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Reports of decreasing quaking aspen (Populus tremuloides) cover in forests of the western USA have caused concern about the long-term persistence of aspen on landscape scales. We assessed changes in overstory aspen dominance on the Uncompahgre Plateau in western Colorado over a 20 year period. We measured stand density, species composition and regeneration in 53 undisturbed, mature pure aspen, pure conifer, and mixed aspen/conifer stands originally inventoried between 1979 and 1983. Ages of overstory and understory trees were used to evaluate long-term change in regeneration and overstory development. While pure aspen stands occupy 16% of the study area, mixed aspen and conifer stands cover 62% of the forested landscape...
Categories: Publication;
Types: Citation,
Journal Citation;
Tags: Forest Ecology and Management,
Populus tremuloides Colorado,
aspen,
aspen decline,
vegetation change
Human activities have caused the decline of numerous species and ecosystems. To promote ecosystem resilience, recent management efforts aim to maintain ecosystem patterns and processes within their historical range of variability. There has been substantial concern that quaking aspen, the most widely distributed tree in North America and the most important deciduous tree in the subalpine forests of the Rocky Mountains, has declined significantly in the western landscape during the 20th century. This reported decline has been attributed to conifer encroachment associated with fire exclusion, as well as other causes. To assess long-term changes in the extent of quaking aspen in a 175000-ha study area in western Colorado,...
Categories: Publication;
Types: Citation,
Journal Citation;
Tags: Colorado,
Ecological Applications,
USA,
aspen,
fire,
The importance of efficaciously assessing the risk for introduction and establishment of pest species is an increasingly important ecological and economic issue. Evaluation of climate is fundamental to determining the potential success of an introduced or invasive insect pest. However, evaluating climatic suitability poses substantial difficulties; climate can be measured and assessed in a bewildering array of ways. Some physiological filter, in essence a lens that focuses climate through the requirements and constraints of a potential pest introduction, is required. Difficulties in assessing climate suitability are further exacerbated by the effects of climate change. Gypsy moth (Lymantria dispar L.) is an exotic,...
Categories: Publication;
Types: Citation,
Journal Citation;
Tags: Ecological Applications,
Lymantria dispar,
aspen,
climate change,
climatic suitability,
Repeat photography samples were used to analyze how the structure and site-specific distribution of forests may or may not have changed during the past century in the San Juan Mountains, Colorado. Systematic evaluation of 146 photosets was combined with field observations to identify trends in vegetation change. Both conifers and deciduous trees (e.g., aspen) have increased in extent. Forest recovery from large disturbances that occurred during Euro-American settlement contributed substantially to this increase. Trees also encroached into grass/shrublands, but less than half of photosets show tree invasion, and invasion is more common in small grass/shrubland openings interspersed with forest than in large openings....
Categories: Publication;
Types: Citation,
Journal Citation;
Tags: Forest Ecology and Management,
aspen,
landscape change,
mountain grasslands,
repeat photography,
Aspen are thought to be declining in this region due to a combination of fire suppression, grazing and wildlife management practices, and potentially cool/wet climates of the past century which favor advancing conifer succession. Many scientists are concerned that aspen?s related species may also be losing habitat, thereby threatening the long-term local and regional viability of this important community. To date, few studies have specifically examined the role of aspen?s epiphytic lichen community. This paper presents basic community research describing the application of Indicator Species Analysis for lichens growing on aspen stems in the central Rocky Mountains of North American. Results show unique lichen assemblages...
Categories: Publication;
Types: Citation,
Journal Citation;
Tags: Bear River range,
Evansia,
Idaho,
Indicator Species Analysis,
Utah,
In western North America, quaking aspen (Populus tremuloides) is the most common hardwood in montane landscapes. Fire suppression, grazing and wildlife management practices, and climate patterns of the past century are all potential threats to aspen coverage in this region. If aspen-dependent species are losing habitat, this raises concerns about their long-term viability. Though lichens have a rich history as air pollution indicators, we believe that they may also be useful as a metric of community diversity associated with habitat change. We established 47 plots in the Bear River Range of northern Utah and southern Idaho to evaluate the effects of forest succession on epiphytic macrolichen communities. Plots were...
Categories: Publication;
Types: Citation,
Journal Citation;
Tags: Forest Ecology and Management,
Populus tremuloides,
Rocky Mountains,
aspen,
community analysis,
Phellinus tremulae is an important fungal decay agent common to aspen and a critical component to the cavity-nesting previous termbirdnext term complex found in western aspen stands. Little information exists on the conditions that facilitate infection and spread of P. tremulae in aspen forests. I used Forest Inventory and Analysis (FIA) data to explore the relationships of several tree and stand characteristics to the presence and frequency of P. tremulae in aspen measured across several western states of the United States. Results suggest a strong relationship between tree age, tree diameter, and compacted crown ratio with infection frequency in trees while stand purity, canopy cover and stand age had a positive...
