From quantity to quality: enhanced understanding of the changes in urban greenspace

Landscape Ecology - Accurately quantifying changes in urban greenspace (UG) is the prerequisite for understanding ecosystem service. In addition to quantifying the “real” change of UG,...     

Towards a better mechanistic understanding of edge effects

Context

Predicting and managing edge effects requires an understanding of the mechanisms that drive them. However, analytical methods that dominate edge effects research are not well suited to discriminating mechanisms, because they do not measure ‘indirect’ edge effects: effects that are mediated by covariates in statistical models.

Objective

To discuss the value of indirect effects for improving mechanistic understanding of edge effects.

Methods

We explain how measuring indirect effects improves mechanistic understanding, and provide guidance on how to do so. We also conduct a literature review to examine awareness of indirect effects in empirical studies of mechanisms underpinning edge effects. Finally, we use a recent paper in Villaseñor et al. (Landscape Ecol 30:229–245, 2015) as a case study to discuss how failure to measure indirect edge effects may limit mechanistic understanding.

Results

Indirect effects provide a means to translate conceptual models of edge effects into mechanistic pathways that are testable and quantifiable. Moreover, failure to measure indirect edge effects can result in impacts of habitat edges being underestimated. However, few studies that we identified in our literature review quantified indirect effects (7 %, n = 72). Worryingly, 11 % of studies did not account for indirect effects despite using statistical models that potentially contained them, possibly resulting in incorrect inference.

Conclusions

A better awareness of indirect effects will help researchers to understand the mechanisms that underpin edge effects, while ensuring that impacts of habitat edges are not underestimated.

     

杏雌蕊败育与主要气象因子的关系分析

对杏雌蕊败育与主要气象因子关系的研究表明:杏雌蕊败育率与上年8月的降水量穴x2雪及休眠期低于7.2℃的时数(x13)呈显著的负相关;与休眠期的绝对最低温有正相关趋势,但未达到显著水平;与上年7月、9月的降水量、上年11月、12月的绝对低温及当年2月、3月的最大温差等关系都较小。2个杏品种串枝红与鸡蛋杏的雌蕊败育率与气象因子的逐步回归方程分别为1=207.307-0.468x2-0.0395x13;2=148.103-0.333x2-0.0282x13;由于本试验数据来自干旱的内陆地区山西,可能研究结果不一定适合降水较多的其他地区。     

影响胶东半岛酿酒葡萄着色的气象因素分析

为了探索影响酿酒葡萄着色的气象因素,以胶东半岛16个酿酒葡萄主产县市2016年及2017年7、8、9月的气象资料为素材,重点分析了葡萄转色、成熟期的日照时数、阴天数及降雨量等情况,以期找出2017年酿酒葡萄着色不良的主导原因。结果表明:2017年与2016年相比葡萄着色不佳与转色期的日照时数降低、连阴天增加有一定关联,3个月中以7月各县市日照时数下降幅度最大,相比2016年同期平均下降56.6h,其中招远和龙口锐减达90 h,同比减少均达35%,且以处于转色期的7月下旬降幅最大,减少均超过50 h,8月依然延续了寡照趋势,9月光照明显改善甚至优于2016年同期。2017年连阴天峰值由往年的8月提前到7月,平均达11.8d,较2016年同期增加4.2 d。2017年夏季除了蓬莱、高密及乳山降雨量增加较少外,其他县市7月或8月降雨量均极大超过2016年同期,其中招远、莱阳、牟平7、8月连续降雨,超过2016年同期最高达4.5倍。相反,胶东半岛超过35℃的高温天数较少且集中于7月,而9月日较差≥10℃的天数7个县市多于2016年同期,且内陆县市多于沿海县市。综合判断2017年7、8月光照不足、连阴天增加及降雨量大,有可能是影响当年酿酒葡萄普遍着色不良的主导因素。配合其他因素进一步进行生态因素的研究有助于为酿酒葡萄栽培技术改良提供依据。     

现代园林绿化与城镇规划建设的关系及应用

阐述了现代园林的基础知识,并通过对园林绿化生态效益的分析,概括了现代园林绿化的新概念及在城镇规划中的作用,并浅析如何在城镇中进行现代生态园林绿化的应用。     

探究城市森林公园建设对提升象山城市品位的意义

建设城市森林公园,打造环境优雅、风光奇特、空气清新、景色宜人、树木花草万紫千红的生态景观,是象山新时代发展的必然趋势。经探索研究,象山县可因地制宜打造一个集休闲、健身、生态、文化、游乐、度假于一体的城市森林公园。     

