95th ESA Annual Meeting (August 1 -- 6, 2010)

OOS 56-3 - Disturbance facilitates a secondary spread of invasive plant species:  Management concerns for emerald ash borer infested forests

Friday, August 6, 2010: 8:40 AM
317-318, David L Lawrence Convention Center
Constance Hausman, Division of Natural Resources, Cleveland Metroparks, Fairview Park, OH, John F. Jaeger, Metropolitan Park District of the Toledo Area, OH and Oscar J. Rocha, Department of Biological Sciences, Kent State University, Kent, OH

When the emerald ash borer was first identified in 2002, eradication efforts were implemented to control the beetles spread.  Preliminary research of the eradication program impacts included accelerated canopy gap formation with greater light reaching the forest floor and significant soil compaction caused by the tracked-vehicles. The subsequent shift in community composition that occurred was attributed to the establishment of invasive plants. Therefore, proper tree removal methods need to minimize compounding effects that adversely affect native plant communities.  Our objectives: 1.) create various disturbance intensities with corresponding habitat changes 2.) determine invasive plant establishment patterns across our disturbance gradient  3.)  propose land management practices to minimize the likelihood of invasive plant establishment.  This project compares high disturbance areas with all ash trees removed using tracked-vehicles (Cut plots), to moderately disturbed areas with ash trees removed by hand using chainsaws (Cut w/out compaction), to “undisturbed” areas with ash trees still standing (Uncut plots).  Eighteen 20mx25m plots (6 per treatment) were established within Pearson Metropark Lucas County, Ohio.  The light environment was assessed using hemispherical photos and soil compaction was measured using a soil penetrometer.  The herbaceous understory was determined using % cover of all species present from 7-1m2 subplots within each plot.  All measurements were collected annually for 3 years. 


Immediately following the application of a disturbance treatment, the light environment in the Cut w/out treatment was comparable to the light environment in the Cut treatment.  Soil compaction was only significant in the Cut treatment compared to the Uncut and Cut w/out treatment with no difference detected between the Uncut and Cut w/out treatment.  The understory plant community remained similar over the three year study in both the Uncut control plots and the Cut w/out compaction plots.  There was no difference in species richness or diversity within either treatment over time (P=0.27).  The Cut treatment however, nearly doubled the number of species that colonized after the eradication disturbance (4.7 species in Year 1 to 8.8 species in Year 2) (P<0.001).  All of those establishing species are non-native and are persisting 3 years after the disturbance was first performed.  We determined that the use of tracked-vehicles during the eradication protocol facilitated a greater establishment of invasive plant species.  Ash tree removal should consider the technique necessary to be effective, the impact that technique will have on the future native plant understory and the proximity of the area to potential invasive seed sources.