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561.
562.
Relation of Lake Acidification and Recovery to Fish,Common Loon and Common Merganser Occurrence in Algoma Lakes 总被引:3,自引:0,他引:3
Models are needed that predict both spatial and temporal improvements to ecosystems following reductions of acidifying emissions that produce `acid rain'. Logistic regression models were developed for the occurrence of fish and two fish-eatingbirds, common loons (Gavia immer) and common mergansers(Mergus merganser), using monitoring data collected onlakes across Ontario. These models were applied in the Algomaregion, including the Turkey Lakes Watershed (TLW). Using theWaterfowl Acidification Response Modeling System (WARMS), severalSO2 emission reduction scenarios were simulated, i.e. thosecontributing to measured 1982–1986 sulphate deposition levels, 1994levels (corresponding to full implementation of Canadian SO2emission reductions as stipulated in the 1991 Canada/U.S. AirQuality Agreement), 2010 levels (1994 plus full U.S. reductions),and both a 50% and a 75% further reduction beyond 2010 levels. Some habitat improvements in Algoma were predicted under the 2010scenario for all biota, but substantial increases in habitatquality, especially for mergansers, would occur only under further reductions. The TLW showed little change in chemistry orbiota, while lakes near the Montreal River were predicted toimprove substantially. 相似文献
563.
江西大鄣山夏季鸟类群落多样性研究 总被引:1,自引:0,他引:1
2009年6月至2010年8月采用样线法对江西大鄣山夏季鸟类资源及其生境分布状况进行调查,并计算其物种多样性、均匀性、优势度及不同生境群落间的相似性。共记录江西大鄣山夏季鸟类13目31科78种,其中留鸟45种,夏候鸟21种,冬候鸟7种,旅鸟5种;其中国家二级保护鸟类6种,省级保护鸟类22种;结果表明:东洋种鸟类占有明显优势(500%),古北种次之(282%),广布种占218%。白头鹎(〖WTBX〗Pycnonotus sinensis)和白腰文鸟(Lonchura striata〖WTBZ〗)为当季优势种。6种群落类型中,Shannon Weiner指数与Simpson指数排序均为:阔叶林>农田居民区>针阔混交林>溪流水域>灌木草丛>针叶林。Pielou指数排序为:针阔混交林>溪流水域>阔叶林>农田居民区>灌木草丛>针叶林。Sorenson指数中阔叶林 针阔混交林(〖WTBX〗S〖WTBZ〗=048)为最高。研究结果可为当地森林管理和鸟类保护提供依据 相似文献
564.
Abstract: Remnant plants in urban fringes and native plants in gardens have the potential to contribute to the conservation of threatened plants by increasing genetic diversity, effective size of populations, and levels of genetic connectedness. But they also pose a threat through the disruption of locally adapted gene pools. At Hyams Beach, New South Wales, Australia, four bushland stands of the rare shrub, Grevillea macleayana McGillivray, surround an urban area containing remnant and cultivated specimens of this species. Numbers of inflorescences per plant, fruits per plant, and visits by pollinators were similar for plants in urban gardens and bushland. Urban plants represented a substantial but complex genetic resource, displaying more genetic diversity than bushland plants judged by He , numbers of alleles per locus, and number of private alleles. Of 27 private alleles in urban plants, 17 occurred in a set of 19 exotic plants. Excluding the exotic plants, all five stands displayed a moderate differentiation ( FST = 0.14 ± 0.02), although the urban remnants clustered with two of the bushland stands. These patterns may be explained by high levels of selfing and inbreeding in this species and by long-distance dispersal (several seeds in the urban stand were fathered by plants in other stands). Genetic leakage (gene flow) from exotic plants to 321 seeds on surrounding remnant or bushland plants has not occurred. Our results demonstrate the conservation value of this group of urban plants, which are viable, productive, genetically diverse, and interconnected with bushland plants. Gene flow has apparently not yet led to genetic contamination of bushland populations, but high levels of inbreeding would make this a rare event and difficult to detect. Remnant plants in urban gardens could successfully contribute to recovery plans for endangered and vulnerable species. 相似文献
565.
