Urban waterfowl population: Ecological evaluation of management and planning

An urban population of ducks in Puyallup, Washington, USA was studied for 14 consecutive months beginning in November 1978. Observations were made weekly from four study sites where ducks would congregate at early morning hours. Factors contributing to the presence of waterfowl in Puyallyup included abundant food supplies and a creek corridor that connected fragmented habitats in the urban area to the larger rural populations of waterfowl. Mallards (Anas platyrhynchos) were the most abundant of the 13 species observed and were the only ducks remaining during the nesting season. Habitat size and complexity were important factors influencing the species diversity of a particular site. Nesting success of mallards was poor due to limited distribution of nesting habitat, intraspecific aggression, and human disturbance. Both site-specific and more broad-based strategies are suggested for managing and planning for duck populations in urban areas.     

Does optimal foraging theory explain why suburban Florida scrub-jays (Aphelocoma coerulescens) feed their young human-provided food?

Optimal foraging theory assumes that a forager can adequately assess the quality of its prey and predicts that parents feed their young low-quality foods only when suffering unpredicted reductions in their ability to provision. Wildland Florida scrub-jays feed their young exclusively arthropods, but suburban parents include human-provided foods in the nestling diet, with possible costs in terms of reduced growth and survival. We tested experimentally whether parents feed human-provided foods, given the apparent costs, because: 1) they do not discriminate between food types, 2) they switch to low-quality, abundant foods when natural food availability in the environment is low, or 3) they switch when the time needed to obtain natural food is high. Parents discriminated between natural and human-provided foods by showing a preference for natural foods when rearing young. When the handling time of natural foods was increased experimentally, parents in the suburban and wildland habitats switched to human-provided foods. Supplementation with natural foods increased preference for this food in both habitats. Suburban parents chose more natural foods than wildland parents, suggesting that they have a greater preference for natural foods. Regardless of preferences demonstrated at feeders, parents in both the suburbs and wildlands delivered mostly natural foods to nestlings, independent of natural food availability. Nonetheless, natural foods are likely to be scarcer in the environment than in our experimental tests. Because natural food availability is lower in the suburbs than in the wildland habitat, parents in the suburbs may be forced to switch to human-provided foods when feeding nestlings.     

Wastewater reclamation and reuse in China: Opportunities and challenges

The growing water stress both in terms of water scarcity and quality deterioration promotes the development of reclaimed water as a new water resource use. This paper reviewed wastewater reuse practices in China, and the opportunities and challenges of expanding reclaimed water use were analyzed. Rapid urbanization with the increasing of water demand and wastewater discharge provides an opportunity for wastewater reuse. The vast amount of wastewater discharge and low reclaimed water production mean that wastewater reuse still has a great potential in China. Many environmental and economic benefits and successful reclamation technologies also provide opportunities for wastewater reuse. In addition, the overall strategy in China is also encouraging for wastewater reuse. In the beginning stage of wastewater reclamation and reuse, there are many significant challenges to expand wastewater reuse in China including slow pace in adopting urban wastewater reuse programs, the establishment of integrated water resources management framework and guidelines for wastewater reuse programs, incoherent water quality requirements, the limited commercial development of reclaimed water and the strengthening of public awareness and cooperation among stakeholders.     

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 ~150km 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.     

Integrating ecosystem services evaluation and landscape pattern analysis into urban planning based on scenario prediction and regression model

ABSTRACT

Urban planning has become a widely concern for minimizing the negative effects of urban expansion on terrestrial ecosystems. We developed an interdisciplinary modeling framework to evaluate the effectiveness and shortcomings of urban expansion management strategies. A three-step method was applied to Yinchuan Plain in the northwestern of China, including (1) analyzing the relationship between landscape pattern and ecosystem service values through mathematical statistics; (2) predicting landscape pattern and ecosystem services change under different scenarios based on cellular automaton model (SLEUTH-3r model); and (3) designing and validating optimized scenario through integrating historical analysis experiments and future multi-comparison suggestions. Results have suggested that landscape composition and configuration can significantly affect regional ecosystem service values, especially the connectivity and shape of landscape. Compact urban growth policy and medium environment protection policy are the appropriate setting for urban expansion plan. Optimization validation of the combined designed scenario implied the reliability of this method. Our results highlighted the significance of integrating application of landscape pattern analysis, ecosystem service value evaluation, model simulation and multi-scenario prediction in urban planning.     

