Agricultural Experiment Station SP702-B Biofuels Initiative Biomass Harvesting and Forest Stewardship: A Healthy Balance

The role of cutting low-value trees in proper forest management and the potential implications of biomass harvests for forests and landowners.

Adam Taylor, Assistant Professor and Larry Tankersley, Extension Specialist Forestry, Wildlife and Fisheries

reason are failing to grow well. Tennessee forests: A diverse Likewise, some tree species are mixture not well-suited to certain sites or In a typical hardwood forest will never produce valuable timber in Tennessee there is a mix of tree products. To encourage healthy ages, sizes and species. These dif- forests in the future, and to increase ferent trees have different value. the future value of the timber, these Larger trees are usually higher low-value trees should be removed. value because they can be harvested A partial cutting in the context and processed more efficiently, and of proper silviculture should not be usually they contain more high- confused with high-grading. High- quality wood. The wood products of grading occurs when the best-quality, certain species like walnut, cherry highest-value trees are harvested and oaks are of higher value than exclusively. High-grading provides a others, such as hackberry and soft large immediate payoff for loggers maple, so these tree species are and landowners. Unfortunately, af- generally more valuable. ter high-grading, small, low-quality Forests in Tennessee contain trees and lower-value tree species many small, deformed or diseased are left behind. Forests made up trees, and trees of species that have of these lower-value stems are not little or no value in the current as healthy and do not increase in marketplace. Harvest of these trees timber value like stands that are not for biomass and biofuels may be a The forests of Tennessee are beautiful high-graded. way to provide value to Tennessee’s and diverse. One reason that high-grading forest landowners and to improve occurs is that there are no local the health and productivity of the a component of good silvicultural markets for the small, low-value forest. practice, when the decision about tree stems. Loggers then cannot which trees to cut is based on the justify the harvest of those trees, High-grading: Robbing from the objective of maximizing the long- even though it could improve the future forest term health and productivity of the long-term timber value of the stand. In a typical harvest in Ten- forest. Thus, increased biomass utiliza- nessee, only some of the trees in It is a common misconception tion could encourage proper forest a forest stand are cut at any one that all small trees will grow into management by providing a finan- time. Clear cutting – the harvest of large, high-value trees if given time. cial incentive to remove low-quality all trees at once – is less common. Many small trees are in fact as old trees from forest stands. Partial cutting of a stand can be as their neighbors, but for some Biofuels Initiative 2

The role of biomass in proper forest management When wood is used for biomass products and energy, the species, size and form of the tree stems may not be important factors. Any wood can be burned for energy. All wood species contain the fundamen- tal polymer components – lignin and carbohydrates – that are raw materials for chemical processing. Thus, factors, such as the cost and consistency of supply, can be more important considerations than tim- ber quality when marketing woody biomass. If markets for biomass are available, loggers and landowners may then be able to justify the cost of cutting and hauling the small and deformed trees, the trees of underutilized species and possibly even the limbs and tops from har- vested trees that would otherwise be left in the forest. These items are not suitable for the produc- tion of traditional wood products such as veneer and lumber, but if Woody biomass that is used for fuel, fiber or chemicals is they are left in the forest, they can usually processed as small chips or particles. Log quality and reduce the long-term productivity tree species are less important for biomass than for solid-wood and health of the forest. Thus, a products such as lumber. biomass harvest can be a valuable addition to a traditional timber har- number of concerns: Would all the payments from the increased har- vest by providing a market for the trees in the area be cut to feed the vesting. However, the presence of less valuable products. new mills? Would existing sawmills chip mills did not lead to clearcut- be starved of wood? ting of valuable sawtimber, nor did Will biomass harvests deplete These questions cannot be it result in significant changes in our forests? answered directly because the chip forest management practices. With increasing interest in us- mills were not built in Tennessee. There is good reason that ing woody biomass for energy and However, North Carolina provides valuable sawtimber have not been products, one should consider what an interesting case study. The num- indiscriminately converted into increased tree harvests might mean ber of chip mills in North Carolina pulp chips in North Carolina. Saw- for the forests and people who expanded from two to 18 in the logs have a much higher value than depend on forest resources. In the 1980s and 1990s. Despite this dra- pulpwood and a logger’s livelihood past, there were proposals to build matic increase, a recent study sug- depends on the ability to cut trees new chip mills in Tennessee. These gests that the effects of these chip to produce the highest-value prod- mills would have chipped low-value mills were small overall. The new ucts. The same will be true for bio- hardwood logs to produce raw ma- markets created by the chip mills mass harvests in the future – it will terial for pulp and paper making. tended to increase pulpwood (small always make economic sense for This in an example of a biomass or low-value tree stems that are the highest-quality wood to go to harvest, although the product in not suitable for sawmilling) cutting the highest-value end use (i.e., logs this case would have been paper, levels within existing harvests, or to to the sawmill) and the low-quality not energy. The possible impact of increase harvesting of small stands. material (biomass) for the relatively these mills on the forests and forest Small, private landowners in par- low-value end-use (e.g., energy). industry in Tennessee stimulated a ticular received modestly increased Biofuels Initiative 3

Biomass harvests and A win-win for wood Landowners can benefit from water quality Forests in many areas of the biomass markets when a more Another concern that is fre- United States are growing much complete harvest of their stands in- quently cited in discussions of more quickly than they are being creases revenues. At the same time, timber harvesting is water quality. cut. In Tennessee, almost twice as better forest management, includ- However, water quality reports by much wood grows each year as is ing the removal of diseased trees the Tennessee Department of Envi- harvested. Even when natural tree or undesirable tree species, can ronment and Conservation substan- mortality and forest fires are taken improve the long-term productivity tiate that timber harvesting is not into account, growth exceeds re- and health of the forest stands. a significant threat to water quality movals by more than 35 percent per If the biomass industry is suc- where “Best Management Practices” year. However, some of this growth cessful, there could be high demand are used. A significant emphasis of consists of small or deformed trees for biomass materials, including Tennessee’s Master Logger educa- that will never grow to be large, wood. This could cause increased tional program is to promote soil valuable sawtimber. The increased competition for biomass resources, and water protection. Ongoing harvest of these poor quality trees which could further increase the programs protect Tennessee’s water for bioenergy and bioproducts may prices paid to loggers and landown- by helping landowners and loggers be a way to provide useful markets ers for materials that currently have conduct thoughtful operations. for forest landowners and to im- little or no value. prove the health of our forests. 2006 305(b) Report The Status of Water Quality in Tennessee. From Tennessee Department Available for download at http:// of Agriculture Forest Facts. Avail- www.tennessee.gov/environment/ able for download at http://www. wpc/publications/2006305b.pdf. state.tn.us/agriculture/forestry/tdfff. Accessed July 17, 2007 html. Accessed July 17, 2007

High-quality sawlogs are only one component of Tennessee’s forests. Lower-grade logs can be used for biomass. Biofuels Initiative 4

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SP702B-1M-12/07 R12-1015-006-013-08 08-0094 Programs in agriculture and natural resources, 4-H youth development, family and consumer sciences, and resource development. University of Tennessee Institute of Agriculture, U.S. Department of Agriculture and county governments cooperating. UT Extension provides equal opportunities in programs and employment.