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291.
This article describes the history of the Coachella Valley Multiple Species Habitat Conservation Plan (CVMSHCP), in the Riverside
County region of Southern California. When this collaborative biodiversity conservation planning process began, in 1994, local
participants and supporters had numerous factors working in their favor. Yet, as of April 2007, nearly 13 years had passed
without an approved plan. This is a common problem. Many multiple species habitat conservation plans now take more than a
decade to complete, and the long duration of these processes often results in negative consequences. The CVMSHCP process became
bogged down—despite strong scientific input and many political advantages—due to problematic relationships between the Plan’s
local supporters, its municipal signatory parties, and officials from the state and federal wildlife agencies, particularly
the regional office of the US Fish and Wildlife Service. This case study demonstrates the crucial importance of institutional
structures and relationships, process management, and timeliness in habitat conservation planning. We conclude by offering
several related recommendations for future HCP processes. 相似文献
292.
Mark R. Stevens Philip R. Berke Yan Song 《Journal of Environmental Planning and Management》2008,51(6):737-757
Research suggests that characteristics of local government land-use planners help determine the priority that local communities place on flood hazard mitigation. However, research has not examined the significance of land-use planners' values and role orientations for flood hazard mitigation. Multiple regression analysis is used to examine the influence that land-use planners' values and role orientations have on flood hazard mitigation in a national sample of New Urbanist development projects. Findings indicate that land-use planners' values and role orientations have significant implications for flood hazard mitigation in these projects. The paper recommends that local governments adopt a land-use planning approach to flood hazard mitigation that relies on land-use planners to help direct development away from hazardous portions of development sites. 相似文献
293.
Mhairi Aitken Seonaidh McDonald Peter Strachan 《Journal of Environmental Planning and Management》2008,51(6):777-799
There have been conflicting accounts of the role and influence of local opposition within planning application outcomes for wind power developments. There is an expanding literature that considers public responses to proposed renewable energy developments and much of this suggests that public opposition is a key factor in the slow growth in renewable energy capacity. However, this paper will show that local opposition groups' power over such planning processes is very limited, and in fact extends only so far as delaying an outcome. Through a thematic content analysis of objection letters to one particular proposed wind power development, the key issues raised in connection with the development will be highlighted. Subsequently, these issues will be compared with those discussed in the official report of the planning appeals process, and it will be shown that the concerns of local objectors had little influence over the eventual verdict. 相似文献
294.
The Impact of Urbanization and Protection of Water Resources in Owerri and Environs SE, Nigeria 总被引:1,自引:0,他引:1
Untreated sewage and agriculture are the most important sources of contamination. The study was carried out by conducting a short-term surface water and groundwater pollution survey of the Owerri Urban area and its environs, in order to establish the current levels of pollution. An attempt has been made to show the relationships between pollution levels, population density, industrial and agricultural activities. The spatial distribution of pollutants due to a poor land use system and to human activities was investigated. This emphasises integrated planned development as a preventive measure for arresting pollution levels in fast growing urban centres. The total groundwater stored in the area amounts to 7.87 × 109 m3. Twenty five percent of this is released as base flow into the adjacent rivers (Otamiri and Nworie). The annual groundwater recharge is 3.4 × 109 m3. The enormous volume of groundwater stored and the comparatively low cost of development makes groundwater an excellent alternative supply source for the area (Uma et al., 1984). 相似文献
295.
干旱地区水污染控制系统初探 总被引:2,自引:0,他引:2
应用数学规划方法,科学地组织污染物的排放或科学地协调各个治理环节,以乌鲁木齐市水磨河流域水污染控制系统为例,对干旱地区水污染控制系统进行了初步探索,从而得出干旱地区污水处理费用的合理负担,并得出污染物排放的数量,质量受自然地理条件制约的结论。 相似文献
296.
Nutrient transfer functions: the site of integration between feeding behaviour and nutritional physiology 总被引:6,自引:0,他引:6
Summary. We describe and extend a graphical approach to quantitative nutrition that focuses on the interplay between behavioural and
physiological components of nutritional regulation. The site of integration is the nutrient transfer function, which is the
function describing the time course of nutrient transfer between serially connected nutritional compartments (e.g., from the gut to the blood). The relationship between the shape of the nutrient transfer function and the temporal patterns
of feeding determines the values of two key quantitative parameters of nutrition: the rate ('power') and the efficiency of nutrient acquisition. The approach can be extended to consider, in addition to the short-term behavioural and physiological
decisions made by animals, some ecological determinants and longer-term, life history consequences of such decisions. Most
importantly, this category of models can provide insights into the interplay among the various nutrients in an animal's diet.
We illustrate this using hypothetical examples, and also present preliminary data for the power-efficiency relationships of
protein and digestible carbohydrates in locusts. Finally, we consider existing evidence for the various means available to
these and other insects for regulating such relationships.
Received 24 September 1997; accepted 9 December 1997. 相似文献
297.
Oviposition of carrot fly (Psila rosae) in response to foliage and leaf surface extracts of host plants 总被引:1,自引:0,他引:1
Summary. Foliage of twelve host and two non-host species and surrogate leaves treated with the respective leaf extracts were presented
to laboratory populations of the carrot fly (Psila rosae) in oviposition choice assays. The stimulatory activity of dichloromethane surface extracts and the diethyl ether fraction
of hot water extracts did not reflect accurately the differences in acceptability observed among intact leaves. A better correlation
was found using hexane extracts prepared in a microwave oven. Two out of five fractions of this crude hexane extract obtained
by silica gel column chromatography stimulated oviposition. The diethyl ether fraction, which contained the previously identified
oviposition stimulants (propenylbenzenes, furanocoumarins, polyacetylenes), could account for only a minor part of the variation
in the acceptability of host leaves. The preference hierarchy for intact leaves corresponded better to the ranking of species
according to activity of the methanolic fraction, which apparently contains unknown stimulatory compounds.? The water fractions
of the hot water extracts were shown to reduce egg-laying underneath surrogate leaves treated with a stimulatory extract.
