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231.
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
232.
Managing complex problems in socio-ecological systems (SES) requires innovative approaches, which account for multiple scales, large datasets, and diverse lived experiences. By combining two commonly utilized mixed-methods, public participation GIS (PPGIS) and Q-method (Q), Q + PPGIS has the potential to reveal competing agendas and reduce conflict, but its benefits and weaknesses are comparatively understudied. Using a systematic review, we evaluated how different studies have employed and implemented the Q + PPGIS method. We found 16 studies, comprising 30 publications, with considerable variation in their geographic foci, research disciplines, and addressed SES challenges. These studies exhibit a lack of cohesion between methodological design and implementation and the absence of a consistent application of the method. Nonetheless, Q + PPGIS offers a tool that can guide policy, better inform stakeholders, and reduce conflict based on misconceptions. Resolving the shortcomings identified here will broaden Q + PPGIS utility in geographically situating and representing multiple realities within complex socio-ecological systems challenges.Supplementary InformationThe online version contains supplementary material available at 10.1007/s13280-022-01709-z. 相似文献
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235.
Edwin L. Currier Joseph B. Knox Todd V. Crawford 《Journal of the Air & Waste Management Association (1995)》2013,63(9):860-864
This paper is responsive to needs to describe and predict the environmental effects from power plant cooling ponds. A study was made to determine atmospheric and pond surface conditions required for steam fog to occur from power plant cooling ponds, to define the dimensions of the fog, and to collect data on deposition of ice. Data, collected principally at the 4-Corners Plant over a three-year period, included water surface temperature, ambient meteorological conditions and occurrence and magnitude of steam fog and ice deposition. With strong winds, the fog extended onshore without lifting. With light winds, the fog extended some distance onshore but then lifted to form stratus. With almost calm winds, the steam fog lifted over the pond and drifted downwind as stratus. Steam fog was observed in winds to 28 mph, air-water temperature differences from 21.5° to 68°F and in atmospheric stability categories C, D, E, and F. A fog index number, Ar/(es — ea)°F/mbs, was defined and used for data interpretation, where Ar is temperature of water less temperature of ambient air, es is the saturation vapor pressure of the ambient air and ea is the actual vapor pressure of the ambient air. The probability of occurrence of steam fog as a function of the fog index number varied from 0.04 for an index number less than 10 to 1.00 for an index number greater than 90. From the data, if fog occurred, its extent along the ground was ≥100 feet 88% of the time, ≥500 feet 35% of the time, ≥1000 feet 18% of the time, and ≥5000 feet 12% of the time. If stratus occurred its extent above ground was ≥1 mile 91% of the time, ≥5 miles 55% of the time and ≥10 miles 36% of the time. Measurements showed that steam fog droplet sizes predominate in the 10 micron diameter size. Values of liquid water content up to 0.20 g/m3 were reported. Ice accretion data show build-up rates from 0.23 to 13 mm/hr of rime. 相似文献
236.
John V. Headley Christine Akre F. Malcolm Conly K. M. Peru Leslie C. Dickson 《Environmental Forensics》2013,14(4):335-345
The Athabasca Oil Sands are one of four natural oil sands deposits in Northern Alberta, Canada. As a number of new mines are planned in the area, there is a need to establish background levels of natural hydrocarbon release prior to these developments. To this end, various environmental samples were taken from selected tributaries in the oil sands region of the Athabasca River Basin and analysed by gas chromatography/mass spectrometry (GC/MS) for polycyclic aromatic hydrocarbons (PAHs) and their alkylated analogues. Samples were collected over 3 years (1998-2000) to provide an increased understanding of the spatial distribution, nature and extent of natural hydrocarbon release to the environment. Results indicated that levels of total PAHs were elevated in the tributaries (up to 34.7 µg/g) compared to the main stem Athabasca River (<2 µg/g). As expected, samples from the oil sands deposits contained the greatest amounts of PAHs and alkylated PAHs. Profiles of the alkylated PAM distributions were very similar, indicating that all the samples tested were from a common petrogenic source. 相似文献
237.
