Many of the trees and shrubs in High Park are still green! By November most native tree leaves have changed colour and fallen, but plenty of non-native trees are still green and photosynthesizing. This “autumn niche” is a huge advantage for the non-native species because they are still able to grow just as the canopy opens up and more sunlight is available. Up to 20% of a tree’s annual carbon gain can come in this slim window of time (Fridley 2012). This longer growing season is one of the many ways that non-native plants are able to out-compete the native species. City of Toronto, High Park Stewards and Nature Centre participants work hard to manage invasive trees while bolstering native plant populations.