Effects of Habitat Disturbance from Residential Development on Breeding Bird Communities in Riparian Corridors

This study assessed the relationship among land use, riparian vegetation, and avian populations at two spatial scales. Our objective was to compare the vegetated habitat in riparian corridors with breeding bird guilds in eight Rhode Island subwatersheds along a range of increasing residential land use. Riparian habitats were characterized with fine-scale techniques (used field transects to measure riparian vegetation structure and plant species richness) at the reach spatial scale, and with coarse-scale landscape techniques (a Geographic Information System to document land-cover attributes) at the subwatershed scale. Bird surveys were conducted in the riparian zone, and the observed bird species were separated into guilds based on tolerance to human disturbance, habitat preference, foraging type, and diet preference. Bird guilds were correlated with riparian vegetation metrics, percent impervious surface, and percent residential land use, revealing patterns of breeding bird distribution. The number of intolerant species predominated below 12% residential development and 3% impervious surface, whereas tolerant species predominated above these levels. Habitat guilds of edge, forest, and wetland bird species correlated with riparian vegetation. This study showed that the application of avian guilds at both stream reach and subwatershed scales offers a comprehensive assessment of effects from disturbed habitat, but that the subwatershed scale is a more efficient method of evaluation for environmental management.     

Characterizing vulnerability to water scarcity: The case of a groundwater-dependent, rapidly urbanizing region

Groundwater overdraft is a resource management issue that poses a threat for the security of communities. Impacts of groundwater overdraft are influenced by the biophysical and social contexts of water management. This paper presents a method for assessing vulnerability to water scarcity in spatial terms using biophysical and social indicators. A geographic information system was used to establish areas of vulnerability based upon hydrologic variability in water resource availability within a groundwater basin, three types of water management systems, and 10 sociodemographic characteristics. Our study area is in the rapidly urbanizing Arizona Central Highlands, located 150 km north of the Phoenix metropolitan region, USA. Results indicate that the most biophysically vulnerable places do not necessarily intersect with the most vulnerable populations and that local differences in vulnerability are interrelated, rather than independent, outcomes in a process of socioenvironmental transformation. Vulnerability is influenced by laws that deny access to local surface waters and lead to dependence on fossil groundwater, and by economic reliance on urbanization. Localities attempt to reduce vulnerability through the development of community water systems and the expansion of water frontiers. While such strategies may reduce local vulnerability, they are not sustainable solutions because they transfer risks to other places, and thus contribute to vulnerability elsewhere.     

Multi-scale analysis of oxygen demand trends in an urbanizing Oregon watershed, USA

Human alteration of the landscape has an extensive influence on the biogeochemical processes that drive oxygen cycling in streams. We estimated trends from the mid-1990s to 2003, using the seasonal Mann-Kendall's test, for percent saturation dissolved oxygen (DO), chemical oxygen demand (COD), total Kjeldahl nitrogen (TKN), and ammonia-nitrogen (NH(3)-N) for 12 sites in the Rock Creek watershed, northwest Oregon, USA. In order to understand the influence of landscape change, scale, and stormwater runoff management on dissolved oxygen trends, we calculated land cover change through aerial photo interpretation at full-basin, local (near sample point) basin, and 100m stream buffer scales, for the years 1994 and 2000. Significant (p < or = 0.05) trends occurred in DO (increasing at five sites), COD (decreasing at seven sites), TKN (decreasing at five sites, increasing at one site), and NH(3)-N (decreasing at one site, increasing at one site). Significant land cover change occurred in agricultural land cover (-8% for the entire basin area) and residential land cover (+10% for the entire basin area) (p < or = 0.05). Correlation results indicated that: (1) forest cover negatively influenced COD at the full basin scale and positively influences NH(3)-N at local scales, (2) residential land cover influenced oxygen demand variables at local scales, (3) agricultural land cover did not influence oxygen demand, (4) local topography negatively influenced TKN and NH(3)-N, and (5) stormwater runoff management infrastructure correlated positively with COD at the local scale. This study indicates that landscape factors influencing DO conditions for the study streams act at multiple scales, suggesting that better knowledge of scale-process interactions can guide watershed managers' decision making in order to maintain improving water quality conditions.     

Urban Domestic Gardens (XIV): The Characteristics of Gardens in Five Cities

Domestic gardens make substantial contributions to the provision of green space in urban areas. However, the ecological functions provided by such gardens depend critically on their configuration and composition. Here, we present the first detailed analysis of variation in the composition of urban gardens, in relation to housing characteristics and the nature of the surrounding landscape, across different cities in the United Kingdom. In all five cities studied (Belfast, Cardiff, Edinburgh, Leicester, and Oxford), garden size had an overwhelming influence on garden composition. Larger gardens supported more of the land-use types recorded, in greater extents, and were more likely to contain particular features, including tall trees and mature shrubs, areas of unmown grass and uncultivated land, vegetable patches, ponds, and composting sites. The proportional contribution of non-vegetated land-uses decreased as garden area increased. House age was less significant in determining the land-use within gardens, although older houses, which were more likely to be found further from the urban edge of the city, contained fewer hedges and greater areas of vegetation canopy >2 m in height. Current UK government planning recommendations will ultimately reduce the area of individual gardens and are thus predicted to result in fewer tall trees and, in particular, less vegetation canopy >2 m. This might be detrimental from ecological, aesthetic, social, and economic stand points.     

