Nexus security: governance, innovation and the resilient city

Nexus security is a compound mix of ideas: reconciling human needs and wants with access to multiple resources; diversity of access to those resources and services; resilience in the face of weather- and climaterelated variability; resilience likewise in the face of infrastructure failure; and the personal, individual sense of belonging. At the level of Systems Thinking there is a very close relationship between resilience in the behavior of natural (ecological) systems and resilience in the social dynamics of governance within communities, where such resilience establishes the viability of these communities over centuries, which in turn entails successful stewardship of the man-environment relationship. We use insights from this cross-system mapping — across natural, built, and human systems — to assess, first, the role of city governance in achieving nexus security (or not) and, second, the role of technological innovations in serving the same purpose. More specifically, eight principles, covering resilience and diversity of access to resources and services, are used to gauge security-enhancing features of city buildings and infrastructure. Case studies include new designs of resilient office blocks, nutrient (nitrogen and phosphorus) recovery systems for sanitation and wastewater treatment, and the reconstruction of urban parks for the provision of ecosystem services. Throughout the paper, matters of risk in the face of meteorological variability are prominent. We do not conclude, however, that the presence of risk implies nexus insecurity.     

草原煤矸石堆放的生态环境问题及其治理措施综述

综述了内蒙古自治区煤矸石排放对草原生态系统造成的危害,比较了物理、化学和生物学方法对治理煤矸石的优缺点,重点分析了丛枝菌根真菌技术在煤矸石山生态重建中的应用及其意义,并提出了当前研究工作中存在的问题及以后的研究重点。     

广州市流溪河流域白云区段生态系统服务价值的估算与分析

在分析流溪河流域白云区段生态系统的景观变化和生态环境现状的基础上,依据流溪河流域白云区段的土地详查数据(1993年)及其土地利用变更调查数据(2001年末),引用Constanza等对全球生态系统服务单位公顷价值的平均估算结果,对流溪河流域白云区段生态系统服务价值进行评估。评估结果表明:2001年流溪河流域白云区段生态系统服务的总价值为85190050.43美元,折合人民币70700.75万元,相当于该区域同期GDP的6.22%。由于存在影响核算结果准确性的一些因素,因此,该结果是粗略与保守的估算。     

西昌市生态空间占用及其生态系统安全评估

生态系统安全的概念应该与人类的可持续发展联系在一起,其安全的目标在于为人类的生存和发展提供持续和良好的生态服务功能,在这一意义上,生态安全就是生态系统的可持续性。生态系统安全是新兴的生态系统管理学概念,是新的环境管理和生态系统管理目标。利用生态占用分析方法,对西昌市整个生态系统的生态盈亏和生态系统安全进行评估,得出西昌市目前人均生态赤字0.6 hm2和生态安全受到挑战的结论。并进行了生态占用的敏感性分析：能源资源消耗降低10%,人均生态赤字降低5.32%;产量因子提高10%,人均生态赤字降低14.01%;能源消耗减低10%,同时产量因子提高10%,人均生态空间赤字减少降低19.33%。指出了能源循环利用、资源节约、技术革新和单位面积资源增值等为主要特征的生态产业发展对生态系统保育的意义和效应。     

三峡地区废弃地植被生态恢复与重建的生态学研究

废弃地是一类极度退化的生态系统。对三峡地区的矿山废弃地、退（弃）耕地、工程建设废弃地、垃圾填埋场、地质灾害废弃地、砍伐迹地等废弃地类型的形成原因进行了调查分析,并结合国内外恢复生态学的研究进展,讨论了该地区废弃地植被恢复与重建的一般规律,对该地区废弃地植被恢复与重建的对策及其方法与步骤提出了一些建议。认为人类干扰是该地区废弃地形成的主要原因。废弃地植被的恢复与重建应该遵循规划系统性、设计与施工生态性、目标植被的物种多样性等原则。而土壤基质的固定与恢复、先锋群落的构建、后期管理中生物多样性的逐步丰富是三峡地区废弃地植被生态恢复与重建过程中三个关键的步骤与内容。     

基于组合赋权法的宁波市城市生态系统质量评价

为评价宁波市城市生态系统质量状况,在建立城市生态系统质量指数(UEQI)评价模型的基础上,首先由不同等级指标值线性拟合得到的标准化函数进行原始数据的标准化,然后根据变异系数法与层次分析法相结合的组合赋权法确定指标权重,最后对宁波市9个评价区的城市生态系统质量进行评价对比。结果表明,2006年宁波市城市生态系统质量属于一般水平(UEQI=64),其中宁海县城市生态系统质量最高(UEQI=70),其次为余姚市(UEQI=69)、奉化市(UEQI=68)、主城区(UEQI=67)、北仑区(UEQI=65)、镇海区(UEQI=62)、慈溪市(UEQI=61)和象山市(UEQI=59),而鄞州区的城市生态系统质量最差(UEQI=53)。     

黑龙江省城市生态系统的生态安全研究

城市作为人口高度聚集的人工生态系统,其安全具有脆弱性.本文利用SPSS统计软件统计计算,从选取关键因子入手,采用因子分析方法和聚类分析方法,研究了黑龙江省12座城市生态系统的生态安全,通过因子得分和聚类分级结果得出结论:牡丹江排名第一位,生态安全程度较高;而作为黑龙江省中心城市的哈尔滨生态安全程度却较差,但提高潜力很大.通过分析,针对黑龙江省的实际状况,提出了有针对性的对策.     

