During the late 19th and early 20th centuries, extensive logging reduced the forests of red spruce (Picea rubens) by nearly 99% through portions of West Virginia. In the wake of this disturbance, red spruce has begun regenerating on the ridge and mountaintop areas of Canaan Valley, West Virginia, where heath and grassland communities have both persisted in natural barrens and expanded into formerly forested areas. To understand abiotic and biotic conditions guiding the advance of the red spruce stand, I conducted a broad-scale assessment of thirty-one demographics plots spread across two sites (north Cabin Mountain and Bear Rocks/Dolly Sods), and a more focused assessment of red spruce species associations within thirty-two paired plots at Cabin Mountain. At the 15m x 15m demographics plots, I conducted a count of all P. rubens present, measured specimen height, DBH or diameter at ground level (DGL) for specimens < 1.37m tall, and assessed the relative percent cover of rock, shrub, herbaceous, and tree cover. These data, along with additional abiotic components derived from a DEM, formed the basis of my assessment using a generalized linear mixed model (GLMM) to identify the most significant biophysical variables related to P. rubens count. In the paired plots, I used the relative interactions index (RII) to compare the total cover of each present non-graminoid vascular species and the grouped cover types Rock, Graminoid, Lichen, Litter, and Moss in one 45cm-radius plot with a < 1.37m P. rubens specimen, and one paired 45cm-radius plot in open heath. The significance of differences in total cover were assessed with the Wilcoxon test and Tukey HSD. The GLMM identified percent rock cover and distance from the nearest P. rubens stand to be important correlates of P. rubens count at the demographic plots. Graminoid cover was found to be higher in P. rubens 45cm-radius plots than in paired heath plots, and Vaccinium angustifolium cover was found to be concentrated in 45cm radius plots beyond the first 15cm from the P. rubens stem. These findings reinforce a complex interplay between both the biotic and abiotic characteristics of a microsite and the successful germination and regeneration of a red spruce seedling in the heathland. / Master of Science / During the late 19th and early 20th centuries, extensive logging reduced the forests of red spruce (Picea rubens) by nearly 99% through portions of West Virginia. In the wake of this disturbance, red spruce has begun regenerating on the ridge and mountaintop areas of Canaan Valley, West Virginia, where heath and grassland communities have both persisted in natural barrens and expanded into formerly forested areas. To understand the necessary abiotic and biotic conditions guiding the advance of the red spruce stand, I conducted a broad-scale assessment of thirty-one demographics plots spread across two sites (north Cabin Mountain and Bear Rocks/Dolly Sods), and a more focused assessment of red spruce species associations within thirty-two paired plots at Cabin Mountain. At the 15m x 15m demographics plots, I measured and counted all red spruce present. I collected landscape and community data on each plot using field surveys and a digital elevation model (DEM) to the variables most associated with a higher count of red spruce in each plot. In the 45cm-radius paired plots, I used simple mathematical comparisons to identify positive and negative interactions between red spruce shorter than breast height (1.37m) and different types of cover, including heathland species such as Vaccinium angustifolium (lowbush blueberry), rock, graminoid, and moss. Modeling indicated that rock cover, and distance between the plot and the nearest stand of red spruce, were found to be the most significant variable affecting the count of red spruce at each plot, with increased rock cover and shorter stand distance both associated with higher numbers of spruce. In the paired plots, there was slightly higher graminoid cover associated with the tree than with the open heath plot, and V. angustifolium was more concentrated beyond 15cm from each red spruce specimen. These findings suggest that rock cover is important for tree regeneration both the biotic and abiotic characteristics of a microsite and the successful germination and regeneration of a tree seedling in heathlands.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/101088 |
| Date | 20 June 2019 |
| Creators | White, Helen M. |
| Contributors | Geography, Resler, Lynn M., Carroll, David F., Thomas, Valerie A. |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Detected Language | English |
| Type | Thesis |
| Format | ETD, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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