Flight distance of urban birds, predation, and selection for urban life

Numerous species have adapted to humans, especially invasive species associated with humans in towns and cities. Short flight distances of populations adapted to urban environments reflect changes in behavior and physiology, reflecting phenotypic plasticity or evolution. Here, I tested the hypothesis that the decrease in flight distance to a potential predator (an approaching human) reflected adaptation to urbanization, using a data set of flight distances of 44 common species of European birds in different stages of adaptation to urban environments. Urban populations had consistently shorter flight distances than rural populations of the same species. Variation in relative flight distance of urban populations was predicted by the number of generations since urbanization, as expected by a gradual process of adaptation. Furthermore, species with relatively large populations in urban environments would be an indication of local adaptation to urban environments. Relative flight distance of urban population was shorter for species with large populations in urban compared to rural habitats. Species that had adapted to urban environments as shown by short flight distances were less susceptible to predation by the European sparrowhawk Accipiter nisus than species with relatively long flight distances in urban populations. These findings provide evidence consistent with the hypothesis that recent changes in the tameness of urban birds, as reflected by their relatively short flight distances, is an adaptation to the novel urban environment. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Spatial variations in CO2 fluxes in a subtropical coastal reservoir of Southeast China were related to urbanization and land-use types

Carbon dioxide (CO2) emissions from aquatic ecosystems are important components of the global carbon cycle, yet the CO2 emissions from coastal reservoirs, especially in developing countries where urbanization and rapid land use change occur, are still poorly understood. In this study, the spatiotemporal variations in CO2 concentrations and fluxes were investigated in Wenwusha Reservoir located in the southeast coast of China. Overall, the mean CO2 concentration and flux across the whole reservoir were 41.85 ± 2.03 µmol/L and 2.87 ± 0.29 mmol/m2/h, respectively, and the reservoir was a consistent net CO2 source over the entire year. The land use types and urbanization levels in the reservoir catchment significantly affected the input of exogenous carbon to water. The mean CO2 flux was much higher from waters adjacent to the urban land (5.05 ± 0.87 mmol/m2/hr) than other land use types. Sites with larger input of exogenous substance via sewage discharge and upstream runoff were often the hotspots of CO2 emission in the reservoir. Our results suggested that urbanization process, agricultural activities, and large input of exogenous carbon could result in large spatial heterogeneity of CO2 emissions and alter the CO2 biogeochemical cycling in coastal reservoirs. Further studies should characterize the diurnal variations, microbial mechanisms, and impact of meteorological conditions on reservoir CO2 emissions to expand our understanding of the carbon cycle in aquatic ecosystems.     

Mass balance-based regression modeling of Cd and Zn accumulation in urban soils of Beijing

Accumulation of heavy metals in urban soil can pose adverse impacts on public health and terrestrial ecosystems. We developed a mass balance-based regression model to simulate the heavy metal accumulation in urban soils as a function of time and to explore connections between metal concentration and urbanization processes. Concentrations of Cd and Zn in 68 residential soil samples in the urban area of Beijing were used. The background concentrations, the loss rates and the input fluxes of Cd and Zn in urban soils of Beijing during the last three decades were estimated using a regression of the time series of accumulations of the metals. Based on the regression estimates, we simulated the general trends of Cd and Zn accumulation in the soils from 1978 to 2078. The concentrations of Cd and Zn in urban soil generally increased with the population growth, vehicle use and coal consumption. The mean concentrations of Cd and Zn in urban soil of Beijing would increase by 3 fold over the next 70 years for the current development scenario. The mass balance-based regression approach, which is able to reconstruct the history data of urban soil pollution, provides fundamental information for urban planning and environmental management.     

怀洪新河浮游动物群落特征与水环境因子的关系研究

为研究怀洪新河太湖新银鱼国家级水产种质资源保护区(以下简称保护区)水域浮游动物的群落结构及其与水环境因子的关系,于2014年6月(夏季)在怀洪新河进行采样分析,并对调查区域内的浮游动物及主要环境因子进行了主成分分析(PCA)和典范对应分析(CCA)。结果表明,保护区河段属中营养型河流;保护区浮游动物有4门24属33种,其中轮虫类最多,为11种(占33.33%),其次为原生动物和桡足类,均为8种(占24.24%),最少的为枝角类6种(占18.18%);保护区浮游动物细胞密度平均为1.82×10~4ind./L,生物量平均为2.45mg/L;水温和氨氮是影响水体环境的关键因子;水温、总氮、浊度、氨氮、高锰酸盐指数(COD_(Mn))和pH是影响浮游动物群落结构的主要驱动因子。     

Towards Sustainable Urban Environmental Management in Jiangyin city,East China

Abstract

Dramatic economic and social changes have taken place in Jiangyin city due to rapid and uneven urbanization and industrialization. The environmental degradation has followed driven by these changes since the 1980's. With the pressures and effects of environmental deterioration, the city has implemented environmental management to hold back the trends of negative environmental changes. From the viewpoint of systems, DPSER is a good model for urban environmental changes to understand the causes, pressure, state, effect, existing responses and future action strategies. We took Jiangyin city, a developed city in South Jiangsu province, East China, as an example, and analyzed the characteristics of environmental changes and urban responses using DPSER model. Some operational strategies have been put forward to direct the city environmental management towards a sustainable road step by step.     

城市工业生态经济持续发展中存在的问题及对策

本文根据城市工业生态经济系统的构成及特点，分析了城市工业生态经济系统进行持续发展的现实意义，针对城市工业生态经济持续发展中存在的主要问题进行原因剖析，并提出了相应的治理对策及措施，以达环境与经济及城市生态经济优化决策之目的