SREL Reprint
#2564
INFLUENCE
OF A WILLOW CANOPY ON TREE SEEDLING ESTABLISHMENT FOR WETLAND RESTORATION
Kenneth
W. McLeod,1 Michael R. Reed,1 and Eric A.
Nelson2
1Savannah River Ecology Laboratory, University
of Georgia, P. 0. Drawer E Aiken, South Carolina, USA 29802 and
2Savannah River Technology Center, Westinghouse Savannah
River Company, Aiken, South Carolina, USA 29802
Abstract: Black willow (Salix nigra) is a well-known
pioneer species of disturbed riparian areas. It competes for nutrients,
light, and water, but it may also act as a "nurse" crop,
providing shelter for other species from high light and temperature;
so, the overall effect on species planted under a willow canopy
could be positive or negative. This experiment examined the response
of container-grown seedlings of four tree species outplanted into
three habitats: 1) an existing willow stand, 2) a similar habitat,
but with the willow canopy removed, and 3) an adjacent grass-dominated
area free of willow. After three years, survival rates of overcup
oak (Quercus lyrata), baldcypress (Taxodium distichum),
and water hickory (Carya aquatica) were not reduced under
the willow canopy relative to the other two treatments. Laurel oak
(Q. laurifolia) was killed by several floods during the first
growing season. Height of baldcypress seedlings planted under a
willow canopy was less than for seedlings where the willow had been
removed. Water hickory and overcup oak height were not affected
by the willow canopy. Elevation of the planting sites, indicating
probable soil wetness, was a good indicator of survival when used
in conjunction with the species flood-tolerance. The existing willow
stand was not detrimental to survival of three of the outplanted
tree species. Thus, willow removal is unnecessary for successful
outplanting, saving time and money.
Key Words: restoration,
reforestation, competition, black willow, bottomland hardwood, southeastern
United States
SREL Reprint #2564