Sponsored by the Michigan Forest Association and Michigan State University Extension

Low-Grade Wood
Article #266, January 2018
By Bill Cook

Much of the Michigan forest consists of low-grade trees, which are usually selected for harvest to improve the forest, for a variety of reasons.  However, without markets for low quality wood, forests will suffer.   

     A “low-grade” tree involves a set of criteria by which sawtimber-sized trees are rated for manufacturing potential for human use.  “Sawtimber size” is based on diameter at 4.5 feet from the ground; nine inches for conifers and eleven inches for broad-leaf (hardwood) trees.  After that, defects of many kinds and frequencies will place trees into grades of a numerical rank, with one being the best.  Then, veneer grade is the very cream of the crop, with highly variable specifications. 
     Average grades are the most common, dominated by the maples, pines, and oaks.  A regular bell curve describes the sawtimber volume for both hardwoods and softwoods, meaning there is a lot of low to medium grade sawtimber in Michigan. 
     Smaller diameter trees are not graded.  However, a set of marking criteria are applied that discriminates across a spectrum of characteristics.  Those criteria are adjusted to reflect desired forestowner outcomes.  It’s these pole-sized trees that will eventually grow into sawtimber-sized trees. 
     Increasing the volume of trees in the better quality classes is often an objective in forest management.  With that objective, a range of other benefits are often realized, such as enhanced forest health, better visual quality, and accelerated individual tree growth. 
     Thinning timber stands purposefully manipulates light conditions to favor the growth of selected trees and will encourage tree regeneration.  Lower quality trees are removed to favor higher quality trees, or potentially higher quality trees.  It is easy to sell high quality trees, but forest management is required to produce these trees in greater numbers and over a shorter period of time. 
     All this is about managing the forest and involves tree removal - harvesting and thinning.  In order to remove trees, in any substantial amount, there must be a market.  No market.  No management.  Without management, forest health will decline and society will suffer.  Examples of this gradual process can be seen in Colorado, the Pacific Northwest, and parts of the Northeast.  Once a forest-based infrastructure is lost, it is difficult to rebuild.  This is unfortunate for the forest and for our forest-dependent society. 
      Finding markets for low-grade wood is difficult in some parts of Michigan, especially in southern Michigan, where there are no pulp mills or biomass plants.  The distance to a mill that uses low-grade wood is an important factor in setting the price a forestowner will be paid for standing trees (stumpage).  And, because low-grade wood commands a lower price, that commercially-viable distance will be less for low-grade wood than high-value sawlogs.  A diverse regional forest industry translates into better forests and improved environmental services. 
     A decade ago, several large forest industries shuttered their doors.  This left about a two million cord annual “hole” in market for many kinds of trees.  Since then, statewide, about nine million cords of wood have been added to the inventory each year.  This rapidly-growing inventory presents opportunities for an expanded forest industry, especially for smaller diameter and lower quality wood.  At least one manufacturer has taken advantage of this growing inventory, with Arauco scheduled to begin particleboard production later this year. 
     How much is nine million cords?  It’s a big number.  If that volume of logs were stacked ten feet high, the area would cover over 1500 football fields.  Alternatively, that volume would require a five-story warehouse covering half a square mile.  A ten-foot high stack of logs would stretch about 2700 miles.  This is the volume added to our forest inventory every year.  It’s a social-political decision about how we might capture some of that wood volume. 
     Another potential industry to take advantage of this underutilized resource is wood-based energy, particularly that for heating and cooling.  Heating and cooling is often called thermal energy, as opposed to energy used for electricity generation or transportation fuels.  Low-grade wood is well-suited to supply these markets in the form of chips and pellets.  Expanding these markets could lead to much better wood utilization and forest improvement. 
     Modern wood-burning furnaces and boilers are fully-automatic and quite clean.  Michigan has over 800,000 households that heat, arguably, with more expensive fuels. These are markets where a wood pellet bulk delivery network could provide residential, environmentally-friendly service on a cost-competitive basis. 
     Yet another possibility for some of our growing forest inventory is high-end chemicals and other biomaterials that can be used to replace petroleum-based plastics and make fabrics, insulation, and many other products.  Carbon sourced from wood has a multitude of applications in construction and manufacturing materials.  These are things that typically don’t look like wood!  States such as Virginia and Oregon are well-along this pathway. 
     A “bioeconomy” is a growing global trend where industries are becoming more reliant on renewable organic sources of raw materials.  Recently, Canadian Provinces have signed-on to a Pan-Canadian Framework on Clean Growth and Climate Change agreement that is already beginning to produce a stronger bioeconomy. 
     Low-grade trees need to be removed from forests in order to achieve a wide range of benefits.  These huge wood volumes could sustainably support a number of industries and become significant economic drivers for regional communities.  However, we must first decide that this is a good direction in which to take our forests. 

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TRAILER- This website was created by a consortium of forestry groups to help streamline information about forestry and coordinate forestry activities designed to benefit the family forest owner and various publics that make up our Michigan citizenry. This website is maintained by Bill Cook, Michigan State Extension Forester/Biologist. Direct comments to cookwi@msu.edu or 906-786-1575.

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