A framework designation for the assessment of urban ecological risks

Urban ecological risks stemming from urbanization are increasing and limiting the capability of China to effectuate sustainable urban development. Therefore, addressing urban ecological risks is an urgent need. Numerous factors are involved in urban ecological risks, including air, water, and soil. Additionally, risk sources and risk receptors are complex and diverse. In this study, urban ecological risks are defined as adverse effects and possibility of impacts on urban ecosystem services resulting from urbanization. Urbanization is recognized as the risk source, and the urban ecosystem is considered the risk receptor. Based on this understanding, the components of urban ecological risks are defined, and the relationships between the components of urban ecological risks are illuminated by establishing an indicator system. Based on previous studies on urban ecological risks, an explicit framework for identification, assessment, and management of urban ecological risks is proposed. For purposes of identification, there are three types of risk sources: population growth, industrial development, and the expansion of built land. Stressors include the accumulation of contaminants, consumption of resources, and occupation of space. Assessment endpoints are divided into provisioning, regulating, cultural, and supporting services. In response to urban ecological risks having multiple stressors and multiple assessment endpoints, we assessed risks both with a single stressor/single endpoint and comprehensive ecological risks. In our framework, the physical or material assessment of ecosystem services is adopted as the core method for the analysis of urban ecological risk, because it is believed that the analysis of urban ecological risk should be based on the physical or material assessment of ecosystem services instead of the value assessment of ecosystem services. The results of the single value assessment of urban ecosystem services will cause the deviation from the purpose of urban ecosystem services assessment. The purpose of urban ecosystem services assessment is to maintain and/or improve the capability of urban ecosystems of providing physical or material services, and further to reduce or avoid the occurrence risks of unsustainable cities. Additionally, a multi-level characterization method was adopted for the results of urban ecological risk assessment. In this study, we established a platform to manage urban ecological risks based on landscape ecology and environmental internet of things technologies, and to effectuate online urban ecological risk identification, assessment, and management via this platform.     

Assessment and management of urbanization-induced ecological risks

The urban ecological risk incurred during the processes of urbanization has been constantly accumulating, creating a severe challenge for China to achieve sustainable urban development. At present, research on systematic evaluation of urban ecological risks is still inadequate, especially at an urban ecosystem level. In this special issue, we use Xiamen City as an example to identify the sources and receptors of urban ecological risks, to develop a methodology system of urban ecological risk assessment, and to propose a method for the management of urban ecological risks. This special issue contains 11 research articles resulting from a comprehensive research project funded by China’s National Natural Science Foundation. The innovations reported in this special issue include a framework of urban ecological risk assessment and a standardized procedure for carrying out urban ecological risk assessment using multiple stressors and endpoints.     

A concise review of ecological risk assessment for urban ecosystem application associated with rapid urbanization processes

ABSTRACT

Urban ecological risk (UER) caused by rapid urbanization means potential threat to urban ecosystem structure, pattern and services. The scales of ecological risk assessment (ERA) have been expanded from individual organisms to watersheds and regions. The types of stressor range from chemical to physical, biological and natural events. However, the application of ERA in urban ecosystems is relatively new. Here, we summarize the progress of urban ERA and propose an explicit framework to illumine future ERA based on UER identification, analysis, characterization, modeling, projection and early warning and management. The summary includes six urban ERA-relevant methods: weight-of-evidence (WoE), procedure for ecological tiered assessment of risks (PETAR), relative risk model (RRM), multimedia, multi-pathway, multi-receptor risk assessment (3MRA), landscape analysis and ecological models. Furthermore, we review critical cases of urban ERA in landscape ecology, soil, air, water and solid waste. Based on the Internet of Things (IoT) and cloud computing, an urban ERA management platform integrates various urban ERA methodologies that can be developed to provide better implementation strategies of UER for urban ecosystem managers and stakeholders. We develop a conceptual model of urban ERA based on the urban characteristics in China. The future applications of urban ERA include uncertainty analysis using Monte Carlo techniques on the basis of geospatial techniques and comprehensive urban ERA using nonlinear models or process models.     

