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1.
Jennifer E. Davison Lisa J. Graumlich Erika L. Rowland Gregory T. Pederson David D. Breshears 《Global Environmental Change》2012,22(1):268-274
Human-driven changes in the global environment pose an increasingly urgent challenge for the management of ecosystems that is made all the more difficult by the uncertain future of both environmental conditions and ecological responses. Land managers need strategies to increase regional adaptive capacity, but relevant and rapid assessment approaches are lacking. To address this need, we developed a method to assess regional protected area networks across biophysically important climatic gradients often linked to biodiversity and ecosystem function. We plot the land of the southwestern United States across axes of historical climate space, and identify landscapes that may serve as strategic additions to current protected area portfolios. Considering climate space is straightforward, and it can be applied using a variety of relevant climate parameters across differing levels of land protection status. The resulting maps identify lands that are climatically distinct from existing protected areas, and may be utilized in combination with other ecological and socio-economic information essential to collaborative landscape-scale decision-making. Alongside other strategies intended to protect species of special concern, natural resources, and other ecosystem services, the methods presented herein provide another important hedging strategy intended to increase the adaptive capacity of protected area networks. 相似文献
2.
Diana Duncan Darryll T. Pederson Timothy R. Shepherd James D. Can 《Ground Water Monitoring & Remediation》1991,11(4):144-150
The city of Lincoln draws water from a well field along the banks of the Platte River in east-central Nebraska. We have been able to follow the infusion of atrazine into this well field under induced recharge. Samples of water from the river, several monitoring wells and a production well were analyzed by GC/MS and solid phase extraction and found to change in concentration over the range 0.1 and 5.0 ppb of atrazine through the spring, summer, and fall 1989. Increases in the concentration of atrazine relating to precipitation events in the Platte River Basin were observable in the well water samples and ultimately in Lincoln municipal tap water. Atrazine from the river was seen to move via induced recharge and into well field ground water and away from the river at an observable rate. The concentration of atrazine in the river is dependent upon time of year and precipitation in the river basin. 相似文献
3.
Hypothesized large-scale climatic extremes require verification from distantregions in order toconfirm the magnitude and timing of such events. Three of the most massivehypothesized volcanic events of the past two millennia, occurring in or aboutAD 536, 934 and1258, had profound climatic and demographic repercussions over much of Europe,the MiddleEast, and other areas, according to historical accounts recently described inStothers (1998, 1999,2000) as well as other research. Here we report on frost ring and otherdendrochronologicalevidence derived from a 1738-year tree-ring chronology from Mongolia andmillennial-scaletree-ring data from northern Siberia which demonstrate that these three eventsmay have alsoimpacted conditions in these distant regions. 相似文献
4.
Gully erosion of cultural sites in Grand Canyon National Park is an urgent management problem that has intensified in recent decades, potentially related to the effects of Glen Canyon Dam. We studied 25 gullies at nine sites in Grand Canyon over the 2002 monsoon–erosion season to better understand the geomorphology of the gully erosion and the effectiveness of erosion‐control structures (ECS) installed by the park under the direction of the Zuni Conservation Program. Field results indicate that Hortonian overland flow leads to concentrated flow in gullies and erosion focused at knickpoints along channels as well as at gully heads. Though groundcover type, soil shear strength and permeability vary systemat‐ically across catchments, gradient and, to a lesser degree, contributing drainage area seem to be the first‐order controls on gully extent, location of new knickpoints, and ECS damage. The installed ECS do reduce erosion relative to reaches without them and initial data suggest woody checkdams are preferable to rock linings, but maintenance is essential because damaged structures can exacerbate erosion. Topographic data from intensive field surveys and detailed photogrammetry provide slope–contributing area data for gully heads that have a trend consistent with previous empirical and theoretical formulations from a variety of landscapes. The same scaling holds below gully heads for knickpoint and ECS topographic data, with threshold coefficients the lowest for gully heads, slightly higher for knickpoints, and notably higher for damaged ECS. These topographic thresholds were used with 10‐cm digital elevation models to create simple predictive models for gully extent and structure damage. The model predictions accounted for the observed gullies but there are also many false‐positives. Purely topographical models are probably inadequate at this scale and application, but models that also parameterize the variable soil properties across sites would be useful for predicting erosion problems and ECS failure. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
5.
Darryll T. Pederson 《Ground water》1979,17(6):604-607
Abstract. This investigation was to determine whether data on irrigation-well registration forms as reported by well drillers can be used in hydrologic studies. Transmissivity maps were prepared for Hamilton County, Nebraska using only specific capacity values computed from yield and drawdown data, as reported on irrigation well-registration forms. On one map each control point was the mean of the transmissivity values calculated for all wells in a section. On a second map each control point was the mean of the means for four contiguous sections sharing a common corner. The second map was similar to that of a previously prepared map based on control point values computed from specific capacities of selected wells, test hole logs, and geologic interpretations. These results suggest that reported registration data for a given area have a normal population distribution. In situations where individual data are unverified the data base can be treated as samples of a population where the mean of the means of several samples for adjacent areas is representative of actual field conditions. 相似文献
6.
