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.

     

A systematic review of the relationship between urban forest quality and socioeconomic status or race

The quantity of urban forests in cities is critical for biodiversity conservation and human health, and is known to be distributed unequally. Increasingly, the quality of urban forests are also being recognised as shaping the benefits they provide. Previous studies and reviews have demonstrated that the quality of urban green spaces is associated with patterns of inequality as measured by socio-economic status and race (in the U.S). This study extends this body of knowledge to urban forests by systematically reviewing the urban forest literature (that explicitly study the urban forest) exploring the relationship between urban forest quality and both socio-economic status and race. Two academic databases (SCOPUS and Web of Science) were systematically searched. A total of 2012 papers were screened and 21 articles were included in this study. Almost all studies (20/21) found evidence of inequality, with at least one significant association between measures of urban forest quality and socio-economic status or race. However, 6 studies found contrasting patterns, with lower socioeconomic status areas having higher urban forest quality. There was variation in the type of ‘urban forest’ studied, and variation in the ways both urban forest quality and socio-economic status were measured, making inter-study comparisons difficult. Interestingly, the literature was geographically diverse, and future research could continue to focus on countries in Africa, South America and Asia with diverse needs for and uses of urban forests. In conclusion, this review finds evidence for inequity in the distribution of urban forest quality. Future research that more clearly describes the urban forests being studied and that explores sociocultural variation in perceived quality would allow better generalisation and understanding of forest quality patterns.     

Green infrastructure practices for improvement of urban air quality

Green Infrastructure (GI) practices have shown to be promising in mitigating the air pollution in urban areas of several cities across the world. GI practices such as trees, green roofs and green walls are widely used in United States and Europe to mitigate the air pollution. However, there is yet limited knowledge available in identifying the most suitable GI strategy for an urban area in improving the air quality. Furthermore, it is evident that Australia is still lagging behind in adapting GI to mitigate air pollution, compared with US and Europe. Therefore, this study analyzed the air quality improvement through several GI scenarios consisting of trees, green roofs and green walls considering a case study area in Melbourne, Australia by using the i-Tree Eco software. The results were compared with case studies in different cities across the world. The results showed that the i-Tree Eco software can be successfully applied to an Australian case study area to quantify the air quality improvement benefits of GI. The results were further assessed with several environmental, economic and social indicators to identify the most suitable GI scenarios for the study area. These indicators were quantified using different methods, to assess the effectiveness of different GI scenarios. The results showed that, trees provided the highest air pollution removal capability among the different GI considered for the study area. Combination of different GI such as green roofs and green walls with trees did not provide a significant increment of air quality improvement however, has provided more local benefits such as building energy savings. The results obtained from this study were also beneficial in developing policies related to future GI applications in major cities of Australia for the air quality improvement.     

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。     

Shade factors for 149 taxa of in-leaf urban trees in the USA

Shade factors, defined as the percentage of sky covered by foliage and branches within the perimeter of individual tree crowns, have been used to model the effects of trees on air pollutant uptake, building energy use and rainfall interception. For the past 30 years the primary source of shade factors was a database containing values from 47 species. In most cases, values were obtained from measurements on a single tree in one location. To expand this database 11,024 shade factors were obtained for 149 urban tree species through a photometric process applied to the predominant species in 17 U.S. cities. Two digital images were taken of each tree, crowns were isolated, silhouette area defined and shade factors calculated as the ratio of shaded (i.e., foliage and woody material) pixels to total pixels within the crown silhouette area. The highly nonlinear relationship between both age and diameter at breast height (DBH), and shade factor was captured using generalized additive mixed models.We found that shade factors increased with age until trees reached about 20 years or 30 cm DBH. Using a single shade factor from a mature tree for a young tree can overestimate actual crown density. Also, in many cases, shade factors were found to vary considerably for the same species growing in different climate zones. We provide a set of tables that contain the necessary values to compute shade factors from DBH or age with species and climate effects accounted for. This new information expands the scope of urban species with measured shade factors and allows researchers and urban foresters to more accurately predict their values across time and space.     

