Short rotation woody crop operations differ
from conventional forestry operations because the trees are specifically grown
for fiber harvest on rotations of approximately 5 to 8 years. These stands are typically characterized by
small diameter and high stems per acre.
Several studies explored harvesting operations that could be used in
short rotation woody crops. Handling
multiple small stems and bunching to increase productivity are just two of the
factors that make handling this small diameter material different from conventional-sized
materials. Some of the publications on
the CD refer to using short-rotation crop production for pulp furnish. It may be appropriate to apply these
operational findings to the harvesting of biomass.
Sycamore (Platanus occidentalis), black locust (Robinia pseudoacacia), and Eucalyptus
spp. have been identified for short rotation crop species (Hartsough
and others 1992 and McDonald
and Stokes 1994b).
Over the years, an assortment of equipment
has been built and tested for handling multiple small stems (Hartsough
and Stokes 1997b). The Forest Operations Unit has analyzed a
variety of harvesting systems to identify bottlenecks and find opportunities to
improve productivity when harvesting small stems (Hartsough
and others 1992, Stokes
and Hartsough, 1993a,
McDonald
and Stokes 1994a,
Hartsough
and Cooper 1999b,
and Hartsough
and Cooper 1999c). Even non-traditional woodyard equipment, such
as front-end loaders for forwarding, was investigated (Spinelli
and Hartsough 2001). Many of these studies indicate that average
d.b.h. is the most critical factor in predicting productivity of conventional
felling systems in short rotation stands (McDonald
and Stokes 1994b). System balancing is important when developing
harvesting systems for small diameter stems.
An annotated bibliography (Stokes
and others 1997) summarizes 354
publications that address the operational aspects of woody crops for
energy. It was published in 1997 for the
International Energy Agency Bioenergy multi-national collaborative
agreement. Some of the publications
cited within this document would be difficult to find, even with Internet
search engines available today.
Management of short-rotation woody crops
differs from conventional management in many ways. Hartsough
and Yomogida (1996) provide a
detailed overview of short-rotation woody crop management, from planting, to
weed and pest control considerations, to harvesting and transport. This study was a cooperative effort with the
Another benefit of
growing short-rotation woody crops could be to provide standing inventory
during wet periods for pulp mills (Gallagher
and Shaffer 2002
and Gallagher
and Shaffer 2003). This possibly translates to standing
inventory of biomass for energy plants, too.
Gallagher
and Shaffer (2003) relate mill
inventory and standing inventory usage at three mills over a 3-year
period.