Physical and Environmental Geography Commons^™

Arctic Greening: Characterizing Tundra Vegetation From In-Situ And Remotely Sensed Observations, Shira Ann Ellenson

Graduate Student Theses, Dissertations, & Professional Papers

As the Arctic has warmed at twice the rate of the global average, vegetation productivity has also been increasing. While satellite remote sensing is useful for summarizing Arctic-wide trends, changes in tundra species heights, densities, composition, and distribution can be missed at coarse resolution. Smaller, plot-scale studies are necessary to better understand vegetation dynamics at fine scales occurring on the ground.

In 1995, high-resolution traditional aerial photographs and in-situ measurements of vegetation characteristics were taken at a series of plots established on the Alaskan North Slope. Repeat field surveys in 2021 revealed increases in plant cover for deciduous shrubs and …

Snow-Albedo Feedback In Northern Alaska: How Vegetation Influences Snowmelt, Lucas C. Reckhaus

Theses and Dissertations

This paper investigates how the snow-albedo feedback mechanism of the arctic is changing in response to rising climate temperatures. Specifically, the interplay of vegetation and snowmelt, and how these two variables can be correlated. This has the potential to refine climate modelling of the spring transition season. Research was conducted at the ecoregion scale in northern Alaska from 2000 to 2020. Each ecoregion is defined by distinct topographic and ecological conditions, allowing for meaningful contrast between the patterns of spring albedo transition across surface conditions and vegetation types. The five most northerly ecoregions of Alaska are chosen as they encompass …

Remote Sensing Of Avalanche Paths In Glacier National Park, Montana, Morgan Voss

Graduate Student Theses, Dissertations, & Professional Papers

Snow avalanches are the common form of mass wasting in the high mountain environments of Glacier National Park (GNP), Montana. These natural disturbances play important roles in mountain ecosystems by regularly disturbing montane systems, providing critical habitat for some species, transporting debris, and influencing vegetation and fire dynamics. Since the 1900s, natural avalanche-related activity recorded along important transportation corridors within the park has frequently disrupted transportation.

While many of the steep slopes of GNP are susceptible to avalanching, formal inventories exist only for small, critical portions of the park and they vary substantially from one another. GNP’s protected status does …

Impact Of Drought On Land Cover Changes In Diné Bikéyah – A Study Through Remote Sensing, Anjanette A.J. Hawk

Geography ETDs

This study identifies land cover changes associated with a ten-year drought period and discusses the importance of vegetation change in Diné Bikéyah, a semi-arid land located in a remote part of the southwestern United States (US). This study concludes that drought produced slight changes in vegetation within a 540 km² study area in the Tselani-Cottonwood Chapter (TCC) in Diné Bikéyah. The data for this study consist of three Landsat images for the years 1998, 2002, and 2009. The methods used to analyze these Landsat images included image pre-processing, calculation of normalized difference vegetation index (NDVI) images, and supervised (maximum …

Greening Of The Arctic: Plot-Scale Analysis Of Interactions Between Climate, Vegetation, And Permafrost At Toolik Lake, Alaska (1995 - 2017), Brianna Rick

Graduate Student Theses, Dissertations, & Professional Papers

Air temperatures across the Arctic have increased in recent decades, and through complex feedbacks, vegetation and permafrost (frozen ground) are actively responding as climate warming continues. This study investigates the trends and interactions of observed air, soil-surface temperature (SST), and active-layer thickness (ALT) at Toolik Lake on the Alaskan North Slope between 1995 and 2017, as well as vegetation change over time.

Time series between 1995 and 2017 at CALM site U12B, a 1 ha plot near Toolik Lake, reveal an increase (0.50 °C/decade) in mean summer (Jun-Aug) air temperatures and a decrease (­0.23 °C/decade) in mean summer SST. In …