影响葡萄贮藏质量的几个要素

近年来,随着葡萄贮藏保鲜技术的大面积开发,葡萄保鲜业发展迅速,为广大果农带来了可观的经济效益,但并非都获得令人满意的效果。根据本人多年调查和体会,认为有几个关键的技术环节直接影响葡萄的贮藏质量。1、栽培技术方面葡萄贮藏性能的好与坏,首先取决于其本身的质量,而质量是由栽培管理水平决定的。所以,要提高葡萄的贮藏性能,必须改善栽培管理。目前看,主要有如下几个问题:     

Quantifying the relationship between urban forms and carbon emissions using panel data analysis

Carbon emissions are increasing in the world because of human activities associated with the energy consumptions for social and economic development. Thus, attention has been paid towards restraining the growth of carbon emissions and minimizing potential impact on the global climate. Currently there has also been increasing recognition that the urban forms, which refer to the spatial structure of urban land use as well as transport system within a metropolitan area, can have a wide variety of implications for the carbon emissions of a city. However, studies are limited in analyzing quantitatively the impacts of different urban forms on carbon emissions. In this study, we quantify the relationships between urban forms and carbon emissions for the panel of the four fastest-growing cities in China (i.e., Beijing, Shanghai, Tianjin, and Guangzhou) using time series data from 1990 to 2010. Firstly, the spatial distribution data of urban land use and transportation network in each city are obtained from the land use classification of remote sensing images and the digitization of transportation maps. Then, the urban forms are quantified using a series of spatial metrics which further used as explanatory variables in the estimation. Finally, we implement the panel data analysis to estimate the impacts of urban forms on carbon emission. The results show that, (1) in addition to the growth of urban areas that accelerate the carbon emissions, the increase of fragmentation or irregularity of urban forms could also result in more carbon emissions; (2) a compact development pattern of urban land would help reduce carbon emissions; (3) increases in the coupling degree between urban spatial structure and traffic organization can contribute to the reduction of carbon emissions; (4) urban development with a mononuclear pattern may accelerate carbon emissions. In order to reduce carbon emissions, urban forms in China should transform from the pattern of disperse, single-nuclei development to the pattern of compact, multiple-nuclei development.     

Indigenous and spontaneous vegetation: their relationship to urban development in the city of Leeds, UK

The concepts of indigenous and spontaneous vegetation are considered as subsets of the broader category, semi-natural vegetation. Indigenous vegetation is conceptualised as that which has originated in a rural landscape and developed over a time period of several centuries or more, either naturally or as a result of traditional management methods, together with the environmental conditions supporting it. In contrast, spontaneous vegetation is that which has naturally colonised derelict urban sites, mainly within the last century. An investigation, using map and aerial photographic data, examined the relative proportions of potentially indigenous and spontaneous vegetation on proposed development sites in Leeds, a large industrial city in the UK. Results suggested that spontaneous vegetation occupied approximately 13% by area of the development sites while possible indigenous vegetation occupied as little as 5%. However, further analysis suggested that approximately 25% of the proposed development sites were within 0.5 km of a designated site containing indigenous vegetation. It is argued that both types of semi-natural vegetation can make positive contributions to the urban environment but that public perception of spontaneous vegetation and, in particular, the locations where it occurs, are often negative. Further research into public perceptions of semi-natural vegetation and ways of incorporating it into urban development are required.     

Species richness of urban forest patches and implications for urban landscape diversity

The vascular plant species richness of upland urban forest patches in St. Paul and Minneapolis, Minnesota, was found to be positively related to their size. There was no significant relationship between species richness and the distance of these patches to other patches. Mowing and trampling reduced species richness of patches, whereas planting increased richness. Landscape richness can be maintained at a relatively high level by leaving even small unmown forested patches within a more disturbed matrix. However, maximizing landscape diversity would require leaving large forest stands unmown. It is suggested that cultivation be deliberately used as a mechanism for increasing native species richness in urban forests.     

Effects of urban parks on the local urban thermal environment

Air temperatures in and outside of 60 parks in Taipei city were surveyed to study the effect of different urban parks on their surrounding thermal gradients. Results suggest that the factors governing the temperature of park surroundings are not identical to those of park interiors. Air-temperature gradients surrounding urban parks are influenced by both the horizontal transport of cool or warm air mass above parks and the evapotranspirative air-parcels from trees, creating a cool island larger than the boundaries of cool-island parks, a heat-island larger than the boundaries of strong heat-island parks, and a cool-ring outside weak heat-island parks. Such horizontal air movement is not easily detected using remotely sensed data. During daytime, the thermal environment within a park is dominated by the amount of solar input absorbed by unshaded paved area, which, when strong, can overflow to increase the temperatures of park surroundings; at night, despite park trees causing a warming effect inside parks, park surroundings are cooled by horizontal flow of evapotranspirative air-parcels from park trees. In business and other districts used mostly during daytime, it is recommended that parks and other open spaces be designed with less than 50% paved area and at least 30% trees, shrubs, and other shadings. In residential districts that are used mostly during nighttime, parks and other open spaces are recommended to be designed with more trees. Night irrigation, a measure commonly recommended for the conservation of water, is also recommended to further enhance this nighttime cooling.     

