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71.
Emma C. Underwood Joshua H. Viers James F. Quinn Malcolm North 《Environmental management》2010,46(5):809-819
Past forest management practices, fire suppression, and climate change are increasing the need to actively manage California
Sierra Nevada forests for multiple environmental amenities. Here we present a relatively low-cost, repeatable method for spatially
parsing the landscape to help the U.S. Forest Service manage for different forest and fuel conditions to meet multiple goals
relating to sensitive species, fuels reduction, forest products, water, carbon storage, and ecosystem restoration. Using the
Kings River area of the Sierra Nevada as a case study, we create areas of topographically-based units, Landscape Management
Units (LMUs) using a three by three matrix (canyon, mid-slope, ridge-top and northerly, southerly, and neutral aspects). We
describe their size, elevation, slope, aspect, and their difference in inherent wetness and solar radiation. We assess the
predictive value and field applicability of LMUs by using existing data on stand conditions and two sensitive wildlife species.
Stand conditions varied significantly between LMUs, with canyons consistently having the greatest stem and snag densities.
Pacific fisher (Martes pennanti) activity points (from radio telemetry) and California spotted owl (Strix occidentalis occidentalis) nests, roosts, and sightings were both significantly different from uniform, with a disproportionate number of observations
in canyons, and fewer than expected on ridge-tops. Given the distinct characteristics of the LMUs, these units provide a relatively
simple but ecologically meaningful template for managers to spatially allocate forest treatments, thereby meeting multiple
National Forest objectives. These LMUs provide a framework that can potentially be applied to other fire-dependent western
forests with steep topographic relief. 相似文献
72.
Pharmaceutical compounds are considered the new environmental pollutants but at present few studies have evaluated their ecotoxicity on aquatic invertebrates. This study was aimed to investigate the in vitro cytotoxicity of four common drugs, namely atenolol (ATL), carbamazepine (CBZ), diclofenac (DCF) and gemfibrozil (GEM), on three different cell typologies from the zebra mussel (Dreissena polymorpha): haemocytes, gill and digestive gland cells. Results obtained by the Trypan blue exclusion test revealed that exposure to increasing concentrations (0.001; 0.01; 0.1; 1 and 10 mg L−1) of CBZ, DCF and GEM were able to significantly decrease the viability of each cell type, while the MTT (3(4,5-dimethyl-2thiazholyl)-2,5-diphenyl-2H-tetrazolium bromide) reduction assay highlighted only a slight reduction of mitochondrial activity of gill and digestive gland cells. Overall, DCF was the most cytotoxic drug for zebra mussel cells, followed by GEM, CBZ, while ATL has not a noteworthy toxic potential. Our preliminary results lay the groundwork for further in vitro evaluations, which will allow a better definition of the potential toxicity of these drugs. 相似文献
73.
This study examines the relationship between psychological empowerment and leadership. Empowered supervisors are hypothesized to be innovative, upward influencing, and inspirational and less focused on monitoring to maintain the status quo. Tested on a sample of mid‐level supervisors from a Fortune 500 organization, the hypotheses were largely supported. Supervisors who reported higher levels of empowerment were seen by their subordinates as more innovative, upward influencing, and inspirational. No relationship was found between supervisory empowerment and monitoring behaviours. Implications for theory and practice are discussed, and future research directions are suggested. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献
74.
Payton Quinn Hostetter Nathan J. Evans Allen F. 《Environmental and Ecological Statistics》2019,26(2):107-125
Environmental and Ecological Statistics - Identifying where, when, and how many animals live and die over time is principal to understanding factors that influence population dynamics.... 相似文献
75.
76.
A Rapid Method to Score Stream Reaches Based on the Overall Performance of Their Main Ecological Functions 总被引:1,自引:1,他引:0
David K. Rowe Stephanie Parkyn John Quinn Kevin Collier Chris Hatton Michael K. Joy John Maxted Stephen Moore 《Environmental management》2009,43(6):1287-1300
A method was developed to score the ecological condition of first- to third-order stream reaches in the Auckland region of
New Zealand based on the performance of their key ecological functions. Such a method is required by consultants and resource
managers to quantify the reduction in ecological condition of a modified stream reach relative to its unmodified state. This
is a fundamental precursor for the determination of fair environmental compensation for achieving no-net-loss in overall stream
ecological value. Field testing and subsequent use of the method indicated that it provides a useful measure of ecological
condition related to the performance of stream ecological functions. It is relatively simple to apply compared to a full ecological
study, is quick to use, and allows identification of the degree of impairment of each of the key ecological functions. The
scoring system was designed so that future improvements in the measurement of stream functions can be incorporated into it.
