Document: BET-3-40-52

Ranking the components of ecological resistance to biological invaders in a southeastern riparian forest.

VON HOLLE, B.* and D.SIMBERLOFF

University of Tennessee, Knoxville, TN 37996-1610 USA ¹

Abstract:
Biotic resistance to plant invaders is explored by manipulating diversities among understory (< 1m) riparian plant communities. Diversities were manipulated by eliminating or decreasing the number of species of functional groups from plots. Our functional groups are defined in accordance to their response to the environmental disturbance of flooding. Our functional groups are thus made up of the variations of all possible combinations of above-ground biomass and rooting structure type. Our functional groups are: small above-ground biomass, branching and rhizomatous root structure (SB); small-above-ground biomass, taproot (ST); large above-ground biomass, branching root structure (LB); and large above-ground biomass with a taproot (LT). Success of an invasion is measured by its above- and below-ground biomass. Our proxy measure for total biomass is stem diameter. Stem diameter in plants of Big Stony Creek is highly correlated with total biomass. These 1.5 by 1.5 m plots were planted with adult plants of 10 randomly chosen species from widespread native and introduced species commonly found throughout the floodplains of Big Stony Creek. Each plot was censused and stem diameter and condition of each invader recorded 2 weeks after planting. We analyzed survivorship of functional groups with loglinear models for the analysis of categorical data in a 4-way table. There was a significant interaction between functional group removed in the plot and survivorship of the functional groups added to those plots. Specifically, the survivorship of the SB and ST functional groups were significantly related to the functional groups removed.

Keywords: invasion, resistance, riparian plants

This abstract is being presented at: 10:30 AM in session:
RESTORATION ECOLOGY AND INVASIONS