Investigating the relationship between various measuring methods for determination of establishment success of urban trees

Establishment is a key concept in urban forestry but it is currently inconsistently defined and measured. Thus, several different methods are being used to determine establishment success but their consequences and applications are rarely discussed. With this paper we would like to stimulate an increased discussion regarding these concepts both in relation to a theoretical definition but also to their practical use. The problem was approached through an experiment using sweet cherry (Prunus avium L.) and northern red oak (Quercus rubra L.) trees and the most common methods used for determination of establishment success. The trees were studied during the first three years after transplant and the association between the different measuring methods was examined. A Principal Component Analysis showed that terminal and lateral shoot length were strongly correlated, and that midday- and pre-dawn shoot water potential, and stomatal conductance were strongly correlated. We developed an index for nightly recovery of water status, which showed that terminal shoot growth was not related to nightly recovery until the third year after transplanting. Our results suggest that successful tree establishment is determined differently depending on which method is used for determination but that the differences might decrease with time. The lack of a firm definition of the term establishment may complicate communication, both within the scientific community and in practice.     

A rapid urban site index for assessing the quality of street tree planting sites

Urban trees experience site-induced stress and this leads to reduced growth and health. A site assessment tool would be useful for urban forest managers to better match species tolerances and site qualities, and to assess the efficacy of soil management actions. Toward this goal, a rapid urban site index (RUSI) model was created and tested for its ability to predict urban tree performance. The RUSI model is field-based assessment tool that scores 15 parameters in approximately five minutes. This research was conducted in eight cities throughout the Midwest and Northeast USA to test the efficacy of the RUSI model. The RUSI model accurately predicted urban tree health and growth metrics (P < 0.0001; R² 0.18–0.40). While the RUSI model did not accurately predict mean diameter growth, it was significantly correlated with recent diameter growth. Certain parameters in the RUSI model, such as estimated rooting area, soil structure and aggregate stability appeared to be more important than other parameters, such as growing degree days. Minimal improvements in the RUSI model were achieved by adding soil laboratory analyses. Field assessments in the RUSI model were significantly correlated with similar laboratory analyses. Other users may be able to use the RUSI model to assess urban tree planting sites (<5 min per site and no laboratory analyses fee), but training will be required to accurately utilize the model. Future work on the RUSI model will include developing training modules and testing across a wider geographic area with more urban tree species and urban sites.     

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。     

套袋黄冠梨果面褐斑病发生的气象因子分析

本文根据近些年来套袋黄冠梨果面褐斑病发生情况,结合相关气象因子资料,综合分析得出,套袋黄冠梨果面褐斑病的发生与高湿低温有密切关系,降雨是诱导发病的关键气象因子：     

Integrating community gardens into public parks: An innovative approach for providing ecosystem services in urban areas

When planned coherently, urban green spaces have the potential to provide cities with a range of unique ecosystem services that support ecosystem and human health. This paper draws on existing green space planning literature to argue that the integration of community gardens into standardised and previously under-utilised public park landscapes represents an innovative approach to providing ecosystem services. Particular focus is given to the challenges facing green space planning in Perth, Western Australia. At an individual level, community gardens provide a venue for an alternative and more accessible form of physical activity – gardening – and a restorative park environment that is a more attractive destination for neighbourhood walking. At the community level, gardens can facilitate bridging interactions between different social groups, whilst providing opportunities for local residents to participate actively in green space planning processes. Perhaps most importantly, community gardens can provide unique opportunities for environmental education that lead to enhanced local ecological outcomes. The paper concludes with a brief overview of the main challenges likely to be faced with this integration, and some strategies that may allow them to be overcome. It is hoped this paper will provide a background for future case studies, and a catalyst for increasing integration between formal green space planning and community garden development.     

