Spatially targeting the distribution of agricultural input stockists in Malawi

Developing the rural agricultural input markets in sub-Saharan Africa can improve the current low productivity of smallholder farmers. Malawi has seen significant efforts in addressing the availability of agricultural inputs at village level in the last few years; for example, the improvement of rural agro-dealer networks. Nevertheless inputs are still difficult to obtain for many remote smallholder farmers. Spatial analysis can help in the expansion of input stockists, especially agro-dealer networks, by assessing the coverage of existing input outlets and deriving optimum locations for village-level input stockists.We address three research questions. First, what is the locational efficiency of the current village-level stockists of inputs (Citizens Network for Foreign Affairs – Rural Agricultural Market Development Trust trained network of agro dealers and public sector)? Secondly, how many village-level stockists of markets are needed to reach 60% of the population in the central region of Malawi within one hour? Finally we address the potential spatial components of the sustainability of input stockists relating to the potential demand from smallholder farmers and the access to bulk supplies. The problem of finding the optimum location for village-level stockists of markets is addressed in two stages, using spatial analysis in conjunction with location–allocation models. First, the locational efficiency of the existing network of stockists of inputs is determined, followed by the establishment of a set of optimal sites for village-level stockists of inputs. A final step explores the viability of stockists and calculates the population surrounding the stockists taking into account competition from other sources of inputs and the accessibility of the selected stockists to potential wholesalers who are bulk distributors of farm inputs.Our results show that locational efficiency can be assessed in terms of the differential access of households to resources and transport. Often, these differences are not considered in covering problems and can have a large effect on the physical access to inputs. The results can be used to define which areas are inherently difficult to serve with agricultural inputs and could inform efforts to provide incentives to remote areas. Further implications for input policies in Malawi are that improvements in road infrastructure might not directly benefit the poorest farmers (if they are walking) but could serve to reduce the wholesale prices and therefore the retail price. In addition, the improvement in roads might increase the number of potential customers of any particular stockist, with economies of scale allowing the reduction of prices while ensuring a satisfactory profit margin for the stockist. The results of our models imply that Citizens Network for Foreign Affairs may need to train stockists over a wider area to increase the access to inputs of those smallholder farmers with least resources.     

广州公园绿地使用率研究--以广州烈士陵园和番禺新造镇公园为例

公园绿地是城市典型的开敞空间,对维护城市生态和人居环境健康、绿化和美化城市环境、加强市民间交往、营造平等和谐的社会气氛有着重要意义。公园绿地使用率体现了城市对居民的服务水平。文章运用实地考察、抽样调查、访问分析等手段,分析广州市公园绿地的使用率,并以广州起义烈士陵园和番禺新造镇公园为例进行说明。结果表明：可达性和安全性分别是影响中心城区和郊区公园绿地使用率的最主要因素。     

Behavioural response of a trophic specialist, the Iberian lynx, to supplementary food: Patterns of food use and implications for conservation

Prey scarcity compromises population survival, especially for specialist predators. Supplementary feeding is a management tool that can be applied to reverse the decline of food-limited populations. We analyse how a population of Iberian lynx, a threatened food specialist, initially reacted to, and subsequently used, supplementary food. Twenty-seven feeding stations (FS) with domestic rabbits were placed in the Doñana Biological Reserve, SW Spain, between 2002 and 2005. We recorded lynx tracks inside and around stations to analyse spatio-temporal patterns of use, as well as the performance of several station designs. Iberian lynx used 62% of the FS installed, and consumed most of the supplied food. All station designs were used and food provision apparently covered the energetic needs of the lynx inhabiting the reserve. There was spatial aggregation in the use of the FS. Fourteen weeks were needed on average for lynx to become familiar with feeding stations and making a regular use of the supplementary food. Seasonal variations in consumption frequency appeared to be modulated by fluctuations of wild rabbit numbers throughout its annual cycle as well as by variation in energy demand of breeding females. The Iberian lynx responded positively to our supplementary feeding programme. We show that this technique allows the persistence of lynx populations during long periods in areas where wild rabbits are extremely scarce. Supplementary food may be used to sustain lynx whenever rabbit populations need recovery, as well as in the context of lynx restocking or reintroduction programmes.     

The green walk—An analysis for evaluating the accessibility of urban green spaces

The importance of urban green spaces in providing ecosystem services to the population is increasingly being recognised by scientists, policy makers and the general public. Across cities, urban planners are seeking to reconcile the location of urban green spaces and accessibility of the public. The main aim of our paper is to assess the accessibility of urban green spaces and to identify perceived benefits along the travel route to urban green spaces, starting from a selected case study in Romania. We started from a spatial analysis of a service area for an urban park in Bucharest (Tineretului). With the help of network analyst in ArcGis Pro we established the boundaries of the service area (using urban park boundaries, street network, traffic restrictions) and applied two methods of travel to the park (walking and cycling). We applied a survey to 202 respondents, collecting information on the routes and methods of reaching the park, as well as the perceived benefits and disservices of selecting the preferred method and route. The main results revealed different patterns delimited by a number of criteria: age (elder population preferred public transport and shaded routes), income (people with higher incomes selected travelling by car and accessing elements with parking facilities), group structure (people with children selected routes perceived as safe). This type of analyses can represent useful instruments for urban planners in developing and managing urban green spaces in close relation with neighbouring spaces and facilities.     