The city as a refuge for insect pollinators

Research on urban insect pollinators is changing views on the biological value and ecological importance of cities. The abundance and diversity of native bee species in urban landscapes that are absent in nearby rural lands evidence the biological value and ecological importance of cities and have implications for biodiversity conservation. Lagging behind this revised image of the city are urban conservation programs that historically have invested in education and outreach rather than programs designed to achieve high‐priority species conservation results. We synthesized research on urban bee species diversity and abundance to determine how urban conservation could be repositioned to better align with new views on the ecological importance of urban landscapes. Due to insect pollinators’ relatively small functional requirements—habitat range, life cycle, and nesting behavior—relative to larger mammals, we argue that pollinators put high‐priority and high‐impact urban conservation within reach. In a rapidly urbanizing world, transforming how environmental managers view the city can improve citizen engagement and contribute to the development of more sustainable urbanization.     

A multi-level characterization method for the assessment of urban ecological risks

Urban ecological risk characterization is the final step in risk assessment and an important foundation upon which risk managers build risk aversion, risk control, and emergency handling strategies. In this study, we reviewed present risk characterization methods and proposed a multi-level characterization method for the assessment of urban ecological risks. The new characterization method consists of four elements: urban ecological risk sources, risk source probabilities, assessment endpoint indicators, and assessment endpoint indicator probabilities. Using this method, results of risk assessments can be organized into different levels of detail to meet different risk management goals.     

Ecological risk assessment from the perspective of soil heavy metal accumulations in Xiamen city,China

Contamination of soils by heavy metals is of rising concern in many cities in China undergoing rapid urbanization. Here, we evaluate the severity of soil contamination by four heavy metals (arsenic, chromium, copper, and lead) at 146 urban and suburban sites within the city of Xiamen, Fujian, China. A multivariate regression model was proposed and developed to simulate heavy metals accumulation in urban and suburban soils, to identify the concentration and spatial distribution of heavy metals in soils, and to assess ecological risks by 2020. Results showed that, overall, Xiamen soils should be subject to low ecological risks due to heavy metals contamination by 2020, the ecological risks for urban soils were greater than suburban soils, nearly half of Xiamen soils are at moderate ecological risks, and many suburban soils experience low ecological risks. The methods demonstrate the potential to predict future ecological risks from heavy metals contamination which could inform pollution prevention and control measures.     

永定河(北京段)生态修复工程运行管理机制研究

在充分调查永定河生态修复运行管理现状的基础上,以阈值跃迁、适应性管理为指导,对现有运行管理现状及存在问题进行深入分析。研究发现目前运行管理存在缺乏理论指导,管理权责不明晰,资金来源不明确以及生态监测体系、原水买卖平台缺失等问题。为实现运行管理目标,研究提出从构建基于适应性管理的流域委员会管理模式、确定管理机构权责、管理资金配置及建立生态修复管理评估体系4个方面完善运行管理机制,为永定河生态修复工程的运行管理及北方缺水城市的水生态修复工程运行管理提供参考与借鉴。     

Ecological risk assessment based on freshwater consumption dynamic analysis of Xiamen City,China

Freshwater is the lifeline of a city. Shortages in urban water supply and ecological losses occur when freshwater supply capacity and demand are imbalanced. Therefore, systematic research on the risk of freshwater consumption in urban areas is urgently demanded. A scientific understanding of the risk of urban water consumption will contribute to the efficient use of freshwater resources and ensure the stability and sustainable development of cities. Taking Xiamen City as the study area, we evaluated the ecological risk of freshwater consumption scenarios in the years 2020 and 2030 using a multilevel characterization method for urban ecological risk, stepwise regression analysis, and a gray prediction model. The results of our evaluation show that freshwater consumption in Xiamen is highly correlated with the total population, the crop acreage, the proportion of secondary industry, and the treatment rate of domestic sewage. In the 2020 and 2030 scenarios, freshwater consumption in Xiamen City is predicted to increase. Meanwhile, with the construction of water conservancy facilities, the supply capacity of freshwater in Xiamen City will be greatly improved. Therefore, the ecological impacts of freshwater consumption in the 2020 and 2030 scenarios were at the middle and low levels. In this study, the validity of the multilevel characterization method described herein for urban ecological risk has been confirmed. However, calculation of scenario probability is a difficult problem in the framework of this method, and future research should address this issue.     

