Biomass can be obtained by harvesting small
(1999) provides a comparison of
environmental effects from a variety of systems used to harvest small
trees. Systems described range from
animal logging to farm equipment to cable systems. The differences in residual stand damage,
cost and efficiency, and soil impacts were surveyed and described for the
harvesting systems. Generally, animal
logging had less impact on soil physical properties than machine logging. Disturbance to surface soil was higher from
machine logging causing more nutrient losses as compared to animal
logging. Machine skidding resulted in
more direct damage to the residuals as compared to animal skidding. Environmental effects from specialized cable
yarding and tractor-mounted tower yarding are also discussed.
Experiments have been performed to determine
if mulching and incorporating the mulch into the soil would improve soil
properties for pine growth. Post-harvest
slash (including stumps) was mulched and incorporated into the soil (wet flats
and pocosins) in a North Carolina study (Lakel and others 1999) prior to bedding. This
treatment was compared to the conventional site preparation treatments for the
area (v-shear and bed with a tractor-mounted plow). This study found that the differing methods
of organic material incorporation did not affect soil moisture or aeration
properties for the soil types in the test.
In other publications, researchers tested the response of soil carbon
and soil physical properties to mulched forest slash (Sanchez
and others 2000
and others 2002a). The treatments included the conventional
treatment as in Lakel and others (1999), plus strip surface mulching, strip mulching with tilling, and
broadcast surface mulching. Machine
costs and production rates for the Rayco Model T275
Hydra-Stumper were determined for each treatment. Potential increases in site productivity
coupled with the collection of carbon sequestration credits could make the
incorporation of forest slash a viable site preparation option.
A study on the Savannah River Site National Environmental Research Park (Sanchez
and others 2002b) also examined
various site preparation treatments involving mulch incorporation. The soil types, treatments and machines used
in this study provide additional data regarding the effects of the treatments
on soil chemical and physical properties.
The study results indicate that incorporating forest slash during site
preparation treatments has a positive effect of increasing soil carbon and
nutrients. Costs and productivity
information were calculated for the CMI RS 500B machine.
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