COMPARISON OF 2 THINNING SYSTEMS .2. PRODUCTIVITY AND COSTS

A side-by-side comparison of two popular thinning systems, a skidder s ystem and a forwarder system, was made during winter logging condition s in southern Alabama. The first report of this study addressed stand and site impacts of these two thinning systems. This report focuses on productivity and costs while thinning an 18-year-old loblolly pine pl antation. The skidder system used a feller-buncher with a shear head f ollowed by a grapple skidder that transported bunches of trees and del imbed them with a gate delimber. A loader/slasher combination processe d trees into 7.5-foot lengths and loaded tractor trailers. The forward er system used two machines: a harvester and a forwarder. The harveste r felled, delimbed, and bucked trees into 7.5-foot or cut-to-length pu lpwood. The forwarder loaded processed wood and transported it to seto ut trailers. Production rates were sampled using time and production s tudies for each machine in the two systems. Production rates and estim ated costs were combined for each system to give overall system costs. System production was limited by the woods transport vehicles, the si ngle skidder for the skidder system, and the forwarder for the forward er system. Weekly production rates were 261 cords for the skidder syst em and 249 cords with cut-to-length wood and 200 cords with 7.5-foot w ood for the forwarder system. Cost per cord was slightly lower for the forwarder system using cut-to-length wood as compared to the skidder system, a difference of $0.14, and higher for the forwarder system in 7.5-foot wood, a difference of $3.77.