Development and application of a comprehensive ecological risk assessment indicator system in Xiamen,China

Urban ecological risk is one of the important factors that may restrict the social and economic development. Therefore, it is of great significance to carry out a comprehensive assessment of ecological risks so that an ecological risk prevention and control plan can be scientifically formulated. In this paper, a comprehensive ecological risk assessment indicator system of Xiamen was established based on local ecological properties and socioeconomic status. This indicator system covers seven indicators including air pollution, soil pollution, water pollution, fresh water consumption, change in land use, occupation of key zones with ecological functions, and road network expansion. Based on this indicator system and in conjunction with the single factor assessment of ecological risks, this study constructed a model of comprehensive ecological risk assessment and forecasted the comprehensive ecological risk of Xiamen in 2020. The results showed that the comprehensive ecological risk level of Xiamen in 2020 is medium and the main stressors are the discharge of air and water pollutants. From the perspective of risk receptors, i.e. the ecosystem services, the risk posed to the ecosystem services associated to the maintenance of air quality and water purification is the highest. Therefore, this study proposed the recommendations on ecological risk prevention and regulation in Xiamen based on the comprehensive assessment of ecological risks, in the hope to provide scientific support for local ecological protection and sustainable development.     

Ecological issues and risk assessment in China

As a result of economic development and population explosion, global ecological environments have been severely disturbed and markedly changed. An ecological crisis involving desertification, soil erosion, degradation of land quality, loss of biodiversity and global climate change has been brought about all over the world. In order to manage ecosystems efficiently, it is necessary to assess ecological risk at multiple scales. Ecological risk is the probability that a region and/or site will experience defined ecological or environmental problems. In this paper, the ecological risks of soil erosion, desertification, and acid deposition have been assessed on a national scale according to natural and human factors, such as topography, soil, vegetation and climate. This assessment has provided very useful information for ecological environmental management in China.     

Some specialized risk assessment methodologies for vertebrate populations

We present three empirical methods for risk assessment in field studies of free-ranging vertebrates. First, we advocate statistical inference concerning population recruitment or mortality in response to ecological hazards. Second, if inferences about both recruitment and mortality are available, one can use a Leslie- Lefkovitch matrix to estimate the finite rate of population change () as a function of ecological hazards. Third, designed experiments can be conducted on samples of marked animals in natural environments to assess impacts and risks. These methods rely on either sophisticated capture-recapture or radio-tracking models, and on well-developed analysis theory. The use of uniquely marked animals is somewhat analogous to the use of tracers in other areas of risk assessment. We present examples of each approach and discuss some limitations.     