Application of the target fish community model to an urban river system

Several models have been developed to assess the biological integrity of aquatic systems using fish community data. One of these, the target fish community (TFC) model, has been used primarily to assess the biological integrity of larger, mainstem rivers in southern New England with basins characterized by dispersed human activities. We tested the efficacy of the TFC approach to specify the fish community in the highly urbanized Charles River watershed in eastern Massachusetts. To create a TFC for the Charles River we assembled a list of fish species that historically inhabited the Charles River watershed, identified geomorphically and zoogeographically similar reference rivers regarded as being in high quality condition, amassed fish survey data for the reference rivers, and extracted from the collections the information needed to define a TFC. We used a similarity measurement method to assess the extent to which the study river community complies with the TFC and an inference approach to summarize the manner in which the existing fish community differed from target conditions. The five most abundant species in the TFC were common shiners (34%), fallfish (17%) redbreast sunfish (11%), white suckers (8%), and American eel (7%). Three of the five species predicted to be most abundant in the TFC were scarce or absent in the existing river community. Further, the river was dominated by macrohabitat generalists (99%) while the TFC was predicted to contain 19% fluvial specialist species, 43% fluvial dependent species, and 38% macrohabitat generalist species. In addition, while the target community was dominated by fish intolerant (37%) and moderately tolerant (39%) of water quality degradation, the existing community was dominated by tolerant individuals (59%) and lacked intolerant species expected in the TFC. Similarity scores for species, habitat use specialization, and water quality degradation tolerance categories were 28%, 35% and 66%, respectively. The clear pattern of deviations from target conditions when observing fish habitat requirements strongly suggests that physical habitat change should be a priority for river enhancement in the Charles River. Comparison of our target and existing fish communities to those from a comprehensive study of Northeastern fish assemblage responses to urban intensity gradients revealed very similar results. Likewise, comparison of our TFC community and affinity scores to those of other TFCs from similar regions also yielded similar results and encouraging findings. Based on the positive results of these comparisons, the utility of the findings from the inference approach, and the widespread adoption of the TFC in the Northeast US, it appears that the TFC approach can be used effectively to identify the composition of a healthy fish community and guide river enhancements in both highly urbanized and non-urbanized streams and rivers in the Northeast US.     

Impacts of Urbanization on Stream Habitat and Fish Across Multiple Spatial Scales

We analyzed the relation of the amount and spatial pattern of land cover with stream fish communities, in-stream habitat, and baseflow in 47 small southeastern Wisconsin, USA, watersheds encompassing a gradient of predominantly agricultural to predominantly urban land uses. The amount of connected impervious surface in the watershed was the best measure of urbanization for predicting fish density, species richness, diversity, and index of biotic integrity (IBI) score; bank erosion; and base flow. However, connected imperviousness was not significantly correlated with overall habitat quality for fish. Nonlinear models were developed using quantile regression to predict the maximum possible number of fish species, IBI score, and base flow for a given level of imperviousness. At watershed connected imperviousness levels less than about 8%, all three variables could have high values, whereas at connected imperviousness levels greater than 12% their values were inevitably low. Connected imperviousness levels between 8 and 12% represented a threshold region where minor changes in urbanization could result in major changes in stream condition. In a spatial analysis, connected imperviousness within a 50-m buffer along the stream or within a 1.6-km radius upstream of the sampling site had more influence on stream fish and base flow than did comparable amounts of imperviousness further away. Our results suggest that urban development that minimizes amount of connected impervious surface and establishes undeveloped buffer areas along streams should have less impact than conventional types of development.     

生态城市建设中的生态农业对策--以南京为例

建设生态城市是城市发展的必然要求。都市生态农业是建设生态城市的必要条件。本文以南京为例，讨论建设都市生态农业的具体对策。     

生态学理念在城市化进程战略环境评价中的应用

城市化，生活化是人类历史发展的必然趋势，城市化进程中，SEA是实施城市可持续发展战略的有效工具，在城市化进程SEA中引入以可持续发展为核心的生态学理论是引导城市环境协调发展的重要一环，本文探讨了生态学理论在SEA中运用，为保证城市的持续有序发展，在城市化进程中，SEA应充分考虑环境可持续性，社会可持续性，经济可持续性，土地可持续性。