A multi-stem feller-buncher cycle-time model for partial harvest of small-diameter wood stands

Abstract

Due to the increased partial harvest of small-diameter stems and the lack of feller-buncher time-consumption information in Maine, it was necessary to develop new cycle-time equations. Data were collected from seven different sites in Maine with six different operators to capture the variability in site and stand conditions as well as operator experience and proficiency. The results showed that over 55% of the trees harvested were cut in accumulations of two or more trees. Significant variables in the final model included sum of dbh and stem count per accumulation. An approach to simulate a list of accumulations with the required variables is described based on a tree list with dbh classes. Treating the combination of operator, machine, and site conditions as a random effect in a linear mixed-effects model resulted in an adjusted R ² of 0.40 for fixed and random effects. The combination of operator, machine, and site conditions explained 32% of the variance caused by random effects. The results of this study can be incorporated into existing harvest cost prediction programs to improve estimates for this region.

Keywords:

• productivity
• time study
• whole-tree harvest
• Maine
• Northeast USA
• New England

Acknowledgement

We would like to thank the University of Maine's Cooperative Forestry Research Unit and the Maine Agricultural and Forest Experiment Station (Publication No. 3338) for funding this project. Special thanks go to all the land managers, contractors, and operators who participated in this study. We would also like to thank Drs. Robert Seymour and Aaron Weiskittel for their input and help during the study-design and data-analysis phases of this study. Our thanks go to University of Maine students Casey Elmer, for his help in the data-collection phase during the summer of 2012, and Andrew Nelson, for his help with R-related questions. We would also like to thank Mark Brown, of the University of the Sunshine Coast in Australia, and Rory Eckardt, forest operations analyst, for their review of this paper before submission.

*Member of the Forest Products Society.