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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

Maple Syrup Production

Maple syrup is one of our oldest agriculture crops and is one that is solely North American. Iowa is not generally thought of as being a maple syrup producing state, but it does have a few commercial producers in the northeastern part of the state. Currently the local market for maple syrup and candies is greater than the supply.

A potential producer of maple syrup must carefully analyze their individual situation before embarking on this labor intensive enterprise. One must have maple species (sugar maple, black maple, silver maple or boxelder) at least ten inches in diameter, the resources to invest in the necessary equipment and supplies, and the large amount of time and labor required by this enterprise.

Sap Collection

Trees must be at least ten inches in diameter to tap. Use one tap for trees 10-15 inches in diameter, two taps for 16-20 inch trees, three taps for 21-25 inch trees and, no more than four taps for trees over 25 inches in diameter. Trees should be tapped before the sap begins to run in the trees. Sap collection usually begins in Iowa in late February or early March and lasts for approximately three weeks.

Special equipment required to collect sap includes: brace and bit for boring the holes in the trees, spiles to transfer the sap from the tree to buckets or bags, buckets or sap bags for collection, a system to transport the sap to the evaporator such as a bulk tank or plastic tubing with pumps, and storage facilities for the sap until it is processed into syrup.

using an evaporator for boiling maple syrup at Iowa State University Forestry greenhouse — Boiling Sap to Produce Maple Syrup at Iowa State University Forestry Greenhouse

Evaporation

Maple sap averages around 2% sugar content; maple syrup is approximately 66% sugar. Actual sugar content of sap varies widely from tree to tree and from

season to season, but maple sap at 2% sugar content requires 43 gallons of sap to produce a gallon of syrup. This concentration of sap to syrup is accomplished by boiling the sap in an "evaporator". Simple evaporators are open pans over a heat source or more expensive and complex systems for continuous production of syrup.

Minimum equipment required for evaporation include the flat evaporator pan with a source of heat (usually wood or LP gas), filters, sap and syrup hydrometers for determining syrup and sap density, bottles, seals and labels. Maple syrup production is very labor intensive. For a small operation of 50 taps, 150-200 hours of labor will be required.

Yield

Yield of syrup varies from season to season and from tree to tree. In Iowa the average yield of syrup per tap varies from one-half to one quart. In addition, there are some quality differences between species (sugar and black maple are preferred) and quality variation during the sap flow season (late sap may be less desirable). Local markets will probably not make a distinction between syrup from different species. Most producers sell their product locally, but some wholesale opportunities for large scale production exist in both Minnesota and Wisconsin for syrup produced in Iowa.

Management

Good management is necessary to both increase profitability and reduce risks. Excellent sanitary practices are a must to produce a high quality product and avoid potential liability claims. Care in the boiling and finishing processes is necessary to avoid scorching or imparting a undesirable flavor to the final product. Minimizing the time period between sap collection and boiling will improve syrup quality and minimize losses due to spoilage. Because this is a food product, licensing and permits through the Iowa Department of Agriculture may be required.

Both sap yield and sugar content can be improved through sugar bush management. Forestry practices which promote crown development will increase the yield and sugar content.

Other Resources:

Maple Syrup Production in Iowa Publication

American Hazelnut

American Hazelnut Corylus Americana The American hazelnut (Corylus americana) is found throughout Iowa except in the northwest corner.

Habitat: Commonly found in wood edges and dry open woods.

Hardiness: Zones 4 through 9

Growth Rate: Moderate to Rapid

Mature Shape: Rounded

Height: 15 to 18 feet

Width: 10 to 12 feet

Site Requirements: American hazelnut grows moist loamy to well drained sandy and clay soils. Adaptable to adverse soil conditions.

Flowering Dates: March - May

Seed Dispersal Dates: September - October

Seed Bearing Age: 3 years

Seed Bearing Frequency: Yearly

Seed Stratification: Seeds need 5 months cold stratification at 34°F to 40°F

American Hornbeam

American Hornbeam Carpinus caroliniana Hornbeam (Carpinus caroliniana) is an attractive small tree that is common, but not abundant in its natural range. It has many common names, the most common include: blue beech because of its very smooth gray bark, and musclewood referring to its muscle-like branches which are irregularly fluted.

Habitat: Grows on moist, rocky, wooded slopes. Commonly found in NE Iowa

American hornbeam leaves — American Hornbeam Leaves - Photo by Paul Wray, Iowa State University

Hardiness: Zones 3 through 9

Growth Rate: Slow

Mature Shape: Symmetrical canopy with a smooth outline; ovular dense crown

Height: 25-35 feet

Width: 15-25 feet

Site Requirements: Prefers deep, fertile, moist, acidic soil and grows best in partial shade, but will grow in full sun. Not drought-tolerant.