Air pollution-oriented ecological risk assessment in Xiamen city,China

Urban energy consumption is one of the most important causes of air pollution. Air pollution-oriented ecological risk assessment is of great significance to the promotion of urban environmental protection. This paper focuses on ecological risk in Xiamen city caused by air pollutant discharge from urban energy consumption. The Long-range Energy Alternatives Planning model was used to establish two scenarios of energy consumption in Xiamen city, and based on different scenarios, we estimated urban energy consumption and discharge quantity of air pollutant (DQAP). A box model and an expert scoring method were used to calculate the air pollution burden (APB) of SO₂, NO₂, CO, PM₁₀ and PM_2.5 and to obtain the probabilities of different air pollution loads. An ecological risk assessment model was developed and utilized to predict Xiamen city’s ecological risks in 2020. The results showed that under an energy-saving scenario, the ecological risks for PM_2.5, SO₂ and NO₂ are high, whereas the ecological risks for CO and PM₁₀ are low. Under a baseline scenario, the ecological risks for PM_2.5, SO₂ and NO₂ are moderate, whereas the ecological risks for CO and PM₁₀ are low. In addition, the APB of SO₂, NO₂, CO, and PM_2.5, but not of PM₁₀, is predicted to rise. In the simulation, energy generation from coal is the main source of air pollution. Although the DQAP from automobiles is not high, it is predicted to rise year-on-year. In summary, the ecological risk due to pollution in Xiamen city is high, and the main pollutants are SO₂, NO₂ and PM_2.5.     

Collembola dispersion,selection, and biological interactions in urban ecosystems: a review

Environmental and ecological degradation can be monitored by biological indicators such as plants, yet little research has been done using subterranean organisms such as collembola, especially in cities. Collembola, a soil fauna group, can be used to assess soil quality and to decipher assembly rules of soil organisms in cities. Here, we review 75 articles on soil collembola in an urban context. We found that soil properties and landscape characteristics influenced soil communities. There is a need for more connectivity between green urban spaces to allow the dispersion of collembola. Little information is available on the assembly of collembola communities, on biotic interactions and on dynamics of colonisation.

     

Methodology for an urban ecological footprint to evaluate sustainable development in China

The ecological footprint (EF) is a method for measuring sustainable development through ecological impact. A methodology is presented for predicting urban ecological footprints. Urban energy use and natural resource consumption were analyzed to calculate an EF based on land type (arable, pasture, forest, fossil energy land, built-up area and water area) and consumption (food, housing, transportation, goods, services and waste). The result was then compared with the local ecological carrying capacity to develop criteria for sustainable ecological footprints. Case studies of four cities in China (Guangzhou, Ningbo, Suzhou and Yangzhou) illustrate the urban EF approach. The time series of EF in a case study of Guangzhou for 1991–2001 was analyzed and the consumption–land-use matrix of urban EF was established. The results show that the cities are ecologically unsustainable, with average ecological conflicts per capita of more than 2 ha. The urban EF method is useful to measure urban sustainable development and provides policy proposals for decision-making. However, the EF method still has limitations and weaknesses.     

A study on vertical greening practice emphasizing ecological benefits in Xiamen City of China

Through the practice of vertical greening, which is an important method for modern city greening, a city’s natural geographic conditions and rich plant resources can be efficiently utilized. Using vertical greening to shape the characteristics of a city is a promising method for sustainable development. Integration of vertical greening with urban characteristics offers huge ecological and cultural benefits. Vertical greening was adopted in China much later than other developed cities in the world and is still in the exploratory stage in most of the cities. As one of the pioneer cities to carry out vertical greening in China, Xiamen has managed to project it as one of the city highlights. In this study, we analyzed the problems that Xiamen City faced during its development and the important role vertical greening has played in the urban landscape. In addition, humanistic and ecological benefits of vertical greening are illustrated through an experimental study.     

Ecological risk assessment of pesticide residues in Taihu Lake wetland, China

As a major ecosystem type, wetland provides invaluable ecological services. Environmental pollution, especially pesticides pollution should be paid more attention to keep wetlands healthy. Based on the risk quotient method, coupled with a probabilistic risk assessment model, this paper proposed a methodology suitable for ecological risk assessment of pesticide residues for wetland ecosystems. As an important industrializing and ecologically vulnerable area in China, the Taihu Lake wetland was chosen for the case study. The risks of eight pesticides in Taihu Lake wetland were assessed, as single substances and in mixtures. The assessment indicates that risks of the representative species are not significant. In general, the herbicide is found to be more toxic for algae, whereas insecticides pose more risks to zooplankton, insect and fish. For each pesticide in the wetland, the ecological risk it poses is acceptable. But the combined ecological risk posed by mixture can harm more than 10% of species of the wetland ecosystem, mainly dominated by dichlorvos, dimethoate and malathion contributions. These results imply that pesticide residues have been posing pressures on the ecosystem of the Taihu Lake wetland. It is recommended that proper countermeasures should be implemented to reduce the risks.     

