas showed an inverted J-shaped distribution,characterized by a high abundance of small *** juliflora invasion was associated with high soil OC,Na,Ca,P,bulk density,and moisture *** seed numbers and species richness were highest in the moderately and highly invaded *** sampled tree species were associated with mycorrhiza but the percentage of root length colonization by different arbuscular mycorrhizal fungus structures varied significantly(p<0.05)across invasion categories and ***:Our results revealed that although *** invasion negat

关键词： encroachment Structural and species diversity Shrubs Arbuscular mycorrhiza Rangelands

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Consumer Choice, Firm Performance and Channel Coordination in a Dual-Channel Distribution System

引用

American Journal of Operations Research 2014年第4期4卷 217-227页

作者： Wei Song Renwen Wang Yelin Fu Xiaobao Peng University of Science and Technology of China Hefei China

The expanding role of the Internet in consumer purchasing activities has created substantial new opportunities accessing to end-consumers. More and more manufacturers are beginning to sell products to potential consumers directly online while continuing to sell through the traditional brick-and-mortar retailers, a phenomenon leading to intense channel competition and conflicts. Using game theory, this research examines the effect of market segments, consumer choice and the acceptance of direct online channels on firm performance and the whole system’s profit. The analysis indicates that the addition of direct online channel does not necessarily harm the incumbent retailers. A win-win zone is proposed, in which both the manufacturer and the retailer benefit from the encroachment.

关键词： Dual-Channel encroachment Consumer Choice Win-Win Zone Game Theory Channel Coordination

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Influence of Tree Density on Vegetation Composition and Soil Chemical Properties in Savanna Rangeland of Eastern Cape, South Africa

引用

Agricultural Sciences 2021年第10期12卷 991-1002页

作者： Sive Tokozwayo Keletso Mopipi Eric Cofie Timpong-Jones Department of Rural Development & Agrarian Reform D&#246 hne Agricultural Development Institute Stutterheim Eastern Cape South Africa Department of Livestock & Pasture University of Fort Hare Alice Eastern Cape South Africa Livestock and Poultry Research Center School of Agriculture College of Basic and Applied Sciences University of Ghana Legon Ghana

The proliferation of woody species alters the vegetation structure, leading to loss of rangeland productivity. It aimed to assess the influence of tree density on vegetation and soil chemical properties at three levels of encroachment;open, moderate and dense. Each level of encroachment was replicated 3 times, a 5000 m2 plot was marked per replicate. Four belt transects 200 m2 were placed per plot. Woody species within each belt transect per replicate were identified and recorded to evaluate woody species composition. Grass species composition was assessed using a step point method. Soil was sampled per replicate and analysed for chemical properties. Results showed that 71% of grasses were increasers and 29% decreasers. Digitaria eriantha and Eragrostis obtusa were the most dominant species. Vachellia karoo and Aloe ferox were the most dominant woody species. The dense had high nitrogen (1.48%) compared to the moderate (0.23%) and the open (0.17%). Increaser species, soil carbon, soil pH increased with the increase of tree density. It was concluded that the replacement of highly palatable grasses with inferior ones was due to improper rangeland management practices. It was recommended that land users form rangeland management associations and set up conservation agreements for proper management of resources.

关键词： encroachment Composition Density Rangeland

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Impact of Controlling Shareholder Equity Pledge on Corporate Value

引用

Journal of Economic Science Research 2020年第1期3卷 55-65页

作者： Haifeng Li Haiyi He Yuanyuan Zhang Shenzhen Hi-Tech Investment Group Co. LtdChengduSichuan611130China School of Finance Southwestern University of Finance and EconomicsChengduSichuan611130China School of Securities and Futures Southwestern University of Finance and EconomicsChengduSichuan611130China

As an innovative financing behavior,equity pledge breaks the limit of traditional financing,and broadens the financing channels of companies and major *** paper comprehensively considers the impact of controlling shareholder equity pledge on corporate value from three research *** main conclusions are as follows:(1)When the equity pledge is not considered,the cash flow rights and voting rights of the company owned by the controlling shareholder are positively correlated with corporate *** is,this presents incentive effect,but the existence of the separation of the two powers brings the second type of agency problem and reduces corporate value.(2)When considering the equity pledge,the controlling shareholder’s equity pledge may weaken the incentive effect and strengthen the encroachment effect which causing a reduction of corporate value.(3)Based on the accounting point of view,the controlling shareholder’s equity pledge is negatively correlated with the corporate performance,while the concentration of ownership dilutes this negative effect.(4)The balance of equity weakens the negative effect of the controlling shareholder’s equity pledge on corporate value,thereby reduces the negative impact of the equity pledge.

关键词： Separation of powers Equity checks and balances Equity concentration Incentive effect encroachment effect

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：