The mesic forests distributed within the Rocky Mountains of northern Idaho are unique because many species contained within the forest are separated from their main distribution along the Pacific Northwest coast. It remains unclear whether most species within the inland disjunction survived the glacial periods of the Pleistocene, or whether they were more recently dispersed from coastal populations. To see if the dominant tree taxa of the mesic forests today could have persisted in a refugium south of the large ice sheets, four sediment cores were used to reconstruct the vegetation and climate history of the region. A nearly continuous record of pollen and sediment composition (biogenic silica and inorganic and organic matter) over the last ca. 120,000 years provides evidence of a dynamic ecosystem. Over a long timescale, the slow shifts in vegetation are attributed to the changes in climate. During the last interglacial period, the region was warmer and drier with a Pinus dominated mixed conifer forest. Approximately 71,000 years ago, a Pseudotsuga/Larix forest became established in the area as a response to the increased available moisture. As climate cooled and glaciers expanded the Pinus and Picea forest was the dominant vegetation type until ca. 40,000 years ago. The environment during the Last Glacial Maximum (LGM) was so harsh that no vegetation record was recorded. After the LGM, climate warmed, enabling a Pinus and Picea forest to establish and persist until the Holocene. The mesic taxa that dominate the modern forests did not arrive in northern Idaho until the mid- to late-Holocene. The recent arrival of the dominant tree species, Thuja plicata and Tsuga mertensiana, suggests that they likely did not persist in a refugium during the last glaciation. Instead, these species recently dispersed from coastal populations, but expansion into their interior distributions was likely limited by both climate and species competition in already established forests. During the late-Quaternary, the deposition of thick tephra layers (>20 cm) from the eruptions of Glacier Peak (ca. 13,400 years ago) and Mt. Mazama (ca. 7,600 years ago) also facilitated an abrupt and persistent change in vegetation in northern Idaho.

No description available.

The human health effects of acute exposure to high levels of ionizing radiation are well understood; however, when these irradiations occur at low levels, there is controversy as to their potential health threat (BEIR V, 1990). For individuals living in areas where the level of naturally occurring background radiation is relatively high, the issue of additional exposure to anthropogenically derived sources of ionizing radiation may be of some concern. This study investigates the presence of radionuclides in surface soils near a United States Environmental Protection Agency (EPA) Superfund site near Pocatello, Idaho, where two phosphorus production facilities have operated for more than fifty years. It is hypothesized that airborne particulates from these facilities are migrating into a residential community, and are accumulating in the uppermost soil layers. Soil samples were collected from seven sites located between 1.3 and 6.7 km along a transect aligned with the prevailing downwind direction. The transect origin lies at the northern boundary of the Superfund site, and the sites were selected for their ease of public access. Samples were collected at four different 2.5 cm depths (10 cm total) for each site, and these samples were analyzed for their gamma emissions. Statistical evaluations of the sample data yielded results of no significant difference in nuclide concentrations between soil layers, or between sample sites (��=0.05). This investigation corroborates the EPA discovery that nuclide concentrations in surface soils decrease rapidly beyond 1 km from the site boundary. This study extends the available information regarding the presence of radionuclides in off-site surface soils by approximately 4 km in the prevailing downwind direction. Additionally, these data appear to contradict the EPA's conclusion that no residential exposure is occurring via a surface soil pathway. This investigation finds that surface soil exposures, at locations such as public parks and schools, may be occurring from radionuclide concentrations that are as high as 4 times that of published background radiation levels. / Graduation date: 2002

No description available.

No description available.

This creative project inspected the design of water conserving landscapes by restoring native vegetation. Water conserving design principles discovered in the background research were applied to the redesign of the Old Fort Boise Park in Parma, Idaho. Important issues that were explored included discussing the need for water conserving landscape designs that result in functional spaces that meet the needs of intended users. The main focus of water conservation was implemented by using native plants that typically require less water than non-native species. The project developed a park master plan that could demonstrate to Idaho residents that native plants, when carefully sited, result in lower maintenance, aesthetically pleasing visual qualities, environmentally sensitive performances and could be integrated into landscapes on private or public properties. Rather than viewing the Idaho native plants as unattractive and dull, this project explored the idea that under cultivation and as part of the site character a carefully designed water conserving naturalized landscape has a beauty unsurpassed by traditional landscapes. The park redesign also employed educational and interpretive systems wherein native plants were highlighted and identified. These educational and interpretive systems could assist park users, especially local residents, in familiarizing themselves with many of the beautiful native species that are common in the surrounding deserts, prairies, hills and mountains. The creative project examined one particular site, while it developed principles and concepts applicable to other sites throughout the Great Basin Region. / Department of Landscape Architecture

Thesis. 1977. M.S.--Massachusetts Institute of Technology. Dept. of Earth and Planetary Sciences. / Microfiche copy available in Archives and Science. / Bibliography : leaves 48-50. / M.S.

In the canyon grasslands of Garden Creek Ranch Preserve in Idaho, where the threatened plant Silene spaldingii occurs and invasion by the exotic species Centaurea solstitialis and Bromus tectorum is proceeding rapidly, I examined environmental and community patterns of site invasion, and evaluated the apparent influence of invasion on Silene population vigor. In addition, two separate lightning fires at the preserve presented the opportunity to examine the short-term influence of late-season fire on this species and its associated bunchgrass plant community. I found that Silene-supporting sites most often invaded by exotics were on relatively gentle slopes that received more incident radiation. This pattern may relate, in part, to light requirements of Centaurea solstitialis. Invaded sites were also typically at higher elevations, which may indicate they were moister and therefore more productive. The plant communities in invaded Silene-supporting sites were similar to plant communities in uninvaded sites, although invaded sites tended to have greater legume and exotic annual grass cover. Exotic species invasion did not appear to influence negatively the vigor of Silene populations, as indicated by similar plant height and comparable levels of flowering, fruit and seed set in invaded and uninvaded populations. The similarity in Silene vigor between invaded and uninvaded sites may reflect a moderating influence of site productivity in invaded populations, or may indicate that mature Silene plants and the exotic species partition space or resources differently, potentially reducing competition between them. However, Silene recruitment may be limited by competition from weeds; my data did not allow a rigorous test of this possibility. Fire apparently decreased cover of Festuca idahoensis and increased cover of Lupinus sericeus in the first year after burning, while cover of Pseudoroegneria spicata, exotic grasses, and most other forb species did not differ between burned and unburned areas. Silene cover and abundance within populations were similar before and after fire. Burning did not appear to influence levels of flowering, change the number of flowers or capsules produced per stem, or alter the number of seeds per capsule. Burning decreased plant size slightly, and decreased the proportion of flowers that matured to seed-filled capsules. Silene and the plant communities that support this species appear well suited to late season fire, however the response to burning in other seasons or at higher frequencies remains unknown in this study area. / Graduation date: 2003

An ecological baseline study of the diatom flora was conducted on the headwaters of Henrys Fork of the Snake River, Idaho. The diatom flora of this spring fed drainage basin consisted of both phytoplankton and periphyton. Thirty-nine genera, two hundred forty-four species, eighty-two additional varieties, and seven additional forms were identified from these waters. Species of Melosira, Stephanodiscus, Fragilaria, Synedra, and Asterionella were found in the plankton of Henrys Lake and Island Park Reservoir. Diatoma, Fragilaria, Synedra, Eunotia, Achnanthes, Navicula, Pinnularia, Gomphonema, Cymbella, Nitzschia, and Surirella were the important genera present in the periphyton.

Call number: LD2668 .T4 1929 A81