Response of three hardwood species to irrigation and fertilization on an upland site

Increased pressure for hardwood fiber has renewed interest in intensive culture of hardwoods, including irrigation and fertilization. The response of sweetgum (Liquidambar styraciflua L.), sycamore (Platanus occidentalis L.), and eastern cottonwood (Populus deltoides Batr. ex. Marsh.), to two irrigation and two fertilizer regimes was assessed in the upper Coastal Plain of Alabama. Total height, groundline diameter, and/or dbh (depending on height) were recorded on individual seedlings (sweetgum and sycamore) and planted cuttings (eastern cottonwood) for four growing seasons. Eastern cottonwood had significantly lower survival than either of the other two species. Fertilization significantly increased height and dbh for sycamore and sweetgum, while irrigation increased height and dbh of sycamore and eastern cottonwood. Fertilization and irrigation decreased moisture stress to similar extents. After four growing seasons, sycamore responded best across all treatment combinations when growth and survival were considered simultaneously