Leaves: Alternate, simple, double-toothed with equal leaf base

Flowering Dates: April - June

Seed Dispersal Dates: November - Spring

Seed Bearing Age: 15 Years; Peaks at age 25-50; Ceasing around 75 years

Seed Bearing Frequency: 3-5 years

Seed Stratification: Seeds need stratification for 2 months at 40°F

American hornbeam fruit — American Hornbeam Fruit - Photo by Paul Wray, Iowa State University

Hornbeam has alternate simple leaves, with fine teeth and tapering to a sharp point. Winter twigs are very fine reddish brown in color with three bundle scars. It is a member of the birch family and will have the male catkin flower buds present in the winter months. The fruit is a small nut about 1/3” in diameter, lying at the base of 3-lobed leafy bract; the fruits are clustered on a hanging stalk. The bark is thin, slate gray to light gray in color and very tight, seldom forming any ridges or breaking into plates.

It is native to the eastern third of Iowa and can also be found growing up the Iowa and Des Moines rivers. It is a common, but not abundant tree, often growing in multiple stem clumps. Like ironwood, it is very shade tolerant and thrives in the understory of our upland oak-hickory woodlands. It prefers a moister site than Ironwood and will often be located on north and east slopes or on the upper stream terraces.

It is a small tree, seldom reaching a foot in diameter or more than 30 feet tall. The wood is very tough with exceptional strength characteristics and has been used for tool handles and other minor uses requiring tough wood. Because it is such a small tree, its commercial value for lumber is almost non existent. It does have high density and makes excellent firewood.

It has great potential as an ornamental tree, because of its gray fluted stems and good reddish-orange fall color. It is somewhat difficult to transplant and does best in a moist, sheltered location of the landscape and will tolerate some shading.

American hornbeam flowers — American Hornbeam Fruit - Photo by Paul Wray, Iowa State University

American hornbeam bark — American Hornbeam Bark - Photo by Paul Wray, Iowa State University

Apple

The common apple (Malus pumila), also known as the orchard apple or domestic apple is a deciduous, small to medium-sized tree which can grow from 30 to 70 feet, with a short, stout trunk. The leaves are 2 to 4 inches long, oval to ovate in shape, with fine sharp-toothed margins. On top, the leaves are bright green and smooth; the leaf bottom is paler with fine white down. Unlike the prairie crabapple (Pyrus ioensis) described below, the common apple is not native to Iowa.

Hardiness: Zones 3 through 10 - depending on species

Growth Rate: Moderate

Mature Shape: Ovular spreading or horizontal upright.

Height: Dwarf varieties are 5 to 8 feet tall. Semi-dwarf get to be 12 to 16 feet tall. Standard varieties can grow to be 20 and 30 feet tall.

Width: Depends upon variety

Site Requirements: Grows well in moist, well-drained soil

Flowering Dates: May

Seed Dispersal Dates: September

Seed Bearing Age: 4 years

Seed Bearing Frequency: Yearly

Cultivation: A seed from an apple will grow a tree if planted in proper conditions, but the fruit of that tree will often be smaller and poorer than the apple from which the seed was taken. Therefore, apple trees are most often grown from buds. A bud from a strong apple tree is made to grow on the roots of a seedling apple tree by a process called budding, which is a kind of grafting.

Red apple fruit — Apples - Photo by Jerry A Payne, USDA Agricultural Research Service, Bugwood.org

The common apple originated in Eurasia, and brought to North America by early colonists. It is now naturalized in North America. There are thousands of cultivars exhibiting a wide variety of characteristics (leaves, fruits, flowers, twigs).

The wood is heavy, hard, and tough and used for making crafts, good for fuel, and used to smoke meat. The fruit, commonly known as "apples," having many domestic uses ( culinary dishes and libations) is also used as a food source for many kinds of wildlife such as white-tailed deer, black bear, raccoons and foxes.

It is suggested that wild apple trees seen in mountain habitat may have taken root due to discarded cores by lumberjacks and hikers (pack it out).

Pests that Can Affect Apple Trees

Apple twig with buds — Apple Twig - Photo by Bill Cook, Michigan State University, Bugwood.org

Apple tree with fruit — Apple Tree - Photo by Howard F. Schwartz, Colorado State University, Bugwood.org

White and pink apple flowers — Apple Flowers - Photo by Paul Wray, Iowa State University

Prairie Crab Apple

Habitat: Found growing in prairie settings, dry brush uplands and open woods throughout the state

It is said that the prairie or Iowa crab apple (Pyrus ioensis) is the most beautiful and fragrant of all the wild crab apples.