库尔勒香梨外观品质影响因素研究

研究了树冠不同结果部位、果实饱满种子数和盛花期喷布植物生长调节剂对库尔勒香梨外观品质的影响。结果表明,果实饱满种子数与库尔勒香梨果形有关,果实脱萼洼顶、平均单果重113.0g、果形指数1.15,是库尔勒香梨果实的理想指标;相比于树冠顶部,树冠下部的库尔勒香梨果实较理想,以树冠下部东面为最佳结果部位;盛花期喷布多效唑、乙烯利有利于生产理想果实,建议不喷布赤霉素、吡效隆和生长素。     

Optimising the organic components of topsoil mixtures for urban grassland

In order to optimise the organic components of topsoil mixtures for urban grassland, we conducted two pot experiments, each with seven topsoil mixtures and perennial ryegrass (Lolium perenne) as the experimental crop. The mineral base material of the topsoil mixtures was a blend of crushed bedrock (0–2 mm), sand and agricultural topsoil. The organic components comprised three types of organic waste-based products (WBP), namely sewage sludge (SS), water sludge (WS) and garden-park compost (GPC), which were added in varying ratios to a total amount of 0.3 m³ WBP m^?3. In both experiments, mineral nitrogen (N) availability was the key limiting factor for plant growth. Plant growth increased with increasing amounts of the N-rich SS, whereas WS and/or GPC alone resulted in sparse biomass production. Topsoil mixtures with 0.1 m³ m^?3 each of SS, WS, GPC or with 0.1 m³ SS m^?3 and 0.2 m³ WS m^?3 resulted in favourable growth patterns and acceptable soil chemical properties. Topsoil mixtures containing ≤0.1 m³ SS m^?3 can therefore be recommended for the establishment of urban grassland. With >0.1 m³ SS m^?3, N and phosphorus (P) were applied in excess, causing intensive plant growth and strongly increased readily available phosphorus (P-AL) content in topsoil. We therefore suggest revision of the current Norwegian regulations, which permit inclusion of 0.3 m³ SS m^?3 in topsoil mixtures for urban greening.     

Selection of trees for urban forestry in the Nordic countries

Trees in the urban environment are subjected to a number of stresses which are very different from those suffered by trees in typical rural conditions. The stresses listed in this paper should be a basis for the selection criteria used in urban tree improvement programs. The basic properties of trees are climatic adaptation, disease resistance and a large phenotypic plasticity. Properties related to the urban situation are related to stresses caused by social factors, the restrictive soil volume and crown space, soil pollution, air pollution, de-icing salt, wind and drought. In addition, aesthetic factors, growth form and growth potential and resistance to breakage of limbs are important selection criteria. The priority ranking of the selection criteria depends on the environment wherein the plants are to be used. The need to broaden the range of species and cultivars planted in Nordic cities should have high priority, and selection programs should, therefore, include new species of urban trees. A practical selection should be made within the four major Nordic climatic regions, which are the northern maritime, northern continental, southern maritime and southern continental regions. The establishment of broad co-operation in the selection of plant materials for urban uses is discussed.     

A semantic model for assessing the experience of urban biodiversity

Biodiversity is a significant element of our everyday experience of urban environments, though it is generally only perceived subconsciously. Thus, there is a need to develop a method for defining and measuring experienced biodiversity. As a first step towards such a method, a semantic test was presented to a group of 102 participants. The test consisted of a form containing words/expressions selected as possible components of biodiversity. The participants rated the words on a five-grade scale, and the form was completed at six different study sites. Statistical analyses indicated that words with biological content were strongly correlated with biodiversity, as were words associated with wilderness and variation. Correlations with words of preference were less strong. Following factor analysis, a biodiversity experience index was calculated based on the factor loadings of words strongly correlated with biological diversity. The index was then calculated for all six sites. It was suggested that the index, by measuring words/expressions with higher linguistic codability, offers a valuable tool for assessing experienced biodiversity. It was further concluded that areas containing spontaneous vegetation and water obtained higher biodiversity index scores than did areas characterized by a short-cut lawn and more uniform vegetation.     

