The influence of salinity on the germination and distribution of Taxodium distichum (L.) Rich., bald cypress, along the northeast Cape Fear River

UNCW Author/Contributor (non-UNCW co-authors, if there are any, appear on document)
Erin L Fleckenstein (Creator)
Institution
The University of North Carolina Wilmington (UNCW )
Web Site: http://library.uncw.edu/
Advisor
Courtney Hackney

Abstract: A survey of three sites along the Northeast Cape Fear River, NC indicated that natural regeneration of Taxodium distichum (bald cypress) only occurred at the most oligohaline site along a salinity gradient. Floodwater salinity from 2000-2006 at this site was routinely < 0.1, while salinity at the other two downstream sites was <2 and 2-9, respectively. Germination and emergence of T. distichum seeds collected from the Northeast Cape Fear River were evaluated in a range of salinities (0, 2, 4, 6, 8, 10, and 12). Seeds germinated in all salinities, but at lower rates with increasing salinity. Salinity significantly impacted germination above 6 (p=0.001). Establishment, the ability to germinate, emerge and survive the duration of the study, occurred only in the lowest salinities, 0 and 2, suggesting that salinity is a major factor limiting T. distichum recruitment and establishment along the Northeast Cape Fear River. The results of this study indicate that as sea level rise increases, salt water intrusion will likely restrict T. distichum from tidal swamps along the lower Cape Fear River, where mature stands now occur. A vegetation survey was conducted at three sites along the Northeast Cape Fear River, a natural salinity continuum, to assess the persistence of Taxodium distichum and associated vegetation when exposed to rising sea level. Three permanent plots measuring 20 x 50 m were established at each of the sites and surveyed using the NCVS protocol. A total of 89 species representing 54 families were identified. Live T. distichum were absent from the site furthest downstream, the most saline. Both NMS and DCA ordinations show that the vegetation assembles along a continuum of average tidal duration and soil sulfate concentrations (a proxy for salinity intrusion). Swamps dominated by T. distichum are being replaced by salt and brackish marsh species, such as Juncus roemerianus, due to sea level rise. A lack of allochthonous riverine input may accelerate the process of vegetation regression. These swamps will be limited to upstream areas of higher elevation and those exposed to freshwater flooding.

Additional Information

Publication
Thesis
A Thesis Submitted to the University of North Carolina at Wilmington in Partial Fulfillment of the Requirement for the Degree of Masters of Science
Language: English
Date: 2009
Keywords
Baldcypress--Effect of salt on, Baldcypress--North Carolina--Southeastern, Baldcypress--Geographical distribution--Effect of salt on
Subjects
Baldcypress -- North Carolina -- Southeastern
Baldcypress -- Effect of salt on
Baldcypress -- Geographical distribution -- Effect of salt on