Public green spaces and human wellbeing: Mapping the spatial inequity and mismatching status of public green space in the Central City of Shanghai

Public green spaces are fundamental and indispensable to urban settlements, given the diverse social, economic and environmental benefits that they can provide. However, the absence of knowledge regarding the allocation and access status quo consistently hinders the suitability and rationality of follow-up green space planning, which could eventually impair the livability and sustainability of cities. This study evaluates disparities in access to public green space for urban residents and the spatial mismatches among public green space provision, residents’ visits and the demands of socially vulnerable groups within the Central City of Shanghai. The results show that disparities in public green space accessibility exist pertaining to social status and household composition status. Sub-districts with higher social status or larger proportions of family households composed by children and married inhabitants tend to have better public green space access. In contrast, sub-districts with larger proportions of aged or unemployed populations unexpectedly show worse public green space access. To a certain degree, this reduced access can be considered to be an environmental injustice. Additionally, the mismatches among public green space provision, residents’ visits and the demands of socially vulnerable groups are observed to vary in space, indicating potential problems of resource shortage, supply-demand mismatch, underuse and congestion. The findings could offer urban planners and policy-makers insights into optimizing public green space resources and equitably providing proximal public green space to urban residents, especially vulnerable groups, such as children, the elderly and the unemployed.     

Connectivity in Heterogeneous Landscapes: Analyzing the Effect of Topography

Animal response to landscape heterogeneity directs dispersal and affects connectivity between populations. Topographical heterogeneity is a major source of landscape heterogeneity, which is rarely studied in the contexts of movement, dispersal, or connectivity. The current study aims at characterizing and quantifying the impacts of topography on landscape connectivity. We focus on ‘hilltopping’ behavior in butterflies, a dispersal-like behavior where males and virgin females ascend to mountain summits and mate there. Our approach integrates three elements: an individual-based model for simulating animal movements across topographically heterogeneous landscapes; a formula for the accessibility of patches in homogenous landscapes; and a graphical analysis of the plots of the simulation-based vs. the formula-based accessibility values. We characterize the functional relationship between accessibility values and landscape structure (referred to as ‘accessibility patterns’) and analyze the influence of two factors: the intensity of the individuals’ response to topography, and the level of topographical noise. We show that, despite the diversity of topographical landscapes, animal response to topography results in the formation of two, quantifiable accessibility patterns. We term them ‘effectively homogeneous’ and ‘effectively channeled’. The latter, in which individuals move toward a single summit, prevails over a wide range of behavioral and spatial parameters. Therefore, ‘channeled’ accessibilities may occur in a variety of landscapes and contexts. Our work provides novel tools for understanding and predicting accessibility patterns in heterogeneous landscapes. These tools are essential for linking movement behavior, movement patterns and connectivity. We also present new insights into the practical value of ecologically scaled landscape indices.     

Impacts of Accessibility on TOD: Measurement of Accessibility Around Transit Stations of Addis Ababa,Ethiopia

Today Transit-Oriented Development (TOD) is used as a tool to create a livable urban environment by improving the integration between land-use and transportation systems.The capital city of Ethiopia,Addis Ababa,aims to promote a sustainable transportation system by launching its first Light Rail Transit (LRT) network.Mitigate the need for mass transport,congestion,make transit a better choice,and encourage local economic development.Hence,a method was introduced to analyze the spatial and statistical conditions of accessibility on the existing transit stations of Addis Ababa.The methodology proposed measured the impact of accessibility around the existing TOD by defining a criterion that establishes the accessibility level[5-6].These criteria included proximity,urban densities,land-use diversity,and design of the urban spaces.The urban form of a place depends on accessibility.Mobility changes the character of a place.If the place changes,accessibility is likely to change.Therefore,TOD features that directly correlated with accessibility along the rail-based train stations will be explored.     

基于GIS的城市公园可达性分析

研究以城市公园分类图、道路图和水系图为基础数据资料,在遥感（RS）和地理信息系统（GIS）技术支持下,运用空间可迭性的概念与原理,采用费用加权距离方法,对南昌市的公园绿地空间分布特征、可达性及其原因进行分析,生成公园可达性的时间等值圈图,通过对生成图表的分析得知：南昌市公园绿地分布不均衡,不太合理;公园可达性较好,存在一定的差异,昌北可迭性优于昌南;居民需驾车前去的公园少。城市绿地可达性分析是衡量城市绿地服务功能社会公平性的有力手段,因此,它将丰富我国城市绿地评价的核心指标体系,亦可为城市规划者和建设者合理规划与布局城市绿地提供科学的依据和参考。     

四川省生态旅游发展问题浅析

通过对四川省生态旅游发展过程中几个焦点问题的探讨，阐述关于生态旅游的含义、生态旅游资源开发、景区控制以及可进入性的看法。     

The choice of target site is crucial in artificial miRNA-mediated virus resistance in transgenic Nicotiana tabacum

MicroRNAs (miRNAs) are negative regulators of gene expression via mRNA degradation or translational repression. The potential of artificial miRNAs (amiRNAs) as antiviral agents has been used in plant biotechnology. In this study, we designed eight amiRNAs derived from Potato Virus Y (PVY) Coat Protein RNA sequences and generated transgenic tobacco plants to express these amiRNAs to confer virus resistance against PVY. Together with transient assays, the hairpin amiRcp precursors that mimic natural miRNA precursor molecules proved to be effective in expressing amiRcps and silencing the target gene. Virus resistance assay revealed that not all amiRcps targeting viral CP sequence are equally effective in preventing PVY infection. Plants with amiRcp-8 targeting the 3′ end (nt735–nt754) region exhibited high virus resistance up to 64.69%. The amiRcp-6 harboring RNA sequence (nt567–nt586) induced the lowest percentages with only 17.05%. Besides, northern blots showed that there was a correlation between the resistance level and the accumulation of amiRNA expression. Furthermore, we used bioinformatics approach to predict the mRNA structure and found that targeting sequences of loose structure benefit to improve the virus resistance level. Our results indicate that the selection of appropriate target sequence is crucial for transgenic plant against virus and provide useful guideline for the design of pathogen-derived amiRNAs.