Grazing Disturbance, Plant Species Interactions and Exotic Invasion in Central Florida Agricultural Wetlands

EPA Grant Number: F6F11250
Title: Grazing Disturbance, Plant Species Interactions and Exotic Invasion in Central Florida Agricultural Wetlands
Investigators: Boughton, Elizabeth A.
Institution: University of Central Florida
EPA Project Officer: Hahn, Intaek
Project Period: August 21, 2006 through August 21, 2009
Project Amount: $95,803
RFA: STAR Graduate Fellowships (2006) RFA Text |  Recipients Lists
Research Category: Academic Fellowships , Ecological Indicators/Assessment/Restoration , Fellowship - Plant Ecology


A fundamental ecological problem in the proliferation of exotic species is determining which factors promote invasions. The objective of this research is to examine two factors that may interact to promote exotic invasion in wetlands; cattle grazing and plant facilitation.

I hypothesize that disturbance by cattle grazing coupled with facilitation by a native dominant species, Soft Rush (Juncus effusus), promotes the successful invasion of the exotic, Alligatorweed (Alternantha philoxeroides) and the exotic Torpedo Grass (Panicum repens). Soft Rush is an unpalatable species and plants that are near Soft Rush may be protected from grazing, thus Soft Rush may facilitate invasion of exotic species. I will also examine the response of two native species, Buttonweed (Diodia virginiana) and Maidencane (Panicum hemitomum), to grazing and Soft Rush interactions.


The experiment will take place on a cattle ranch within two different pasture-types. “Improved” pastures are converted to exotic forage grass, fertilized, with intense grazing management and “semi-native” pastures are unconverted and unfertilized with less intense grazing. Experimental subplots will be set up within an array of wetlands in each pasture-type and treatments will include a factorial design with three factors: Grazing, Soft Rush, and Clipping. Two transplants of each of the four study species will be added to each subplot and plant survival and demography will be followed for two years concluding with biomass measurements.

Expected Results:

I predict that exotic species will be more successful in subplots with grazing and Soft Rush as compared to subplots with grazing and no Soft Rush. I expect native species to have a neutral or negative response to Soft Rush interactions under grazing conditions. Exotic invasion success should be higher in the more disturbed “improved” pastures compared to the “semi-native” pastures. This project will provide information for managing wetlands dominated by native species and will benefit both agricultural and conservation interests.

Supplemental Keywords:

Exotic invasions, wetland, plant interactions, facilitation, competition, wetland restoration, cattle ranching, grazing, eutrophication, land use, agriculture, Juncus effusus, Panicum repens, Alternantha philoxeroides, Panicum hemitomum, Diodia virginiana,, Scientific Discipline, Ecosystem Protection/Environmental Exposure & Risk, Habitat, Environmental Monitoring, Ecology and Ecosystems, habitat dynamics, plant conservation, diversity of species, grasslands, invasive plant species, plant diversity, wetland habitat, ecological consequences

Progress and Final Reports:

  • 2007
  • 2008
  • Final