Current situation and development of Chinese urban forestry

This paper introduces Chinese urban forestry research in terms of the concept, forest types, ecosystem services, spatial structure, planning and construction, assessment and management. Modern Chinese urban forest had a close relationship with traditional landscape architecture. Urban forest services had been quantified in some case cities, and determined by urban forest spatial patterns and internal structures. Based on landscape ecology and urban planning, urban forest spatial patterns have been analysed and planned rationally in some cities. However, studies on urban forestry generally lack long-term, continuous and systemic observations, as well as in-depth research on ecological processes and mechanisms. The development trends in urban forestry in China might include extensive application of '3S' technology, research on the relationship between urban forest landscape spatial patterns and their ecological effects, economic assessment, ecological and economic benefits and studies on the negative effects of pollutants.     

津河水系的修复对天津城市生态环境的影响

针对天津城市生态环境特点和背方城市大气污染现状,探讨了津河水系的修复对改善城市环境质量,丰富城市景观以及修复城市生态环境的重要意义。     

How to address data privacy concerns when using social media data in conservation science

Social media data are being increasingly used in conservation science to study human–nature interactions. User-generated content, such as images, video, text, and audio, and the associated metadata can be used to assess such interactions. A number of social media platforms provide free access to user-generated social media content. However, similar to any research involving people, scientific investigations based on social media data require compliance with highest standards of data privacy and data protection, even when data are publicly available. Should social media data be misused, the risks to individual users' privacy and well-being can be substantial. We investigated the legal basis for using social media data while ensuring data subjects’ rights through a case study based on the European Union's General Data Protection Regulation. The risks associated with using social media data in research include accidental and purposeful misidentification that has the potential to cause psychological or physical harm to an identified person. To collect, store, protect, share, and manage social media data in a way that prevents potential risks to users involved, one should minimize data, anonymize data, and follow strict data management procedure. Risk-based approaches, such as a data privacy impact assessment, can be used to identify and minimize privacy risks to social media users, to demonstrate accountability and to comply with data protection legislation. We recommend that conservation scientists carefully consider our recommendations in devising their research objectives so as to facilitate responsible use of social media data in conservation science research, for example, in conservation culturomics and investigations of illegal wildlife trade online.     

Ecological network and emergy analysis of urban metabolic systems: Model development,and a case study of four Chinese cities

Analysis of the structure and function of urban metabolic systems is an important goal of urban research. We used network pathways and network utility analysis to analyze the basic network structure of the urban metabolic system and the complex ecological relationships within the system, providing a new way to perform such research. Using four Chinese cities as examples, we developed an ecological network model of the urban metabolic system. By using network pathway analysis, we studied the changing relationships between metabolic length and the number of metabolic pathways, and between metabolic length and reachability. Based on the distribution of the number of metabolic pathways, we describe the basic structure and intercompartment relationships of the system. By using the sign distribution in the network utility matrix, we determined the ecological relationships and degree of mutualism between the compartments of the system. The basic components of the system consisted of the internal environment, the external environment, and the agricultural, industrial, and domestic sectors. With increasing metabolic length, the ecological relationships among the components of the system became more diverse, and the numbers of metabolic paths and their reachability improved. Although the basic network structure of the four cities was identical, the mutualism index differed. Beijing's mutualism index was superior to that of Shanghai, and much higher than those of Tianjin and Chongqing. By analyzing the structure and function of the urban metabolic system, we provide suggestions for optimizing the structure and adjusting the relationships, and propose methods for the application of ecological network analysis in future urban system research.