Grassland disturbance helps reinvigorate plots of land for birds
By Ben Beaman, Pheasants Forever Michigan State Coordinator
Management of invasive and undesirable species in a restored grassland is complex but doable and something I plan to discuss in subsequent articles. But today, we’ll discuss succession and how to manage it.
Succession is the process by which the plant species makeup of a given plot of land changes over time. The classic process starts with a bare dirt field, which immediately grows up with short-lived annual grasses and forbs.
These annuals are quickly outcompeted by perennial grasses and forbs, which are, in turn, outcompeted by brush and small trees, which grow into bigger trees that shade out the ground and eventually become a mature forest. This process governs all ecosystems, in one way or another, and is something to consider no matter what habitat you manage.
But grassland management aims to maintain the cover in the early stages of succession before brush and trees start to creep in and shade out your grasses and wildflowers.
Fortunately, there is an antidote to succession, and it’s called disturbance. Disturbance is any event that causes an area to move backward in the succession process.
Disturbance must occur every three to five years to maintain a healthy grassland. The primary disturbances habitat managers employ to keep their grasslands from becoming woodlands are mowing, disking, grazing/haying and prescribed fire. Grazing and haying don’t apply to most landowners. The other three are more attainable, so here are the pros, cons and considerations.
Mowing is the easiest method of achieving succession in a restored grassland, but it’s also one of the least beneficial. On the plus side, it does an excellent job of knocking back invading brush, is relatively cheap and efficient, and most landowners either own or have access to a brush-hog type mower capable of completing the task. The main downside of mowing is that it does a poor job of killing invading brush, and those plants will quickly regrow. For this reason, mowing often needs to be paired with a targeted application of herbicide to brush and tree stumps after cutting.
Glyphosate (Roundup) can work during the growing season, but a more potent chemical like Triclopyr (Garlon) is more effective. Be careful with this stuff, though. It kills just about any plant it touches, including the ones you want to encourage. Mowing also leaves all of the duff (chopped-up bits of old vegetation) in the field, making it harder for chicks and other small critters to navigate at ground level. For this reason, I usually view mowing as a backup plan when one of the following two options doesn’t come together.
Light disking is the next best option, particularly in a more mature grassland where the grasses have started to outcompete the wildflowers.
Disturbing the roots and soil of your established grassland stimulates the wildflowers, allowing them to return more prominently in the stand. Unfortunately, disks are more specialized equipment that not every landowner can access. And disking can also make certain noxious weed species angry and come back stronger — specifically Canada Thistle. If this happens, you’ll need some targeted herbicide to help control it.
Prescribed fire is unquestionably the best and definitively the least-utilized method for maintaining restored grasslands. The warm-season grasses and wildflowers planted in most grassland projects are all fire-adapted and rebound quickly from a burn because their primary growth point is located at or below the soil level, and their deep root systems store energy reserves far below the soil surface where they are safe from the flames. Most undesirable species don’t have this benefit and are killed outright in a well-managed fire, particularly if you time your burn appropriately. Spring burns can hammer brush species and undesirable cool-season grasses because those species invest a lot of energy in above-ground leafy growth at that time. Summer and early fall burns tend to invigorate wildflower species and are a great option if more flowers are your objective.
Fire also opens up the understory for all small critters to move about freely and stimulates the growth of the good grasses and wildflowers you want to encourage.
The reason fire is under-utilized as a grassland management tool is obvious: fire is scary. The idea of lighting your property on fire terrifies most landowners, and understandably so. But if you plan your grassland project with prescribed fire in mind, it can be conducted safely and efficiently with little threat to the surrounding area. The Michigan Landowner’s Guide developed by MI DNR has a chapter about prescribed fire in the grassland management section. Google it, and then bookmark it! It’s an invaluable tool for MI habitat managers. It details how to plan and establish firebreaks, weather and environmental factors, basic fire behavior, how to write a burn plan and even which local authorities to contact beforehand.
I highly recommend building firebreaks into your grassland restoration plans even if you don’t think you’ll likely use prescribed fire as a management tool. Plans can change down the road, and incorporating these into your design now will give you the flexibility to burn later if you ever change your mind. And if using prescribed fire to manage grasslands is something you are interested in, I strongly advise that you enlist the help of a trained professional.
Your local Pheasants Forever chapter likely knows qualified contractors or has experienced members with the necessary training to help you plan and conduct a safe and efficient burn.
Grassland management is a long-term commitment, but it’s worth the effort. Succession WILL spoil your efforts if you let it, especially in a state like MI where just about everything wants to be woods. Targeted disturbance, planned well ahead of time, will allow you to maintain a healthy, productive grassland for years to come.