Medieval Warming, Little Ice Age, and European impact on the environment during the last millennium in the lower Hudson Valley, New York, USA 总被引：1，自引：0，他引：1
Dee Cabaniss Pederson Dorothy M. Peteet Dorothy Kurdyla Tom Guilderson 《Quaternary Research》2005,63(3):363-249
Establishing natural climate variability becomes particularly important in large urban areas in anticipation of droughts. We present a well-dated bi-decadal record of vegetation, climate, land use, and fire frequency from a tidal marsh in the Hudson River Estuary. The classic Medieval Warm Period is evident through striking increases in charcoal and Pinus dominance from 800–1300 A.D., paralleling paleorecords southward along the Atlantic seaboard. Higher inputs of inorganic sediment during this interval suggest increased watershed erosion during drought conditions. The presence of the Little Ice Age ensues with increases in Picea and Tsuga, coupled with increasing organic percentages due to cooler, moister conditions. European impact is manifested by a decline in arboreal pollen due to land clearance, increased weedy plant cover (i.e., Ambrosia, Plantago, and Rumex), and an increase in inorganic particles to the watershed. 相似文献
7.
Chelsea L. Pederson James S. Klaus Peter K. Swart Donald F. Mcneill 《Sedimentology》2019,66(6):1989-2010
Microbial carbonate mud in the modern (<4 kyr) palustrine environment of the Florida Everglades is surprisingly susceptible to early diagenetic alteration. The low‐Mg calcite crystals show an open, trellis‐like crystal structure that yields a high surface area to volume ratio. This textural complexity, likely to be a result of organic influence, leads to abundant reaction sites vulnerable to both dissolution and subsequent precipitation. Rapid degradation of organics is attributed to both aerobic and anaerobic metabolisms. Geochemical signatures suggest increased denitrification within the freshwater environment and increased sulphate reduction at the (slightly) brackish mangrove transition zone. A transition from a freshwater to brackish depositional environment is likely to follow the Holocene sea‐level transgression. The textural complexity in these microbial carbonates causes an unexpectedly low preservation potential of original textural and geochemical signatures, even in low‐Mg calcite. Given the potential for early diagenesis of palustrine and perhaps other microbial carbonates, they should be used cautiously as archives for palaeoenvironmental proxies. 相似文献
8.
Clint C. Muhlfeld J. Joseph Giersch F. Richard Hauer Gregory T. Pederson Gordon Luikart Douglas P. Peterson Christopher C. Downs Daniel B. Fagre 《Climatic change》2011,106(2):337-345
Climate warming in the mid- to high-latitudes and high-elevation mountainous regions is occurring more rapidly than anywhere
else on Earth, causing extensive loss of glaciers and snowpack. However, little is known about the effects of climate change
on alpine stream biota, especially invertebrates. Here, we show a strong linkage between regional climate change and the fundamental
niche of a rare aquatic invertebrate—the meltwater stonefly Lednia tumana—endemic to Waterton-Glacier International Peace Park, Canada and USA. L. tumana has been petitioned for listing under the U.S. Endangered Species Act due to climate-change-induced glacier loss, yet little
is known on specifically how climate impacts may threaten this rare species and many other enigmatic alpine aquatic species
worldwide. During 14 years of research, we documented that L. tumana inhabits a narrow distribution, restricted to short sections (~500 m) of cold, alpine streams directly below glaciers, permanent
snowfields, and springs. Our simulation models suggest that climate change threatens the potential future distribution of
these sensitive habitats and the persistence of L. tumana through the loss of glaciers and snowfields. Mountaintop aquatic invertebrates are ideal early warning indicators of climate
warming in mountain ecosystems. Research on alpine invertebrates is urgently needed to avoid extinctions and ecosystem change. 相似文献
9.
Gregory T. Pederson Lisa J. Graumlich Daniel B. Fagre Todd Kipfer Clint C. Muhlfeld 《Climatic change》2010,98(1-2):133-154
The physical science linking human-induced increases in greenhouse gasses to the warming of the global climate system is well established, but the implications of this warming for ecosystem processes and services at regional scales is still poorly understood. Thus, the objectives of this work were to: (1) describe rates of change in temperature averages and extremes for western Montana, a region containing sensitive resources and ecosystems, (2) investigate associations between Montana temperature change to hemispheric and global temperature change, (3) provide climate analysis tools for land and resource managers responsible for researching and maintaining renewable resources, habitat, and threatened/endangered species and (4) integrate our findings into a more general assessment of climate impacts on ecosystem processes and services over the past century. Over 100 years of daily and monthly temperature data collected in western Montana, USA are analyzed for long-term changes in seasonal averages and daily extremes. In particular, variability and trends in temperature above or below ecologically and socially meaningful thresholds within this region (e.g., ?17.8°C (0°F), 0°C (32°F), and 32.2°C (90°F)) are assessed. The daily temperature time series reveal extremely cold days (≤??17.8°C) terminate on average 20 days earlier and decline in number, whereas extremely hot days (≥32°C) show a three-fold increase in number and a 24-day increase in seasonal window during which they occur. Results show that regionally important thresholds have been exceeded, the most recent of which include the timing and number of the 0°C freeze/thaw temperatures during spring and fall. Finally, we close with a discussion on the implications for Montana’s ecosystems. Special attention is given to critical processes that respond non-linearly as temperatures exceed critical thresholds, and have positive feedbacks that amplify the changes. 相似文献
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