Time and cost study of pruning a 12-year-old loblolly pine plantation.

摘要

A time and motion study was conducted to determine time and cost of pruning thinned, 12-year-old loblolly pine (Pinus taeda) plantations in Texas, USA, to a height of 25 feet. The study incorporated thinning treatments to stand density indices (SDI) of 70, 120, and 170. Pruning times with labour and equipment costs were used to determine per acre and per tree pruning costs at each stand density. Pruning costs were used to determine stumpage price premiums necessary to breakeven on a pruning investment. Calculations were performed with various hourly wage and interest rates. The average per tree pruning time for a pair of workers was 2 minutes and 16 seconds, which results in a net average of 11.6 trees pruned per hour per worker. Per acre combined labour and equipment costs ranged from $58.09 to $288.59 depending on stand density and wage paid. Cost per tree ranged from $0.55 to $1.00 depending on stand density and wage paid. Breakeven values ranged from $63.55 to $2,584.14/ac depending on stand density, wage paid, alternative rate of return, and rotation age..