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Recovery and Resilience of Appalachian Herbs

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abstract
The herbaceous layer of rich cove forests in the Southern Appalachians represent one of the highest biodiversity habitats in North America. These forests, however, have undergone large-scale logging disturbance that has altered 99% of the original forested landscape, leaving few old growth forests. With logging rotations of 100 – 150 years, understanding long-term recovery and resilience in the diverse herb community in terms of not just diversity, but also the processes structuring the community is necessary for understanding and conserving this species rich community. The studies presented here address long-term recovery of the herbaceous community while taking into account spatial and temporal variation in the community. Intersite heterogeneity was accounted for by comparing paired sites of old growth forest and mature forest that were logged 100 – 150 years ago. To address both patterns and processes, several components of the herb layer were addressed: species richness, abundance, composition, spatial patterns, environmental filtering and trait based species assembly. The results demonstrate that understory herb communities do not return to their pre-disturbance states even after over a century of recovery in nearly all important respects. Both species richness and abundance was greater in old growth forests than mature forests, and species composition differed significantly between the two. The mechanisms that assemble communities play out over long time scales and different processes operate in old growth forests compared to mature forests. Species composition in old growth forests is largely explained by environmental variables while mature forests have not reached equilibrium with the environment. Environmental filtering happens slowly over time with less and different environmental coupling in logged forests. Additionally, mechanisms of competitive coexistence are not yet fully structured in mature forests. Succession in the understory herb layer of cove forests takes much longer than suspected, and recovery time exceeds the 100 – 150 years between harvest rotations. These findings show that mature forest stands should not be used as a baseline for herb layer recovery. Continued assessment over time will determine if and when the herb layer regains the species richness, abundance, composition and, more importantly, the ecological processes that interact to form communities in old growth forests.
subject
community structure
diversity
logging
Appalachian
cove forest
herbaceous
contributor
Wyatt, Julie (author)
Silman, Miles (committee chair)
Berenhaut, Kenneth (committee member)
Smith, William (committee member)
Weigl, Peter (committee member)
Zeyl, Cliff (committee member)
date
2009-05-08T21:24:28Z (accessioned)
2010-06-18T18:59:52Z (accessioned)
2009-05-08T21:24:28Z (available)
2010-06-18T18:59:52Z (available)
2009-05-08T21:24:28Z (issued)
degree
Biology (discipline)
identifier
http://hdl.handle.net/10339/14899 (uri)
language
en_US (iso)
publisher
Wake Forest University
rights
Release the entire work immediately for access worldwide. (accessRights)
title
Recovery and Resilience of Appalachian Herbs
type
Dissertation

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