Validation of an Invertebrate Community Index for Urban Streams for an Alabama Coastal Plains Watershed1

Abstract: The purpose of this study was to validate the application of an invertebrate community index (ICI) to assess the biological integrity of urban streams. Validation involved comparing chemical and habitat data to ICI scores from 20 urban streams and four least‐impacted streams in the Choctawhatchee and Pea River watersheds located in Southeast Alabama. Chemical and habitat data were collected to support whether the ICI accurately predicts the health of the streams. A significant difference between urban and least‐impacted ICI scores, habitat evaluation scores, chemical variables, taxa richness, and Shannon‐Wiener diversity were observed when urban sites were compared with least‐impacted sites using Mann‐Whitney U‐test. Urban sites having low ICI scores, low species richness and diversity, and poor habitat showed greater impairment than least‐impacted sites. Cluster analysis of macroinvertebrate assemblages indicated two clusters. Significant differences between clusters in habitat evaluations, chemical parameters, and ICI scores showed that some urban sites were more degraded than other urban sites in the study. Differentiation between least‐impacted and urban sites indicated that the ICI provided valid biotic assessments. Therefore, this study validated that the ICI is capable of predicting the biological integrity of urban streams in the Choctawhatchee and Pea River watersheds.     

区域城市化水平综合评价及其地域差异研究——以江苏省为例

从城市化内涵出发,基于人口、经济发展、居民生活和地域环境构建了反映城市化发展水平的评价指标体系。然后,运用综合评价方法,对江苏省13个城市的城市化发展水平进行了评价分析,并通过聚类分析对其进行分类,目的是找出各城市之间的优势和差距。同时借助于GIS技术手段,将这种城市化差异反映在空间区域上,从而有针对性地制定提高江苏省各区域之间城市化水平的对策。     

Assessing Influences of Hydrology,Physicochemistry, and Habitat on Stream Fish Assemblages Across a Changing Landscape1

Abstract: We evaluated the impact of land cover on fish assemblages by examining relationships between stream hydrology, physicochemistry, and instream habitat and their association with fish responses in streams draining 18 watersheds of the Lower Piedmont of western Georgia. Several important relationships between land use and physicochemical, hydrological, and habitat parameters were observed, particularly higher frequency of spate flows, water temperatures, and lower dissolved oxygen (DO) with percentage impervious surface (IS) cover, higher habitat quality with percentage forest cover, and elevated suspended solid concentrations with percentage pasture cover. Fish assemblages were largely explained by physicochemical and hydrological rather than habitat variables. Specifically, fish species diversity, richness, and biotic integrity were lower in streams that received high frequency of spate flows. Also, overall fish assemblage structure as determined by nonmetric multidimensional scaling was best described by total dissolved solids (TDS) and DO, with high TDS and low DO streams containing sunfish‐based assemblages and low TDS and high DO streams containing minnow‐based assemblages. Our results suggest that altered hydrological and physicochemical conditions, induced largely by IS, may be a strong determinant of fish assemblage structure in these lowland streams and allow for a more mechanistic understanding of how land use ultimately affects these systems.     

Linking Hydrologic Alteration to Biological Impairment in Urbanizing Streams of the Puget Lowland,Washington, USA1

