Large site prep tractors for fire line establishment in southern pine stands in Alabama
Trials of fire line establishment with a mulcher were conducted with a 261 kW Caterpillar 586C site prep tractor and Cat HM825 mulcher head (2.5 m cutting path). The fire lines were intended for the application of prescribed fire. The trials were on three sites and in two stand types (cutover and thinned pine), and at three production speeds (0.6, 0.8, and 1.2 km/h). The slowest speed (0.6) was a two-pass application at 1.2 km/h. Treatments were applied in 16 blocks to 48 segments which ranged from 100 to 300 m in length. Mineral soil exposure ranged from 50% to 80% of the treatment width for all but one block. Slower speeds produced significantly greater mineral soil exposure with some significant interactions of site and treatment. Productive delays were caused by maneuvering and retreatment of skips, due to sudden changes in terrain or obstacles. Productive delays were 9% and 27% of the total time in cutover and thinned stands, respectively. Even with productive delays, most design speeds could be achieved. At the higher speeds, mulched fire line costs ($/km) were near current costs for bladed trails. However, mulcher productivity (km/h) could be 2 to 3 times greater than dozers in open woodlands or young stands where the mulcher can easily navigate. Opportunities for using a wheeled mulcher to create fire lines might include locations that can take advantage of onroad travel between sites or locations that require spot treatments of high fuel loads in high-risk locations.