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281.
This paper presents results of an international comparative research project, funded by the UK Economic and Social Research Council (ESRC) and the Academy for Sustainable Communities (ASC) on the ‘learning potential of appraisal (strategic environmental assessment — SEA) in spatial planning’. In this context, aspects of ‘single-loop’ and ‘double-loop’ learning, as well as of individual, organisational and social learning are discussed for emerging post-EC Directive German practice in the planning region (Zweckverband) of Brunswick (Braunschweig), focusing on four spatial plan SEAs from various administrative levels in the region. It is found that whilst SEA is able to lead to plan SEA specific knowledge acquisition, comprehension, application and analysis (‘single-loop learning’), it is currently resulting only occasionally in wider synthesis and evaluation (‘double-loop learning’). Furthermore, whilst there is evidence that individual and occasionally organisational learning may be enhanced through SEA, most notably in small municipalities, social learning appears to be happening only sporadically.  相似文献   
282.
Characterizing fish assemblages in lentic ecosystems is difficult, and multiple sampling methods are almost always necessary to gain reliable estimates of indices such as species richness. However, most research focused on lentic fish sampling methodology has targeted recreationally important species, and little to no information is available regarding the influence of multiple methods and timing (i.e., temporal variation) on characterizing entire fish assemblages. Therefore, six lakes and impoundments (48–1,557 ha surface area) were sampled seasonally with seven gear types to evaluate the combined influence of sampling methods and timing on the number of species and individuals sampled. Probabilities of detection for species indicated strong selectivities and seasonal trends that provide guidance on optimal seasons to use gears when targeting multiple species. The evaluation of species richness and number of individuals sampled using multiple gear combinations demonstrated that appreciable benefits over relatively few gears (e.g., to four) used in optimal seasons were not present. Specifically, over 90 % of the species encountered with all gear types and season combinations (N?=?19) from six lakes and reservoirs were sampled with nighttime boat electrofishing in the fall and benthic trawling, modified-fyke, and mini-fyke netting during the summer. Our results indicated that the characterization of lentic fish assemblages was highly influenced by the selection of sampling gears and seasons, but did not appear to be influenced by waterbody type (i.e., natural lake, impoundment). The standardization of data collected with multiple methods and seasons to account for bias is imperative to monitoring of lentic ecosystems and will provide researchers with increased reliability in their interpretations and decisions made using information on lentic fish assemblages.  相似文献   
283.
In recent years, elk have begun recolonizing areas east of the Rocky Mountains that are largely agro-forested ecosystems composed of privately owned land where management of elk is an increasing concern due to crop and forage depredation and interspecific disease transmission. We used a Geographic Information System, elk use locations (n = 5013), random locations (n = 25,065), discrete-choice models, and information-theoretic methods to test hypotheses about elk resource selection in an agro-forested landscape located in the Pine Ridge region of northwestern Nebraska, USA. Our objectives were to determine landscape characteristics selected by female elk and identify publicly owned land within the Pine Ridge for potential redistribution of elk. We found distance to edge of cover influenced selection of resources by female elk most and that in areas with light hunting pressure, such as ours, this selection was not driven by an avoidance of roads. Female elk selected resources positioned near ponderosa pine cover types during all seasons, exhibited a slight avoidance of roads during spring and fall, selected areas with increased slope during winter and spring, and selected north- and east-facing aspects over flat areas and areas with south-facing slopes during winter months. We used our models to identified a potential elk redistribution area that had a higher proportion of landcover with characteristics selected by elk in our study area than the current herd areas and more landcover that was publicly owned. With appropriate management plans, we believe elk within the Potential Elk Redistribution Area would predominantly occupy publicly owned land, which would help minimize crop and forage damage on privately owned lands.  相似文献   
284.
