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Abstract
Using both natural and field experiments, this dissertation examines the impact of single and compound disturbance (windthrow and salvage logging) severity on herbaceous species diversity and composition in Georgia and Tennessee.
Following a brief review of relevant literature, I first examine the effect of varying severity on herbaceous species diversity and composition in an experimental wind disturbance of the Georgia Piedmont one, three, and four years post-disturbance. I present evidence that disturbance severity, as quantified by 50% or 100% of tree basal area felled, increases herbaceous diversity most noticeably one year post-disturbance in a closed-canopy forest, but the effect decreases three and four years post-disturbance. Herbaceous compositional dissimilarity was consistently observed between most treatments in all years without apparent connection to disturbance severity.
Next, I examine the impact of compound wind and salvage logging on herbaceous diversity and composition in a wiregrass-dominated fire frequent longleaf pine woodland of Georgia three years post-disturbance. I present evidence that varying severity did not affect a change in herbaceous diversity. However, herbaceous compositional dissimilarity was observed in two out of six treatment comparisons.
Finally, I examine the long-term impact of wind and salvage logging on herbaceous diversity and composition in the Tennessee Coastal Plain. This study built upon prior work that sampled herbaceous species two years post-disturbance; my contribution enabled a retrospective of over two decades. Twenty-two, twenty-three, and twenty-four years post-disturbance, neither herbaceous diversity nor composition varied with disturbance severity, as defined by the presence or absence of salvage logging. The nondifferences are likely due to the progression of time.
I found that single disturbance severity had the strongest impact on herbaceous diversity one year post-disturbance in a closed-canopy forest; however, a compound disturbance (wind plus salvage logging) had no apparent effects on herbaceous diversity three and twenty-plus years post-disturbance in an open-canopy woodland and closed-canopy forest. Both single and compound disturbance impacted herbaceous composition short-term but not long-term post-disturbance. At present, it appears that wind and salvage logging have temporary but not long-lasting effects on the herbaceous diversity and composition of the southeastern United States.
Following a brief review of relevant literature, I first examine the effect of varying severity on herbaceous species diversity and composition in an experimental wind disturbance of the Georgia Piedmont one, three, and four years post-disturbance. I present evidence that disturbance severity, as quantified by 50% or 100% of tree basal area felled, increases herbaceous diversity most noticeably one year post-disturbance in a closed-canopy forest, but the effect decreases three and four years post-disturbance. Herbaceous compositional dissimilarity was consistently observed between most treatments in all years without apparent connection to disturbance severity.
Next, I examine the impact of compound wind and salvage logging on herbaceous diversity and composition in a wiregrass-dominated fire frequent longleaf pine woodland of Georgia three years post-disturbance. I present evidence that varying severity did not affect a change in herbaceous diversity. However, herbaceous compositional dissimilarity was observed in two out of six treatment comparisons.
Finally, I examine the long-term impact of wind and salvage logging on herbaceous diversity and composition in the Tennessee Coastal Plain. This study built upon prior work that sampled herbaceous species two years post-disturbance; my contribution enabled a retrospective of over two decades. Twenty-two, twenty-three, and twenty-four years post-disturbance, neither herbaceous diversity nor composition varied with disturbance severity, as defined by the presence or absence of salvage logging. The nondifferences are likely due to the progression of time.
I found that single disturbance severity had the strongest impact on herbaceous diversity one year post-disturbance in a closed-canopy forest; however, a compound disturbance (wind plus salvage logging) had no apparent effects on herbaceous diversity three and twenty-plus years post-disturbance in an open-canopy woodland and closed-canopy forest. Both single and compound disturbance impacted herbaceous composition short-term but not long-term post-disturbance. At present, it appears that wind and salvage logging have temporary but not long-lasting effects on the herbaceous diversity and composition of the southeastern United States.