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201.
Research on human dimensions of ecosystems through the ecosystem services (ES) concept has proliferated over recent decades but has largely focused on monetary value of ecosystems while excluding other community-based values. We conducted 312 surveys of general community members and regional researchers and decision-makers (specialists) to understand local perceptions and values of watershed ES and natural resource management in South America’s southern Patagonian ecoregion. Results indicated that specialists shared many similar values of ES with community members, but at the same time their mentalities did not capture the diversity of values that existed within the broader community. The supporting services were most highly valued by both groups, but generally poorly understood by the community. Many services that are not easily captured in monetary terms, particularly cultural services, were highly valued by community members and specialists. Both groups perceived a lack of communication and access to basic scientific information in current management approaches and differed slightly in their perspective on potential threats to ES. We recommend that a community-based approach be integrated into the natural resource management framework that better embodies the diversity of values that exist in these communities, while enhancing the science-society dialog and thereby encouraging the application of multiple forms of ecological knowledge in place-based environmental management.  相似文献   
202.
Discovery of a fossil (30–35 million-year-old) urolith from Early Oligocene deposits in northeastern Colorado provides the earliest evidence for the antiquity of bladder stones. These are spherical objects with a layered phosphatic structure and a hollow center. Each layer is composed of parallel crystals oriented perpendicular to the surface. Macroscopic and microscopic examination and X-ray diffraction analysis, along with comparison with 1,000 contemporary uroliths, were used as evidence in the confirmation of this diagnosis. Raman microspectroscopy verified the presence of organic material between layers, confirming its biologic origin.  相似文献   
203.
We evaluated the relationships between landscape characteristics and lake water quality in receiving waters by regressing four water quality responses on landscape variables that were measured for whole watersheds and three different buffer distances (30, 60, and 120 m). Classical percolation theory was used to conceptualize nutrient pathways and to explain nonlinear responses. The response variables were total nitrogen (TN), total phosphorus (TP), chlorophyll-a (Chl-a), and Secchi transparency (SD). Landscape data were obtained from satellite image-derived maps of 130 watersheds in Iowa using geographic information systems software. We developed regression models with a stepwise protocol selecting the optimal number of significant explanatory variables. Configuration variables such as contagion, the cohesion of cropland and urban land, and the aggregation index of forest were very important and more important than variables assessing landscape composition (e.g., percentage farmland). Whole watershed models predicted between 15 and 67% of the variability in TN, TP, Chl-a, and SD. Proximity-explicit data offered only slightly improved statistical power over land cover data derived from the entire watershed for variables TN, Chl-a. and SD, but not for TP.  相似文献   
204.
Foraging guilds of North American birds   总被引:2,自引:0,他引:2  
We propose a foraging guild classification for North American inland, coastal, and pelagic birds. This classification uses a three-part identification for each guild—major food, feeding substrate, and foraging technique—to classify 672 species of birds in both the breeding and nonbreeding seasons. We have attempted to group species that use similar resources in similar ways. Researchers have identified foraging guilds generally by examining species distributions along one or more defined environmental axes. Such studies frequently result in species with several guild designations. While the continuance of these studies is important, to accurately describe species' functional roles, managers need methods to consider many species simultaneously when trying to determine the impacts of habitat alteration. Thus, we present an avian foraging classification as a starting point for further discussion to aid those faced with the task of describing community effects of habitat change.  相似文献   
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Whangapoua Estuary, Great Barrier Island, New Zealand, is central to a proposed Marine Reserve, and is currently managed for conservation by the Department of Conservation. This paper describes the sequential impacts of Maori and European people on the process of estuarine vegetation succession in time and space, and the rate of estuarine sedimentation. Multiple cores from one estuary gave confidence in assessing the temporal sequence of vegetation change, but bioturbation and other disturbance factors made it difficult to interpret 14C dates from the estuarine environment. The modern vegetation zonation pattern on the estuary is an active succession, which has been generated by rapid estuary in-filling, probably initiated as a consequence of erosion following Maori burning of the adjacent forest. European forest clearance for agriculture resulted in a further increase in estuarine sedimentation, and may have re-activated earlier sediments trapped in adjacent swamps. The combined effects of two phases of human exploitation have resulted in large-scale loss of nutrients and top-soil from catchments throughout Great Barrier Island. Conservation management of the estuary should take account of the anthropogenic impacts that have driven the plant succession and created the current vegetation zonation pattern. This pattern is neither static nor ‘natural’, but rather an on-going response to the changing human activities in the surrounding catchment.  相似文献   
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208.
Microbial communities can greatly affect the mobility and fate of subsurface contaminants, yet relatively little is known about the functioning of microorganisms in subsurface environments. Major advances in DNA sequencing capability and the advent of genome‐enabled studies have produced key insights into how microorganisms adapt to environmental conditions and/or biotransform subsurface contaminants starting from analyses of genome content. These techniques enable the researcher to detect how an organism responds to its environment and, potentially, to devise better methods to promote specific microbial activity in subsurface environments. The U.S. Department of Energy sponsors genome research through the Genomics:GTL program. One of the applications of this research is to better understand and control biological processes influencing the mobility of contaminants of concern to DOE such as metals and radionuclides. Genome and gene expression techniques have led to new insights into the functioning of subsurface microbial communities, but the true potential of these techniques is still to be revealed. As genome‐enabled science progresses, techniques for evaluating gene expression patterns of whole communities will advance the understanding and development of optimized in situ bioremediation and more realistic simulations of microbial contaminant biotransformation. © 2006 Wiley Periodicals, Inc.*  相似文献   
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210.
The rate and extent of accumulation and washout of arsenic, during daily oral administration of the herbicide monosodium methanearsonate (MSMA) were evaluated in Iranian dairy sheep and goats. Subjects received a dose of 10 mg of MSMA as arsenic per kg of body weight daily for 28 consecutive days. The total arsenic concentration in blood and milk was measured during and after the period of MSMA administration while arsenic in urine and feces was measured for 10 days following administration of last dosage of MSMA. Arsenic was accumulated slowly during 28 days of MSMA administration and steady states were essentially complete in sheep after 20 days and in goats following 25 days of MSMA administration. Blood arsenic concentration decreased rapidly after termination of MSMA administration. In both test animals, the half-lives of washout were smaller than accumulation. The concentration of arsenic in the urine and feces of both species did not increase significantly over controls and animals were free of arsenic relatively shortly after administration stopped. These data indicate that arsenic from MSMA is mainly absorbed from gastrointestinal tract and is not significantly accumulated in the body. Arsenic is eliminated from body by way of urine and feces with urinary excretion being the most important route.  相似文献   
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