High temperatures and time to budbreak in low chill apricot ‘Palsteyn’. Towards a better understanding of chill and heat requirements fulfilment

The efficiency of different temperature cycles in inducing budburst of one-year-old shoots of the apricot cultivar ‘Palsteyn’ from dormancy was evaluated. Three replications of shoots were collected during two consecutive years from adult trees, following the accumulation of different amounts of chilling in the field. Thereafter, shoots were exposed to different temperature cycles in growth chambers, for 60 days. The temperature treatments included a continuous temperature of 5 °C; daily temperature cycles of 19/5 h at 5/15 °C, at 5/20 °C, and at 5/25 °C; and the same temperature cycles for the remainder of the 60-day period, after pretreatment at 5 °C for 30 or 45 days. After the temperature treatments, shoots were forced at 25 °C until budburst. The mean time to budburst (MTB) (in days) of lateral vegetative, terminal vegetative and reproductive buds was evaluated. The efficiency of the different treatments was greatly influenced by the date on which shoots were cut. High temperatures had a more positive effect on the reduction of MTB when chilling accumulation had occurred in the field instead of the growth chamber. After partial chilling accumulation in the field, high temperatures (25 °C) combined with low temperatures are more efficient than cycles of moderate temperatures (15 or 20 °C) to induce an earlier budburst. In view of these results, a parallel accumulation of both chilling and heat requirements after partial chilling accumulation is suggested. The application of these results could assist in the development of more accurate models for the prediction of the overcoming of dormancy and blooming.     

Components of small urban parks that predict the possibility for restoration

In densifying cities, small green spaces such as pocket parks are likely to become more important as settings for restoration. Well-designed small parks may serve restoration well, but earlier research on restorative environments does not provide detailed information about the specific components of the physical environment that support restoration. In this study we assessed the extent to which hardscape, grass, lower ground vegetation, flowering plants, bushes, trees, water, and size predicted the judged possibility for restoration in small urban green spaces. We took individual parks as the units of analysis. The parks were sampled from Scandinavian cities, and each park was represented by a single photo. Each photo was quantified in terms of the different objective park components and also rated on psychological variables related to restoration. The ratings on the psychological variables being away, fascination, likelihood of restoration, and preference were provided by groups of people familiar with such parks. The variables most predictive of the likelihood of restoration were the percentage of ground surface covered by grass, the amount of trees and bushes visible from the given viewing point, and apparent park size. Formal mediation analyses indicated distinctive patterns of full and partial mediation of the relations between environmental components and restoration likelihood by being away and fascination. Our results provide guidance for the design of small yet restorative urban parks.     

The effects of cultural factors on yield and curd quality of autumn cauliflower

The effects of six cultural treatments on (a) marketable yield, (b) percentage marketable plants and (c) percentage perfect quality curds produced, were studied on representative varieties of three groups of autumn cauliflower in experiments carried out over a period of five years. The treatments included a comparison of the use of graded and ungraded seed, transplanting and direct-drilling of the crop, different transplant ages, selection for uniformity at planting or thinning time, and plant density and nitrogen levels during the early seedling stage of growth.

In general the yields and quality of drilled and transplanted crops were similar with all varieties each year and neither the use of graded seed nor the nitrogen treatments had any significant effect on yield or curd quality. Both increasing plant density in the seedbed and increasing age of transplant caused a reduction in yield on most occasions. The effects of the treatments on yield and quality are discussed in relation to their effects on the maturity characteristics of the crops.     

Evaluating the potential for urban heat-island mitigation by greening parking lots

Artificial urban land uses such as commercial and residential buildings, roads, and parking lots covered by impervious surfaces can contribute to the formation of urban heat islands (UHIs), whereas vegetation such as trees, grass, and shrubs can mitigate UHIs. Considering the increasing area of parking lots with little vegetation cover in Nagoya, Japan, this study evaluated the potential for UHI mitigation of greening parking lots in Nagoya. The relationships between land surface temperature (LST) and land use/land cover (LULC) in different seasons were analyzed using multivariate linear regression models. Potential UHI mitigation was then simulated for two scenarios: (1) grass is planted on the surface of each parking lot with coverage from 10 to 100% at an interval of 10% and (2) parking lots are covered by 30% trees and 70% grass. The results show that different LULC types play different roles in different seasons and times. On average, both scenarios slightly reduced the LST for the whole study area in spring or summer. However, for an individual parking lot, the maximum LST decrease was 7.26 °C in summer. This research can help us understand the roles of vegetation cover and provide practical guidelines for planning parking lots to mitigate UHIs.