Woodland Management

The wooded areas on Missouri farms have great potential as habitat for a variety of wildlife species. When protected, the forest interior provides food and cover for deer and turkey, den trees for squirrels and furbearers, and snags for nesting woodpeckers. The forest edge produces browse for deer and nesting areas for songbirds.

• Woodland Interiors
• Woodland Edges & Openings

The difference between a good wildlife woodland and a poor one may be nothing more than a fence or proper management of the trees. This chapter offers ideas for managing your woodland for both wildlife and timber production.

Woodland Interiors

Protection from grazing

Grazing livestock do serious damage to woodlands. Much of this damage is not immediately visible and shows up only as long-term effects, such as tree decline and loss, soil erosion and compaction, and wildlife habitat destruction. Tree seedlings and saplings are the first to be eaten or destroyed. Saplings are broken, stripped of bark and trampled. Even large trees suffer wounds from rubbing and the chipping of hooves at the base of the tree. Livestock hooves mix the leaf litter into the soil, speeding decomposition and exposing bare soil to erosion. The pores in the soil that allow air and water to move down to tree roots are sealed off. Rainwater that should infiltrate into the soil runs off the surface. The fine, hairlike feeder roots located several inches under the ground are exposed and damaged. Trees become weakened and growth rate is slowed. Damaged and exposed tree roots are excellent entry points for insect and disease pests. The appearance of a grazed woodland changes as trees are harvested or die of old age, and there are no young trees to take their place. Often, trees that are more resistant to grazing increase in number as the less resistant, but more valuable, trees are eliminated. Hickories, with their tap root, can tolerate more soil compaction than oaks and will increase in number. Honey locust seedlings are thorny and seldom eaten by livestock and, therefore, thrive in grazed woodlots. Since there is little else for cattle to eat in the woods, plants are consumed from the ground up to as high as the cattle can reach, creating a browse line. Wildlife needing dense brush and low-growing plants have difficulty surviving in a grazed woodland. The ability of trees to produce fruit depends on their vigor and health. Grazed woodlands are less vigorous and the trees produce fewer seeds - including acorns, which are a staple food for woodland wildlife. Cattle grazing in a woodlot may eat the entire acorn crop, leaving nothing for wildlife. Ungrazed forest land provides excellent protection for the soil. In contrast, the soil erosion on a grazed woodland can be as much as 110 times greater than on an ungrazed woodland.

Hardwood forests produce poor-quality forage for livestock. One acre of a managed pasture is worth from 20 to 40 acres of woodlands in grazing value. The best investment is to manage existing pasture land and allow the woodlands to grow trees and wildlife.

To return a grazed woodland to good wildlife habitat, fence out livestock. Check with local Natural Resources Conservation Service and Farm Service Agency offices for possible cost-share programs to help offset fencing costs.

Timber stand improvement

Timber stand improvement, or TSI, is the removal of selected trees from a timber stand to improve the health and growth of the remaining trees. Most unmanaged timber stands become overcrowded, causing a shortage of water, nutrients and sunlight for all trees. TSI reduces competition in a stand and allows the landowner to decide which trees to keep.

Proper spacing of trees is the key to any TSI operation. Trees too closely spaced will soon become crowded, slowing their growth. Trees spaced too far apart waste growing space and encourage larger crowns at the expense of taller, straighter trunks. To estimate the best distance between trees in a stand, measure one or several trees at a height of 4 1 /2 feet above the ground - a measurement known as "diameter at breast height," or DBH. Multiply the average DBH (in inches) by two and use that number as the distance in feet to leave between trees. For example, if a tree is 11 inches in diameter, multiply by two for an answer of 22. Twenty-two feet is the proper spacing to leave between that tree and the trunk of its nearest competitor tree.

When you are thinning a timber stand, the most important trees to leave uncut are the final harvest trees or crop. These trees will have the highest value as wood products.

Other trees to leave standing are those that will be removed in future thinnings, but are needed in the meantime to fill growing space.

This leaves the least desirable, surplus trees, which can be cut for firewood or other purposes. Characteristics of surplus trees include:

• poor-quality wood
• multiple sprouts from one stump
• swellings or bumps on the trunk - indicating internal damage
• fire scars or other damage to the trunk
• many wide-spreading branches.

These TSI practices are used mostly to improve timber values. When you are improving a timber stand for wildlife habitat, it is often necessary to leave some of the surplus trees and, occasionally, even cut a good crop tree.

Trees to leave for wildlife habitat are:

• Den trees - those with an opening leading into a hollow interior.
• Wolf trees - those with a short trunk but wide, spreading crown. These are especially important if they produce large amounts of mast (acorns and nuts) and are in an area dominated primarily by small trees that have not reached mast-producing age. Leave at least one for every two acres.
• Tall, fruiting trees - including hackberry, black cherry, mulberry, black gum and persimmon.

Protecting snags and den trees

A snag is a standing dead tree. Den trees are live trees with a natural hollow in the trunk or limbs. Both are essential habitat for many kinds of woodland wildlife.

Once a tree dies, the slow process of decay begins. As the heartwood in a snag softens, woodpeckers excavate nest holes, which are later used by other wildlife.

