Life Sciences Commons^™

Aspen Fencing In Northern Arizona: A 15-Year Perspective, James M. Rolf

Aspen Bibliography

Aspen clearcuts in the 1960s and 1970s on the Peaks Ranger District of the Coconino National Forest in northern Arizona failed to regenerate successfully because of browsing primarily by elk. Since 1985, over 400 acres have been successfully regenerated using fencing of various designs to exclude elk. The expense and visual impact of establishing and maintaining over 20 miles of fence along with continued damage to aspen greater than 3.0 inches d.b.h. outside the fenced areas have resulted in the Arizona Game and Fish Department increasing the elk hunting permits by 400% in an effort to reduce the elk herd …

Aspen's Ecological Role In The West, William H. Romme, Lisa Floyd-Hanna, David D. Hanna, Elisabeth Bartlett

Aspen Bibliography

Aspen exhibits a variety of ecological roles. In southern Colorado, the 1880 landscape mosaic contained a range of stand ages, of which half were >70 years old and half were younger. Pure aspen stands in southern Colorado are widespread and may result from previous short fire intervals that eliminated local conifer seed sources. Aspen regeneration in northern Yellowstone Park is controlled by ungulate browsing pressure and fire, so it has been limited since 1920. However, an episode of aspen seedling establishment occurred after the 1988 fires. We urgently need additional detailed, local case studies of aspen ecology to inform management …

Do Pine Trees In Aspen Stands Increase Bird Diversity, Mark A. Rumble, Todd R. Mills, Brian L. Dystra, Lester D. Flake

Aspen Bibliography

In the Black Hills of South Dakota, quaking aspen (Populus tremuloides) is being replaced by conifers through fire suppression and successional processes. Al- though the Black Hills National forest is removing conifers (primarily ponderosa pine [Pinus ponderosa])toincreasetheaspencommunitiesinsomemixedstands,ForestPlan guidelines allow four conifers per hectare to remain to increase diversity in the remaining aspen stand. We compared bird species richness in pure ponderosa pine, mixed stands dominated by ponderosa pine with quaking aspen, mixed stands dominated by aspen

with ponderosa pine, and pure aspen stands. Stands dominated by ponderosa pine had lower (P

Landscape Dynamics Of Aspen And Conifer Forests, D.L. Bartos

Aspen Bibliography

No abstract provided.

Nitrogen Mineralization In Aspen/Conifer Soils After A Natural Fire, M.C. Amacher, D.L. Bartos, T. Christopherson, A.D. Johnson, D.E. Kutterer

Aspen Bibliography

No abstract provided.

Persistence Of Aspen Regeneration Near The National Elk Refuge And Gros Ventre Valley Elk Feedgrounds Of Wyoming, D.T. Barnett, T.J. Stohlgren

Aspen Bibliography

We investigated aspen (Populus tremuloides) regeneration in the Gros Ventre River Valley, the National Elk Refuge, and a small part of Grand Teton National Park, Wyoming, to see if elk (Cervus elaphus) browsing was as damaging as previously thought. We conducted a landscape-scale survey to assess aspen regeneration across gradients of wintering elk concentrations using 68 randomly selected aspen stands in the 1,090 km2 study area. Forty-four percent of the stands sampled supported regeneration of saplings (stems greater than 2 m in height but less than 10 cm in diameter). There were no significant differences of regeneration across elk winter …

First-Year Postfire And Postharvest Soil Temperatures In Aspen And Conifer Stands, Michael C. Amacher, Amber D. Johnson, Debra E. Kutterer, Dale L. Bartos

Aspen Bibliography

Aspen (Populus tremuloides Michx.) stands are in decline throughout the Interior Western United States because of fire suppression, overbrowsing by domestic livestock and native ungulates, and forest succession. We measured summertime soil temperatures in stable aspen, decadent aspen, and mixed aspen/conifer stands; a mixed aspen/conifer clearcut; as mixed aspen/conifer forest that was burned in a lightning-caused fire; and a decadent aspen stand and mixed aspen/conifer stand that received prescribed burns. Soil temperature fluctuations and mean soil temperatures were greater in cut and burned areas than in untreated stands. In untreated stands, mean soil temperature increased in the order: mixed …