YOU-HUA CHEN 《Conservation biology》2009,23(3):537-545
Abstract: Identification of priority areas is a fundamental goal in conservation biology. Because of a lack of detailed information about species distributions, conservation targets in the Zhoushan Archipelago (China) were established on the basis of a species–area–habitat relationship (choros model) combined with an environmental cluster analysis (ECA). An environmental‐distinctness index was introduced to rank areas in the dendrogram obtained with the ECA. To reduce the effects of spatial autocorrelation, the ECA was performed considering spatial constraints. To test the validity of the proposed index, a principal component analysis–based environmental diversity approach was also performed. The priority set of islands obtained from the spatially constrained cluster analysis coupled with the environmental‐distinctness index had high congruence with that from the traditional environmental‐diversity approach. Nevertheless, the environmental‐distinctness index offered the advantage of giving hotspot rankings that could be readily integrated with those obtained from the choros model. Although the Wilcoxon matched‐pairs test showed no significant difference among the rankings from constrained and unconstrained clustering process, as indicated by cophenetic correlation, spatially constrained cluster analysis performed better than the unconstrained cluster analysis, which suggests the importance of incorporating spatial autocorrelation into ECA. Overall, the integration of the choros model and the ECA showed that the islands Liuheng, Mayi, Zhoushan, Fodu, and Huaniao may be good candidates on which to focus future efforts to conserve regional biodiversity. The 4 types of priority areas, generated from the combination of the 2 approaches, were explained in descending order on the basis of their conservation importance: hotspots with distinct environmental conditions, hotspots with general environmental conditions, areas that are not hotspots with distinct environmental conditions, and areas that are not hotspots with general environmental conditions. 相似文献
566.
We compared the composition and structural characteristics of reclaimed and native woody plant communities near Fairfield,
Texas, to evaluate the effectiveness of woodland reclamation 3–11 years since establishment. Species composition, foliage
density, canopy cover, and woody plant densities were recorded in plots randomly placed along transects bisecting blocks of
reclaimed and native woodlands. During summer, vertical foliage densities at heights ≤2 m were similar among native and reclaimed
areas. Foliage density and canopy cover declined in reclaimed blocks during winter, but remained relatively constant in native
woodlands, where evergreens and vines were more common. Canopy cover was absent in reclaimed woodlands <6 years old but increased
with age in 6 to 11-year-old blocks. These data indicated that approximately 27 years will be needed before trees in reclaimed
blocks will achieve the stature of canopy trees in native woodlands. Reclaimed woodlands contained different woody plant species
and had lower woody stem densities compared to native woodlands. On average, stem densities in reclaimed blocks were six times
lower than densities in native woodlands. Comparisons with planting records indicate that survival of most commonly planted
woody species was low. Only green ash(Fraxinus pennsylvanica), Russian oliver(Elaeagnus commutata), smooth sumac(Rhus glabra), and redbud(Cercis canadensis) had estimated survival rates >50%. Reclamation procedures used at Big Brown Mine (BBM) during 1981–1988 have not produced
woodland habitats with vegetative characteristics comparable to premined woodlands and may not be providing the cover needed
to encourage use by certain wildlife species. Procedures for improving woodland reclamation are recommended. 相似文献
567.
We assessed the relationship between riparian management and stream quality along five southeastern Minnesota streams in 1995
and 1996. Specifically, we examined the effect of rotationally and continuously grazed pastures and different types of riparian
buffer strips on water chemistry, physical habitat, benthic macroinvertebrates, and fish as indicators of stream quality.
We collected data at 17 sites under different combinations of grazing and riparian management, using a longitudinal design
on three streams and a paired watershed design on two others. Continuous and rotational grazing were compared along one longitudinal
study stream and at the paired watershed. Riparian buffer management, fenced trees (wood buffer), fenced grass, and unfenced
rotationally grazed areas were the focus along the two remaining longitudinal streams. Principal components analysis (PCA)
of water chemistry, physical habitat, and biotic data indicated a local management effect. The ordinations separated continuous
grazing from sites with rotational grazing and sites with wood buffers from those with grass buffers or rotationally grazed
areas. Fecal coliform and turbidity were consistently higher at continuously grazed than rotationally grazed sites. Percent
fines in the streambed were significantly higher at sites with wood buffers than grass and rotationally grazed areas, and
canopy cover was similar at sites with wood and grass buffers. Benthic macroinvertebrate metrics were significant but were
not consistent across grazing and riparian buffer management types. Fish density and abundance were related to riparian buffer
type, rather than grazing practices. Our study has potentially important implications for stream restoration programs in the
midwestern United States. Our comparisons suggest further consideration and study of a combination of grass and wood riparian
buffer strips as midwestern stream management options, rather than universally installing wood buffers in every instance.
