Date of Award
8-2024
Document Type
Thesis
Degree Name
Master of Science (MS)
Department
Forestry and Environmental Conservation
Committee Chair/Advisor
Dr. Stefanie Whitmire
Committee Member
Dr. Jamie Duberstein
Committee Member
Dr. Skip Van Bloem
Committee Member
Dr. William Conner
Abstract
Coastal forested wetlands are identified as some of the highest-priority ecosystems for climate change mitigation. Here, we present two studies conducted in these unique ecosystems.
The first assessed changes in aboveground vegetative C stocks along the estuarine-riverine gradients of the Winyah Bay in South Carolina and the Savannah River in Georgia, using a space-for-time substitution to increase understanding of the impacts to upper estuarine forested wetlands from relative sea level rise. Standing C stocks on the Savannah River averaged 183.6 Mg C ha-1, while sites on the Winyah system averaged 162.3 Mg C ha-1. The largest aboveground C pools were found at sites furthest upriver, decreasing downstream as salinity rose. These data, alongside predicted sea-level rise suggest a marked decrease in future aboveground C stocks in forested wetlands situated in and around tidal estuaries.
Our second study investigated the radial and azimuthal patterns of sap flow in species (baldcypress and water tupelo) common to the freshwater swamps of the southeastern US, suspecting that these diverse species may exhibit similar sap flow patterns under permanently flooded conditions. Granier-style thermal dissipation probes were used to measure daytime sap flux at 15 mm and 25 mm depths into the active xylem of both species to assess radial patterning and at each cardinal direction on the bole of each species to assess azimuthal patterning. Analysis of sub-daily time series data found significant (p < 0.05) effects on sap flux by time of day, month, species, and depth. We did not find any differences between the two depths with water tupelo (p > 0.5), but average baldcypress flux rates at 15 mm were significantly higher than those at 25 mm (p < 0.0001). Azimuthal patterns were not detected for either species, contradicting previous studies. This study supports the treatment of azimuthal sap flow variation as a random variable rather than one with predictable directionality, and demonstrates that common radial sap flow patterns may not be generalizable across diverse environmental settings. Because our study found temporal variation in sap flux rates, the inclusion of these temporal factors could improve modeling estimates of individual tree water use.
Recommended Citation
Shipway, Chris, "I’m a Forest, Not a Saltmarsh, Captain: Carbon and Sap Flow Dynamics in Coastal Forested Wetlands of the Southeastern United States" (2024). All Theses. 4330.
https://open.clemson.edu/all_theses/4330