Aspen Ecosystems: Objectives For Sustaining Biodiversity, R.B. Campbell, D.L. Bartos

Aspen Bibliography

Recognizing the historical abundance of major vegetation cover types is the foundation for estimating the magnitude and significance of conversion from one cover type to another and the proportion of existing cover types that are in properly functioning condition. Techniques to determine desired conditions are discussed. Existing situations for the need to treat ecosystems where aspen (Populus tremuloides Michx.) occur are prioritized: highest—mixed-conifer with aspen but where conifers comprise greater than 50% of the canopy; high—aspen/sagebrush transition; and moderate—aspen dominated landscapes. Though aspen stands are evaluated, aspen landscapes are discussed in the context of aggregations of many stands. Within …

Ecology And Management Of Aspen: A Lake States Perspective, D.T. Cleland, L.A. Leefers, D.I. Dickmann, L.G. Eskew

Aspen Bibliography

Aspen has been an ecologically important, though relatively minor, compo- nent of the Lake States (Michigan, Wisconsin, and Minnesota) forests for millennia. General Land Office records from the 1800s indicate that aspen comprised a small fraction of the region’s eastern forests, but was more extensive on the western edge. Then Euro-American settlement in the 1800s brought land clearing, timber harvesting, and subsequent widespread wildfires that increased aspen-birch acreages consider- ably. Although aspen-birch acreage has declined since the 1930s, it remains the region’s second most prevalent forest type. Aspen management is probably the most contentious issue confronting forest managers in the …

Mycorrhizal Fungi Of Aspen Forests: Natural Occurrence And Potential Applications, C.L. Cripps

Aspen Bibliography

Native mycorrhizal fungi associated with aspen were surveyed on three soil types in the north-central Rocky Mountains. Selected isolates were tested for the ability to enhance aspen seedling growth in vitro. Over 50 species of ectomycorrhizal fungi occur with Populus tremuloides in this region, primarily basidiomycete fungi in the Agaricales. Almost one-third (30%) were ubiquitous with aspen and were found on all three soil types. Over one-third (37%) were restricted to the acidic, sandy soil of the smelter-impacted Butte-Anaconda area, revealing a subset of fungi that tolerate these conditions. Mycorrhizal fungi were screened for their ability to enhance aspen growth …

Changes In Landscape Patterns And Associated Forest Succession On The Western Slope Of The Rocky Mountains, Colorado, Daniel James Manier, Richard D. Laven

Aspen Bibliography

Using repeat photography, we conducted a qualitative and quantitative analysis of changes in forest cover on the western slope of the Rocky Mountains in Colorado. For the quantitative analysis, both images in a pair were classified using remote sensing and geographic information system (GIS) technologies. Comparisons were made using three landscape metrics: total relative cover, mean relative patch size, and number of patches per major vegetation type. We noted several important changes in the pattern of the landscape and the structure of the forests. The relative area covered by interspersed, nonforested rangelands has decreased significantly, and the total forest cover …

Aspen Response To Prescribed Fire And Wild Ungulate Herbivory, Steve Kilpatrick, Diane Abendroth

Aspen Bibliography

No abstract provided.

Hydrologic Recovery Of Aspen Clearcuts In Northwestern Alberta, R H. Swanson, R L. Rothwell

Aspen Bibliography

A 3-year study of evapotranspiration from aspen clearcuts 1 to 14 years of age indicated the following: (1) The annual evapotranspiration from 1- to 5-year-old clearcuts ranges from 0 to 143 mm less than a mature forest on the same site. Evapotranspiration is highly dependent upon the amount of precipitation. (2) These effects can vanish in as few as 2 years with low precipitation (300 mm) or persist for 40 to 45 years with high precipitation (600 mm). These results were confirmed by data from the Spring Creek experimental watershed. Simulated water yield increase from the harvested catchment averaged 16 …

