Characteristics and motivations of potential users of urban allotment gardens: The case of Vila Nova de Gaia municipal network of urban allotment gardens

Demand for urban allotment plots has recently increased in Portugal but little is known about the characteristics and motivations of the demanding population, and if and how its characteristics affect its motivations.In this article, we use the Municipal Network of Urban Allotment Gardens (MNUAG)¹ launched by the Portuguese municipality of Vila Nova de Gaia for an exploratory Case Study research. Based on the data collected in the MNUAG application forms submitted in the period 2012–2013, we describe the characteristics and the motivations of the population demanding for urban allotment gardens (UAG)² and run a logit model to find if and how the motivations are influenced by the characteristics.The population of applicants to the MNUAG is quite diverse. It has a balanced gender distribution and an average age of 47 years. Most of the applicants are between 25 and 64 years old, and belong to households with 2–4 members.To supplement family budget, occupation of leisure times, and access to organic farming are its most important motivations, followed by environmental concerns, the practice of physical exercise, and education.Motivations are influenced by the characteristics. This study has identified two groups of applicants with contrasting motivations. Food security is the only significant motivation for the unemployed and low-income applicants. Food safety, health concerns, environmental concerns, recreation, and education are common and frequent motivations among the upper and intermediate professional groups.Results can have future implications on the MNUAG, namely on the UAG location and typology, plot number, and plot size. To meet the demand of all the types of applicants, while fostering social cohesion, the municipality should reinforce its current small UAG structure and add to the MNUAG one or two productive parks.     

Incorporating local ecological knowledge into urban riparian restoration in a mountainous region of Southwest China

Modern cities use straightened and concrete watercourses with simple greening for riparian zones, which has been criticised for insensitivity to natural system integrity and cultural identity. This increases the challenge to urban ecologists, landscape designers and managers to conceive innovative and effective design solutions that do not jeopardise hydraulic efficiency yet are culturally acceptable to local communities. This paper introduces the field of local ecological knowledge (LEK) as rich sources of inspiration and design solutions to meet this challenge. LEK refers to knowledge and practices of various local cultures about the relationship of living beings (including humans) with their environments. Wepropose a pragmatic framework that integrates LEK with modern landscape design. It includes steps: (1) investigate existing practices, skills andmeasures relating to LEK; (2) explore how and whereLEKcan inspire or integrate withdesign. Here we propose three aspects for integration in accordance with the nature of landscaping process: overall structure, component and maintenance.(3)evaluate and test the integration in terms of its acceptability by local communities. Taking the riparian revegetation project of Hanfeng Lake Urban Wetland Park (Chongqing Municipality) as an example, we illustrate the utility of this framework. 11 local common practices relating to LEK were identified. According to thethree aspects for integration, alternative design solutions were offered. The survey showed that LEK based designwas more highly valued than other conventional ways in terms of useracceptance. We conclude that LEK provides actionable ecologically sound and culturally desirablesolutions for urbanlandscape. We also recognise that LEK evolveswith changing environments and new harmonious and dynamic human-nature relationships arecontinually re-forming. The process of acquisition and application of LEK could encourage multidisciplinary and synthetic approaches to urban ecosystems. Such adaptability and interdisciplinary engagementare crucial totoday’schanging and complexurban environments.     

Two faces to the greenery on housing estates–mitigating climate but aggravating allergy. A Warsaw case study

Interest in the climate and an awareness of the beneficial cooling influence exerted on it by biologically-vital areas is growing, as climate change progresses, hot weather is more frequent as well as the urban heat island more intense. It is necessary to protect existing greenery in the cities and to introduce new planting. However plants in a warmer climate can produce larger amounts of pollen and are more readily able to initiate an allergic reaction among those prone to them. That means—not every greenery is advantageous for humans in the cities. In the research two housing estates built at different times and differ in type, density and age of buildings, as well as in the composition and the percentage of biologically vital area and the species planted were examined. Detailed inventory of tall greenery entailed the trees and shrubs and next their assumed allergenic potential was made. Cooling effect likely is derived from the difference in greenery, but the other factors such as differences in the density of buildings and spatial organization of the estate could also influence it. The older estate with the ratio of biologically vital areas of 54.3% is characterised by more favourable local climate than the newer estate, with the ratio of biologically vital areas equals 40.7% and young vegetation. On the newer one the perceptible thermal conditions did not differ significantly compared with the city centre. Unfortunately, on Koło Estate trees creating mild thermal conditions are also the trees promoting allergies most severely: birches, poplars and limes. And they are planted usually around playgrounds and kindergarten. The trees of high allergenicity should be partially removed, even risking small worsening thermal conditions.     

