Physical Sciences and Mathematics Commons^™

Environmental Factors Associated With Triploid Aspen Occurrence In Intermountain West Landscapes, James A. Walton

All Graduate Theses and Dissertations, Fall 2023 to Present

Polyploidy is common among plants and can contribute to physiological and morphological differences, altering how plants respond to environmental changes, promoting genetic diversification and even species radiation. Quaking aspen (Populus tremuloides), a keystone species associated with high plant and animal diversity is frequently found in mixed diploid/triploid populations in the Intermountain West. Triploid aspen carries an extra chromosomal copy, whereas the diploid type contains two chromosomal copies. High mortality rates and widespread population declines in aspen are of increasing concern in the Intermountain West, and often ascribed to changing climates and drought stress events. The goal of this …

Regeneration Of Quaking Aspen And Understory Vegetation Change After Fire Risk Reduction Treatment, Allison M. Trudgeon

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Quaking aspen (Populus tremuloides Michx.) is a keystone species that, when coexisting with conifers (i.e., seral aspen), often undergoes stand-replacing disturbances to sustain long term vigor. Historically, mixed-to-high severity fire reduced fuels and regenerated aspen, but such disturbances have become less common in recent decades. This has often led to high fuel loading, and many seral aspen stands are at now risk of an unpredictable, high-severity fire, posing a threat to development in the wildland-urban-interface. The lack of a commercial market for aspen, and the risk of conducting prescribed fire, means there are few alternate management options. This has …

Effect Of Foliage And Root Carbon Quantity, Quality, And Fluxes On Soil Organic Carbon Stabilization In Montane Aspen And Conifer Stands In Utah, Antra Boča

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Soil organic carbon (SOC) positively affects many soil properties (e.g., fertility and water holding capacity), and the amount of carbon (C) in soil exceeds the amount in the atmosphere by about three times. Forest soils store as much C as is found in trees. Tree species differ in their effect on SOC pools. Quaking aspen forests in the Western US often store more stable SOC in the mineral soil than nearby conifers. During the last decades a decline in aspen cover, often followed by conifer encroachment, has been documented. A shift from aspen to conifer overstories may negatively affect the …

A Comparison Of Soil Moisture And Hillslope-Stream Connectivity Between Aspen And Conifer-Dominated Hillslopes Of A First Order Catchment In Northern Utah, Amy R. Burke

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Mountain headwater catchments in the semi-arid Intermountain West are important sources of surface water because these high elevations receive more precipitation than neighboring lowlands. The hydrology of these mountain catchments is especially important as the region faces water shortages and conflicts. Conifer encroachment on aspen stands has been observed across the western US and can result in a decline in water yield. The overall objective of this study was to further our understanding of hillslope-stream connectivity in a headwater catchment of Northern Utah and any observable differences in this connection between aspen and conifer hillslopes. Hillslopes are the fundamental unit …

Soil Organic Carbon And Site Characteristics In Aspen And Evaluation Of The Potential Effects Of Conifer Encroachment On Soil Properties In Northern Utah, Mical K. Woldeselassie

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

In the Intermountain West, aspen (Populus tremuloides) has declined mainly due to a combination of successional processes, fire suppression and long-term use of ungulates which has led to replacement by conifers, sagebrush or other shrub communities. Conifer encroachment is believed to cause critical changes in the ecosystem properties. In order to understand the impacts of conifer encroachment on soil properties such as soil organic carbon (SOC) storage, soil morphology, and soil chemical properties, and the implications of such changes, it is very important to assess the soil properties under the two vegetation types. The objectives of this study …

Comparison Of Water Dynamics In Aspen And Conifer: Implications For Ecology Water Yield Augmentation, Eric Martin Lamalfa

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Differences in water dynamics between deciduous aspen (Populus tremuloides) and co-occurring evergreen conifer species in the Northern Rocky Mountains result from complex physical and biological interactions. A comprehensive evaluation of individual water transfer mechanisms was used to elucidate the relative importance of several components of the hydro logic cycles of aspen and conifer, and determine which water transfer mechanisms have potential to cause differences in net water yield.

Adjacent aspen and conifer stands were monitored to determine snow accumulation and ablation (snow survey), soil moisture recharge (capacitance probes), snowpack sublimation (sublimation pan), transpiration period (thermal dissipation probes), and …

Factors Influencing Epiphytic Lichen Communities In Aspen-Associated Forests Of The Bear River Range, Idaho And Utah, Paul C. Rogers

All U.S. Government Documents (Utah Regional Depository)

In western North America, quaking aspen (Populus tremuloides Michx.) is the most common hardwood in montane landscapes. Fire suppression, grazing, wildlife management practices, and climate patterns of the past century are some of the threats to aspen coverage in this region. Researchers are concerned that aspen-dependent species may be losing habitat, thereby threatening their long-term local and regional viability. Though lichens have a rich history as air pollution indicators, I believe that they may also be useful as a metric of community diversity associated with habitat change. To date, few studies have specifically examined the status of aspen’s epiphytic lichen …

Aspen Indicator Species In Lichen Communities In The Bear River Range Of Idaho And Utah, Paul C. Rogers, Roger Rosentreter, Ronald J. Ryel

