OUTDOOR CORNER: GRAZING PUTS AN UNNATURAL STRESS ON WOODED AREAS

Woodlands are fragile. This statement might seem odd to people who think of woodlands as rugged and indestructible. And without man's intervention, they generally are. Fires, disease, tornadoes and rainstorms all have an effect but forests are adapted to these naturally occurring stresses.

However, when man introduces unnatural stresses, such as acid rain, chemicals, exotic insects and introduced disease, a healthy forest can be devastated. Woodlands aren't able to cope with stresses that are a product of man's activity.

Livestock grazing is a prime example of unnatural stress. It causes broken limbs, compacted and eroding soils and destruction of seedlings. Livestock can damage protective bark and break limbs from healthy trees.

Woodland grazing seems like a good idea. Woodlands offer summer shade, winter wind protection and calving season shelter. Fencing costs to exclude livestock are high. However, woodland grazing benefits neither the forest, nor livestock.

Healthy, ungrazed forests simulate giant sponges. Vegetation lessens the impact of raindrops. Leaf litter further dissipates the force much like house shingles. Once the energy of the rain is minimized, it soaks into the litter and the soil beneath. Sedimentation and erosion problems are kept to a minimum through such water storing systems.

Grazing livestock destroy the energy dissipating and water storing capabilities of woodlands, increasing erosion eight to 110 times. Falling rain contacts the bare, compacted earth and continues its rapid downhill journey carrying large volumes of soil in suspension. Without the woodland "sponge" effect, erosion, flooding and sedimentation increase.

Accelerated erosion occurs as the protective surface is destroyed. Valuable topsoil is lost, and ugly, active gullies form. Falling rain concentrates and rushes rapidly downhill, choking stream channels that are unable to accommodate the sudden deluge.

Also, without the storage effect of woodland leaf litter, flooding on a large scale occurs, creating problems downstream. Rushing water carries soil particles downhill, eventually filling streams, road ditches and water supplies. Sedimentation results in fish kills and cost millions of dollars annually.

Ungrazed woodlands contain a healthy diversity of tree species of various ages and size classes. Timber Stand Improvement (TSI) recommendations can take full advantage of a healthy forest. Missouri Department of Conservation foresters make TSI suggestions for Missouri landowners free of charge.

With grazing, the composition of woodlands changes. Just like undesirable plant species in pastures increase with overgrazing, unwanted trees begin to dominate grazed woodlands. Desirable oaks often die, as numerous, minute feeder roots near the surface are trampled. Less valuable hickories, which aren't as affected by soil compaction, begin to appear.

Thorny honey locusts also increase. They are seldom eaten because of their thorns, but cattle will eat the honey locust seed pods and further spread this species in their manure.

Grazed woodlands lack seedlings to replace older trees as they die or are harvested, since seedlings and saplings are the first to suffer from grazing. Livestock damage protective bark and break limbs on healthy trees. Without replacement trees, woodlands eventually disappear.

Woodlands supply neither the quantity nor quality of forage that grazing animals require. Cattle are grazers and prefer grasses and legumes for food, though they can be forced to eat plants they normally wouldn't choose, such as oak leaves.

Deer, and some other woodland animals, are browsers and eat a wide variety of woodland plants. A nip of oak leaf, a bite of annual broadleaf and a nibble of sumac for dessert is sufficient for deer. Woodlands are the "pastures" for browsing animals. Cattle are not efficient browsers.

Studies show that it takes 20 to 40 acres of woodland pasture to produce the quantity of forage supplied by one acre of grassland. Excessive weight loss, poor quality of meat and general stress affecting animal health results when livestock graze woodlands, due to distances traveled to obtain food requirements.

Healthy wildlife populations depend on healthy woodlands. Brushy ground cover provides annual weed seeds and insects for food. Protection from predators and weather is another important function of woodlands. Grazed woodlands become too open and park-like for wildlife. Hungry livestock consume everything from ground level to as high as they can graze. This removes food and cover that wildlife could otherwise use.

Fence and exclude livestock from woodlands. Livestock should be completely excluded from small woodlands. To take advantage of shade and protection from weather, exclude livestock from the main portion of larger woodlands, but leave enough woodland unfenced for these purposes, or consider planting livestock shelterbelts where they are needed. Planting stock is available from the Department of Conservation or through the Natural Resource Conservation Service (NRCS). Free technical assistance is available.

Fencing, like other major land improvement practices, costs money. Many Soil and Water Conservation Districts will share a percentage of the costs for fencing qualified woodlands. Check with Soil and Water Conservation District Supervisors and the County NRCS District Conservationist.

If fencing costs are a problem, consider electric fencing, which is cheaper and easier to install than standard fencing and will do an adequate job of keeping out livestock. Another option might be to use pastures with woodlands for hayland and graze fields not adjacent to woodlands. No fencing is needed for haylands.

The first step is to keep livestock out of woodlands. Once that is accomplished, woodlands can be managed for timber resources. For more information about managing woodlands, contact the Department of Conservation or the Natural Resource Conservation Service.

Joe Garvey is a district forester for the Missouri Department of Conservation.