Myron P. Zalucki Stephen B. Malcolm Christopher C. Hanlon Timothy D. Paine 《Chemoecology》2012,22(2):75-88
Growth rate and survival of first-instar larvae of Danaus plexippus, a milkweed specialist, depended on milkweed species, and was related to the amount of latex produced from wounds, leaf cardenolide
concentrations and the presence of leaf hairs. Larval growth was more rapid and survival was higher on leaves of Asclepias californica with experimentally reduced latex, and this species has characteristically high latex, low- to mid-range cardenolide concentrations,
and very hirsute leaves. Similarly, growth was higher on reduced latex leaves of both A. eriocarpa (a high latex/high cardenolide, hirsute species) and A. erosa (glabrous fleshy leaves, high latex/high cardenolides). There were no differences in either survival or growth rate between
larvae on reduced latex or control leaves of the low latex/low cardenolide A. fascicularis with soft glabrous leaves and both survival and growth rate were higher on this species than the other species tested. Larval
growth rates on leaves with reduced latex were similar among ten milkweed species tested to date but differed from growth
rates on intact leaves suggesting that latex and possibly included cardenolides are both important in first-instar monarch
larval growth, development and survival. We show for a range of ecologically important milkweeds that experiments on cut plant
material (no latex outflow) lead to higher growth rates compared to intact plants. Such laboratory assays based on detached
leaves will be misleading if the objective is to determine the impact of treatments such as Bt-maize pollen on monarchs on field plants. 相似文献
238.
Max C. A. Torbenson David W. Stahle Ian M. Howard Joshua M. Blackstock Malcolm K. Cleaveland James H. Stagge 《Journal of the American Water Resources Association》2023,59(1):1-15
We present four reconstruction estimates of Arkansas River baseflow and streamflow using a total of 78 tree-ring chronologies for three streamflow gages, geographically spanning the headwaters in Colorado to near the confluence of the Arkansas-Mississippi rivers. The estimates represent different seasonal windows, which are dictated by the shared limiting forcing of precipitation on seasonal tree growth and soil moisture—and subsequently on the variability of Arkansas River discharge. Flow extremes that were higher and lower than what has been observed in the instrumental era are recorded in each of the four reconstructions. Years of concurrent, cross-basin (all sites) low flow appear more frequently during the 20th and 21st Centuries compared to any period since 1600 A.D., however, no significant trend in cross-basin low flow is observed. As the most downstream major tributary of the Mississippi River, the Arkansas River directly influences flood risk in the Lower Mississippi River Valley. Estimates of extreme high flow in downstream reconstructions coincide with specific years of historic flooding documented in New Orleans, Louisiana, just upstream of the Mississippi River Delta. By deduction, Mississippi River flooding in years of low Arkansas River flow imply exceptional flooding contributions from the Upper Mississippi River catchments. 相似文献
239.
Defining ecologically relevant scales for spatial protection with long‐term data on an endangered seabird and local prey availability 下载免费PDF全文
Richard B. Sherley Philna Botha Les G. Underhill Peter G. Ryan Danie van Zyl Andrew C. Cockcroft Robert J.M. Crawford Bruce M. Dyer Timothée R. Cook 《Conservation biology》2017,31(6):1312-1321
Human activities are important drivers of marine ecosystem functioning. However, separating the synergistic effects of fishing and environmental variability on the prey base of nontarget predators is difficult, often because prey availability estimates on appropriate scales are lacking. Understanding how prey abundance at different spatial scales links to population change can help integrate the needs of nontarget predators into fisheries management by defining ecologically relevant areas for spatial protection. We investigated the local population response (number of breeders) of the Bank Cormorant (Phalacrocorax neglectus), a range‐restricted endangered seabird, to the availability of its prey, the heavily fished west coast rock lobster (Jasus lalandii). Using Bayesian state‐space modeled cormorant counts at 3 colonies, 22 years of fisheries‐independent data on local lobster abundance, and generalized additive modeling, we determined the spatial scale pertinent to these relationships in areas with different lobster availability. Cormorant numbers responded positively to lobster availability in the regions with intermediate and high abundance but not where regime shifts and fishing pressure had depleted lobster stocks. The relationships were strongest when lobsters 20–30 km offshore of the colony were considered, a distance greater than the Bank Cormorant's foraging range when breeding, and may have been influenced by prey availability for nonbreeding birds, prey switching, or prey ecology. Our results highlight the importance of considering the scale of ecological relationships in marine spatial planning and suggest that designing spatial protection around focal species can benefit marine predators across their full life cycle. We propose the precautionary implementation of small‐scale marine protected areas, followed by robust assessment and adaptive‐management, to confirm population‐level benefits for the cormorants, their prey, and the wider ecosystem, without negative impacts on local fisheries. 相似文献
240.