Influence of tree crown characteristics on the local PM10 distribution inside an urban street canyon in Antwerp (Belgium): A model and experimental approach

Apart from influencing the amount of leaf-deposited particles, tree crown morphology will influence the local distribution of atmospheric particles. Nevertheless, tree crowns are often represented very rudimentary in three-dimensional air quality models. Therefore, the influence of tree crown representation on the local ambient PM₁₀ concentration and resulting leaf-deposited PM₁₀ mass was evaluated, using the three-dimensional computational fluid dynamics (CFD) model ENVI-met^® and ground-based LiDAR imaging. The modelled leaf-deposited PM₁₀ mass was compared to gravimetric results within three different particle size fractions (0.2–3, 3–10 and >10 μm), obtained at 20 locations within the tree crown. Modelling of the LiDAR-derived tree crown resulted in altered atmospheric PM₁₀ concentrations in the vicinity of the tree crown. Although this model study was limited to a single tree and model configuration, our results demonstrate that improving tree crown characteristics (shape, dimensions and LAD) affects the resulting local PM₁₀ distribution in ENVI-met. An accurate tree crown representation seems, therefore, of great importance when aiming at modelling the local PM distribution.     

Estimation of urban tree canopy cover using random point sampling and remote sensing methods

Trees play an important role in urban areas by improving air quality, mitigating urban heat islands, reducing stormwater runoff and providing biodiversity habitat. Accurate and up-to-date estimation of urban tree canopy cover (UTC) is a basic need for the management of green spaces in cities, providing a metric from which variation can be understood, change monitored and areas prioritised. Random point sampling methods, such as i-Tree canopy, provide a cheap and quick estimation of UTC for a large area. Remote sensing methods using airborne Light Detection And Ranging (LiDAR) and multi-spectral images produce accurate UTC maps, although greater processing time and technical skills are required. In this paper, random point sampling and remote sensing methods are used to estimate UTC in Williamstown, a suburb of Melbourne, Australia. High resolution multi-spectral satellite images fused with LiDAR data with pixel-level accuracy are employed to produce the UTC map. The UTC is also estimated by categorising random points (a) automatically using the LiDAR derived UTC map and (b) manually using Google Maps and i-Tree canopy software. There was a minimum 1% difference between UTC estimated from the map derived from remotely sensed data and only 1000 random points automatically categorised by that same map, indicating the level of error associated with a random sampling approach. The difference between UTC estimated by remote sensing and manually categorised random point sampling varied in range of 4.5% using a confidence level of 95%. As monitoring of urban forest canopy becomes an increasing priority, the uncertainties associated with different UTC estimates should be considered when tracking change or comparing different areas using different methods.     

A citywide survey of the pine processionary moth Thaumetopoea pityocampa spatial distribution in Orléans (France)

