Family: Salicaceae

Origin, Description & Uses
Populus tremuloides, commonly known as quaking aspen or trembling aspen, is a fast-growing deciduous tree native to a broad range extending from subarctic regions of North America south into Mexico. It is well known for its smooth pale bark and rounded leaves that flutter or “quake” in even light breezes. Quaking aspen forms dense groves through spreading underground roots and is valued for its striking fall color, wildlife habitat, and ability to quickly colonize disturbed areas. It is sometimes planted as an ornamental shade tree in cooler climates and is also used for pulpwood, furniture components, and ecological restoration projects.

Risks & Threats
Although Populus tremuloides is not currently known to be naturalized in the Hawaiian Islands, it possesses traits that are cause for concern in tropical island ecosystems. Its ability to spread aggressively through root suckers and form dense colonies could allow it to outcompete other vegetation under suitable conditions. Fast growth, prolific vegetative reproduction, and adaptability to disturbed habitats increase its invasive potential if introduced into favorable high-elevation or cooler environments in Hawaii. Dense stands may alter native plant communities, water availability, and habitat structure. Because of these risks, choosing a low risk or native alternative is recommended whenever suitable alternatives are available.

High Risk Traits:

• Broad climate suitability, and elevation range exceeds 1000 m, demonstrating environmental versatility
  
• Possibly naturalized (confirmation needed)
  
• Disturbance-adapted aggressive tree
  
• Invades and controlled in conifer forests
  
• Other Populus species have become invasive
  
• Tolerates many soil types
  
• Forms dense stands within native range
  
• Reproduces sexually (seeds) and asexually (vegetative)
  
• Hybridizes with other Populus species
  
• Reproduces by root suckers and stump sprouts
  
• Able to reproduce by suckers at 1 year and by seed at 2-3 years
  
• Seeds dispersed by wind, water and intentionally by people
  
• Prolific seed production (on a 4-5-year cycle)
  
• Able to resprout after repeated cutting

Low Risk Traits:

• A temperate species which may only be able to grow at higher elevation regions of tropical and subtropical islands
  
• Unarmed (no spines, thorns or burrs)
  
• Provides fodder for livestock
  
• Non-toxic to animals
  
• Ornamental
  
• Shade-intolerant
  
• Dioecious
  
• Seeds rapidly lose viability
  
• Herbicides may provide effective control