Quaking Aspen Reproduce From Seed After Wildfire In The Mountains Of Southeastern Arizona, Ronald D. Quinn, Lin Wu

Aspen Bibliography

Quaking aspen regenerated from seed after a stand replacement wildfire in the Chiricahua Mountains of southeastern Arizona. The wildfire had created gaps in the canopy so that aspen were able to establish from seed. Seedlings were found at a mean density of 0.17 m–2, 30 m or more from the nearest potential seed trees. Six clumps of aspen seedlings contained 18–186 trees, occupying areas of 145–500 square meters at densities of 0.09-0.27 m–2. White-tailed deer (Odocoileus virginianus) browsed 14.3% of the seedlings. Occasional sexual reproduction of aspen may be a general trait of the species throughout the western portion of …

Restoration Of Aspen-Dominated Ecosystems In The Lake States, Douglas M. Stone, John D. Elioff, Donald V. Potter, Donald B. Peterson, Robert Wagner

Aspen Bibliography

A reserve tree method (RTM) of harvesting was installed in six 70 to 75 year old aspen dominated stands to determine if retaining 10 to 15 dominant aspen per acre would decrease sucker density to facilitate restoration of a conifer component. A reserve shelterwood cut was applied to three additional stands to evaluate performance of white pine planted under 50% crown cover. After the first full growing season following harvest, 96% of the RTM harvested areas were stocked; sucker density averaged 27000 per acre versus 38.2 k per acre on a clearcut control, 41% greater. Basal diameter of dominant suckers …

Multiple Factors Affect Aspen Regeneration On The Uncompahgre Plateau, West-Central Colorado, Barry C. Johnston

Aspen Bibliography

In 1996, I inventoried over 90 aspen stands in 12 timber sales that had been clearcut >3 years previously. Units that regenerated adequately were larger, had higher slope angles, and had soils with a thick Mollic surface layer. Units that regenerated inadequately often had plant species that indicated high water tables. The factors associated with inadequate regeneration were high water tables, heavy browsing, soils with a thin Mollic surface layer, and logging practices that compact large portions of the unit. One of these factors alone often does not lead to inadequate aspen sprouting. Most often, inadequately regenerated aspen stands have …

Landscape-Scale Dynamics Of Aspen In Rocky Mountain National Park, Colorado, Margot W. Kaye, Kuni Suzuki, Dan Binkley, Thomas J. Stohlgren

Aspen Bibliography

Past studies of quaking aspen in Rocky Mountain National Park suggested that the aspen population is declining due to intensive browsing by elk (Cervus elaphus). These studies were conducted in the elk winter range, an area of intensive elk impact. The elk summer range experiences less intense grazing pressure. We tested the hypothesis that impacts of elk would be greater in the elk winter range than the summer range with landscape-scale data from the Park. The detrimental effects of elk on aspen are highly localized and, at larger spatial scales, elk browsing does not seem to be influencing the aspen …

Manipulations To Regenerate Aspen Ecosystems, Wayne D. Shepperd

Aspen Bibliography

Vegetative regeneration of aspen can be initiated through manipulations that provide hormonal stimulation, proper growth environment, and sucker protec- tion—the three elements of the aspen regeneration triangle. The correct course of action depends upon a careful evaluation of the size, vigor, age, and successional status of the existing clone. Soils and site productivity, competition from other plants, and the potential impact of browsing animals upon new regeneration should also be consid- ered. Treatments may include doing nothing, commercial harvest, prescribed fire, mechanical root stimulation, removal of competing vegetation, protection of regenera- tion from herbivory, and in limited circumstances, regenerating aspen …

Long-Term Aspen Exclosures In The Yellowstone Ecosystem, Charles E. Kay

Aspen Bibliography

Aspen has been declining in the Yellowstone Ecosystem for more than 80 years. Some authors have suggested that aspen is a marginal plant community in Yellowstone and that recent climatic variation has adversely affected aspen, while others contend that excessive browsing by native ungulates is primarily responsible for aspen’s widespread decline. To test these hypotheses, I measured all the long-term aspen exclosures (n = 14) in the Yellowstone Ecosystem. Aspen stands inside all exclosures successfully produced new stems greater than 2 m tall without fire or other disturbance, while few outside stands successfully regenerated due to repeated browsing. Understory species …

