exotic weed establishment and movement through landscape corridors. what are we doing about it? john...
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Exotic Weed Establishment and Movement Through Landscape Corridors. What are we doing about it?
John Rademacher
Hierarchy Weed Classification
Weed
Native Exotic
Non Invasive Invasive
Non Noxious Noxious
Federal State
Exotic Weed Establishment within Road and Trail Corridors
Average viable seeds found on the undercarriage of United Kingdom vehicles (Hodkinson et al 1997)
Ave
rage
via
ble
see
ds p
er c
ar
0
0. 5
1
1. 5
2
2. 5
Oct. 1994 J une. 1995
Exotic Weed Establishment within Road and Trail Corridors
Seeds are able to survive livestock digestion.
On average it takes 2-3 days to completely digest forage.
Cattle can walk up to 14km per day.
Viability of seeds prior to digestion depends on species.
In forested landscapes livestock use road systems as primary travel paths and foraging areas.
Exotic Weed Establishment within Road and Trail Corridors
Historically invasive grass species were used to stabilize road sides especially on highly stressed or disturbed landscapes.
Invasive grass species have been used to increase wildlife forage, hay and residential landscaping.
Seed viability
Beal (started in 1879, 1st published in 1911), Michigan State University buried seed of 21 common plant species.
1920, 8 species germinated
1940, 3 species germinated
1980, 2 species germinated
Info Source: David Priestley's book on Seed Aging (Comstock Publishers, Cornell Univ. Press), published in 1986.
Viable common lambsquarters found in archeological sites, 1700 years old.
How patch vegetation effects weed movement
Exotic species richness across an area of road influence ARI for three road corridors (Tyser et al 1992)E
xotic species richnessDistance from road (m)
0
0.5
1
1.5
2
2.5
0 10 20 30 40 50 60 70 80 90 100
P r imar y r oad
Secondar y r oad
T r ai l
How patch vegetation effects weed movement
Exotic species richness across an area of road influence ARI for two closed canopy patch types (Watkins et al 2003)
Exotic species richness
Distance from road (m)
0
0.5
1
1.5
2
2.5
0 5 10 15 20
How patch vegetation effects weed movement
Closed canopy forest controls perpendicular spread.
Open canopy forest allows perpendicular and parallel spread.
Potential weed habitat extends 15m into every closed canopy forested patch touching the clear cut
Landscape Weed Management
Eradicate – Remove all individuals (newly established weed species, small population or high economic damage)
Contain – Stop the spread (medium sized population and large populations close to sensitive habitat)
Control – Slow the spread (large populations)
Eradication Control
Contain
Time
Invader abundance
Phases of noxious weed invasion. Ease of treatment declines from left to right (Hobbs et al 1995)
Landscape Weed Management
Nez perce National Forest, Clearwater Ranger District
Noxious weed control and prevention
Weed free hay and straw (quarantine livestock for 3 days)
Herbicide application
Biological control
Mechanical control
Try to leave at least a 15 meter closed canopy buffer around forested roads
Reduce road densities in susceptible areas
Questions?