This oviposition-deterring effect was particularly strong with the non-preferred species Pimpinella major, which is also highly resistant in the field. Hence, unidentified inhibitory compounds may also contribute to differential
accept ability of host plants. It is concluded that antixenotic (non-preference) resistance of host plants to carrot fly attack
depends on complex mixtures of semiochemicals.
Received 11 June 1997; accepted 26 November 1997. 相似文献
298.
Summary. A diverse group of brown seaweeds produce bouquets of C11 metabolites, some of which act as pheromones that cue gamete release or attract sperm to eggs following release. We demonstrate
that these C11 metabolites and their degradation products also frequently and strongly deter feeding by the herbivorous amphipod Ampithoe longimana, but rarely by the herbivorous sea urchin Arbacia punctulata. Across the range of concentrations tested, seven of twelve C11 metabolites or mixtures that we tested deterred feeding by the amphipod, but only two of eleven deterred the sea urchin.
For those compounds where we could rigorously contrast the magnitude of deterrence against the amphipod with the magnitude
of deterrence against the urchin, the amphipod was deterred significantly more than the urchin by five of six metabolites.
Thus, C11 compounds were more frequently and more strongly deterrent to the amphipod than to the sea urchin. These findings for C11 metabolites conflict with previous investigations, where other classes of seaweed chemical defenses have been shown to deter
feeding by large mobile herbivores like urchins and fishes but to be relatively ineffective against mesograzers, especially
the species of amphipod that we used here. Our results suggest that C11 metabolites are unusual among the known seaweed chemical defenses in that they are especially effective against mesograzers,
which often consume seaweed spores, zygotes, and juveniles. The high concentrations of C11 metabolites in brown algal eggs could allow these defenses to be especially important in defending gametes, zygotes, or young
sporelings from herbivorous mesograzers.
Received 26 February 1998; accepted 9 April 1998. 相似文献
299.
K. Håkan Olsén J. Torbjörn Järvi Ian Mayer Erik Petersson Frederieke Kroon 《Chemoecology》1998,8(1):9-17
Summary. In the present experiment the behaviour and endocrine status of males of the brown trout, Salmo trutta L., (Salmoniformes: Salmonidae) were studied when males were kept in a stream tank with a nest digging female. Groups of
mature adult males and precocious intact or anosmic male parr were placed with the nesting female so that the group resembled
a natural spawning situation with big anadromous fish acting as dominant males and precocious parr acting as “sneakers”. A
control experiment was also run with only males without a female present. In intact parr there were significant positive correlations
between the per cent of the total observation time spent with a female, milt volume, and plasma concentration of 17α, 20β-dihydroxy-4-pregnen-3-one.
Anosmic parr had significantly lower volumes of strippable milt and gonadal steroid hormone levels compared with intact parr.
However, no differences were found in the control experiment. Significantly fewer anosmic parr attended and courted the nesting
female and those anosmic fish that attended the female had significantly lower plasma levels of gonadal hormones. Intact parr
also displayed a greater number of agonistic acts against other parr without any difference in fighting ability. No differences
in aggression occured in the control experiment. In adult males together with a female, post-experimental gonadal steroid
hormone levels were higher than pre-experimental levels. Positive correlations between aggression and androgen hormone levels
were observed in adult males. No differences in plasma hormone levels were observed between adult males and intact precocious
males. The results show that olfactory occlusion results in low steroid hormone levels and milt volumes in precocious males
placed in a spawning situation. The courting behaviour was also affected by anosmia. Odours from the nesting female may have
caused the enhanced plasma hormone levels and stimulated the males to attend the female.
Received 15 May 1997; accepted 29 June 1997. 相似文献
300.
Summary. Chemical defense against herbivores has rarely been investigated for freshwater plants, possibly due to the common misconception
that herbivory on aquatic macrophytes is low and would not select for chemical defenses. In previous work, the freshwater
angiosperm Saururus cernuus was shown to be a low preference food for omnivorous crayfish despite its high nutrient value and relatively soft texture.
We used feeding by the crayfish Procambarus clarkii to guide fractionation of the deterrent lipid-soluble extract of this plant, leading to the identification of seven deterrent
lignoid metabolites, (–)-licarin A, (+)-saucernetin, (–)-dihydroguaiaretic acid, (–)-sauriols A and B, (–)-saucerneol, and
(–)-saucerneol methyl ether. Lignans have been implicated in terrestrial plant chemical defenses as insect growth inhibitors,
insect toxins, nematocides, antibacterial, and antifungal agents. However, these activities have rarely been demonstrated
using ecologically relevant methodologies in terrestrial systems, and never before in freshwater systems. The widespread nature
of lignans amongst very distantly related plants, along with their rich diversity of molecular structure, suggests that they
could play a large role in mediating plant-herbivore interactions. In addition to the lignoid compounds we identified, there
were other compounds present in low concentration or unstable compounds that were deterrent, that did not appear to be lignans,
but that we were unable to identify. This plant thus appears to be defended by a complex mixture of natural products.
Received 6 June 2000; revised 23 August 2000; accepted 2 September 2000 相似文献