Many birds, mammals and reptiles use tree cavities throughout the year for nesting, feeding, perching, escape cover and protection from the weather. Fewer or no den trees usually means less wildlife in an area.

In a typical woodlot, trees with cavities are often in short supply, so it is important to protect both existing and potential den trees. Old, open-grown, large-crowned trees should be protected because they are likely to become good den trees. They also produce nuts, seeds and fruits, making them doubly valuable for wildlife.

White oak, post oak and other members of the long-lived white oak group make the best den trees, but black or red oak, hickory, American elm, sugar maple, American sycamore, eastern cottonwood, black gum, ash and basswood also are excellent.

As a general rule, seven snags or living den trees per acre provide an adequate number of cavities. Live den trees will last longer and are often fruit or nut producers. Standing dead trees attract insects and do not compete with other trees for water, nutrients and sunlight. Consider the option of deadening undesirable trees but not removing them.

A woodland management plan for wildlife should include the following practices for protecting snags and den trees within a woodlot:

• Leave at least one snag and one den tree larger than 20 inches at DBH for every acre of woodlot.
• Leave at least four snags ranging between 10 and 20 inches at DBH per acre.
• Leave at least two snags and two den trees ranging between 6 and 10 inches at DBH.

Preserving existing snags and den trees, as well as protecting potential den trees, helps the woodlot become a productive wildlife area for many years to come.

Den trees and snags can be created by wounding selected trees. Open wounds allow fungi to enter the tree and begin the decay process. It may take several years for trees to develop cavities. This process can be hastened through the following techniques:

• Cut a limb (the larger the better) about 6 inches from the trunk of the tree. Ash, elm, cottonwood, sycamore, silver maple and basswood are especially prone to develop natural cavities from cuts.
• Chop a section of bark from the trunk of a suitable tree, preferably one that already shows signs of damage or decay. Select trees at about 100-foot intervals.
• Drill a hole, at least 2 inches in diameter and 3 inches deep, into the trunk of a tree. If possible, make the hole under a limb that is 3 inches or more in diameter. For more immediate results, put up bird houses and den boxes. See building plans in Chapter 10.

Woodland Edges & Openings

Edge is the transition zone between habitat types. This zone offers critical wildlife food and cover. The amount, diversity and quality of the edge directly affects wildlife populations.

An ideal edge has crops, brush, small trees and large trees.

High-quality edge is a wide band of plants that gradually changes from one cover type to another. It has grasses, weeds, shrubs, vines and small trees that provide wildlife foods, such as berries, seeds, browses and insects. It also offers cover for nesting and protection from weather and predators.

Good edges usually require deliberate action on the part of the landowner. High-quality woodland edge can be created by planting shrubs or small trees in a 30-foot or wider strip at the edge of the field. Another option is to allow the border to naturally revert to native plants and
supplement with plantings if necessary. The natural process usually is rapid and reliable after the elimination of grazing, plowing and mowing. Conversion of heavy sod, such as fescue, to edge habitat can be hastened by plowing, disking or applying herbicide to the border strip, which allows native species to invade.

Large trees, such as those shown above, should be deadened, allowing brush to come up in their place.

Some crop-field acreage is considered too valuable to remove from production. An alternative in such areas is to create edge in the woodlot by removing some trees.

If a field is bordered by trees that affect the growth of crops along the edge, it actually may be cost efficient to let an edge develop between the trees and the field. This is true because the return from low-yield field edges may not offset the cost of seed, fertilizer and site preparation.

Large trees of low commercial value within 30 feet of the crop field should be removed for firewood or deadened to allow sunlight to reach the smaller shrubs. Within 15 feet of the crop field, small trees, such as dogwoods, hawthorns, plums and red cedars, also should be cut. Some trees should be cut low so that sprouting will occur at ground level. Vines attached to trees should not be cut when felling the tree.

Large woodland tracts can lack the variety of plants necessary to support diverse wildlife populations. A 1-acre opening in a forest often provides as much as 10 times the amount of plants used by wildlife as 1 acre of mature timber. Annual weeds, grasses and seedlings found in these openings produce food, nesting sites and escape cover for wildlife.

Five to 10 acres of small clearings per 100 acres of woods is desirable. These openings should range from 1 to 3 acres in size. Smaller woodlots surrounded by pastures and farm fields will reduce the need for forest openings. On larger woodlands, open space is provided by roads, utility rights-of-way, log landings or small clearcuts.

Five to 10 acres of small clearings per 100 acres of woods is desirable. These openings should range from 1 to 3 acres in size. Smaller woodlots surrounded by pastures and farm fields will reduce the need for forest openings. On larger woodlands, open space is provided by roads, utility rights-of-way, log landings or small clearcuts.

Woodland Management Tips:

• Protect woodlands from grazing.
• Deaden large trees along woodlot edge.
• Plant 30-foot wide strip of shrubs along mature woodland edge.
• Use root plow to reduce competition along woodlands next to crop fields.
• Create small openings within large timber blocks.
• Encourage vines and fruiting shrubs.
• Apply timber stand improvement practices.
• Don’t cut den trees and snags.
• Leave brush piles from firewood cutting.
• Install squirrel den boxes.
• Fence a 100-foot wide zone along all wooded streambanks to exclude livestock. Stop all cutting and mechanical activities in this area.