Abstract: We used a retrospective approach to identify hydrologic metrics with the greatest potential for ecological relevance for use as resource management tools (i.e., hydrologic indicators) in rapidly urbanizing basins of the Puget Lowland. We proposed four criteria for identifying useful hydrologic indicators: (1) sensitive to urbanization consistent with expected hydrologic response, (2) demonstrate statistically significant trends in urbanizing basins (and not in undeveloped basins), (3) be correlated with measures of biological response to urbanization, and (4) be relatively insensitive to potentially confounding variables like basin area. Data utilized in the analysis included gauged flow and benthic macroinvertebrate data collected at 16 locations in 11 King County stream basins. Fifteen hydrologic metrics were calculated from daily average flow data and the Pacific Northwest Benthic Index of Biological Integrity (B‐IBI) was used to represent the gradient of response of stream macroinvertebrates to urbanization. Urbanization was represented by percent Total Impervious Area (%TIA) and percent urban land cover (%Urban). We found eight hydrologic metrics that were significantly correlated with B‐IBI scores (Low Pulse Count and Duration; High Pulse Count, Duration, and Range; Flow Reversals, T_Qmean, and R‐B Index). Although there appeared to be a great deal of redundancy among these metrics with respect to their response to urbanization, only two of the metrics tested – High Pulse Count and High Pulse Range – best met all four criteria we established for selecting hydrologic indicators. The increase in these high pulse metrics with respect to urbanization is the result of an increase in winter high pulses and the occurrence of high pulse events during summer (increasing the frequency and range of high pulses), when practically none would have occurred prior to development. We performed an initial evaluation of the usefulness of our hydrologic indicators by calculating and comparing hydrologic metrics derived from continuous hydrologic simulations of selected basin management alternatives for Miller Creek, one of the most highly urbanized basins used in our study. We found that the preferred basin management alternative appeared to be effective in restoring some flow metrics close to simulated fully forested conditions (e.g., T_Qmean), but less effective in restoring other metrics such as High Pulse Count and Range. If future research continues to support our hypothesis that the flow regime, particularly High Pulse Count and Range, is an important control of biotic integrity in Puget Lowland streams, it would have significant implications for stormwater management.     

湖北省经济发展与耕地资源变化的关系

近20年来,湖北省在经济快速发展的同时,伴随着耕地面积的快速减少,这对我国粮食安全战略产生了一定隐患。选择GDP、全社会固定资产投资总额、城市化水平与耕地面积作为主要分析指标,应用对比分析与最小二乘法分析了1990~2007年湖北省经济发展与耕地面积变化的关系,其能够解释耕地资源占有量的9298%的变化。研究结果表明：湖北省近20年的经济发展与耕地面积变化呈负相关关系,经济增长是耕地面积减少的主要原因,但随着经济发展水平上升和土地集约利用水平提高,单位经济增长付出的土地代价会逐渐下降;同时经济发达地区比经济欠发达地区耕地流失严重,平原地区比丘陵地区耕地减少量大。研究结果可以为湖北省在今后经济发展过程中,如何合理利用土地和保护有限的耕地资源提供一定的科学依据,为其他省份进一步研究经济发展中的耕地变化提供借鉴。     

西部大开发：城镇化建设与农田资源保护协调发展问题

城镇作为现代经济生活的主载体,对经济发展的作用巨大,然而城镇的建设与发展又是要占用大量农田资源。我国地少人多,土地资源稀缺,现行可耕地主要集中于中、西部地区,因此西部大开发,妥善处理城镇化建设与农田资源保护协调发展关系就显得尤为重要。本文在论述城镇化建设与农田资源保护的矛盾现状基础之上,试图提出西部地区城镇化建设中相应的农田资源保护对策。     

中国西部城市化基本特征分析——以新疆为例

本文以新疆为例,探讨了新疆城市化的基本特征和规律,总结经验教训,以朝正确认识西部地区城市化的基本特征,从而为西部大开发中城市化发展战略的制定提供有价值的借鉴和参考。     

城市化进程监控：从“人口规模论”到可持续人居环境度

本文论述了运用人居环境可持续发展来监控城市化进程的可能性,并提出了一定的方法。     

西部大开发要走可持续发展之路

西部地区生态环境条件十分脆弱,水土流失、荒漠化问题严重;各种自然灾害多发,远离目前国家的经济发展中心,由于距离远远输成本高使自然资源失去了价格上的部分优势。西部地区自然条件和经济社会发展的特殊性,要求我们在西部大开发中坚持生态建设,保护环境,节约资源,趋利避害,推进城市化,依靠科技创新,以最小的资源环境代价发展经济,实现人口资源、环境与经济社会发展的良性循环。     

转型期耕地数量动态变化及最佳非农转化量的实证研究——以江苏省为例

伴随着我国经济的快速发展和城市化进程的加快，对土地资源的需求量急剧上升，作为土地中的精华——耕地资源也在农业部门和经济建设之间面临着如何分配的矛盾。如何确保耕地资源在粮食安全和经济发展间的优化配置已经成为一个迫切需要解决的问题。本文试图通过对江苏省耕地数量的变动态势进行分析，并运用区域容许耕地转换量化模型（MAC）来确定江苏省可以允许转换的耕地的最优数量，借此来确定区域耕地保护的底线及调控指标，为城市化进程中区域耕地资源的优化配置提供一种依据和解决思路。