Is it an Apple or a Crab Apple?

The rule of thumb is if the fruit is under 2", than it is a crab apple, and if the fruit is larger than 2", than it is an apple. However, many trees overlap and hybridize, confounding a biological distinction between apples and crab apples.

Small, red, berries on crab apple tree — Prairie Crab Apple Fruit - Photo by Paul Wray, Iowa State University

Crab apple leaves — Prairie Crab Apple Leaves - Photo by Paul Wray, Iowa State University

crab apple tree blooming with white flowers — Crab Apple Tree in Bloom, Photo by Paul Wray, Iowa State University

three varieties of crab apple flowers - two pink and one white — Prairie Crab Apple Flowers - Photos by Paul Wray, Iowa State University

Austrian Pine

Although not native to Iowa, the Austrian pine (Pinus nigra), also called European black pine, has been planted quite widely in the state and especially in the western one-third where it has been planted both in farmstead windbreaks and as an ornamental. Due to many disease problems this species is no longer recommended in Iowa.

Hardiness: Zones 3b through 7 - Survives in zone 8, though rarely seen. Grows best in colder climates.

Growth Rate: Medium (grows 35 to 50 feet after 20-30 years)

Mature Shape: Densely pyramidal when young. Becomes a large, flat-topped tree with a rough, short trunk and low, stout, spreading branches.

Height: 50 to 60 feet tall (some have been seen at
100 feet tall)

Width: 20 to 40 foot spread

Site Requirements: A very hardy tree that can survive city conditions better than most pines, but also enjoys the seaside environment and tolerates sandy soils well, too. Very tolerant of soils, if moist, but can stand some dryness and exposure. Resists heat and drought. Can succeed in fairly heavy clay.

Leaves: Stiff, sharp needles that occur in bundles of two

Flowering Dates: May - June

Seed Dispersal Dates: October - November

Seed Bearing Age: 15-40 Years

Seed Bearing Frequency: Every 2-5 years

The tree grows moderately fast, 75 to 100 feet tall when mature, and is hardy and is quite drought resistant. When grown in the open, it holds its branches quite close to the ground. The needlelike leaves occur in bundles of two, are 4 to 6 inches long, are stiff and sharp pointed, and of a light green color. The egg-shaped cones are 2 to 3 inches long and 1 to 1-1/4 inches wide. The cones open during the late fall and early winter.

Side by side view of young Austrian pine fruit and mature cone — Austrian Pine Fruit - Photos by Paul Wray, Iowa State University

Diseases that Can Affect Austrian Pine

Insects that Can Affect Austrian Pine

Austrian pine flower cluster — Austrian Pine Flowers - Photo by Paul Wray, Iowa State University

Austrian pine twigs — Austrian Pine Twigs - Photo by Paul Wray, Iowa State University

Austrian pine needles — Austrian Pine Leaves, Photo by Paul Wray, Iowa State University

Balsam Fir

Balsam Fir Abies balsamea The balsam fir (Abies balsamea) is a medium-sized tree, 50 to 60 feet in height. It is native to northeast Iowa where it grows on moist slopes.

Habitat: Grows on steep north facing slopes. Found in northeast Iowa.

Hardiness: Zones 3 through 6

Growth Rate: Slow

Mature Shape: Densely pyramidal

Height: 40-70 feet

Width: 15-20 feet

Site Requirements: Plant trees in sun to light shade with moist, well-drained soils. Protect trees from drying winds. Balsam firs do not tolerate heat well.

Leaves: Blunt needles

Flowering Dates: May

Seed Dispersal Dates: October

Seed Bearing Age: 15 Years

Seed Bearing Frequency: Every 3-5 years

Seed Stratification: One month at 34°F to 40°F

Balsam fir leaves - needles — Balsam Fir Leaves - Photo by Paul Wray, Iowa State University

The leaves are blunt needles 3/4 to 1-1/2 inches long, dark green on the upper surface to silvery white on the lower surface and spreading at nearly right angles to the branch. The fruit is an oblong, cylindrical cone 2 to 4 inches long, purplish in color and growing upright on the upper branches. When ripe, the cone breaks up into pieces, so one never finds a mature cone on the ground. The brown bark breaks into small plates covered with scales. The young bark is often covered with pitch blister, hence the name "balsam."