RID=" ID=" The Unit is jointly sponsored by the US Geological Survey, Biological Resources Division; the Minnesota Department
of Natural Resources; the University of Minnesota; and the Wildlife Management Institute. 相似文献
568.
Jennifer L. Phillips Jill Ory Andr Talbot 《Journal of the American Water Resources Association》2000,36(6):1287-1308
ABSTRACT: The Umatilla River Basin Fisheries Restoration Plan was initiated in the early 1980s to mitigate salmonid losses caused by hydroelectric development and habitat degradation. The objectives are to enhance the abundance of endemic steelhead and reintroduce extirpated chinook and coho salmon. The project prompted collaborative effort among federal, state, and tribal agencies, and local water users. It has incorporated habitat restoration, flow enhancement, fish passage improvements, and population supplementation through artificial production. Water exchanges have successfully increased minimum flows during spring and fall migration. While flows remain depressed compared to historic conditions, there is potential for improved habitat, passage, and homing. The mean adult‐to‐adult return rate of hatchery‐reared steelhead exceeded replacement and that of the naturally‐spawning population. Although the smolt‐to‐adult survival rates of hatchery‐reared fish fluctuate, salmonid escapement has increased in recent years, permitting steelhead and spring chinook harvest. Enumeration of potential spawners and observed redds reveals an increase in natural production of all supplemented species. Comparison of hatchery‐reared and naturally‐spawning steelhead populations revealed differences in life history characteristics (in age composition and sex ratios) though run timing and genetic stock compositions of the two components of the populations have not differed. Sustained monitoring is needed to determine benefits of integrating habitat restoration and artificial production in restoring salmonid populations. 相似文献
569.
H. Roger. Hamilton 《Journal of the American Water Resources Association》1996,32(4):761-766
ABSTRACT: This paper describes a concept for identification and ranking of outdoor recreation habitats using principles of ecology as a guide. The Habitat Evaluation Procedures (HEP) is a commonly used technique for assessment of human impacts on the vigor of wildlife species, and serves as the model for the Recreation Habitat Analysis Method (RHAM). Recreation activities are dependent on habitat attributes for their success just as are wildlife species. A sample model is described for recreation activities at large, multipurpose lakes. RHAM could be applied to recreation experiences in a variety of settings including smaller water bodies and riparian and terrestrial ecosystems. 相似文献
570.
JOSEPH L. EBERSOLE WILLIAM J. LISS CHRISTOPHER A. FRISSELL 《Environmental management》1997,21(1):1-14
/ Ecological restoration is increasingly invoked as a tool for the maintenance and regeneration of biodiversity. Yet the conceptual foundations and assumptions underlying many restoration management activities are frequently unclear or unstated. Unforeseen, undesirable consequences of restoration activities may emerge as a result. A general conceptual framework for restoration is needed to better accommodate dynamic habitat systems and evolving biota in restoration strategies. A preliminary framework for stream habitat restoration emphasizing stream habitat-biota development is proposed. As developing systems, streams and stream biota exhibit temporal behaviors that change with stream environments. Underlying the dynamic development of streams is potential capacity. Streams express this capacity as an array of habitats over time and across the landscape. Human land uses in the western United States have rapidly altered aquatic habitats and the processes that shape habitat. As a result, the diversity of native fishes and their habitats has been suppressed. Restoration is fundamentally about allowing stream systems to reexpress their capacities. Several steps are provided to guide stream restoration activities. Key tasks include: identification of the historic patterns of habitat development; identification of developmental constraints; relief of those constraints; classification of sensitive, critical, or refuge habitats; protection of the developmental diversity that remains; and monitoring of biotic responses to habitat development. KEY WORDS: Stream habitat; Stream biota; System capacity; System development; Restoration; Classification 相似文献