Influence of a willow canopy on tree seedling establishment for wetland restoration

Black willow (Salix nigra) is a well-known pioneer species of disturbed rip arian areas. It competes for nutrients, light, and water, but it may also a ct as a "nurse" crop, providing shelter for other species from high light a nd temperature; so, the overall effect on species planted under a willow ca nopy could be positive or negative. This experiment examined the response o f container-grown seedlings of four tree species outplanted into three habi tats: 1) an existing willow stand, 2) a similar habitat, but with the willo w canopy removed, and 3) an adjacent grass-dominated area free of willow. A fter three years, survival rates of overcup oak (Quercus lyrata), baldcypre ss (Taxodium distichum), and water hickory (Carya aquatica) were not reduce d under the willow canopy relative to the other two treatments. Laurel oak (Q. laurifolia) was killed by several floods during the first growing seaso n. Height of baldcypress seedlings planted under a willow canopy was less t han for seedlings where the willow had been removed. Water hickory and over cup oak height were not affected by the willow canopy. Elevation of the pla nting sites, indicating probable soil wetness, was a good indicator of surv ival when used in conjunction with the species flood-tolerance. The existin g willow stand was not detrimental to survival of three of the outplanted t ree species. Thus, willow removal is unnecessary for successful outplanting , saving time and money.