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。     

Evaluating the supply-demand relationship for urban green parks in Beijing from an ecosystem service flow perspective

The mismatch between the spatial patterns of urban green parks (UGP) and population in urban areas is a common phenomenon in Chinese cities and elsewhere. Whether and to what extent such mismatch may impact the realization of Ecosystem Service (ES) provided by the former remain unclear. Stemming from the Ecosystem Service Flow (ESF) perspective, this paper argues that the distance-decay effects and spatial heterogeneity in the propagation process of the ESF with different conveyors may render the various types of ES demonstrating different location sensitivity in both provision and realization terms. We then present an “is-ought” framework for analyzing the supply-demand relationship of ES, which features deductively obtained ES provision potential and empirically observed ES realization, both are spatially explicitly mapped. Refined ontological and distance-decay modeling methods and mobile signaling data were introduced to implement the framework taking Beijing as a case. For the two typical types of ES in urban environments, the recreational and thermoregulating services, we find that there indeed exists under- or over-supply of ES along the center-periphery gradient of the city. The findings have policy implications for the planning and management of UGP.     

试论猕猴桃科普与果实品质提升的重要性

自1978年以来,猕猴桃在我国商业化研发和种植已超过40年,种植面积和产量均已位居世界第一,但果实品质良莠不齐,很难与国外果品比拼。根据多年的从业经验并结合国内外产业考察及技术咨询中的问题进行总结,探讨了我国目前猕猴桃果实品质整体水平不高的主要原因:猕猴桃作为雌雄异株栽培的果树,果农及大部分管理者对其栽培技术缺乏了解导致盲目引种、措施落实不到位、技术应用缺乏针对性和创新不足、社会化服务与供给侧改革不完善、品牌意识淡薄、缺乏市场引导机制与消费者需求信息等方面,都是从不同层面影响到猕猴桃果实品质的主要因素。猕猴桃产业发展和果实品质提升是一个系统性工程,统筹和协调控制好与果实品质相关的主要因子,促成猕猴桃果实内部品质的整体提升,才能"管"出高品质的猕猴桃,引导产业向纵深发展。     

Bioculturally valuable but not necessarily worth the price: Integrating different dimensions of value of urban green spaces

The social processes that took place in the past left a mark not only on cultural heritage but also on ecosystems and biodiversity, which is now depicted in the concept of biocultural diversity. The related “biocultural value” represents yet another dimension of the value of urban green spaces which we attempt to integrate into monetary valuation with the use of hedonic pricing. We compare the impacts of different green spaces on property prices in Łódź, Poland, differentiating green spaces based on their biocultural value. Furthermore, we use quantile regression and analyze the heterogeneity of estimates according to the price of the apartment. Our study indicates that while there is a general desire to live close to the green space, biocultural value does not translate into any positive impact on property prices.     

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:     

不同生境下橘小实蝇种群消长规律及其与气象要素的相关性

【目的】弄清常绿和落叶果树两种不同生境下橘小实蝇种群消长规律及其与气象要素相关性,为制定针对性强及有效的综合防控措施提供参考依据。【方法】采用性信息素诱捕的动态监测法,2015—2017年调查常绿和落叶果树两种不同生境橘小实蝇种群消长规律,采用SPSS软件分析其与旬均最高气温、旬均最低气温、旬均气温,旬均降雨量和旬均日照时数5个气象要素相关性。【结果】在常绿果树柑橘园和落叶果树月柿园内,1—2月最冷月份均可诱到少量雄成虫,并表现出1—2月诱虫量多的年份当年的诱虫总量也多,当年橘小实蝇可能会大发生;两种不同生境下橘小实蝇的始盛期、盛发期和盛末期基本一致,多数年份分别在5月中下旬、5月下旬至11月中下旬和12月上中旬;旬均最高气温和旬均最低气温是影响两种生境下橘小实蝇种群消长规律最重要的气象因子。【结论】常绿和落叶果树两种不同生境下橘小实蝇种群消长规律相似。冬季诱捕虫量多的年份,当年橘小实蝇可能会大发生;旬均最高气温和旬均最低气温是影响两种生境下橘小实蝇种群消长规律最重要的气象因子。     

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.