Growth of three hardwood species through 18 years on a former agricultural bottomland.

The effects of seed source, fertilization, disking, and mowing on the growth of sweetgum (Liquidambar styraciflua L.), American sycamore (Platanus occidentalis L.), and green ash (Fraxinus pennsylvanica Marsh.) were examined 18 yr after planting to determine the best system for afforestation of a previously farmed bottomland site in southwest Tennessee. Natural regeneration on the site as well as variations in soil bulk density and soil series were analyzed. Overall survival was significantly higher for sweetgum (93%) and green ash (95%) than for sycamore (88%). Height growth of sweetgum was significantly greater than that of sycamore, which was significantly greater than that of green ash. Sycamore and sweetgum of Virginia Coastal Plain origin did not differ from those of Louisiana Gulf Coast origin in growth or survival. Height and dbh of all three species were significantly increased by fertilization only on plots that were not also disked or mowed. Disking and mowing significantly increased the growth of unfertilized trees more than tkat of fertilized trees. Natural regeneration resulted in dense stands (3,445 trees/ac) dominated by sweetgum. ? he combination of fertilization and mowing significantly increased soil bulk density. Soils on the study site were more variable than previous county soil surveys indicated. South. J. Appl. For. 24(3):159-165.