Invasive Trees and Shrubs

Invasive plants are typically non-native species that, when introduced, reduce abundance and diversity of native plants communities. This can cause loss of habitat and food sources for wildlife, lower biodiversity, reduced groundwater levels, and other negative impacts. Invasive plant species are a widespread threat to ecosystems across the world. The more area taken up by invasive trees and shrubs, the greater their threat to the ecosystem overall.

Invasive Russian Olives, by Paul Tashjian.

How is it measured?

The percent of area taken up by invasive plants was compared to that taken up by non-invasive plants. This percent area was re-scaled so that 0-10% cover by invasive plants results in an A score, 10-20% cover by invasives a B+, 20-30% a B, 30-50% a C, 50-75% cover by invasive plants a D, and 75-100% a failing score of F.