Timber Stand Improvement

Timber Stand Improvement  For Beginners

By Lane Rumelhart

Timber Stand Improvement (TSI) can mean different things to different people. Ultimately, it depends on the goals landowners have for their timber. For some, the goal is to improve timber quality by focusing on higher-value trees to maximize economic return. For others, TSI is aimed at promoting wildlife habitat to diversify plants and attract a wider variety of species. Whatever the goal may be, TSI refers to a set of practices used to enhance the overall quality and health of forested areas. 

Approximately 8% of Iowa is covered by timber, which equates to about three million acres. Most of these forests are located along river corridors in the northeast and southeast parts of the state. Given the small amount of timber left in our state, TSI practices have become more important. Iowa’s forests face several threats, including invasive species, habitat fragmentation and development pressure. TSI can help negate some of these problems.

Where Do I Start?

TSI can be a daunting topic. Most landowners don’t have a degree in forestry and need help getting started. The first step an Iowa landowner can take is to contact their district forester. District foresters play an important role in helping manage, conserve and promote Iowa’s forested lands. They can help by developing management plans, providing technical assistance, giving direct TSI guidance, and even planting trees in areas where desirable natives are scarce. To find your forester, go to the Iowa DNR Forestry Page and click on the “Find your District Forester” section.

Making a Plan

People interested in getting their hands dirty can develop and implement their own TSI. One of the simplest and most effective TSI practices for landowners is invasive species removal. Often plants such as tartarian honeysuckle and autumn olive grow vigorously under a forest canopy, choking out young, native species. A cutting tool such as a brush cutter and a bottle of Tordon can go a long way in a day’s worth of work clearing out invasives. After you cut the plant, fully cover the stump with a light layer of Tordon to ensure the plant will not resprout. Ideally, invasive species removal should be done in the summer months for identifying plants and maximum herbicide effectiveness. It’s important to learn to identify these unwanted species before entering the field to ensure you are only removing non-native, aggressive plants. 

Removal of unwanted species isn’t the only thing you can do to improve the quality of your timber. The next step may be to look at your tree density. Any kind of thinning, pruning, girdling or removal should be done in late fall or winter. This timing helps reduce risk of pathogens, especially in oak trees. It also allows clearer visibility, and frozen ground helps prevent soil disturbance.

Thinning out timber can be physically and emotionally difficult. Some owners don’t want to remove large, mature trees. A healthy timber, once thinned through TSI, should have somewhere between 60 to 100 trees per acre. Most of Iowa’s timbers can produce healthy stands of desired species such as oak and walnut. Owners with an overabundance of mature trees have some options. For the sake of simplicity, let’s focus on oak trees. 

Evaluating Timber

Some oak trees are better producers of acorns than others. If possible, pay attention to the mast these trees produce each year. Some white oaks can produce every year, while most species of red oaks will produce once every few years. Identify your desired oaks, then look at what surrounds them. Trees within 15 to 20 feet of another tree’s trunk likely can be removed or girdled. Elm, hackberry, ironwood, locust, cedar and basswood trees are commonly found growing and competing with oaks. These trees can be removed. This will help sunlight reach the forest floor, allowing better growth of natives. It also will reduce the number of plants fighting for subsoil moisture and nutrients. 

It’s more challenging when several oak trees are packed tightly into a small area. In this scenario, envision multiple mature trees all around the same age. In the realm of TSI, less is more. Identify the most desired oaks (typically the white oak family) and remove the others. This will result in better mast production, more light hitting the forest floor, and overall improvement of timber quality. These trees don’t have to be wasted. If conducting a large TSI project, a logging company may be interested in taking the logs, and even reimburse you for some of the board feet hitting the ground. If nothing else, you could end up with a fresh supply of firewood. If you have areas with better age diversity, it is better to leave a good mix of age classes. This will ensure future generations of timber.

Diversity

Species diversity is important. Owners wanting to take on their own TSI project should study native trees and be able to identify species on their property. It is never a good idea to completely wipe out a native species from an existing piece of timber. Owners also should not be solely focused on removal, but rather introduction of trees to areas being improved. If an area is cleared of invasive species, there may be few trees growing and a need for supplemental plants. Trees planted from a pot will need to be watered a few times for a better chance of survival. Bare root seedlings often are sold in a dormant state and can be planted in the fall with minimal maintenance, and have a higher success rate. 

Almost all of Iowa’s timber fragments could benefit from TSI. Many resources are available, such as the district foresters mentioned earlier. You also can reach out to your local USDA/FSA office to ask about financial assistance and other programs that may benefit your property. There are many private foresters who offer services mentioned earlier in this article. You also can search helpful videos online that show safe and ethical TSI practices. 

Whatever steps you decide to take, prioritize safety and bring someone along to help you. TSI work can be dangerous and should be well planned in advance of putting boots on the ground. Whether your goals are to improve the economic value of your trees or have better habitat for wildlife, familiarizing yourself with TSI practices will benefit you, your timber, and generations to come.