Climate-forward trees and shrubs for Colorado urban forests
The Problem
Urban landscapes in Colorado are changing rapidly owing to climate-driven stresses and recent increases in endemic threats (e.g., Ips beetles) and invasive pests (e.g., emerald ash borer). Notably, both abiotic and biotic threats to urban landscapes are inherently linked, whereby trees and shrubs weakened by drought and heat stress are more susceptible to pest attack, and conversely, pest infestations compromise plant’s ability to respond to abiotic stress. Further, the recent invasion of emerald ash borer in Colorado is likely to result in mass removal of one of the focal urban trees in the state – ash, and thus provides an opportunity to address the issue of urban monocultures and promote diversifying urban landscapes. This problem of recurring monoculture plantings is not unique to Colorado, however, and is a common feature of most urban forests in the U.S., further weakening its long-term health and sustainability. The current approaches to urban landscape design are largely based on nursery inventory of trees and shrubs, and do not prioritize diversification of the landscape or include research-based data on adaptability of these varieties to abiotic stresses that continue to arise due to climate changes.
Solutions
We need to create research-based predictions for trees and shrubs that are likely to be adapted to our future climate, validate their resilience to the extremes common in our environment and biotic stresses (pests and diseases), and promote production of these plants among nursery producers. A cohesive and highly visible outreach campaign to promote climate-forward plants among homeowners and municipalities is needed to facilitate widespread installation of these trees and shrubs and diversifying urban landscapes. Stay tuned for more!