Stream habitat assessments are conducted to evaluate biological potential, determine anthropogenic impacts, and guide restoration projects. Utilizing these procedures, managers must first select a representative stream reach, which is typically selected based on several criteria. To develop a consistent and unbiased procedure for choosing sampling locations, the Illinois Department of Natural Resources and the Illinois Natural History Survey have proposed a technique by which watersheds are divided into homogeneous stream segments called valley segments. Valley segments are determined by GIS parameters including surficial geology, predicted flow, slope, and drainage area. To date, no research has been conducted to determine if the stream habitat within a valley segment is homogeneous and if different valley segments have varying habitat variables. Two abutting valley segments were randomly selected within 13 streams in the Embarras River watershed, located in east-central Illinois. One hundred meter reaches were randomly selected within each valley segment, and a transect method was used to quantify habitat characteristics of the stream channel. Habitat variables for each stream were combined through a principal components analysis (PCA) to measure environmental variation between abutting valley segments. A multivariate analysis of variance (MANOVA) was performed on PCA axes 1–3. The majority of abutting valley segments were significantly different from each other indicating that habitat variability within each valley segment was less than variability between valley segments (5.37 ≤ F ≤ 245.13; P ≤ 0.002). This comparison supports the use of the valley segment model as an effective management tool for identifying representative sampling locations and extrapolating reach-specific information.  相似文献   
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286.
According to indicator models of sexual selection, females can benefit from choosing males with above average epigamic traits, but empirical evidence for such benefits is scarce. Here, we report results from an experiment with 29 pairs of house sparrows (Passer domesticus) where the intensity of nest defense against a mounted mustelid predator was related to the size of the black throat and breast patch (“badge”) in males. Using principal components analysis (PCA), original response variables of both sexes were reduced to two factors: “Approach” to the predator and “Distant warning”. “Approach”, the more risky behavior, increased from small- through medium- to large-badged males and decreased in their females. Since large-badged males have a higher certainty of paternity (i.e. greater benefits from defense) and may be older and more experienced (i.e. incur lower costs), the most likely explanation for male defense intensity increasing with badge size is an improving benefit/cost ratio. The resulting optimal response of their females and evolutionarily stable participation in joint parental care is illustrated by a graphical model. It shows that females would, indeed, benefit directly from choosing large-badged males. This, however, is no proof of a direct evolutionary tie between badge size and paternal behavior, as assumed by indicator models of sexual selection. It may simply represent a spurious relationship, originating from the correlation of badge size and defense with confidence of paternity. Received: 22 September 1997 / Accepted after revision: 3 November 1997  相似文献   
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288.
Entomophagy—eating insects—is getting a lot of attention these days. However, strict vegans are often uncomfortable with entomophagy based on some version of the precautionary principle: if you aren’t sure that a being isn’t sentient, then you should treat it as though it is. But not only do precautionary principle-based arguments against entomophagy fail, they seem to support the opposite conclusion: strict vegans ought to eat bugs.  相似文献   
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290.
Fragestellung Wie gestaltet und ggf. ver?ndert sich die wissenschaftliche Produktivit?t der Umweltchemie und ?kotoxikologie in Deutschland? So einfach die Frage klingt: Sie ist schwer zu beantworten, denn auf Fachgebieten, die per se interdisziplin?r sind, sind überlappungen zu Nachbargebieten die Regel und Abgrenzungen schwierig, zum Teil unm?glich, weil in der Literatur nicht erkennbar oder nicht erfasst. Umweltchemie und ?kotoxikologie sind oft „drin“, stehen aber nicht „drauf“ – auf den Institutsnamen, den Projekttiteln oder den Zeitschriftentiteln. Bei in hohem Ma?e interdisziplin?ren Arbeiten – Tendenz steigend – sind wir Wissenschaftler in manchen F?llen sogar selbst verlegen um eine abgrenzende Zuordnung oder empf?nden eine solche als inad?quat oder artifiziell. Ansatz Der Vorstand der Fachgruppe hat die bibliometrische Analyse anhand von Zeitschriftenstichproben als eine probate Herangehensweise für diese Frage gew?hlt. Nicht erfasst werden in einer solchen Stichprobe Arbeiten, die in Zeitschriften ver?ffentlicht wurden, die prim?r nicht der Umweltchemie oder ?kotoxikologie, sondern einem anderen Fach zugerechnet werden. Von der Analyse erfasst werden insbesondere aber die vielen umweltchemischen und ?kotoxikologischen Arbeiten von Wissenschaftlern, deren Arbeitsschwerpunkt in einem anderen Feld liegt und die nur gelegentlich auf unseren Gebieten arbeiten, gleich welche Berufs- und Institutsbezeichnung sie tragen m?gen. Diese Fehlerquelle zu vermeiden, erscheint für relative junge F?cher und stark interdisziplin?re Arbeitsgebiete priorit?r.  相似文献   
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