Date of Award
Bachelor of Science
Ecology, Microclimate, Thermal Gradients, Plant Sciences, Terrestrial Laser Scanning, Temperature Logging
Thermal microclimates are an important component of natural ecosystems because they provide appropriate niche space for many organisms; however, they are not widely studied because of their small scale. Likewise, variation in these microclimates may significantly impact animal thermoregulation and plant physiological processes and be especially important in the face of climate change. The goal of this study is to determine how the size and structure of Quercus ilicifolia shrubs influences ground temperature gradients. We hypothesized that differences in leaf cover and leaf area index (LAI) would cause temperature under shrubs to cool relative to the ambient temperature, and that higher LAI shrubs will create steeper temperature gradients. The study was conducted using five Quercus ilicifolia (scrub oak) shrubs of varying height and structure in the Albany Pine Bush Preserve. Five temperature logging devices were distributed in a transect from the center of the shrub to twice its radius into the surrounding herbaceous vegetation. Leaf area and leaf area index (LAI) were measured and shrubs were scanned using a terrestrial laser scanner to obtain a 3D point cloud. This was used to calculate shrub canopy volume. The most highly significant thermal gradient present was in the daily maximum temperatures, showing that as one moves closer to the shrub center, the maximum temperature cools continually. However, the remaining temperature data confirmed that differences in shrub structure (leaf area, LAI) do not influence the magnitude of the thermal gradient. While the amount of shade cover did not impact temperature variation among individual shrubs, we found that there was a consistent temperature gradient from the center to 2x the radius outside the shrub. We concluded that temperature gradients shift independently of shrub structure, but are nonetheless present underneath and directly adjacent to shrubs. Using data obtained from laser scanning, we found a significant association (p2) and volume (m3). Overall, we have shown that TLS is a useful way to support field measurements, and scans could be useful in identifying shrubs to scale to a landscape-level microclimate model. This information demonstrates that there are alternative ways to study the impacts of climate change on a small-scale, and may provide the tools to necessary to map optimal habitat space for many species.
Silbey, Alyssa, "Analyzing Thermal Gradients Using Terrestrial Laser Scanning in Scrub Oak Habitats" (2020). Honors Theses. 2497.