Optimal management and productivity of Eucalyptus grandis on former phosphate mined and citrus lands in central and southern Florida: influence of genetics and spacing.
Eucalyptus short rotation woody crops (SRWC) with superior genotypes are promising in central and south Florida due to their fast growth, freeze resilience, coppicing ability, and site tolerance. Four Eucalyptus grandis cultivars, E.nergyTM G1, G2, G3, and/or G5, were established in 2009 at varying planting densities on a reclaimed clay settling area (CSA) in phosphate mined land in central Florida and a bedded former citrus site in southern Florida. Planting densities were 1025, 2050, and 3416 trees/acre on the CSA, and 581, 869, 1162, 1452, and 1742 trees/acre on the citrus site. Modified land expectation values (LEV) for coppicing species are reported for G2, G3, and/or G5 SRWCs on CSAs and citrus land. Optimal coppice stage and cycle lengths to the nearest 1/10th year were estimated for each cultivar × spacing × land scenario, assuming a range of coppice yields, cultural treatments (weed control and fertilization), plantation establishment and maintenance costs, stumpage prices, and real discount rates of 6, 8, and 10 percent. For example, at a 10 percent discount rate, stumpage price of $14 green/ton, costs of $250, 50, 974, 55, 90, and 10/acre for land preparation, bedding, planting, pre- and post-establishment weeding, fertilization, and annual management, respectively, and expected coppice yields, the LEV of CSAs under G3 at 1025 trees/acre was $561/acre or an equal annual equivalent of ∼$56/acre/year. Currently, Eucalyptus is primarily harvested for landscape mulch, but markets are likely to expand into bioenergy and pulpwood applications.