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Conclusions: Caribou subpopulation persistence and landscape occupancy depends highly on the degree of forest cover, cover type, and distance from human presence. Thresholds/Learnings: Synopsis: This study evaluates factors influencing the persistence and landscape occupancy of caribou subpopulations in southern British Columbia. Data from 235 radio-collared caribou across 13 subpopulations were used to derive a landscape occupancy index. The index was analyzed against 33 landscape variables including, land cover, terrain, climate, and human influence. At the metapopulation level, the persistence of subpopulations correlated with the extent of wet climate conditions and the distribution of old forests and alpine...
Aim: Greater sage-grouse (Centrocercus urophasianus), a shrub-steppe obligate species of western North America, currently occupies only half its historical range. Here we examine how broad-scale, long-term trends in landscape condition have affected range contraction. Location: Sagebrush biome of the western USA. Methods: Logistic regression was used to assess persistence and extirpation of greater sage-grouse range based on landscape conditions measured by human population (density and population change), vegetation (percentage of sagebrush habitat), roads (density of and distance to roads), agriculture (cropland, farmland and cattle density), climate (number of severe and extreme droughts) and range periphery....
Abstract (from http://www.bioone.org/doi/abs/10.3955/046.089.0305): It is hypothesized that climate impacts forest mosaics through dynamic ecological processes such as wildfires. However, climate-fire research has primarily focused on understanding drivers of fire frequency and area burned, largely due to scale mismatches and limited data availability. Recent datasets, however, allow for the investigation of climate influences on ecological patch metrics across broad regions independent of area burned and at finer scale. One area of particular interest is the distribution of fire refugia within wildfire perimeters. Although much recent research emphasis has been placed on high-severity patches within wildfires,...
This study examines the time series behaviour of oil production for OPEC member countries within a fractional integration modelling framework recognizing the potential for structural breaks and outliers. The analysis is undertaken using monthly data from January 1973 to October 2008 for 13 OPEC member countries. The results indicate there is mean reverting persistence in oil production with breaks identified in 10 out of the 13 countries examined. Thus, shocks affecting the structure of OPEC oil production will have persistent effects in the long run for all countries, and in some cases the effects are expected to be permanent.
Categories: Publication; Types: Citation; Tags: OPEC, Oil production, Persistence
Detailed empirical models predicting both species occurrence and fitness across a landscape are necessary to understand processes related to population persistence. Failure to consider both occurrence and fitness may result in incorrect assessments of habitat importance leading to inappropriate management strategies. We took a two-stage approach to identifying critical nesting and brood-rearing habitat for the endangered Greater Sage-Grouse (Centrocercus urophasianus) in Alberta at a landscape scale. First, we used logistic regression to develop spatial models predicting the relative probability of use (occurrence) for Sage-Grouse nests and broods. Secondly, we used Cox proportional hazards survival models to identify...
This study examines the time series behaviour of oil production for OPEC member countries within a fractional integration modelling framework recognizing the potential for structural breaks and outliers. The analysis is undertaken using monthly data from January 1973 to October 2008 for 13 OPEC member countries. The results indicate there is mean reverting persistence in oil production with breaks identified in 10 out of the 13 countries examined. Thus, shocks affecting the structure of OPEC oil production will have persistent effects in the long run for all countries, and in some cases the effects are expected to be permanent.
Categories: Publication; Types: Citation; Tags: OPEC, Oil production, Persistence
Although the five species of prairie dogs (Cynomys spp.) are recognized as important components of grassland ecosystems in western North America, they have experienced major population declines due to poisoning, outbreaks of sylvatic plague, recreational shooting, and habitat conversion. From May 2000 to October 2001, we investigated 270 colonies of Gunnison’s prairie dog (Cynomys gunnisoni) in Arizona. Because these colonies were classified as active in previous surveys (1987, 1990–1994, 1998), we were able to examine their persistence. Most (70%) of the colonies became inactive between the initial and recent surveys, with colony extinctions spanning our study area. Colony persistence was positively associated...
    map background search result map search result map Factors influencing the dispersion and fragmentation of endangered mountain caribou populations Factors influencing the dispersion and fragmentation of endangered mountain caribou populations