This Is AuburnElectronic Theses and Dissertations

Restoration of Native Plants Through Chemical Control of Alligatorweed (Alternanthera philoxeroides) at Eufaula National Wildlife Refuge




Allen, Shannon

Type of Degree



Forestry and Wildlife Sciences


Moist-soil management is a technique used to improve quality of wetland habitats for a variety of waterbird species, but alien invasive plant species may impact success of moist-soil management. Alligatorweed (Alternanthera philoxeroides (Mart.) Griseb.) is an alien invasive wetland plant that competes with and displaces important native plant species used as food sources by migratory waterfowl. Control of alligatorweed is a priority for managers whose goal is to provide waterfowl habitat. In this study, I varied timing and rate of application of triclopyr and imazapyr herbicides to evaluate effects on alligatorweed and native plants during the year of application and one year later. Four experimental blocks were established at Eufaula National Wildlife Refuge of Alabama and Georgia on the Chattahoochee River in April 2004. Treatments consisted of herbicides (n = 2), application rates (n = 3), and application dates (n = 3), which were randomly assigned to experimental plots (5m2) within each block. Control plots (n = 6) were randomly assigned to each block at each application date. I estimated plant biomass and species composition by clipping all aboveground plant parts in randomly placed quadrats (0.25m2; n = 2) in experimental plots in October 2004 and October 2005. Percent cover tracked alligatorweed response during the first and second growing season after treatment. Imazapyr controlled alligatorweed more effectively at April application in 2004, but triclopyr resulted in greater native plant biomass and native plant seed biomass than imazapyr. There was no difference between herbicides at July application. High application rates resulted in less alligatorweed biomass and greater native plant biomass at April application, but there was no difference between rates at July application. Alligatorweed and native plant biomass did not differ between triclopyr and imazapyr in October 2005, but September application resulted in less alligatorweed biomass than April or July. One year after treatment, plots treated with high rates contained less alligatorweed biomass than plots treated with low rates.