都市圈“三生空间”协同变化及其对生态系统服务的影响

[目的]“三生空间”时空变化及其对生态系统服务影响的研究可以揭示人地关系及其变化规律,为区域国土空间管控提供理论依据。[方法]本研究以典型都市圈——济南都市圈为例,分析了2000—2018年“三生空间”变化趋势,刻画了三生空间协同变化类型与特征,并评价了济南都市圈生态系统服务价值及其变化,最终揭示了“三生空间”变化对区域生态系统服务的影响。[结果]总体变化特征上,生活生产空间是唯一面积增长的“三生空间”类型,且其面积相对变化速度在各类型中最快,对应动态度为2.4%;400 245.31 hm²的生产生态空间转入生活生产空间,是生活生产空间扩张的主要来源;“三生空间”协同变化可划分为5种特征明显、空间上互不重叠的类型,包括生态—生活协同变化型,生产—生活协同变化型,生态变化主导型,三生稳定型,生活变化主导型;在各协同变化类型中,生活变化主导型区县的生态系统服务价值下降最为剧烈[-3 015.89元/(hm²·a)];在各转换类型中,生产生态空间向生活生产空间的转换对区域生态系统服务价值的不利影响最明显。[结论]研究提出了“三生空间”协同变化类型...     

局部凸空间中凸幂凝聚算子的不动点定理及其应用

首先给出了局部凸空间中一类新的算子--凸幂凝聚算子的定义,推广了Banach中的凝聚算子,并获得了这类凸幂凝聚算子的一个不动点定理.作为应用,本文建立了一类半线性发展方程的解的存在性结果.     

Planning small for winning big: Small urban green space distribution patterns in an expanding city

While major urban areas are expanding, becoming more crowded, vegetated lands areshrinking. Built-up densification limits the planning of large urban green spaces,depriving urban dwellers of the benefits provided by such structures. In this context,small public urban green spaces (SPUGS) become of high value for urban landscapes,and their distribution throughout the city should aim to compensate the lack of largergreen areas. The driving forces of SPUGS distribution may be linked to the urbanfunctions they are usually paired with.The current study aimed to determine which are the urban functions that benefit ofhigher amounts of SPUGS in their proximities and to map the distribution and densityof SPUGS within Bucharest, helping us expose the green deprived communities.Results revealed that multi-dwelling residential areas are the ones with higher share ofSPUGS within walking distance. Nevertheless, analysis on SPUGS deprivation withinthe city showed that communist planned residential neighbourhoods are greener thanthe ones developed in the past three decades. Healthcare and commercial functionswithin the city recorded smaller shares of SPUGS in their proximity, highlighting thatvulnerable groups (such as ill people) are exposed to less vegetation, and that publicplanning documents are not encouraging developers to allocate more land for greenfeature development.These results are relevant for projecting the quality of outdoor environmentsthroughout Romania’s capital and for assessing potential future managementchallenges. The outcomes of this research provide local policy makers and plannerswith the vulnerable areas in which immediate action for expanding the greeninfrastructures should take place. At the same time, the methodological approachdescribed in the study proved to be efficient in assessing the distribution of SPUGSthroughout the city and the determinants of this distribution. It can be easily replicatedin other cities by scholars and planners.     

How did the COVID-19 pandemic impact urban green spaces? A multi-scale assessment of Jeddah megacity (Saudi Arabia)

The outbreak of the COVID-19 pandemic emerged as a global public health threat. In this crisis period, urban parks provided multiple ecosystem services and direct/indirect benefits to mental and physical health. However, the use patterns, attitudes, and perceptions of urban park visitors remained unexplored in Saudi cities. This study aimed to find out the use patterns, attitudes, and perceptions of people regarding urban parks during the COVID-19 pandemic, and the findings were compared with non-pandemic periods. Two urban parks (Al Masarah Garden and Al Jamaa Garden) in Jeddah megacity (Saudi Arabia) were assessed, and 215 respondents were surveyed to fulfil the objectives of the study. The study applied a questionnaire survey and field observations to understand the impact of the COVID-19 pandemic on the use patterns, attitudes, and perceptions of urban park visitors. Non-parametric tests (Kruskal–Wallis and Mann–Whitney tests) were performed to find out the impact of sociodemographic factors (such as age, gender, and education). From the results, it was found that the COVID-19 pandemic had a substantial impact on the use, attitudes, and perceptions of urban parks in comparison with non-pandemic periods. The number of park visitors decreased during the COVID-19 pandemic, but urban parks were crucial to people’s mental and physical well-being. The findings of this study may help to understand the importance of urban parks as green spaces and to implement measures to enhance the quality and quantity of urban green spaces in Saudi cities.     

