This thesis examines vegetation community change at two temporal scales in the
Piedmont of North Carolina. Using long-term plots in the Duke Forest, I examine
decadal-scale changes in community composition of the forest understory and shed light
on the potential drivers of that change. Using historical data from colonial survey
records, I study presettlement forest communities of the Piedmont and attempt to
reconstruct Piedmont forests as they may have been in the time before European arrival.
The pattern of successional change in southeastern United States Piedmont
forests has been assumed from chronosequence studies over the last half century.
However, these assumptions for forest understory herb-layer populations and
communities have not been tested using long term data sets. Using permanently marked
plots in the Duke Forest (Durham, NC, USA) re-censused after a 23 year time step,
species richness and community changes at 25m2 and 1000m2 scales are examined. I look
at changes across life forms and examine these changes in relation to measured stand
and environmental factors. Although total species richness stayed relatively constant
through the 23 year step, herb richness declined with a concomitant increase in woody
richness. Plot composition change was remarkably consistent and this change was not
correlated to any measured stand or environmental factors. These community-level
changes are consistent with previously reported changes in the understories of
hardwood dominated stands in the Duke Forest, suggesting that landscape scale drivers
may be more important than within-stand successional processes in patterning
herbaceous communities at this time. Combined with growing evidence from other
studies, this work indicates that forests in the temperate region may be experiencing
changes different from those predicted by successional chronosequence studies. It
indicates that one of the primary drivers of this change is the explosive growth of deer
populations in the last two decades.
Witness trees recorded in historical surveys have been used to reconstruct
presettlement vegetation in many parts of North America, leading to a better
understanding of vegetation patterns before the effects of Europeans. For some parts of
North America, Government Land Office records make the process of reconstructing
vegetation patterns easier - thus more is known about these areas. Because of the unique
and unplanned nature of settlement in the southeastern U.S., less is known about the
presettlement vegetation in this area of the country. Using a reconstructed cadastral map
of a section of the North Carolina Piedmont, I was able to plot the positions of trees on
the historical landscape. These data were then used to understand and reconstruct the
composition of presettlement forests. Although the vegetation of some areas of the
Piedmont is similar to what was expected, I find significant differences with the
expected presettlement composition. In particular, pine species were common in some
areas and rare in others, indicating that different disturbance regimes were active on the
landscape. / Dissertation
| Identifer | oai:union.ndltd.org:DUKE/oai:dukespace.lib.duke.edu:10161/198 |
| Date | 07 May 2007 |
| Creators | Schwartz, Miguel James |
| Contributors | Christensen, Norman L., Peet, Robert K., Richter, Daniel D., Terborgh, John W., Urban, Dean L. |
| Source Sets | Duke University |
| Language | en_US |
| Detected Language | English |
| Type | Dissertation |
| Format | 5045051 bytes, application/pdf |
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