grassland restoration network

By Pati Vitt, Lake County Forest Preserves

This is a post from Lake County Forest Preserve, Lake County Nature Blog. https://www.lcfpd.org/blogs/

Just as the COVID-19 pandemic was starting to grip the world, another global milestone was occurring: The United Nations declared 2021-2030 the “Decade of Ecosystem Restoration.” The official launch date coincides with World Environment Day on June 5, 2021. In an effort to ensure that both people and nature enjoy a sustainable future, it represents a worldwide strategy to stop and reverse habitat degradation across the planet.

According to the Society for Ecological Restoration, the gold standard result for an ecological restoration project is an ecosystem that’s on a self-organizing trajectory to full recovery from human activity. What does that mean? It means little to no human intervention or management is necessary to ensure the health and resilience of that ecosystem. However, there’s a lot of work to be done to set a degraded, or highly altered, ecosystem back on that path. When you visit a preserve and see large pieces of equipment at work, they’re often in use with an eye toward doing just that.

The intensity and frequency of restoration work required depends where along a spectrum a particular natural area starts. An area with low impact might be something like a remnant prairie, which will require little management except for the restoration of controlled burns or the reintroduction of native grazers such as bison (Bison bison). On the other end are those lands most in need of intensive restoration, like former agricultural fields. Generally, the more altered the landscape and the more human activity present there, the more intervention is needed.

In the Midwest, many farm fields have been engineered to increase crop yield. This is often done by changing the original hydrology of the habitat with drain tiles, so what was once a wetland becomes cropland. Drain tiles are perforated pipes laid below the soil surface, effectively lowering the water table to encourage root growth of planted crops.

As you might guess, drain tiles are a significant alteration of the original environment. This alteration means that restoration of former agricultural lands, such as the project area at Grant Woods, can be quite complex. Several steps are often needed, and each step requires decision-making.

One factor to consider is how recently the area was farmed. A field that lies fallow for a long time is referred to as an “old field.” The natural process of ecological succession might push the habitat toward one dominated by native plant species that are generalists. In other words, generalist plants can grow in many settings and aren’t very particular about habitat quality. When a farm field goes fallow, these native plants may disperse themselves into it from adjacent areas.

But invasive shrubs and trees can dominate an old field, as well. Invasive plant control can be the first step in a restoration. It may be accomplished with controlled burns, physical removal of woody invasive plants, herbicide application, or all of the above. If only herbaceous (i.e. plants with non-woody stems), invasive species are involved, you might plow the field to allow new native seed to establish rapidly. If invasive species are relatively sparse, as they might be in a newly fallow field, one strategy could be over-seeding the field with fast-growing, native grass species. Following seeding, crews would then selectively apply herbicide to reduce invasive species abundance and boost the success of the newly planted grasses.

Once those grasses are well-established, perhaps within a year or two from seed, the next step is to add herbaceous species such as goldenrods, asters and legumes to diversify the plant community. In the very early stages of a restoration—the establishment phase—continuing to control invasive species is critical. Frequent control measures will occur for about five years as native plants become well established. The intensity and frequency of control, though, will decrease over time.

Many farm fields have hedgerows that grow between them. Hedgerows may contain trees, shrubs and fences. They’re variably used to mark property ownership boundaries, control where livestock wander, or act as a windbreak. Removing hedgerows increases connections between fields. Depending upon the size of the trees, heavy equipment may be employed. One common piece of equipment called upon for this task is a skid steer with a Fecon mower attached.

The Fecon mower attachment is ideal for shredding and mulching woody material very quickly. Large areas of invasive buckthorn (Rhamnus cathartica) can be removed efficiently by this tool. The skid steer may be equipped with large wheels for versatile movement, or it could have tracks that reduce damage to the soil by distributing the weight of the machine over a bigger area. An additional way to avoid damage is to limit the use of a skid steer to times of year when the soil is very dry or when the ground is completely frozen.

At Grant Woods this winter, we’re removing invasive trees and shrubs, including buckthorn, box elder (Acer negundo) and white poplar (Populus alba), often confused for birch trees. Our end goals are to open up the tree canopy to encourage oak regeneration, and to support a diverse community of native shrubs and herbaceous species beneath the oaks that remain. We’ll plant additional trees and shrubs, which will provide habitat for birds and other animals. Once the restoration is complete, the project area will be continuous habitat.

As you can see, restoration projects are long-term endeavors, requiring detailed planning and execution to successfully set a natural area back on the path to recovery. Site history, current flora and fauna populations, hydrology, and more must be considered. Results will not reveal themselves overnight—plants take time to grow from seed, of course—but we’ll be here to document and share them as they happen.