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Tree Tips

March/April 2015

Representatives of Conserve Lake County reported the following information from a recent Urban Tree Conference at the Morton Arboretum:

  • Oaks remain the kings of trees, as they should, given that oak species support, for example, over 450 species of butterflies and moths, whereas non-native gingkoes support just three. With over a dozen native oak species to choose from, they provide diversity, too. Given that Lake County has lost 88% of its historic oak ecosystems, anything that promotes oaks is good.
  • The debilitating practice of volcano mulching around a tree is an oddly Midwestern practice. Mulch should be spread evenly 2 - 3 inches deep in a circle that reaches as wide as the outermost branch tips. Mulch should not touch the trunk or it might lead to disease.
  • Those guys at ComEd actually don’t enjoy carving our trees into misshapen freaks. It’s just that whoever planted those trees long ago forgot that little trees grow into big trees and it’s not safe to have live electrical wires snapping about here and there.
  • Invasive buckthorn is well-documented as harmful to songbirds, frogs and other forms of wildlife - but it’s Lake County’s most common tree. Forty-one percent of our trees are buckthorn and we have the highest percentage within the Chicago region. Our next most common tree? Ash.
  • All 13 million of the region’s ash trees are expected to die this decade. About 10% of Lake County’s trees are either green or white ash, every one of them vulnerable to the emerald ash borer that is chewing its way across the land.
  • To save money and extend the life of a tree, you must prune it correctly when it’s young. It’s stunning to learn the number of things that, easily fixed on young trees, turn into expensive problems on big trees.

Conserve Lake County (formerly Liberty Prairie Conservancy), is a 501 (c)(3) non-profit organization founded in 1995. Its mission is to preserve open land, restore natural areas and inspire commitment to land conservation for the benefit of people and wildlife in Lake County, Illinois. Check out its website at to use its resources and free on-site advice about native, eco-friendly landscapes, and to participate in the Conservation@Home program.

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