Modeling changes in the coastal ecosystem of the Pearl River Estuary from 1981 to 1998

The coastal ecosystem of the Pearl River Estuary (PRE) has been overfished and received a high level of combined pollution since the 1980s. Ecopath with Ecosim was used to construct two ecosystem models (for 1981 and 1998) to characterize the food web structure and functioning of the ecosystem. Pedigree work and simple sensitivity analysis were carried out to evaluate the quality of data and the uncertainty of the models. The two models seem reliable with regards to input data of good quality. Comparing the variations of outputs of these two models aimed to facilitate assessment of changes of the ecosystem during the past two decades.The trophic structure of the ecosystem has changed with an increase in the biomass proportion of lower trophic level (TL) organisms and a decrease in top predator biomass proportion. All the indices of ecosystem maturity examined show that the system was in a more mature condition in 1981 than in 1998, although the system has been in a condition of stress due to anthropogenic disturbances, such as environmental pollution and habitat destruction since 1981. The ecosystem was aggregated into six and seven integral TLs in 1981 and 1998, respectively, using the trophic aggregation routine of Ecopath. Most of the total system biomass and catch took place at TL II and III in both years. But the distribution of the total system biomass and catch at different TLs changed with decreasing proportions in higher TLs in 1998. The mean transfer efficiency was 9.1% and 10.2% in 1981 and 1998, respectively.Comparative network analysis allowed quantification of the importance of direct and indirect trophic interactions among functional groups. Moreover, a method derived from the mixed trophic impact (MTI) analysis allowed estimating importance of groups in terms of “keystoneness” and identifying the keystone species in the two models over the past two decades. The results indicate that there were no clear keystone species in 1998 but two keystone species at medium trophic levels were identified in 1981. Moreover, organisms located at low trophic levels such as phytoplankton, zooplankton and benthic invertebrates were identified to have relatively high keystoneness in the ecosystem.     

Emergy-based urban health evaluation and development pattern analysis

The objective of this study is to measure and evaluate the ecosystem health levels of 31 Chinese capital cities in 2004 through an emergy synthesis framework. A system of indicators was developed corresponding to the four factors of urban ecosystem health including efficiency, structure, impact and flux. Furthermore, combined with individual indices, an emergy-based urban ecosystem health index (EUEHI) was proposed to measure and evaluate the health levels among various typical cities in China, which offers an integrated evaluation tool in view of urban production, trade and consumption. The results showed that there are intrinsic differences among six clusters associated with driving mechanisms distinguishing the rankings of urban health levels. After lining the cities of similar health levels with cluster map, the spatial distribution of the urban health is found to be arch-shaped, increasing initially and then decreasing from coast to inner land. This kind of spatial hierarchy is per se compatible and consistent with the hierarchical theory of emergy synthesis. The results also revealed double restrictions of urban health between economy and environment. Moreover, the interaction analysis was used for mirroring the driving mechanism of urban ecosystem health. Three conclusions were arrived at. Firstly, environmental health is inversely related to the economic health in China, indicating that cities cannot achieve win–win between environment and economy in the current urban development mode. Secondly, based on economy-driven mode, four quadrants were divided in the city division map, wherein 43.33% of the concerned cities developed in high economy-restriction mode, which means low economic level is still an important limiting factor for the major cities of China. Finally, based on environment-driven mode, two sections were divided, of which weak environmental dominance mode expounds the special characteristics of urban environment with obvious fragility. 23.33% of the 30 cities were in the intermediate state, which means a few correspondingly unhealthy cities should develop concrete polices for the urban ecosystem restoration.     

Integrated biogeochemical modelling of nitrogen load from anthropogenic and natural sources in Japan

This study proposed an integrated biogeochemical modelling of nitrogen loads from anthropogenic and natural sources in Japan. Firstly, the nitrogen load (NL) from different sources such as crop, livestock, industrial plant, urban and rural resident was calculated by using datasets of fertilizer utilization, population distribution, land use map, and social census. Then, the nitrate leaching from soil layers in farmland, grassland and natural conditions was calculated by using a terrestrial nitrogen cycle model (TNCM). The Total Runoff Integrating Pathways (TRIP) was used to transport nitrogen from natural and anthropogenic sources through river channels, as well as collect and route nitrogen to the river mouths. The forcing meteorological and hydrological data is a 30-year (1976–2005) dataset for Japan which were obtained by the land surface model, Minimal Advanced Treatments of Surface Interaction and Runoff (MATSIRO). For the model validation, we collected total nitrogen (TN) concentration data from 59 rivers in Japan. As a comparison result, calculated TN concentration values were in good agreement with the observed ones, which shows the reliability of the proposed model. Finally, the TN loads from point and nonpoint sources were summarized and evaluated for 59 river basins in Japan. The proposed modelling framework can be used as a tool for quantitative evaluation of nitrogen load in terrestrial ecosystems at a national scale. The connection to land use and climate data provides a possibility to use this model for analysis of climate change and land use change impacts on hydrology and water quality.