The Impact of Vertebrate Herbivores on Primary Production of Sagittaria Marshes in the Wax Lake Delta, Atchafalaya Bay, Louisiana.
Date of Award
Doctor of Philosophy (PhD)
James G. Gosselink
Aboveground production of tidal freshwater marshes dominated by Sagittaria latifolia or Sagittaria platyphylla is best estimated with nondestructive techniques. A nondestructive method for estimation of Sagittaria aboveground biomass and production was developed using multiple regression. This technique yielded estimates of aboveground biomass of Sagittaria ranging from 0 to 1875 g/m$\sp2$; harvested aboveground biomass of Sagittaria ranged from 85 to 1356 g/m$\sp2$. Aboveground production was estimated nondestructively on the basis of permanent plots (465-3809 g/m$\sp2$/yr) and destructively on the basis of end-of-season biomass (775-4056 g/m$\sp2$/yr). Destructively estimated belowground production ranged from 233 to 1199 g/m$\sp2$/yr. Aboveground production was positively correlated with elevation, whereas belowground production seemed more related to dominant species. The effects of vertebrate grazing on above- and belowground biomass and production were insignificant in the first year of this study. In the second year, grazing significantly decreased aboveground biomass and production (measured nondestructively) of Sagittaria at the intermediate elevations. At the highest elevation other plant species invaded and Sagittaria production decreased, when furbearer grazing was prevented. At the lowest elevation S. platyphylla was dominant, and compensatory growth seemed to occur in this species. Production estimates based on end-of-season biomass and leaf longevity were considered less reliable for testing grazing effects than estimates based on a nondestructive method because herbivory affected the longevity of the studied species.
Visser, Jenneke Maria, "The Impact of Vertebrate Herbivores on Primary Production of Sagittaria Marshes in the Wax Lake Delta, Atchafalaya Bay, Louisiana." (1989). LSU Historical Dissertations and Theses. 4816.