Olympic Habitat Development Study
US FOREST SERVICE

 

Station 6 - Non-native plants

Although non-native plants are present in many forested stands on the Olympic Peninsula, there were none at Fresca when the study started and none became established in either of the control area or in the skip (unthinned portion) of the variable-density thinned stand. 5 species of non-native plants (all herbaceous species associated with open habitats) were found at sometime in the VDT (variable-density thinning) plots - 4 in the gaps and 2 in the thinned area (1 species was in both the gaps and thinned areas).

The non-native species found were:

Common name
Scientific name
Found in


common foxglove
wall-lettuce
wood groundsel
germander speedwell
hairy cat's-ear
Digitalis purpurea
Mycelis muralis
Senecio sylvaticus
Veronica chamaedrys
Hypochaeris radicata
gaps
gaps and thinned matrix
gaps
gaps
thinned matrix


These species were only found in very small quantities (0.3% cover was the maximum recorded - for foxglove in gaps in year 7) and by year 10 only 2 species still remained, both at very low covers and both in gaps (foxglove at 0.1% cover and wall lettuce at <0.1%). We anticipate that these species will disappear or only be present at extremely low levels in the future as they are generally only found in open areas rather than in closed forests.


 

Hairy cats-ear (Hypochaeris radicata) is a widespread non-native plant. Although very similar to a dandelion, it is differentiated by having forked stems, pubescent leaves, and the lobes in the leaves do not turn backward. (Image from www.weedalogue.com)
The wood groundsel (woodland ragwort) develops quickly in open or disturbed areas but did not persist in our VDT areas. (Image from www.wikipedia.org) Hairy cats-ear (Hypochaeris radicata) is a widespread non-native plant. Although very similar to a dandelion, it is differentiated by having forked stems, pubescent leaves, and the lobes in the leaves do not turn backward. (Image from www.weedalogue.com) Common foxglove (Digitalis purpurea) was introduced into gardens for its showy flowers; however, the abundant seed production of this poisonous plant allows it to spread widely.
Hairy cats-ear (Hypochaeris radicata ) is a widespread non-native plant.
Although very similar to a dandelion, it is differentiated by having forked stems, pubescent leaves, and the lobes in the leaves do not turn backward.
(Image from www.weedalogue.com)