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Lumber

Woodland owners may elect to process standing trees on their property for personal use. Cutting, milling, drying, and machining native lumber may or may not save money compared to buying from commercial sources.  However, individuals just may prefer to use their own resources for specific applications. If native hardwoods are to perform satisfactorily, definite guidelines should be followed.  

Match the Species to the Intended Use 
First, match the species to the intended use. Become familiar with the characteristics of the different woods on your property, and select the right one for the job. Don't use low strength, soft woods where a strong, hard wood is required. If the application calls for a wood with low shrinkage and good workability, choose the right species.  

Dry the Wood to the Correct Moisture Content 
Second, make sure the wood is dried to the correct moisture content. Wood used outdoors needs to be dried to 12 to 15 percent moisture content. This level of moisture content can be realized by thoroughly air drying lumber using recommended stacking methods and exposure conditions. However, wood used indoors for furniture, paneling, or trim must be dried to a moisture content between six and eight percent. The lower level of moisture content cannot be achieved by air drying; special lumber dry kilns that control temperature, humidity, and air movement are typically used to achieve this lower level of moisture content.

Finish or Treat the Wood 
Third, a finish or treatment will generally enhance the performance of hardwood lumber. When using hardwoods outside, a preservative treatment or an exterior stain may be the best choice. For interior applications where a high level of durability is required and a clear finish is desired, several coats of polyurethane varnish is recommended.

Wood for Fuel

The use of firewood in stoves, furnaces and fireplaces is often considered for home heating by homeowners.  Before running out and buying a new wood stove or chain saw, consider some facts about your wood supply and the effort and resource needed to produce it.

Most species of wood contain approximately the same amount of energy per pound, assuming they are at the same moisture content.  Firewood at 20% moisture content or air seasoned for at least one year has approximately 7,000 Btu’s of energy per pound.  Species differences occur in firewood because of the density variation across species.  In Iowa basswood weighs about 25 pounds per cubic foot and shagbark hickory weighs about 51 pounds per cubic foot. Firewood is often measured and sold by the stacked volume.  A cord of wood is a stack of firewood 4” x 4’ x 8’ or 128 cubic feet of wood and air.  A cord of air dried basswood weighs a ton and shagbark hickory weighs two tons; therefore, a cord of shagbark hickory has twice the heat value as a cord of basswood.

Species of Wood Weight per Cord (lbs)
Shagbark Hickory 4072
Basswood 1984
Osage Orange 4792
Red Oak 3536
Green Ash 3296
Silver Maple 2752
Cottonwood 2272

Consider the heat equivalents for home heating.  Assuming that the wood appliance is 60% efficient compared with either LP or natural gas at 85% efficiency or electricity at 100%.  A cord of basswood is equivalent to 9700 cubic feet natural gas, 108 gallons of LP or 2427 kilowatts of electricity; a cord of shagbark hickory is equivalent to 20,000 cubic feet of natural gas, 223 gallons of LP or 4994 kilowatts of electricity.

Firewood must be seasoned or dried.  To accomplish this, requires that the wood be cut and stacked for at least a year before burning.  The average wood usage in Iowa for home heating is 3-7 cords per year.  

Using firewood for home heating requires a good supply of firewood.  A few trees in the backyard is not sufficient.  Most woodlands in Iowa are capable of producing or growing up to a cord of wood per acre per year with good management.  Firewood burners should have a minimum of 5 to 10 acres of a well stocked (land fully occupied with trees) and well managed woodland to provide the fuel for heating the average home.  

 If the homeowner is planning on using wood as an alternative source of energy, consider all aspects of wood burning including the cost of the stove and installation, supply of wood, production cost including equipment such as chainsaw, splitter, and pickup, storage of the wood, planning at least a year ahead of time, and the hassles of feeding and tending the wood burning equipment.

Burning wood can have impacts on the environment through smoke pollution outdoors, indoors and damage to the woodland or forest through unwise practices.  It is safe to say that if wood from a sustainable managed forest is properly processed, dried and burned in a properly installed and maintained efficient wood burner, the environmental impacts will be minimized.

Thinning Woodlands for Firewood Production

The goal of fuelwood harvests should be to make the woodland better after the harvest than before. Concentrate this timber stand improvement practice on young stands (6-10 inches in diameter) because their growth increase will be greater. Thinnings should be done to allow desirable trees more growing space. Care must be exercised in harvesting to ensure that the quality of the woodland is not reduced.

First, identify the "crop trees". Start at any location in the forest stand and on the average of every 20 feet, identify and mark with a non damaging marker such as plasctic or cloth flagging the best trees. The best trees are generally of high value species and trees with the best form and potential to develop into high quality sawlogs when they are mature. 

A species priority list from high to low might include black walnut, red oak, white oak, black oak, bur oak, ash, maple, basswood, and hickory. Crop trees must also have good form; trees that are tall, straight and have a clear trunk should be selected over less desirable forms.  

When working with Iowa woodlands, work with what is in the forest. You will generally mark a variety of tree species, some with excellent form and some with less desirable form, but always the best in that growing space. Crop tree spacing will vary from less than 10 feet to more than 30 feet, but always try to select the best 100 trees per acre. 

