Green Horizons

The greatest threat to our forests

By Brian Schweiss | MDC Private Land Forestry Programs

Photo courtesy of Brian Schweiss

Forest threats are everywhere shown here is a dense bush honeysuckle that is choking the life out of the forest.

Our abundance of trees puts many Missouri citizens at ease about the health and condition of our Missouri Woods. We tout their value in terms of beauty, soil conservation, homes for wildlife, and wood products. Spring woods turn green and then change to vibrant colors in fall for a season of growth, but unknown to many, our forests are in a perilous transition.

There are many threats to our forests that often go unnamed and undiscussed. Invasive plants are silently creeping through our native woods. If you knew what to look for, you could likely find invasive plants in woods near you. Many of our forests have become overgrown withbush honeysuckle and other exotic shrubs. The invasive plants become established in the understory of a mature forest and then proceed to choke out all other native shrubs and seedlings needed to repopulate our forests. Before you know it, you have overstory trees in decline because of age or other reasons and nothing in the understory to replace them. A great victory for bush honeysuckle and other invaders but a loss for the long-term sustainability of our native forests.

Timber harvests that do not take into account future forest conditions and needs are another threat. A national woodland owner survey indicates that 31% of landowners have had a timber sale. Yet only 3% had a management plan and only 16% of landowners had sought advice on woodland management. Twelve percent of landowners plan to have a timber sale in the next five years. Will they use a forester? Will they leave quality trees for future generations? Or will they harvest the best and leave the rest? Foresters call this last approach hi-grading and it degrades the forest ecosystem and results in a forest of less value over time.

Our forests are also at risk of being converted to other uses. This happens in many forms from the rapid conversion due to advancing urban occupation, to a slower conversion by unmanaged cattle grazing in the forest understory where no plan for regeneration exists and the site gradually converts to pasture.

While all of these threats are real and need to be addressed, the threat that trumps all others, the greatest menace to Missouri trees and woods is a silent killer. The greatest threat is contentment. Most people are happy with their woods. It gives them what they need with minimal action. But like Kryptonite to Superman, contentment leads to a slow, agonizing decline and death of trees and woods, an issue with foreboding consequences.

How can doing nothing be bad for trees? A forest was never meant to be static. It benefits from a certain level of disturbance achieved through careful management. Various wildlife species will respond favorably or unfavorably dependingon species and disturbance type. Lack of management and the overcrowding of trees that results can lead to several issues: Trees are more prone to insect and disease attacks; there is less food and cover for certain wildlife; trees grow slower; trees decline and die from overcrowding; tree species transition to less desirable ones.

Without disturbance, a forest will continue to grow, but it becomes over-crowded and trees will begin to die, sometimes individually and sometimes in groups. Over-crowded trees will also become susceptible to other stressors. Over time, a preponderance of shade tolerant species that have lower commercial and wildlife value will dominate the site.

Humans at one time were great contributors to disturbance. Native Americans burned the forests creating more open conditions for hunting and other purposes. Early pioneers harvested, cleared and abandoned land creating a series of disturbances. Unfortunately, many landowners today choose to do nothing which has serious future implications to the health and quality of the trees.

Missouri forests have rebounded from the massive harvesting of the early 1900s and the subsistence farming that followed. They have gone through a great period of regrowth and are reaching a point of maturity. A significant percentage of Missouri's woods are in excess of 60 years of age, with some more than 80 years. For some species, this is their life span. The era of growth in Missouri forests has been excellent, now it is time for the era of management.