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Patterns of shifting tree species composition and diversity loss in 19 old-growth forest stands in Pennsylvania

Schumacher, Henry Bernard (2008) Patterns of shifting tree species composition and diversity loss in 19 old-growth forest stands in Pennsylvania. Master's Thesis, University of Pittsburgh. (Unpublished)

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A century of fire suppression and overbrowsing by deer have likely altered patterns of forest regeneration, with detrimental consequences for the future diversity, composition, and function of old-growth stands. We quantified the diversity and composition of tree species in the canopy and understory layers of 19 old-growth stands in Pennsylvania to evaluate the consequences of existing regeneration patterns for the future composition of these communities.Despite relatively high canopy diversity across all stands, the understory composition of all stands converged to a homogeneous subset of the canopy species. In addition, understory layers had unusually low stem densities, lower species diversity than their respective canopies, and showed a significant lack of mid-tolerant species. Oak species, which often require fire to regenerate, were common in the canopy of 12 stands, but absent from the understory layer of all stands. Our findings suggest that deer browsing and fire suppression are partly responsible for this dramatic alteration of understory species composition. The lower diversity and homogenized species composition of the understory indicates that the future composition of these stands will not resemble the current composition. Alteration of tree species composition is likely to have detrimental effects on the survival of species dependent upon old-growth habitat.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Schumacher, Henry Bernardhbs2@pitt.eduHBS2
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairCarson, Walterwalt@pitt.eduWALT
Committee MemberTraw, Brianmbtraw@pitt.eduMBTRAW
Committee MemberTonsor, Stephentonsor@pitt.eduTONSOR
Date: 4 June 2008
Date Type: Completion
Defense Date: 20 March 2008
Approval Date: 4 June 2008
Submission Date: 31 March 2008
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Institution: University of Pittsburgh
Schools and Programs: Dietrich School of Arts and Sciences > Biological Sciences
Degree: MS - Master of Science
Thesis Type: Master's Thesis
Refereed: Yes
Uncontrolled Keywords: canopy replacement; conservation; disturbance; forest diversity
Other ID:, etd-03312008-080045
Date Deposited: 10 Nov 2011 19:33
Last Modified: 15 Nov 2016 13:37


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