Abstract Detail



Ecology

Huebner, Cynthia [1].

Estimating Spread Rates of Invasive Plants within Disturbed and Undisturbed Forests in Different Land Types.

Invasion by nonnative plants is more likely to occur in response to a disturbance, but we also know that undisturbed forests are not immune to invasion.  Though rates of spread for a few individual plants have been estimated, the spread rates of nonnative invasive species (NNIS) within disturbed vs. undisturbed forests have not been estimated.  Such rates are likely to vary across different land types and under different landscape mosaics.    
Twenty-three 80+ year old forest stands and 15 clear-cut stands within the Monongahela National Forest, WV were surveyed for invasive plants from 2001-2018 every five-to-six years.  These stands were selected from three different ecological land types.  Stands (3-10 ha) had one 500-m2 plot located approximately every 20 m, and each plot with four 1-m2 subplots.  Frequency of plots and subplots with NNIS was determined each year.   Percent cover of all understory plants was determined in the subplots and total NNIS cover estimated for each plot.  In 2011, three of the clear-cut stands had a crop-tree release.
The 80+ stands had 7.8 m2 of NNIS cover per plot, with NNIS in 31% of the plots, and a spread rate of 0.49 m2/yr.   The 12 clear-cuts without the crop-tree release had 34.2 m2 of NNIS cover per plot, with NNIS in 60% of the plots, and a spread rate of 2.14 m2/yr. The most mesic land type of the 80+ stands had the highest cover, frequency, and rate of invasion, while the moderately-mesic clear-cuts showed the highest levels of invasion.  Stands in the moderately-mesic land type were nearest to open/non-forested land as well as paved roads for both the 80+ and clear-cut stands.  The three clear-cuts with the additional crop-tree release harvest had 149.0 m2 of NNIS, with NNIS in 77% plots, and a spread rate of 27.4 m2/yr.  Subplots with NNIS in the 80+ stands showed no change in native species cover between 2001 and 2017, while 34% of the plots in the clear-cuts, most in the least-mesic land type, showed a decrease in native species cover with the remaining plots showing an increase in native species abundance associated with increasing NNIS. 
Thus, harvested sites show spread rates that are as much as five times those of undisturbed forests, but productive land types may respond to a harvest with an increase in native species as well as NNIS.


1 - USDA Forest Service, 1514 Westbrook Dr, Morgantown, WV, 26508, United States

Keywords:
Invase plant species
Spread rates
Forest management.

Presentation Type: Oral Paper
Number: 0006
Abstract ID:171
Candidate for Awards:None


Copyright © 2000-2019, Botanical Society of America. All rights reserved