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Publication #CIR 1516

Assessing the Economic Feasibility of Short-Rotation Woody Crops in Florida1

Matthew Langholtz, Douglas R. Carter and Donald L. Rockwood2

Plantations of short-rotation woody crops (SRWCs) use fast-growing tree species that coppice, i.e., resprout from the stump, for repeated harvests that minimize planting costs. Under coppice management, 3-5 growth stages (coppices) can be harvested during the SWRC life (rotation or cycle), with each coppice lasting 2-10 years. SRWCs can produce wood for biomass, mulch, pulpwood, and other products, while also providing environmental services. For example, SRWC plantations can be irrigated with municipal wastewater or fertilized with treated biosolids or municipal compost, simultaneously increasing biomass production, reducing fertilizer costs, and intercepting nitrates and phosphates to reduce nutrient loading in waterways (Rosenqvist et al., 1997; Labrecque et al., 1997; Aronsson & Perttu, 2001; Rockwood et al., 2004; Licht & Isebrands, 2005; Langholtz et al., 2005; Mirck et al., 2005). SRWCs can also help build soil organic matter, recycle nutrients, and maintain vegetative cover to restore ecological functions of mined lands and other degraded lands (Stricker et al., 1993; Bungart & Huttl, 2001; Rockwood et al., 2006). SRWCs established on agricultural lands as shelterbelts or buffer zones to protect riparian areas are likely to reduce soil erosion and runoff of agricultural inputs and improve wildlife habitat (Joslin & Schoenholtz, 1997; Tolbert & Wright, 1998; Thornton et al., 1998). In spite of these benefits, SRWC production is not always economically viable, and evaluating the economics of SRWC production is not easy.

Because SRWCs can have multiple coppices per rotation, evaluating the economics of SRWCs is more complicated than that of conventional forestry. For example, in the evaluation of a pine plantation, the future value of harvested timber is discounted to the year of planting, and planting costs are subtracted to calculate the net present value (NPV) of one harvest rotation. NPV is then used to calculate land expectation value (LEV), i.e. the value of the land assuming the adoption of this forestry practice. However, in the case of SRWC systems, multiple coppices require that the value of every coppice is discounted to the beginning of the rotation. Furthermore, the costs associated with establishment of each rotation and coppice stage must be discounted differently, and determining the optimum harvest scheduling and replanting age is also more complicated than for conventional forestry. Theory behind economic evaluation and optimization of SRWCs is described by Medema & Lyon (1985),Tait (1986), and Smart & Burgess (2000) . Economics of SRWC systems in Florida are evaluated by Langholtz et al. (2005;2007).

The Florida Institute of Phosphate Research (FIPR) has supported research in the development of SRWCs as commercial tree crops on phosphate mined lands in Florida. A product of this research is a SRWC Decision Support System (DSS) that can be used to evaluate the economic viability of SRWC systems. The DSS allows a user to input operational costs, planting densities, stumpage prices and other variables and calculate NPVs, LEV, equal annual equivalent (EAE), internal rate of return (IRR), and benefit/cost ratio of a SRWC system. The DSS is in the form of a Microsoft® Excel spreadsheet (Figure 1).

Figure 1. 

The SRWC Decision Support System spreadsheet.


[Click thumbnail to enlarge.]

The DSS allows users to enter variables in yellow cells in the “Inputs” section on the left side of the worksheet and view results in green cells in the “Outputs” section on the right. Input variables include stumpage price, capital cost, and costs of each start-up, rotation, coppice, and year. The user can specify what portion of total biomass is harvested, the number of coppices, and their harvest ages. Financial incentives for renewable energy or other environmental benefits can be incorporated on a per-ton basis in the stumpage price. The DSS uses growth and yield functions developed from measurements of two planting densities of Eucalyptus amplifolia in a field trial of SRWCs on a phosphate mine clay settling area (CSA) near Lakeland, FL. Yields for each growth stage are displayed, and can be modified by adjusting the initial planting density or by adjusting yields under the general parameters. Ranges of values used to assess SRWC production on CSAs are shown in Table 1.

Under all possible combinations of the assumptions in Table 1, the profitability of E. amplifolia on CSAs varies widely, with LEVs ranging from -$909 to $6,740 acre-1. Under the base case scenario identified in Table 1, the resulting LEV is $308 acre-1 assuming an interest rate of 10% and $2,633 acre-1 assuming an interest rate of 4%. LEV, EAE, and IRR results of the base case scenario under a range of discount rates and stumpage prices are shown in Table 2.

This DSS does not automatically determine optimum harvest ages or the optimum number of stages per cycle, which both require dual optimization of continuous functions. DSS users can either input probable harvest and replanting ages and “zero in” inputs to maximize economic returns, or contact the authors to arrange a customized DSS. The DSS in either Excel or MathCad format could be modified to incorporate alternative growth and yield functions that might be developed for other SRWC species or conditions. For more information see the FIPR report “Commercial Tree Crops for Phosphate Mined Lands”, Rockwood et al. (in press).

Acknowledgements

We acknowledge the assistance of Steve Segrest of the Common Purpose Institute and funding by the Florida Institute of Phosphate Research.

References

Aronsson, P., Perttu, K., 2001. Willow vegetation filters for wastewater treatment and soil remediation combined with biomass production. Forestry Chronicle. 77, 2, pp. 293-299.

Bungart, R., Huttl, R. F., 2001. Production of biomass for energy in post-mining landscapes and nutrient dynamics. Biomass and Bioenergy. 20, 3, pp. 181-187.

Joslin, J.D., Schoenholtz, S. H., 1997. Measuring the environmental effects of converting cropland to short-rotation woody crops: A research approach. Biomass and Bioenergy. 13, 4-5, pp. 301-311.

