Filters: Tags: threshold (X)
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Synopsis: Using multi-scale seasonal models, this study explored how broad scale landscape context and local resource heterogeneity influenced local resource selection among threatened forest-dwelling woodland caribou in southern Quebec. Caribou consistently avoided roads, however researchers identified thresholds in road proximity effects. The threshold distance at which caribou avoid roads is 1.25 km for active roads and 0.75 km from derelict roads. Open lichen woodlands were an important cover type for caribou during winter and spring, whereas deciduous forests, wetlands, and even young disturbed stands became important during calving and summer. Landscape cover type and amount explained more variation in habitat...
Categories: Publication;
Types: Citation,
Map Service,
OGC WFS Layer,
OGC WMS Layer,
OGC WMS Service;
Tags: Caribou,
Forest-dwelling woodland cairbou,
Land use configuration,
Landscape context,
Landscape fragmentation,
In this paper we review threshold behaviour in environmental systems, which are often associated with the onset of floods, contamination and erosion events, and other degenerative processes. Key objectives of this review are to a) suggest indicators for detecting threshold behavior, b) discuss their implications for predictability, c) distinguish different forms of threshold behavior and their underlying controls, and d) hypothesise on possible reasons for why threshold behaviour might occur. Threshold behaviour involves a fast qualitative change of either a single process or the response of a system. For elementary phenomena this switch occurs when boundary conditions (e.g., energy inputs) or system states as expressed...
Categories: Publication;
Types: Citation;
Tags: Threshold,
behaviour,
controls,
geo-ecosystems,
human,
Landscape connectivity is critical to species persistence in the face of habitat loss and fragmentation. Graph theory is a well-defined method for quantifying connectivity that has tremendous potential for ecology, but its application has been limited to a small number of conservation scenarios, each with a fixed proportion of habitat. Because it is important to distinguish changes in habitat configuration from changes in habitat area in assessing the potential impacts of fragmentation, we investigated two metrics that measure these different influences on connectivity. The first metric, graph diameter, has been advocated as a useful measure of habitat configuration. We propose a second area-based metric that combines...
Categories: Publication;
Types: Citation,
Journal Citation;
Tags: Connectivity,
Fragmentation,
Graph theory,
Landscape Ecology,
Percolation theory,
Conclusions: Summarizes findings from a review of literature intended to identify critical thresholds for conservation based in empirical studies of landscape fragmentation. Presents a conceptual overview of landscape fragmentation and habitat loss, as well as guidelines and thresholds relating to landscape indicators such as patch size, habitat amount, edge effects, riparian buffers, and habitat connectivity. Thresholds/Learnings: Many. See Kennedy et al. 2003. Synopsis: This report summarizes findings from a review of literature intended to identify critical thresholds for conservation based in empirical studies of landscape fragmentation. In presenting a conceptual overview of landscape fragmentation and habitat...
Categories: Publication;
Types: Citation,
Map Service,
OGC WFS Layer,
OGC WMS Layer,
OGC WMS Service;
Tags: Agriculture,
Biodiversity,
Conservation,
Dams,
Ecosystems,
Native Americans are one of the most vulnerable populations to climate change in the United States because of their reliance upon the natural environment for food, livelihood, and cultural traditions. In the Southwest, where the temperature and precipitation changes from climate change are expected to be particularly severe, tribal communities may be especially vulnerable. Through this project, researchers sought to better understand the climate change threats facing the Pyramid Lake Paiute Tribe of northwestern Nevada. Researchers found that the Tribe’s vulnerability to climate change stems from its dependence on Pyramid Lake, which may experience reduced water supply in the future. This will potentially have negative...
Categories: Project;
Types: Map Service,
OGC WFS Layer,
OGC WMS Layer,
OGC WMS Service;
Tags: 2012,
CASC,
Completed,
Federal,
Fish,
Stands of quaking aspen (Populus tremuloides) rank among the most biologically diverse plant communities across the intermountain region of western North America. Marked declines of aspen have occurred in recent decades, likely due to a combination of effects from changes in fire regimes, herbivory, climate (e.g. drought), and interspecific competition with conifer species. However, it is poorly understood how the effects of these factors are manifested at a landscape scale over decadal time periods. Analysis of field data combined with topographic information collected across the 500,000 ha Owyhee Plateau in southwestern Idaho revealed that aspen in the area occur in three different biophysical settings; First,...
Categories: Publication;
Types: Citation,
Journal Citation;
Tags: Forest Ecology and Management,
VDDT,
aspen,
disturbance dynamics,
encroachment,
In this paper we review threshold behaviour in environmental systems, which are often associated with the onset of floods, contamination and erosion events, and other degenerative processes. Key objectives of this review are to a) suggest indicators for detecting threshold behavior, b) discuss their implications for predictability, c) distinguish different forms of threshold behavior and their underlying controls, and d) hypothesise on possible reasons for why threshold behaviour might occur. Threshold behaviour involves a fast qualitative change of either a single process or the response of a system. For elementary phenomena this switch occurs when boundary conditions (e.g., energy inputs) or system states as expressed...
Categories: Publication;
Types: Citation;
Tags: Threshold,
behaviour,
controls,
geo-ecosystems,
human,
Dust deposition to mountain snow cover, which has increased since the late 19(th) century, accelerates the rate of snowmelt by increasing the solar radiation absorbed by the snowpack. Snowmelt occurs earlier, but is decoupled from seasonal warming. Climate warming advances the timing of snowmelt and early season phenological events (e.g., the onset of greening and flowering); however, earlier snowmelt without warmer temperatures may have a different effect on phenology. Here, we report the results of a set of snowmelt manipulations in which radiation-absorbing fabric and the addition and removal of dust from the surface of the snowpack advanced or delayed snowmelt in the alpine tundra. These changes in the timing...
The economic limit of an oil and gas asset occurs when income from production is less than the direct cost of operation. Economic limits determine the threshold for profitable operations and are often considered from a conceptual perspective rather than as an object for empirical assessment. The purpose of this paper is to derive empirical estimates of the economic limit of offshore structures in the Outer Continental Shelf Gulf of Mexico. We classify 1962 decommissioned structures between 1986-2009 by structure type, primary production, water depth and year of removal, and compute end-of-life production, adjusted gross revenue, and water cut thresholds according to various levels of categorization. During the last...
Categories: Publication;
Types: Citation;
Tags: Decommissioning,
Economic,
Production,
Revenue,
limit,
The dataset contains simulated net primary productivity (NPP) and greenhouse gas emissions (CH4, N2O, CO2) under a series of combinations of soil salinities (0.1, 0.5, 1, 2, 4, 6, 8, 10 psu) and water table depth (WTDs) (-30, -20, -10, -5, 0, 5, 10, 20, 30 cm) for tidal forest and oligohaline marsh sites along the Savannah River and Waccamaw River, USA.
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