Although the methodology was specifically designed for Auckland streams, the principles can be readily adapted to other regions
and stream types. 相似文献
77.
78.
Some birds exploit the aggressiveness of others that are more capable of defending their nests against predators. Usually this behaviour is selected for through improved breeding success for the timid (associate) species. The risk of predation from the more aggressive (host) species is generally rare but may select against the behaviour. The breeding success of red-breasted geese (Branta ruficollis) nesting in association with peregrine falcons (Falco peregrinus) in arctic Siberia was investigated from 1995 to 1999. Nest-predation risk for geese within colonies was positively correlated with distance from the falcons' eyries and negatively correlated with colony size. Though predation risk from the hosts was low, the risk of being attacked by the falcons was high, which we suggest explains why the likelihood of geese deserting their nests was negatively correlated with distance from the eyries. The optimal distance geese nested from eyries was 46 m, though only 37% of pairs managed to nest within 20 m of this. In years with low predation pressure, some geese within colonies nested farther from the falcons. This may be the first evidence to suggest a trade-off between costs and benefits in a nesting association, both of which are directly mediated by the host's nest defence behaviour. 相似文献
79.
Estimator bias and efficiency for adaptive cluster sampling with order statistics and a stopping rule 总被引:2,自引:0,他引:2
Practical problems facing adaptive cluster sampling with order statistics (acsord) are explored using Monte Carlo simulation for three simulated fish populations and two known waterfowl populations. First, properties of an unbiased Hansen-Hurwitz (HH) estimator and a biased alternative Horvitz-Thompson (HT) estimator are evaluated. An increase in the level of population aggregation or the initial sample size increases the efficiencies of the two acsord estimators. For less aggregated fish populations, the efficiencies decrease as the order statistic parameter r (the number of units about which adaptive sampling is carried out) increases; for the highly aggregated fish and waterfowl populations, they increase with r. Acsord is almost always more efficient than simple random sampling for the highly aggregated populations. Positive bias is observed for the HT estimator, with the maximum bias usually occurring at small values of r. Secondly, a stopping rule at the Sth iteration of adaptive sampling beyond the initial sampling unit was applied to the acsord design to limit the otherwise open-ended sampling effort. The stopping rule induces relatively high positive bias to the HH estimator if the level of the population aggregation is high, the stopping level S is small, and r is large. The bias of HT is not very sensitive to the stopping rule and its bias is often reduced by the stopping rule at smaller values of r. For more aggregated populations, the stopping rule often reduces the efficiencies of the estimators compared to the non-stopping-rule scheme, but acsord still remains more efficient than simple random sampling. Despite its bias and lack of theoretical grounding, the HT estimator is usually more efficient than the HH estimator. In the stopping rule case, the HT estimator is preferable, because its bias is less sensitive to the stopping level. 相似文献
80.
Digging Deeper: A Case Study of Farmer Conceptualization of Ecosystem Services in the American South
Courtney?E.?QuinnEmail author John?E.?Quinn Angela?C.?Halfacre 《Environmental management》2015,56(4):802-813
The interest in improved environmental sustainability of agriculture via biodiversity provides an opportunity for placed-based research on the conceptualization and articulation of ecosystem services. Yet, few studies have explored how farmers conceptualize the relationship between their farm and nature and by extension ecosystem services. Examining how farmers in the Southern Piedmont of South Carolina discuss and explain the role of nature on their farm, we create a detail-rich picture of how they perceive ecosystem services and their contributions to the agroeconomy. Using 34 semi-structured interviews, we developed a detail-rich qualitative portrait of these farmers’ conceptualizations of ecosystem services. Farmers’ conceptualization of four ecosystem services: provisioning, supporting, regulating, and cultural are discussed, as well as articulation of disservices. Results of interviews show that most interviewees expressed a basic understanding of the relationship between nature and agriculture and many articulated benefits provided by nature to their farm. Farmers referred indirectly to most services, though they did not attribute services to biodiversity or ecological function. While farmers have a general understanding and appreciation of nature, they lack knowledge on specific ways biodiversity benefits their farm. This lack of knowledge may ultimately limit farmer decision-making and land management to utilize ecosystem services for environmental and economic benefits. These results suggest that additional communication with farmers about ecosystem services is needed as our understanding of these benefits increases. This change may require collaboration between conservation biology professionals and extension and agriculture professionals to extended successful biomass provisioning services to other ecosystem services. 相似文献