Sorting and arranging forest residues
Humboldt State University completed its first stage for Subtask 1.1 — Sorting and arranging forest residues in July 2014. Three field-based treatments were carried out for sorting the forest residues (no sorting, moderate sorting, and intensive sorting) in three different harvest units on industrial timberland in Korbel, California.
Treatment for sorting study started right from the felling. The feller buncher separated the biomass trees (below 8 inch diameter and non-merchantable species) from the sawlog trees, as opposed to the usual practice of bunching them together or using the forest residues as “slash mats.” This research aimed to develop new strategies and methods for sorting and arranging forest residues resulting from harvest and fuel reduction thinning operations.
(Click on the upper left image below to go to slideshow view with full captions for each image.)
All harvested materials including sawlogs, non-merchantable, and small diameter trees were brought to the roadside by a shovel loader for further processing. The trees were separated based on species to hardwood (tanoak) and three conifer piles (Douglas fir, Western hemlock and Coast redwood).
Forest residues were sorted by the processor (John Deere, 2454D) at the log landing into a) processed hardwood, b) processed conifers, c) unprocessed hardwood tops, d) unprocessed conifer tops. The goal of Subtask 2.1 was to develop quality feedstock supplies, which were compatible with the specification set for Biomass Conversion Technology by minimizing contamination, and to further facilitate comminution.
The processed tops were de-limbed up to the top 6 inches. The unprocessed tops were bucked at the top 6 inch diameter and had branches with leaves and needles still attached on them.
Log decks were scaled for determining the machine productivity for each sorting treatment operation. Eric Murray (Left), forestry senior at Humboldt State University, and Anil Raj Kizha., Post-Doctoral Researcher, measuring the log decks.
Creating Teepees in the no sorting treatment sub-unit. The next objective of the subtask was to reduce moisture content in the feedstock, develop techniques to improve handling, and enhance transportation efficiency. With this regard, four different forest residue pile arrangements (criss-cross, processor piled, teepees and scattered on the floor) were tested.
Teepees were varying size and were generally 30-40 feet tall and over 100 feet in diameter. On average, it took the loader around 20-30 minutes to create a typical teepee pile; however, this varied with the amount of residue on the ground, how scattered the residues were, and operators skills. Teepees have sufficient air flow and are usually burnt during appropriate seasons. They are comprised of all slash material from the harvesting operation including unmerchantable whole trees, chunks, tops, limbs, etc. Anil Raj Kizha., Post-Doctoral researcher in front of a teepee created for the study.
Creating Criss-cross piles. This pile structure was designed exclusively for the purpose of the study. On an average it took the loader around 18 minutes to create a criss-cross pile with a size of 10 feet tall and 40 ft x 30 ft . The whole pile was erected on a couple of logs to ensure proper air flow from the bottom as well. Furthermore, the piles were primarily located close to the roads and had sufficient slope to drain water during a rain fall event.
Covered criss-cross and processor piles: Two of the processor pile and one criss-cross pile were covered with plastic to understand the effects of pile covering.
Transect sampling of Teepees: Three transects were placed at 120 degrees. Wood discs (samples) were collected from previously determined part of the transects.
The discs were collected from each pile at pre-determined location using a transect sampling method. Discs of slash material from different diameter class and species were collected.
Collecting wood discs (samples) from a teepee pile. The moisture content of the samples collected was determined by the oven dry method. Jeffrey Paulson, forestry senior at Humboldt State University, showing the wood discs which he has cut.
The wood discs were initially weighed in the field and the moisture content measurements were also taken using a moisture meter. Later in the lab, the samples were dried at 1030 C for over four days after which it is weighed again. Eric Murray (left), forestry senior at Humboldt State University and Adenise Ulchak (right), a foreign exchange student from Brazil, taking measurement in field.
