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Many individual wetlands are interconnected by complex hydrological processes, acting as a large wetland system (WS) with specific structure and function in certain temporal and spatial scale. An understanding of the holistic attributes of a WS is especially critical for the long-term persistence and biodiversity maintenance of various wetlands. In this study, we developed a framework to use ecological network analysis (ENA) in a holistic assessment to WSs. The Baiyangdian WS in China and the Okefenokee WS in USA were presented as two examples. Network models of two WSs were developed to facilitate the application of network analysis, in which network nodes represent river segments, lakes and reservoirs, and network links are directional representations of water flow between nodes. Using 25 network indicators, we compared two WSs to show how ENA can be used to provide a unified benchmark for holistic comparisons. Results show there is a large difference, such as system activity, inner organization and so on, between two WSs. The Baiyangdian WS is a sparsely connected system with a connectance of 0.13 while the Okefenokee WS is a well connected system with a connectance of 1.08. Comparing with the Okefenokee WS, the Baiyangdian WS has higher inner organization (2.25 bits versus 1.27 bits) but lower system activities (0.19 m3y-1/m2 versus 0.34 m3y-1/m2). System ascendency of the Baiyangdian WS is slightly lower than that of the Okefenokee WS (0.43m3y-1/m2 versus 0.42 m3y-1/m2). On the basis of the current results, we proposed the network-based indicators for assessing the holistic attributes of WSs. This study could provide a novel prospective and methodology for evaluating system attributes at the system level and contributes to the basin-wide wetland protection and water resources management. [ABSTRACT FROM AUTHOR]

In this paper we have two objectives-one empirical; one methodological. Although China's leaders are beginning to pay attention to health care in rural China, there are still concerns about access to health services. To examine this issue, we use measures of travel distances to health services to examine the nature of coverage in Shaanxi Province, our case study. The mean distance by road to the nearest health center is still more than 6 km. When we use thresholds for access of 5 and 10 km we find that more than 40 (15) percent of the rural population lives outside of these 5 (10) kilometer service areas for health centers. The nature of the access differs by geographical region and demographic composition of the household. The methodological contribution of our paper originates from a key feature of our analysis in which we use Geographic Information System (GIS) network analysis methods to measure traveling distance along the road network. We compare these measures to straight-line distance measures. Road distances (produced by network analysis) produce measures (using means) that are nearly twice as great as straight-line distances. Moreover, the errors in the measures (that is, the difference between road distances and straight-line distances) are not random. Therefore, traditional econometric methods of ameliorating the effects of measurement errors, such as instrument variables regression, will not produce consistent results when used with straight-line distances. [ABSTRACT FROM AUTHOR]

From 1998 through to 2000, we satellite-tracked the movements of 13 Oriental White Storks (Ciconia boyciana) on their autumnal migration in order to identify their important stopover sites for preserving links from the Russian Far East breeding sites to the wintering sites in south-eastern China. New analytical methods of satellite tracking data were employed to derive robust information on the locations of stay sites, the number of stopovers made during migration, and the distance traveled without making stopovers. Based on the derived information, we modeled a stay site network as an abstraction of the storks’ potential migration routes from their breeding sites to wintering sites. Using network analysis techniques, we explored how the loss of stopover sites could affect the connectivity of potential migration routes. The results suggested that if the seashore stopover sites facing Bohai Bay in eastern China were lost, the storks’ wintering sites along the Yangtze River in south-eastern China would be isolated. Among the seashore stopover sites, Jiantuozhi Gley Mire (39.185°N, 118.627°E), located on the northern seashore of Bohai Bay, was considered particularly important for migrating storks, because it was used every year by the storks we tracked. If conservation needs of this critically located site fail to be addressed, the stay site network of storks can create weak links in the chain of migration and, if‘broken’, storks will have great difficulties in completing their autumnal migration. [ABSTRACT FROM AUTHOR]