There is a growing recognition that urban trees provide various valuable benefits and services such as enhanced human wellbeing. However, they also have a cost in terms of public health either directly (allergies) or by harboring species representing health risk for humans. This paper focuses on such a forest insect species, the pine processionary moth Thaumetopoea pityocampa. Its caterpillars develop gregariously during winter in a conspicuous silk nest in coniferous hosts. When disturbed, the larvae release urticating hairs that cause human or animal serious health problems. The purpose of our survey was to (1) inventory all individual trees belonging to potential host species and estimate the density of T. pityocampa (2) assess the spatial pattern of the insect population at the city scale. We conducted an exhaustive inventory of potential coniferous host trees in five municipalities (ca. 5000 ha) in the north of Orléans, France. Each tree was identified, geo-referenced and the number of moth nests it hosted was counted. A total of 9321 urban trees representing 11 coniferous taxonomic units were investigated. The distribution of T. pityocampa exhibited a marked spatial structure citywide. Geostatistics allowed to draw risk maps revealing strong patchiness. We provide the first estimate of T. pityocampa host tree preference in an urban context and found that Pinus nigra, P. pinaster and P. sylvestris were the most attacked trees. We also report numerous cases of T. pityocampa occurrence on the exotic ornamental Himalayan cedar Cedrus deodara. The management implications of our findings are two-fold: (1) risk maps constitute a useful framework for communication and public information, and can help developing control strategies; (2) some species frequently used for ornamental purposes are poor quality hosts regarding T. pityocampa and should therefore be preferred in public place usually frequented by vulnerable people (schools, nurseries, hospitals).     

城市沿河不同垂直结构绿带四季温湿效应的研究

选择北京北五环清河两侧不同垂直结构类型的绿地作为研究对象,利用小尺度定量测定技术方法,分析城市河流廊道绿地不同垂直结构绿地的温湿效应,为河流廊道绿带的建设提供科学依据。结果表明:春、夏、秋3季具有降温增湿效应,其中夏季降温增湿效应最强,春、秋2季降温增湿效应差别不大;绿地的降温增湿能力与环境温度相关,3季日间降温增湿效应最强时段均在环境温度最高时段的14:00-16:00。春、夏、秋3季不同结构绿地类型降温增湿幅度排序为乔-灌-草>乔-草>灌-草>草地,而冬季绿地除草地外,其余3种绿地均具有保温降湿效应,其中乔-灌-草绿地保温降湿效应最强,乔-草和灌-草型绿地差别不大;草地在冬季表现为降温增湿效应。     

基于生态理念的蚌埠黑虎山景区规划探析

城市边缘风景名胜区是城市大环境绿化的龙头,对改善城市生态环境具有重要意义。以蚌埠黑虎山景区规划为例,在概述黑虎山景区现状及发展优劣势的基础上,提出了基于生态理念的城市边缘风景名胜区的规划思想和方法,以期为城市边缘风景名胜区的建设和发展提供思路。     

广州市主要湖泊沉积物磷的赋存形态

以广州市主要城市湖泊为研究对象,从环境地球化学角度阐明沉积物中磷的总量、主要赋存形态与其潜在释放风险和环境效应的内在联系,为广州市城市湖泊环境特征评估及后续的生态修复提供基础数据和理论支撑。2016-2017年对广州市8个主要城市湖泊花都湖、白云湖、东山湖、流花湖、天河湖、海珠湖、荔湾湖、麓湖表层沉积物的总磷（TP）及各形态磷的含量与分布特征进行研究,并运用单因子污染指数法和生物有效性指数法对沉积物磷污染程度进行评价。结果表明：广州市湖泊表层沉积物TP含量为368～5 276 mg/kg,平均3 277 mg/kg,其含量分布特征表现为东山湖>白云湖>花都湖>流花湖>天河湖>荔湾湖>麓湖>海珠湖。TP中以无机磷（IP）为主要存在形式,占TP含量的67.56%～87.44%,IP中又以铁结合态磷（Fe-P）为主,占TP含量的32.77%～60.24%,均值为42.88%。相关分析表明TP与Fe-P和有机磷OP,Fe-P与De-P,Ca-P与OP呈显著的正相关关系,表明其来源的相似性。通过分析可将广州市湖泊分为受珠江干流直接影响、接纳河涌入水、相对...     

基于可控邻域作用元胞自动机模型的城市扩张模拟

提出了一种城市元胞自动机（CA）模型,使用二分Logistic回归从历史数据中挖掘位置特征变量对元胞状态转换的影响,引入邻域因子,实现了可控邻域作用。采用该模型对长沙市区及部分周边地区的城市扩张进程进行了模拟和预测,并对预测结果进行了评价。