Logging utilization studies describe how trees are harvested in commercial operations and account for how the various tree parts are used. This information helps land managers evaluate their logging operations and can reveal utilization trends over time and within various regions.
Logging utilization data is particularly valuable to NARA researchers because it provides a basis used to estimate the amount of forest residues available after harvesting operations. The biomass projections based on this data are shown on maps used in supply chain analyses , and the data is incorporated into biomass projection models and life cycle analyses being developed by NARA researchers.
Recently, a report titled Logging Utilization in Idaho: Current and Past Trends was published. A majority of the authors are with the Bureau of Business and Economic Research (BBER) based at the University of Montana (a NARA affiliate organization), and NARA partially funded the work.
View Logging Utilization in Idaho: Current and Past Trends here.
Report covers logging utilization in 2008 and 2011
Data for this report was obtained during the 2008 and 2011 harvest-seasons and provides a snapshot of utilization over a dynamic period for the logging industry. The previous utilization study for this region was conducted in 1990.
This study looked at active logging sites in Idaho where live green trees were harvested for conversion into wood products. Logging sites were selected at random, and 815 trees were sampled from 33 active logging sites spread across 10 Idaho counties.
The specific objectives for this report are to:
1. characterize Idaho’s timber harvest by tree species and diameter (dbh);
2. characterize Idaho timber harvest operations by felling, yarding, and merchandising methods;
3. compute current Idaho logging utilization factors to express: a) volumes of growing-stock (bole wood) logging residue generated per thousand cubic feet (mcf) of mill-delivered volume, b) proportions of mill-delivered volume coming from growing-stock verses non-growing stock portions of harvested trees, and c) total removals (i.e., timber product and logging residue) from growing stock.
Two opposing trends are affecting the amount of residues available after harvest. On one hand, the volume of forest logging residues has decreased between 1990 and 2011 due to technical advancements in harvesting and milling operations. Seventy-two percent fewer residuals remained after harvest in 2011 than in 1965. In 2011, 1,011 cubic feet (cf) of timber volume from growing stock was harvested for every million cubic feet (mcf) delivered to the mill. Of the 1,011 cf, 987 cf was used and 24 cf was left in the forest or at the landing as forest residue.
Counter the decreasing trend of improved utilization and less residues is that the average diameter of trees harvested in 2011 was smaller than in 1990. During this study, roughly one-half of the mill-delivered volume, growing-stock removals, and growing-stock logging residues came from trees with a diameter at breast height (dbh) less than 16 inches. Smaller diameter trees tend to produce a larger proportion of un-used residues compared to larger diameter trees.
Grand fir, Douglas-fir, western larch and western redcedar accounted for 82% of the total mill delivered volume and 87% of the growing-stock logging residue. Of these species, western redcedar showed the lowest proportion of residue per delivered volume with western larch providing the highest proportion of residue volume.
Additional resources from BBER
BBER is conducting logging utilization fieldwork throughout the NARA four-state region (ID, WA, OR, MT). To date, they have sampled 97 logging sites and over two thousand trees. They are also developing a four-state site-level model that will predict the ratio of logging bole wood residue volume to mill delivered volume as a function of readily available covariates, such as logging systems employed.
BBER offers a number of other analyses and tools useful to the logging industry. For instance, the public can access timber harvest volumes by county, forest industry outlooks, capacity studies and forest economic data from the BBER website.