Labrecque, M., Teodorescu, T. I., Daigle, S., 1997. Biomass productivity and wood energy of Salix species after 2 years growth in SRIC fertilized with wastewater sludge. Biomass and Bioenergy. 12, 6, pp. 409-417.

Langholtz, M., Carter, D., Rockwood, D. L., Alavalapati, J., 2007. The economic feasibility of reclaiming phosphate mined lands with short-rotation woody crops in Florida. Journal of Forest Economics, 12, 237-249.

Langholtz, M., Carter, D. R., Rockwood, D. L., Alavalapati, J. R. R., Green, A., 2005. Effect of dendroremediation incentives on the profitability of short-rotation woody cropping of Eucalyptus grandis. Forest Policy and Economics. 7, 5, pp. 806-817.

Licht, L.A., Isebrands, J. G., 2005. Linking phytoremediated pollutant removal to biomass economic opportunities. Biomass and Bioenergy. 28, 2, pp. 203-218.

Medema, E.L., Lyon, G. W., 1985. The determination of financial rotation ages for coppicing tree species. Forest Science. 31, 2, pp. 398-404.

Mirck, J., Isebrands, J. G., Verwijst, T., Ledin, S., 2005. Development of short-rotation willow coppice systems for environmental purposes in Sweden. Biomass and Bioenergy. 28, 2, pp. 219-228.

Rockwood, D.L., Carter, D., Stricker, J. 2006. Commercial tree crops for phosphate mined lands, final report. Report Number FIPR Project Number: 99-03-141R. Florida Institute of Phosphate Research. Bartow, Florida.

Rockwood, D.L., Naidu, C., Segrest, S., Carter, D., Rahmani, M., Spriggs, T., Lin, C., Alker, G., Isebrands, J. G., 2004. Short-rotation woody crops and phytoremediation: Opportunities for agroforestry? In: Nair,P.K., Rao,M.R., Buck,L.E. (Eds.), New Vistas in Agroforestry, A Compendium for the 1st World Congress of Agroforestry 2004. Kluwer Academic Publishers, Dordrecht, The Netherlands, pp. 51-63.

Rosenqvist, H., Aronsson, P., Hasselgren, K., Perttu, K., 1997. Economics of using municipal wastewater irrigation of willow coppice crops. Biomass and Bioenergy. 12, 1, pp. 1-8.

Smart, J., Burgess, J., 2000. An environmental economic analysis of willow SRC production. Journal of Forest Economics. 6, 3, pp. 193-266.

Stricker, J., Prine, G., Anderson, D. L., Shibles, D. B., Riddle, T. C. 1993. Production and Managment of Biomass/Energy Crops on Phosphatic Clay in Central Florida. Report Number Circular 1084. 1-8. Florida Cooperative Extension Service.

Tait, D., 1986. A dynamic programming solution of financial rotation ages for coppicing tree species. Canadian Journal of Forest Research. 16, pp. 799-801.

Thornton, F.C., Joslin, J. D., Bock, B. R., Houston, A., Green, T. H., Schoenholtz, S., Pettry, D., Tyler, D. D., 1998. Environmental effects of growing woody crops on agricultural land: First year effects on erosion, and water quality. Biomass and Bioenergy. 15, 1, pp. 57-69.

Tolbert, V.R., Wright, L. L., 1998. Environmental enhancement of U.S. biomass crop technologies: research results to date. Biomass and Bioenergy. 15, 1, pp. 93-100.

Table 1. 

Ranges of values used in the DSS to assess SRWCs on a phosphate mine clay settling area.

Input category

Range of DSS Inputs applied for

Start-up costs

$364 - $728* acre -1 ($900 - $1,800 ha -1)

Costs at the beginning of each rotation

$243 - $486* acre -1 ($600 - $1,200 ha -1)

Costs at the beginning of each coppice

$0 - 81 acre -1 ($0* - $200 ha -1)

Discount rate

4%, 7%, and 10%

Stumpage price

$4, $9, and $14 green ton -1 ($10, $20 and $30 dry Mg -1)

Planting density

1,700-3,400* Trees acre -1 (4,200-8,400 Trees ha -1)

Coppice yields

Variable, though likely to decrease about 20%* with each coppice

*Base case scenario.

Table 2. 

DSS calculated land expectation value (LEV, $ acre -1), equal annual equivalent (EAE, $ acre -1), and internal rate of return (IRR, %) for three discount rates (%) and three stumpage prices ($ green ton -1) assuming base case scenarios defined in Table 1.

 

Discount Rate

Stumpage Price

$4.54

$9.07

$13.61

LEV

4

$251

$2,633

$5,245

7

-$323

$977

$2,373

10

-$556

$308

$1,237

EAE

4

$10

$105

$210

7

-$23

$68

$166

10

-$56

$31

$124

IRR

4

5.0%

12.4%

18.3%

7

5.0%

12.4%

18.3%

10

5.0%

12.4%

18.3%

Footnotes

1.

This document is Circular 1516, one of a series of the School of Forest Resources and Conservation, UF/IFAS Extension. First published: May 2007. Reviewed July 2013. Please visit the EDIS website at http://edis.ifas.ufl.edu.

2.

Matthew Langholtz, postdoctoral research associate; Douglas R. Carter, associate professor, and Donald L. Rockwood, professor, School of Forest Resources and Conservation, Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611-0410.


The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other UF/IFAS Extension publications, contact your county's UF/IFAS Extension office.

U.S. Department of Agriculture, UF/IFAS Extension Service, University of Florida, IFAS, Florida A & M University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Nick T. Place, dean for UF/IFAS Extension.