Effects of recovering logging residues on strategy and benefits of forest stand management

In implementing forestry activities such as final felling and thinning, the value of logging residues are a distant consideration to those of commercial timber. However, rising oil prices and concerns for energy security are leading to increasing demand for logging residue as a source of renewable energy. We used a dynamic programming model to conduct computer simulations to examine the benefits of recovering logging residue and the effects of doing so on forest stand management strategies. We assumed an even-aged sugi (Cryptomeria japonica) plantation in Kyushu, Japan. The volume of logging residue to be used for fuel was calculated as either whole tree volume or whole tree volume less the logs utilized for timber. The simulations adopted residue prices from 3.0 to 9.0 JPY/kg. As residue price increased, the strategy for selling thinned trees shifted towards increased allocation of logs from timber to fuel. On the other hand, the optimal rotation age and thinning regime have little change against the price increase. The soil expectation value (SEV) increased with the price of logging residue. At a price of 6 JPY/kg, the SEV increased by 15-63% when logging residue was recovered. This increase in benefit mainly derived from the logging residue generated in clear-cutting; the contribution of thinning to benefit was comparatively small.