Aspen Overstory Recruitment In Northern Yellowstone National Park During The Last 200 Years, Eric J. Larsen, William J. Ripple

Aspen Bibliography

Using a monograph provided by Warren (1926) and two sets of aspen increment cores collected in 1997 and 1998, we analyzed aspen overstory recruitment in Yellowstone National Park (YNP) over the past 200 years. We found that successful aspen overstory recruitment occurred on the northern range of YNP from the middle to late 1700s until the 1920s, after which it essentially ceased. We hypothesized why the browsing influence of Rocky Mountain elk (Cervus elaphus) may be different now than it was historically. At a landscape scale, elk hunting outside YNP may be a significant factor changing elk foraging behavior. At …

Evaluation Of Burned Aspen Communities In Jackson Hole, Wyoming, Charles E. Kay

Aspen Bibliography

Aspen has been declining in Jackson Hole for many years, a condition generally attributed to the fact that lightning fires have been aggressively suppressed since the early 1900s. It is also believed that burning will successfully regenerate aspen stands despite high elk numbers. To test this hypothesis, I evaluated 467 burned and 495 adjacent, unburned aspen stands at eight different locations within Jackson Hole. Aspen suckering was stimulated by burning, but most aspen stands still failed to produce new stems greater than 2 m tall where ungulate use was moderate or high. Only when elk use was low were burned …

Sustaining Aspen In Western Landscapes: Symposium Proceedings, Wayne D. Shepperd, Dan Binkley, Dale L. Bartos, Thomas J. Stohlgren, Lane G. Eskew

Aspen Bibliography

No abstract provided.

Monoclonal Light Chain–Mesangial Cell Interactions: Early Signaling Events And Subsequent Pathologic Effects, William J. Russell, James Cardelli, Ed Harris, R. John Baier, Guillermo A. Herrera

Department of Biochemistry: Faculty Publications

Glomerulopathic monoclonal light chains (G-LC) interact with mesangial cells (MC), resulting in alterations of mesangial homeostasis. Early signaling events control mitogenic activities and cytokine production, which in turn participate in the subsequent pathologic events. Mesangial homeostasis is affected in two very different ways, depending on whether the G-LC is from a patient with light chain deposition disease (LCDD) or light chain–related amyloidosis (AL-Am). In contrast, tubulopathic (T)-LC chains from patients with myeloma cast nephropathy do not significantly interact with MC and result in no alterations in mesangial homeostasis. Therefore, understanding early events in the monoclonal LC–MC interactions is fundamental. MC …

Fisheries Occasional Publication No. 31 - Feeding Lupins To Fish: A Review Of The Nutritional And Biological Value Of Lupins In Aquaculture Feeds, Brett Glencross

Fisheries Occasional Publications

Lupins are the harvested seed of species from the Lupinus genus, a group within the leguminous bean and pea family Fabaceae. Legumes are particularly valuable agricultural crops because of their capacity to provide a grain crop and also fix and return nitrogen to soils and improve the soil value for further cropping. The oilseeds, soybeans and peanuts are also leguminous plants, though traditionally they have been cropped for their oil value, whereas lupins, are cropped for both their protein and nitrogen fixing value (Gladstones, 1998; Perry et al., 1998).

