These invasive trees are a significant concern in Colorado.
In Colorado, several tree species are considered invasive because they spread aggressively, out-compete native plants, and disrupt local ecosystems. These invasive trees are a significant concern in Colorado because they can displace native species, reduce biodiversity, and alter natural ecosystems.
Active management, including removal and replacement with native or non-invasive alternatives, is key to mitigating their impact.
1. Russian Olive
Other trees (and shrubs) to avoid include Ash, Austrees, Black Walnut, Silver Maple, Cottonwood, Shrub Honeysuckle, Japanese barberry, Burning bush, Common buckthorn.
Active management, including removal and replacement with native or non-invasive alternatives, is key to mitigating their impact.
1. Russian Olive
- Description: A thorny, gray-green tree that produces small, silvery leaves and yellow flowers, followed by olive-like fruits.
- Impact: Russian olive trees are highly invasive in riparian areas (near rivers and streams), where they out-compete native plants like cottonwoods and willows. They consume large amounts of water and can change the composition of ecosystems, reducing biodiversity.
- Control: Colorado has banned the sale and planting of Russian olive, and active removal efforts are in place.
- Description: A fast-growing tree with large, compound leaves and clusters of yellowish flowers that produce abundant seeds. Known for its unpleasant odor when crushed.
- Impact: This tree spreads aggressively through seed production and root suckers. It can invade urban areas, roadsides, and open spaces, out-competing native species. Its root system can damage infrastructure, and it releases chemicals that inhibit the growth of other plants.
- Control: Removing young trees by hand or cutting mature trees and treating stumps with herbicides helps control its spread.
- Description: A hardy tree with small, serrated leaves and a rounded crown. It produces vast amounts of seeds, contributing to its invasiveness.
- Impact: Siberian elm is drought-tolerant and spreads rapidly, especially in disturbed soils, such as along roadsides and in urban areas. It can form dense thickets, displacing native vegetation and altering habitats.
- Control: Manual removal and herbicides can help control Siberian elm, though its prolific seed production makes management challenging.
- Description: A shrubby tree with feathery, needle-like leaves and small pink or white flowers. Saltcedar is particularly common in riparian zones.
- Impact: Saltcedar is a notorious water hog, consuming large amounts of water in arid environments. It also deposits salt into the soil, making it inhospitable for native plants. Its spread can lead to reduced water availability and the degradation of habitats.
- Control: Saltcedar removal is labor-intensive and often involves mechanical removal combined with herbicide treatments.
Other trees (and shrubs) to avoid include Ash, Austrees, Black Walnut, Silver Maple, Cottonwood, Shrub Honeysuckle, Japanese barberry, Burning bush, Common buckthorn.
Fast growing with invasive roots systems or ability to send seeds far and wide are on the do not plant list for Colorado homeowners.