全球变化背景下生物入侵对城市生态系统的影响

主要阐述生物入侵在与其他全球变化因子(如臭氧层损耗、CO2浓度增加、酸雨、土地利用方式变化等)的作用下,对城市生态系统稳定性的影响。     

我国都市农业问题研究的学术影响力分析——基于1991-2012年CNKI论文数据的分析

在党和政府高度重视都市农业问题研究的同时,越来越多的学者投入到都市农业问题的研究中,学术界对于都市农业问题的研究日益升温。基于CNKI数据库1991～2012年中关于都市农业问题研究的研究文献获得有关数据,从都市农业问题研究的年代分布、研究人员分布、研究机构分布、学术影响力、学科分布5个方面进行探讨。通过数据分析得出:都市农业问题研究的优势资源主要集中在北京和东部沿海发达省市;研究机构主要集中在高等院校;都市农业问题的研究热点主要集中在农业经济研究领域。建议应加大西部地区的资源配置与研究力度,促进西部地区都市农业问题的研究。     

草坪在城市生态系统中的作用及其应用分析

论述了草坪在城市生态系统中的作用,如改善小气候、净化大气、保持水土等。分析了目前我国城市草坪的应用现状,并对我国草坪业的发展方向进行了研讨。     

Random point sampling to detect gain and loss in tree canopy cover in response to urban densification

Urban tree canopy cover (UTC) is a simple, and common, measure of urban forest resource. Urban infill development is likely to lead to losses in UTC under private tenure, at a time when local governments are setting ambitious targets to increase UTC overall. Simple, statistically rigorous methods are required to benchmark and track change in UTC, whilst identifying which land-use types or tenures experience change.We estimated UTC in six Melbourne suburbs in 2010 and 2015 by randomly sampling 2000 points across public land, public streetscapes and private land. We were able to detect a net change in UTC of <2% over five years to a 95% level of confidence. A significant net decrease in UTC (−2.4%) was only detected in one of the six suburbs. Two suburbs had a net increase in UTC by +2.7% over five years. On private land, there was often areas of UTC loss, but this was generally offset by canopy gain in other areas of the private realm as well as in streetscapes and public land. Losses in UTC on private land were mainly due to tree removal, with or without subsequent construction works.This study describes a simple, but statistically rigorous, method to quantify UTC change and the drivers of change in different land-use types and tenure. Despite studying two suburbs will high rates of infill development, only one suburb showed evidence of net UTC decrease. The ‘dynamic equilibrium’ in UTC, whereby canopy losses area approximately offset by concurrent canopy gain, means that ambitious targets being set by local governments to increase UTC may be difficult to achieve without changes in tree protection and infill development policy and planning.     

Exploring the impact of green space health on runoff reduction using NDVI

This study examines the impact of green space health on local flooding based on the analysis of eighty-two watersheds in four Texas metropolitan statistical areas: Dallas, Houston, San Antonio, and Austin. The runoff records in October 2007 and October 2012 were selected for the assessment. The study met the methodological challenge posed by comparison by using the Normalized Difference Vegetation Index (NDVI) datasets produced based on the Moderate Resolution Imaging Spectroradiometer (MODIS) imagery of the 250-m resolution as a proxy to represent the health of green space. Two linear regression models were employed to explain the variation in mean daily runoff depth in 2007 and 2012, while controlling multiple contextual variables.Results indicate that watersheds containing healthier green spaces were likely to generate lower amounts of runoff in both periods. Standardized coefficients of green space health also show that the NDVI is a powerful and significant predictor to explain variation in runoff. These findings illustrate the important role of urban green spaces in attenuating local flooding and may provide planners and decision-makers with a method to consider, using this kind of objective greenery index in further developing local and regional green infrastructure and land-use plans.     

Urban tree growth and their dependency on infiltration rates in structural soil and structural cells

Expanding tree canopies can be difficult to achieve in built environments because urban land is costly and urban soil inhospitable to vegetation so engineered planting systems offer a potentially valuable tool for achieving sustainable urban forests. Tree water uptake, performance and root distribution were assessed in systems of structural soil and structural cell. Structural soil relies on stone and soil, it is highly porous and designed to support tree root growth and possess pavement strength. The structural cell is made up of rigid structural units with 90% void space which is to be filled with soil. To evaluate tree performance under the conditions of fill and drain regimes in structural soil and structural cell, these two systems were subjected to three simulated infiltration rates. This study was conducted in April 2015 to April 2016 in the tropical equatorial environment of South East Asia. Infiltration rate affected both biomass accumulation and rooting depth. Species and substrate effect was significant for biomass and rooting characteristics but less prominent for transpiration. Biomass was greater for trees in structural cells, and Pouteria obovata was particularly sensitive to prolonged inundation. Rooting depth was always higher in the rapid infiltration indicating the negative effects inundation had on this parameter. Root system in the structural cell was deeper while those in the structural soil were wider. Samanea saman had better adapted to the drain and fill regimes, and this was despite Pouteria obovata being a coastal species and was expected to be flood tolerant. Species and substrate effect was weak (R² ranging from 0.20 to 0.28) but moderate drainage consistently led to higher transpiration. We conclude that structural soil and structural cell are potential solutions and provide a tool to overcome suboptimal urban growing conditions. The application of these solutions will allow for seamless integration of greenery with urban infrastructure.     

2005～2009年我国城市美化植物研究文献计量分析

以《中国期刊全文数据库》为数据源,运用文献计量学的原理和方法,对2005年—2009年国内城市美化植物研究专题文献进行统计分析,探讨这些文献的文献学特征（年代、期刊源和学科方向分布,研究机构特征,科学基金资助,以及合作度与合作率状况）用以明确城市美化植物科研领域的研究能力及今后的研究重点和方向。     

以沈阳泰山路绿地为例探讨精品绿地在城市绿化中的发展

本文以沈阳泰山路绿地为例,从绿地的模式、栽植植物的种类和数量、以及绿地建成后对专业和非专业人员进行的绿地质量评价调查等多方面进行分析,得出精品绿地的建设有利于提高绿地景观水平和植物多样性,并适于在城市绿化中建设发展。     

青奥会背景下南京城市国际化的发展优势、困境与路径选择

青奥会作为一项国际性赛事对于南京提高城市影响力,进一步开发旅游资源,加快公共基础设施建设有着重要的推动作用。在筹备2014年青奥会的背景下,就南京市建设国际化都市的优势、存在问题进行了分析,并对提升城市国际化水平提出了对策建议。     

城市效应对区域雷电活动影响分析与灾害防御

为了研究城市化建设对区域雷电的影响,揭示自然环境的改变对雷电活动规律产生的变化,为不同区域雷电防护重点提供理论依据。本研究利用湖北省5个城市样本2007—2016年闪电定位资料,分析了所选样本城市城区和非城区云地闪密度以及日频、月频、季节变化、雷电流强度。结果表明：城区云地闪密度小于非城区云地闪密度,城市效应减小了城区雷电发概率;云地闪日频次分布城区波动幅度比非城区大,分时城区雷电流平均跨度值明显大于非城区,城区受到局地气候的影响较大;全年各月正闪频次占比城区均大于非城区,雷电高发的月份城区云地闪强度均大于非城区。整体来看,城市效应使城区的云地闪密度降低,强度增加,且呈现出雷电流幅值跨度大等不稳定性,相对于非城区更容易出现极端雷暴事件。