RFID-plants in the smart city: Applications and outlook for urban green management

A city may become smart and green through strategic deployment of Information and Communication Technology infrastructure and services to achieve sustainability policy objectives in which trees have to be involved. Plants not only constitute green space useful to contrast urban pollution effects or provide ecosystemic benefits to residents but they can also be used as bioindicators and their involvement in communication networks can represent a significant contribution to build a smart, green city. The concept of the Internet of Things (IoT) envisages that objects that surround us will be connected and there are no reasons to exclude urban trees from among the “wired object”. Radio frequency identification devices (RFID) may represent a prerequisite of IoT application and they can be used for tree protection and management, thanks to tagging experience carried out on various plant species. RFID tags can be easily associated with plants, externally or internally. This latter approach is particularly indicated if the identification of trees needs to be secured since its production, eliminating the risk of tag losses or removal. Interesting applications may be derived by implementing RFID tags in biomonitoring systems in order to guarantee a real-time data communication in which tags may act as antennas for multifunctional green spaces. Moreover, the virtualization of green areas using sensors and mobile devices can lead to the desktop management of the urban green with the possibility of implementing a real-time navigation throughout the areas. A complex relational network in which data can be collected thanks to geospatial methods can be integrated by an IoT approach in which RFID-plants can play a significant role.     

从H^∞到Zygmund空间的积分算子Cφ^（n,u）的特性

研究了单位圆盘上从有界解析函数空间H∞到Zygmund空间的积分算子Cφ^n,u的有界性和紧性,得到了从混合模空间到Zygmund空间的积分算子的有界性和紧性的充要条件.     

Production Parameters and Economics of Small-Scale Tilapia Cage Aquaculture in the Volta Lake,Ghana

To calculate the potential for cage aquaculture to create economic opportunities for small-scale investors on the Volta Lake, Ghana, a local NGO with technical support from the Government of Ghana ran two trials (one of four and one of six units) of small-scale cage aquaculture in the town of Dzemeni. Cages were built locally from available materials at a cost of approximately US$1000 per 48 m³ cage. An indigenous line of Nile tilapia, Oreochromis niloticus, was stocked either as mixed sex (first trial) or all-males (second trial) at an average rate of 103 fish/m³ and grown on locally available pelleted feeds for approximately six months. Total costs averaged US$2038 per six-month production cycle. Gross yield ranged from 232 to 1176 kg/cage, averaging 460 kg/cage (9.6 kg/m³). Final average weight of mixed sex populations (253.05 ± 47.43g) was significantly less than of all-males (376.7 ± 72.30g). Likewise, percentage of fish over 300 g at harvest was significantly lower in mixed-sex (38.3%) compared to all-male (75.7%) populations. Mortality resulting primarily from poor handling during transport and stocking averaged 70% and was a major determinate of production and profitability. To break even, harvested biomass of fish needed to exceed 15 kg/m³. At 25 kg/m³, small-scale cage aquaculture generated a net income of US$717 per cage per six months (ROI = 30.2%) on revenues of US$3,500. Water quality in the area surrounding the cages was not negatively affected by aquaculture at the scale tested (5 tons of feed per six months).     

城市公园绿地植物群落配置模式的抑菌功能

以淮安市钵池山公园不同配置的植物群落为样地,测定分析其抑菌功能。结果表明:植物群落具有一定的抑菌作用。单一树种群落配置中以雪松(Cedrus deodora)的抑菌效果最好;复层群落配置乔木层中的香樟(Cinnamonum campora)和女贞(Ligustrum lucidum)的抑菌效果比较明显,地被中八角金盘(Fatsia japonica)的抑菌效果最好。植物群落的抑菌效果因树种及环境差异,一天中的不同时刻其表现也不尽相同,2个复层林均在13:30时的抑菌效果最差;冬天常绿树种群落的抑菌效果比落叶树种复层配置的要好。     

早期上海外滩公共景观形成机制及其特征研究

梳理了上海开埠至19世纪末外滩航运港岸功能的形成与演变,及其向经济、商业中心初步转化的轨迹,基于租界时期的土地权属、租地政策和中外关系。从公私矛盾与中外制衡等角度,深入分析了外滩公共景观的形成机制,阐述了早期上海外滩景观的发展及其主要特征。     

Non‐indigenous fish in protected spaces: Trends in species distribution mediated by illegal stocking

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