Categories: Publication;
Types: Citation,
Journal Citation;
Tags: FIA,
Forest Ecology and Management,
Phellinus tremulae,
Populus tremuloides,
aspen,
Many abiotic and biotic factors affect the health of roadside vegetation, including the application of magnesium chloride (MgCl2) dust suppression products. Three hundred seventy kilometers (230 mi) of forested, shrubland, meadow, rangeland, riparian, and wetland roadside habitats were surveyed along major nonpaved roads in two Colorado counties. Dominant species composition and visible damages of woody roadside vegetation were quantified. The majority (72.3% to 79.3%) of roadside vegetation surveyed was considered healthy (less than 5% damage to crown or stem), depending on slope position from the road. Severely damaged (greater than 50% damage) vegetation ranged from 6.4% to 11.4% of roadside cover, with the most...
Categories: Publication;
Types: Citation,
Journal Citation;
Tags: Arboriculture & Urban Forestry,
Aspen,
lodgepole pine,
magnesium chloride (MgCl2),
ponderosa pine,
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 1998, Mexican gray wolves (Canis lupus baileyi) were introduced into the Blue Range Wolf Recovery Area (BRWRA) that spans adjacent portions of Arizona andNewMexico. In 2009 we selected three mixedconifer sites on the Apache National Forest, within the BRWRA of east-central Arizona, to characterize long-term age structure of aspen (Populus tremuloides) and to check for the possible occurrence of a tri-trophic cascade involving Mexican wolves, Rocky Mountain elk (Cervus elaphus nelsoni), and aspen. These mixed-conifer sites included (a) a refugium site, (b) an old-growth site, and (c) a site thinned in 1991?1992. The refugium site was inaccessible to elk and cattle whereas the old-growth and thinned sites were...
Categories: Publication;
Types: Citation,
Journal Citation;
Tags: Apache National Forest,
Arizona,
Forest Ecology and Management,
Mexican wolf,
Rocky Mountain elk,
Aim The recent concern that quaking aspen (Populus tremuloides Michx.) has been declining in parts of western North America due to fire suppression is largely based on trends during the latter part of the 20th century. The aim of the current study was to compare the extent of aspen in the modern landscape with its extent in the late 19th century prior to fire suppression, and to assess the effects of elevation, late-19th century fires, and pre-fire forest composition on the successional status of aspen. Location North-west Colorado, USA. Methods We used a georeferenced 1898 map and modern maps to examine trends in aspen dominance since the late 19th century in a 348,586 ha area of White River and Routt National...
Categories: Publication;
Types: Citation,
Journal Citation;
Tags: Journal of Biogeography,
Populus tremuloides,
aspen,
disturbance,
fire ecology,
Quaking aspen cover 3.3 million hectares in the Upper Colorado River Basin, and these areas are gradually converting to conifer forest by the natural process of ecological succession. This change is being hastened by forest managment practices that reduce fires, destroy pests, or otherwise prevent the natural processes that previously caused conifer areas to revert to the subclimax aspen. The hydrologic consequence has been forecast to cause a runoff reduction in the Colorado River as large as one million acre-feet annually, a major blow to water availability in the Lower Basin. Understanding and dealing with the problems requires quantitative comparision of the evaportranspiration rates of conifer and aspen forests...
Categories: Publication;
Types: Citation,
ScienceBase Citation;
Tags: Chicken Creek watershed,
Colorado River Basin,
Utah,
aspen,
conifers,
Investigations of vegetation stress along non-paved roads treated with a range of magnesium chloride (MgCl2) application rates utilized 60 roadside and 79 drainage plots on 15 and 18 roads, respectively. Evaluations were completed of foliar damage, plant health, biotic and abiotic damage incidence and severity, soil and foliar chemistry and other common site and stand characteristics of Pinus contorta, Populus tremuloides, Picea engelmannii, Abies lasiocarpa, and lower elevation plots dominated by shrubs and grasses. High concentrations of soil magnesium and chloride (400?500 ppm), high foliar chloride (2,000?16,000 ppm depending on species) and high incidence of foliar damage were measured in roadside plots along...
Categories: Publication;
Types: Citation,
Journal Citation;
Tags: Aspen,
Dust abatement,
Engelmann spruce,
Gravel roads,
Lodgepole pine,
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