One of the most common problems associated with much of the acreage that makes up the public open space trust for McHenry County is invasive species infestations. These species can be herbaceous weeds (Canada thistle), trees and shrubs (oriental bittersweet, European buckthorn) or animals (zebra mussels, gypsy moth), which all share a common history and result in many of the same ecological consequences.
These species can reproduce and spread at phenomenal rates, often crowding out native species that must not only compete with the exotic invader, but also with its own natural insect and predator controls. As the overall health of native communities such as woodlands and prairies declines with invasive species invasions, other problems can become exacerbated. For example, healthy woods may be able to withstand an outbreak of gypsy moth infestation if they were not already weakened by invasive species problems. Native mussels that strain detritus from streams for food may find themselves covered with so many zebra mussels that they can no longer sustain themselves.
Every acre of land that is not in agricultural production receives a comprehensive baseline inventory of a number of these species groups in the first full growing season after its purchase by the Conservation District. This alerts district biologists to any endangered or threatened species on the site, allows a grading of its ecological health (A through E) and identifies any immediate environmental problems such as soil erosion, gypsy moth infestations etc
Brush cutting projects, especially those on a large scale can be shocking when first viewed especially if a site user is used to a certain appearance at an area and has grown familiar with it over time. Brush clearing can all more sunlight to reach the ground level native plant species. Butterflies and songbirds will often return to the area after it has been cleared. The Ph and chemistry of a soil can be restored to normal and support growth of more native species.