After the crop trees have been identified, mark the trees which should be removed for firewood. Work with each individual crop tree and looking at its crown or foliage with respect to its competitors. The goal of thinning is removal of competing trees on 3 to 4 sides of the crop tree if they are crowding or overtopping the crop tree. 

Allow the crop trees some room for expansion or growth, but do remove all competition. If the crowns of competing trees are 3 to 4 feet away from the crop tree, it is not interfering with growth at this time, although as they grow larger, it may have to be removed in future thinnings. Follow this procedure for all crop trees in your stand. 

Over thinning around crop trees may result in reduced quality because of epicormic branches which are formed by buds beneath the bark that begin to grow in response to too much sunlight. Never remove trees if their crowns are below the crowns of the crop trees because they will continue to promote self pruning of the crop trees.

Other Resources: 

Woodland Management

Woodland Improvement and Crop Trees in Iowa

 

Marketing Iowa Timber

Each year many landowners receive substantial earnings by properly marketing mature trees from their woodland. However, many other woodland owners receive only a fraction of the real value for their timber because they do not follow recommended marketing guidelines.

  1. Secure the services of a professional forester to help manage your woodland and market your timber. In Iowa, the Department of Natural Resources has District Foresters stationed at 13 locations across the state to provide on-the-ground assistance to landowners interested in managing their woodland resources. In addition, there are several private consulting foresters doing business in the state who provide professional services for a fee.
  2. Maintain control of your woodland during the harvesting and marketing process. Make sure that you, in consultation with your professional forester, select the trees to market; don't allow timber buyers to choose the trees to be harvested. Selling young, small diameter, rapidly growing, high quality trees is not recommended. For example, high value species such as walnut or oak can earn a very high rate of return as they grow from a diameter of 16 inches to 22 inches or larger. In the process of adding six inches in diameter, the volume of the first 16-foot log will double and the value per unit of volume may triple or quadruple; this growth may increase the value of the larger tree by a factor of six or eight.
  3. Sell your timber as standing trees, and secure competitive bids from bonded timber buyers. Advertise the trees that you have marked to as many bonded buyers as possible, and invite sealed bids for the timber. Reserve the right to reject any or all bids.
  4. Sign a legal contract with the successful bidder, and make sure that full payment is received before harvest begins. Monitor the logging operation, and make sure the logger understands that your woodland is important to you and that minimal damage will be appreciated.

 

Woodland Management

Iowa's 2.1 million acres of forests are among the most productive and valuable hardwoods in the United State. Iowa soils, especially those in Northeast Iowa are capable of producing some of the best oak, walnut and ash in the world. Much of Iowa's forest is not managed for optimum production of fine hardwoods. 

Eliminate Grazing by Domestic Livestock

The first step in good management and stewardship of the forest is to eliminate grazing by domestic livestock. Grazing has undesirable effects on the forest soil, the forest vegetation and many times even the livestock causing the damage to the woodland. Forest soils compared to prairie soils are usually shallower more subject to erosion, and less stable.  

Soil compaction caused by grazing results in less water and air infiltration into the soil and more water runoff and erosion; on the average, soil loss rate on grazed woodlands is ten times greater than from ungrazed woodlands. Grazed woodlands, usually, have little desirable regeneration because of continued browsing. Livestock can be harmed by grazing woodlands either by consuming poisonous plants or because of low forage production in the woodland. 

Identify "Crop Trees" 

The second opportunity to improve the woodland occurs when the trees are young. With periodic thinning, the growth rate of desirable trees can be increased; these faster growing trees can be marketed at a much younger age. In addition, through crop tree identification and thinning, better quality and more valuable species of trees can be produced. 

First, identify the "crop trees". Start at any location in the forest stand and on the average of every 20 feet, identify and mark with a non damaging marker such as plastic or cloth flagging the best trees. The best trees are generally of high value species and trees with the best form and potential to develop into high quality sawlogs when they are mature. A species priority list from high to low might include black walnut, red oak, white oak, black oak, bur oak, ash, maple, basswood and hickory. Crop tree spacing will vary from less than 10 feet to more than 30 feet, but always try to select the best 100 trees per acre. 

Goal of Periodic Thinning 

After the crop trees have been identified, mark the trees which should be removed to give the crop tree more room to grow. Work with each individual crop tree and looking at its crown or foliage with respect to its competitors. The goal of thinning is removal of competing trees on 3 to 4 sides of the crop tree if they are crowding or overtopping the crop tree. Do not overthin; overthinning may result in reduced quality of trees by stimulating epicormic branching or reduced natural pruning. 

Ensure Desirable Reproduction for the Future

The third opportunity for improving your woodland occurs when the trees are ready to harvest. The main goal in the harvest should be practices which will ensure desirable reproduction for the future. In many cases, simply removing the harvest trees will result in inadequate regeneration of oak, walnut and ash. Some pre-harvest cultural activities may be necessary to regenerate Iowa's woodlands.

For all forestry practices, on site assistance is available from your Iowa Department of Natural Resources district forester

Other Resources: 

For more information check out the Iowa State University Extension Publication Woodland Improvement and Crop Trees in Iowa or visit the Native Iowa Woodland Understory Restoration website.