Abstract of Dissertation Presented to the Graduate School
of the University of Florida in Partial Fulfillment of the
Requirements for the Degree of Doctor of Philosophy

ECONOMIC AND ENVIRONMENTAL ANALYSIS OF TREE CROPS ON MARGINAL LANDS IN FLORIDA

 

By

Matthew Langholtz

December 2005

Chair:  Donald L. Rockwood

Major Department:  Forest Resources and Conservation

Tree crops can be used to remove contaminants from reclaimed wastewater, restore ecological functions of phosphate and titanium mined lands and to provide renewable energy in Florida.  The economic feasibility of these potential tree crop systems, the value of environmental services they provide and opportunities to make up the current difference between minimum feasible and current market prices are investigated. 

Profitability measured as land expectation value (LEV) of 128 scenarios of Eucalyptus grandis cropping irrigated with reclaimed wastewater ranged from -$2,343 to +$2,762 ha-1 and was greatly reduced by high interest rates, high irrigation costs, and low yields.  Each $1 kg-1 N increment in a dendroremediation incentive increases profit by $223-$376 ha-1, depending on interest rate and site productivity.  Optimum management requires harvests every 2.6 to 4.0 years and replanting after two or three harvests, though the optimum number of stages per cycle would increase with improved coppice growth. 

LEVs of Eucalyptus amplifolia cropping on phosphate-mined lands in central Florida ranged from $762 to $6,507 ha-1 assuming interest rates of 10% and 4%, respectively, establishment costs of $1,800 ha-1, planting costs of $1,200 ha-1, high yields, and a stumpage price of $20 dry Mg-1, excluding CO2 mitigation incentives.  Incorporating CO2 mitigation incentives increased LEV, particularly when incentives recognize the CO2 emissions reduced by biofuels use.  Optimum management necessitates harvests every 2.5 to 3.5 years and replanting after two or five harvests.

Average LEVs of slash pine (Pinus elliottii) stands established on titanium mined lands varied widely with productivity, but on average were profitable and similar to those of unmined lands.  Optimum management is comparable to that of conventional slash pine culture in northeast Florida.  Early-rotation responses to soil amendments suggest that growth and survival can be improved by fertilizer and subsoil treatments, respectively.  Plantation establishment costs including soil amendment as high as $423 to $878 ha-1 ($171 to $355 acre-1) are economically viable depending on growth response.