All U.S. Government Documents (Utah Regional Depository)

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. …

Pine Hollow Exclosures: Effect Of Browsing On An Aspen Community Sprayed With 2, 4-D, United States Department Of Agriculture, Forest Service

Forestry

The Pine Hollow aspen (Populus tremuloides) exclosures on the Ashley National Forest in eastern Utah were sampled in 1984, 19 years after they were established. The effects of 2, 4-D, wildlife, and cattle on plant succession were evaluated. Two exclosures were used to protect the sprayed area from (1) all animal use and (2) only livestock use. A third sprayed area was left open for use by all animals. The aspen overstory was killed as a result of spraying, with sufficient reproduction occurring to restock the stand. However, animal use drastically altered the aspen reproduction, as well as the understory …

Effects Of Prescribed Fire On Biomass And Plant Succession In Western Aspen, United States Department Of Agriculture, Forest Service

Forestry

Biomass of grasses, forbs, shrubs, and aspen suckers was determined annually for three prescribed fires in aspen and aspen-conifer forests in southeastern Idaho and western Wyoming. Fires ranged from low to high severity and overstory mortality from 20 to 100 percent. Over 4 postburn years, production of grasses and forbs averaged 1.5 to 3.3 times that of controls. After 5 years, shrub biomass was 21 to 100 percent of preburn biomass. The varied patterns of seral vegetation and their management implications are discussed.

Effect Of Small Aspen Clearcuts On Water Yield And Water Quality, United States Department Of Agriculture, Forest Service

Forestry

Streamflow and water quality were monitored in a paired watershed study involving the removal of 20 percent of the aspen (on 13 percent of the area) in five small clearcuts from a 217-acre (88-ha) catchment. There were no significant changes in peak flow, timing, or annual yield during the 4 years of posttreatment monitoring. Significant changes in pH, calcium, magnesium, and nitrates in the snowmelt streamflow from ephemeral subdrainages occurred the second year after cutting. At least some of the differences were attributed to the chemistry of the 1976-77 snowfall, which was also significantly different from snow sampled in the …

Sucker Regeneration In A Utah Aspen Clone After Clearcutting, Partial Cutting, Scarification, And Girdling, United States Department Of Agriculture, Forest Service

Forestry

Clearcutting, partial cutting, scarification, and girdling were used to stimulate root suckering in a Utah aspen clone. Regeneration was inventoried yearly during the first 4 years after treatment and again after 12 years. Clearcutting resulted in the greatest number of suckers. In most years, partial cuts (cuts that removed 67 percent of the basal area) had less than 50 percent as much regeneration as the clearcut plots. Girdling stimulated suckering to a lesser degree than cutting. Mortality was high on girdled plots and by the 12th year after treatment few suckers had survived. Scarification had no apparent effect on sucker …

Quaking Aspen - Seed Germination And Early Seedling Growth, United States Department Of Agriculture, Forest Service

Forestry

The suckering of aspen (Populus tremuliodes Michx.) as a highly effective means of vegetative propagation is well known and has been widely studied (Baker 1918; Day 1944; Maini 1967; Schier 1974). Less is known about seed propagation, sometimes viewed as having only minor importance because early research (Baker 1918) had indicated that rare seedling establishment was due to low or nonexistent germinability.

A Hydrologic Model Of Aspen-Conifer Succession In The Western United States, United States Department Of Agriculture, Forest Service

Forestry

Hydrologic impacts of grass-forb to aspen to conifer succession in the Rocky Mountain area are simulated by means of a fundamental model. Model algorithms representing hydrologic processes are sensitive to vegetational changes within the subalpine vegetation zone. Reductions in water yield are predicted as the vegetation on a small Utah watershed proceeds from a grass-forb type to aspen to conifers. Streamflow changes are largely attributable to an interaction between seasonal consumption for each vegetation type and the influence of vegetation type on snowpack. The model synthesizes present understanding and provides a framework for future watershed research.

Variation In Suckering Capacity Among And Within Lateral Roots Of An Aspen Clone, United States Department Of Agriculture, Forest Service

Forestry

Excised roots were used to determine variation in suckering capacity among and within lateral roots of an aspen (Populus tremuloides Michx.) clone. Differences among lateral roots were significant. Within segments of a lateral root sucker production showed a high degree of polarity, increasing from the distal to proximal ends. There was no evidence of a gradient in suckering capacity in a segmented root; i.e., distal segments were not significantly different from proximal ones. This indicated that aging was not a factor regulating suckering within lateral roots. Sucker production was not affected by root length.

Grindstone Flat And Big Flat Exclosures - A 41-Year Record Of Changes In Clearcut Aspen Communities, United States Department Of Agriculture, Forest Service

Forestry

Deer browsing prevented aspen regeneration in both uncut stands and small 1/20-hectare clearcuts, even though nearby large burns regenerated successfully. Size of the clearcut or burned area may be critical in determining success of aspen regeneration; areas less than about 2 hectares in size may adversely concentrate deer use. Shrub production was less under deer use and forb production was less under cattle use than on protected areas. More apsen suckers were produced in uncut stands where cattle grazed than in stands protected from grazing, suggesting a possible relationship between sucker initiation and reduced competition from the herbaceous understory. Removal …