Nonnative Species

Biocontrolled Site

Left image
A 1997 Biocontrol site. Image of grass and wooded area with yellow invasive plants.
Credit: KNRI Staff

Right image
Same site in 2002. Image of same wooded and grass area without the yellow invasive plants.
Credit: KNRI Staff

A comparison of a biocontrolled site from 1997 to 2002.

 

The Exotic Plant Control Program

For several years the park has undergone an exotic plant control program, which includes the use of herbicides on species such as Leafy Spurge and Canada Thistle.

Due to the efforts of the staff, many of these encroaching flora have been set back to manageable zones. Leafy Spurge for example, has been treated with traditional herbicides, biocontrol, and even prescribed fire. Biocontrol techniques using a species of Flea beetles has shown great promise in the past and is at a stage within the park where future control plot should start expanding at a tremendous rate.

The Setbacks

Although the park is making good advances toward controlling the exotic plants in the park, due to the proximity of the two rivers it is unlikely that the total control of some exotic plants will ever occur.

Smooth brome grass is perhaps the largest problem. The ability of the grass to choke out all other native competition has been a constant dilemma at the park. Any areas in the forest that have an open canopy are encroached by smooth brome, and this encroachment prevents forest and grassland successions from occurring.

The Strategies

Different strategies are being used at this time to combat this problem: primarily prescribed burns. These controlled fires target the exotic flora during the periods when the plants are most susceptible.

 

A 1997 Biocontrol site. Image of grass and wooded area with yellow invasive plants.

NPS Photo

 

Same site in 2002. Image of same wooded and grass area without the yellow invasive plants.

NPS Photo