The three key commercial species of lupins are L. angustifolius (Narrow-leafed …

Efficiency Of The Inorganic Fertilization In The Cultivation Of Alfalfa (Medicated Sativa L) And Whitewashing For The Correction Of The Ph Of The Soil, Alex Gonzalo Bravo Morocho

Theses and Dissertations

In our country the necessity to offer new alternatives for the agricultural sector is high-priority especially for the lucern cultivation that every day is surface cultivated especially in the Chimborazo province increases; for what is of our interest to establish the answer from the cultivation to the inorganic fertilization and liming for the flora pH correction, for this way to obtain better yields and for consequence to improve the economic conditions of the farmers. With the result that the titled investigation: Efficiency of the Inorganic Fertilization in the Alfalfa Cultivation (Medicago sativa L) and Liming for the Correction of the …

Distinctive Hydrocarbons Of The Black Dump Fly, Hydrotaea Aenescens (Diptera: Muscidae), David A. Carlson, Ulrich R. Bernier, Jerome A. Hogsette, Bruce D. Sutton

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Hydrotaea aenescens (Wiedemann), the black dump fly, is a potential biological control agent originally from the western hemisphere, now found in many parts of the Palearctic region except for the United Kingdom, where it cannot be imported for any reason. A complication of classical biological control is the problem of strain identification, as one must be able to somehow mark or follow a particular strain that has been introduced into the field or is contemplated for release. Gas chromatographic analysis of the surface hydrocarbons of pooled and individual dump fly adults resulted in reproducible hydrocarbon patterns that differentiated widely distributed …

Gas Exchange And Photosynthetic Acclimation Over Subambient To Elevated Co2 In A C3-C4 Grassland, Laurel J. Anderson, Hafiz Maherali, Hyrum B. Johnson, H. Wayne Polley, Robert B. Jackson

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Atmospheric CO₂ (C_a) has risen dramatically since preglacial times and is projected to double in the next century. As part of a 4-year study, we examined leaf gas exchange and photosynthetic acclimation in C₃ and C₄ plants using unique chambers that maintained a continuous C_a gradient from 200 to 550 µmol mol^-1 in a natural grassland. Our goals were to characterize linear, nonlinear and threshold responses to increasing C_a from past to future C_a levels. Photosynthesis (A), stomatal conductance (g_s), leaf water-use efficiency (A/g_{s …}

Dis And Distributed Watershed Models I, Jurgen Garbrecht, Fred L. Ogden, Paul A. Debarry, David R. Maidment

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

The increasing proliferation of spatial data, geographic information systems (GIS), and models for hydrologic applications provide many new investigation opportunities but also present a number of challenges for the uninitiated water resources practitioner. This two-part paper is intended for the practicing engineer who wants to expand into the arena of spatial data and distributed watershed modeling. It provides an integrated overview of the multiple facets of data-GIS-modeling issues and a source of background information for selection and application of GIS in watershed modeling. This first paper addresses selected spatial data issues, data structures and projections, data sources, and information on …

Automated Gas Sampling System For Laboratory Analysis Of Ch4 And N2O, Spencer L. Arnold, Timothy B. Parkin, John W. Doran, Bahman Eghball, Arvin R. Mosier

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Analyzing the flux of CH₄ and N₂O from soil is labor intensive when conventional hand injection techniques are utilized in gas chromatography. An automated gas sampling system was designed and assembled from a prototype developed at the National Soil Tilth Laboratory in Ames, IA. The sampler was evaluated for accuracy and precision when attached to a Varian 3700 gas chromatograph configured with flame ionization and electron capture detectors. The automated gas sampling system is easy to operate and provides acceptable results (standards ranging from 1.0–5.0 ppmv CH₄ and 0.342–2.0 ppmv N₂O had coefficients of …

Evidence For The Innervation Of Sperm Storage Tubules In The Oviduct Of The Turkey (Meleagris Gallopavo), S. L. Freedman, V. G. Akuffo, M. R. Bakst

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

The presence of neural tissue and smooth muscle elements in the vicinity of the oviductal sperm storage tubules at the uterovaginal junction was assessed by several modes of light microscopy. Isolated neurones and small ganglia were identified in the uterovaginal junction of the turkey oviduct. The nerve cell bodies were observed in the tunica mucosa by bright field microscopy. Immunoreactivity against neurofilament antibody and recombinant fragment C of the tetanus toxin reacted with nerve fibres and the nuclei of neurones. Fluorescence microscopy and confocal laser scanning microscopy revealed that nerve fibres continued from the base of the tunica mucosa into …