Tree Stand Improvement or Forest Thinning
Tree stand improvement (TSI) is a very common forest management practice used to restore the overall health, species composition and openness of a forested community. During TSI operations, undesirable tree species or poorly formed trees are cut and removed in order to concentrate growth and facilitate health and longevity to the remaining desirable trees, primarily oak and hickory species. The highly nutritious oak acorns and hickory nuts are a valuable food source for many species of birds and mammals. Even the leaves, twigs and sap are utilized for food by many insects and other invertebrates. It is now known that oak species collectively support more than 500 species of butterflies and moths alone, more than any other native plant in the United States. Cavities in the trunk can also provide den, nest and roost sites for many other wildlife species, including raccoons, squirrels, woodpeckers and owls. Oftentimes during a TSI operation, a few standing dead trees (snags) and den trees are left in the forest to support wildlife populations.
Historically, periodic natural disturbances such as fire and prolonged droughts helped maintain Missouri’s forests and woodlands as relatively open oak dominated communities. However, fire suppression, urban development and other human-related disturbances in the modern era have significantly altered tree composition and overall forest structure of much of Missouri’s forested landscape. Within just a few decades, fire suppression alone can lead to an overstocked canopy, resulting in a dramatic decrease in sunlight reaching the forest floor. Ultimately, this is an unstable condition. Oak seedlings require ample sunlight to grow into the forest canopy, while less desirable and valuable tree species such as maples, elms, ashes and many non-native species are tolerant of more shaded conditions and often become much more abundant, further reducing oak regeneration. This modern shift in species composition and structure is clearly evident throughout the forested nature reserves in the park.
Through careful selection during the TSI process, we are providing increased space, light and nutrients to support strong and healthy oak woodlands. To help support and speed up the restoration process in Forest Park, hundreds of oak seedlings (as well as other native forest species) are planted each year. These supplemental plantings will help foster oak regeneration and encourage a sustainable forest system for years to come.