Siberian elm (Ulmus pumila)
is a locally, widespread tree common to the southwestern US. It is a mid-size tree that can reach 70 feet tall.
At Watson Woods Riparian Preserve this tree out-competes native cottonwoods, willows, ash, boxelder, and walnuts to the extent that Prescott Creeks has listed it as a Priority 1 species on its High-Priority Noxious Weed List.
A high density of Siberian elm, which easily occurs within the moist environments of the Preserve, can reduce shade-intolerant species (including quality forage) and decrease overall species diversity. The tree can reproduce from seed (which set earlier in the season than most natives) and root sprouts when its canopy is damaged.
Siberian elm is difficult to control once infestations occur. Early detection and long-term planning and implementation of treatments provide the best results.