Skaneateles Conservation Area/Invasive species/Robinia

Robinia pseudoacacia (black locust)
Of the four currently accepted locust (Robinia) species, all are native to North America but none are considered to be native north of Pennsylvania. The locust species that are most likely to be found in the wild in Onondaga County are:


 * Robinia pseudoacacia (black locust), a potentially large tree, which is considered very highly invasive and is common at the SCA;
 * Robinia hispida (brislty locust), which could be somewhat invasive but has not been reported as naturalized in Onondaga County;
 * Robinia viscosa (clammy locust), a shrub or small tree, which is present in the county, but not listed as invasive.

Black locust is native to the lower slopes of the Appalachian Mountains the southeastern United states, with outlying native populations along the slopes and forest edges of southern Illinois, Indiana, and Missouri.

Invasiveness ranking for Robinia pseudoacacia (black locust)
The 2009 invasiveness ranking score was 73/90 = 81.11% (Very High).

Regulated by New York State law.

1. Ecological impact
1.1. Major, possibly irreversible, alteration or disruption of ecosystem processes (10/10)


 * Black locust is a nitrogen-fixing species and can facilitate the invasion of other non-native plants by increasing nitrogen in the soil.


 * Elevated soil ammonium levels have been found to continue for many years after the locust trees are removed.


 * Areas where black locust has been removed (usually with black cherry in the overstory) continue to have higher non-native species richness than native pine-oak stands in the same area.


 * Where black locust has shaded out the ground layer vegetation, fire regimes may have been altered.

1.2. Major alteration of natural community structure (10/10)


 * Shade and soil chemistry changes caused by dense stands of black locust can both increase non-native plant density and decrease native plant density below.


 * In grasslands, black locust can create a dense new tree layer, shading out most of the vegetation below it.

1.3. Major alteration of natural community composition (10/10)


 * Stands of black locust have been shown to reduce native plants through shading and soil chemistry alterations.

1.4. Unknown impact on other species or species groups (U)


 * Studies in other parts of the country have shown decreased in insect communities, but no studies in NY as of 2009.


 * Native species exclusion has been documented in the Northeast.

4. Difficulty of control
4.1. Seeds or vegetative propagules remain viable in soil for at least 1 to 10 years (2/3)


 * Seeds viable for over one year in soil but no evidence for viability over ten years.

4.2. Regrowth from extensive underground system (2/3)


 * Regrowth through ground level meristem and root suckering.

4.3. Management requires a major investment (4/4)


 * Removal of large trees requires major investment in time


 * Plant "killed" by herbicide can continue to resprout several years after treatments.