Got Nature? Blog

When biologists and land managers talk about managing native warm-season grasses (NWSG) they are really talking about managing early-successional plant communities. Early-successional vegetation (i.e., stands of annual or perennial grasses and forbs [broadleaf plants]) provide benefits for a variety of game and non-game wildlife species. Songbirds, northern bobwhite, and ring-necked pheasants use these areas to build nests and raise broods in the summer and for escape and thermal cover in the winter. White-tailed deer also use these areas heavily for bedding, to hide fawns from predators, and the forbs provide deer with excellent nutrition during the summer.

Forbs mixed with grasses help prevent the grasses from falling over and laying flat during the winter.

However, as these stands age their value to most wildlife species decreases drastically! Most stands of planted NWSG have little value, for species such as bobwhite, within 3-5 years of establishment. As the stands age, the tall perennial NWSGs (big bluestem and Indiangrass) become thicker; eventually crowding out all the forbs in the stand and creating a monoculture of grass. In the winter, the grasses fall over or “lodge”, as in the picture, and provide little to no cover.

Forbs mixed with grasses help prevent the grasses from falling over and laying flat during the winter.

This is why programs such as the Conservation Reserve Program require Mid-Contract Management (MCM) during years 4, 5, or 6 of the contract. MCM is aimed at maintaining or enhancing the wildlife value of NWSG stands by thinning the NWSGs providing room for planted and volunteering forbs to grow. These forbs act as supports for the grasses, helping them stand tall all winter, attract pollinators and insects important to foraging songbirds and game birds in the summer, and provide seed throughout the winter. Additionally, thinning the grasses and providing more room for weeds or forbs to grow will make it easier for ground dwelling wildlife to move and forage.

If your stand of NWSGs looks like the picture above, the time to manage them is not now but 2 years ago! However, managing them now can be effective and you have some options!

For most early successional wildlife species, you want the field to be from a 50/50 to 70/30 percent mix of forbs and grasses (favoring forbs). The field should be split into portions and managed on successive years. For larger fields, split the field into 4-5 acres sections. If you have multiple fields on your property you can manage the whole field. The key is to ensure that some cover is left on your farm throughout the winter.

This picture gives you a “quail’s eye view” in a stand of native grasses and forbs with the ideal composition! Notice how the open space between plants and the bare ground would make it easy for a quail to maneuver and feed on insects or seed!

This picture represents the ideal composition of native grass stands; 50% or less of the stand is native grasses and 50% or greater of the stand is comprised of forbs.

September – March

Step 1. Burn or mow a portion of the field.
Step 2. Disk the same portion within a few weeks of burning or mowing the field.
By burning or mowing the field prior to disking, you make it easier for the disk to cut into the soil. The field should be disked so that a majority of the plant debris is worked into the soil and the soil is exposed.
Disking from September through March will result in a more beneficial plant composition than disking in the spring or summer.

May – June or August – September

Step 1. Just after winter and prior to spring green-up (late March or early April) the field should be burned to prepare the field for management. This step is not necessary but can improve the herbicide application. If applying herbicide in Aug-Sep, mowing or burning the field 2-3 weeks prior to application can be beneficial.
Step 2. Apply 2 quarts/acre of glyphosate OR 24 ounces/acre of imazapyr (53% active ingredient) to the field or portions of the field where native grasses are extremely thick.
NOTE: Spot spraying problematic areas are always better than whole field applications, but sometimes whole field applications are warranted.
CAUTION: Imazapyr can harm desirable trees; avoid spraying imazapyr within the drip line of desirable trees.

These management options will reduce or “thin” the native grasses enough to provide forbs from the seed bank with room to grow! The field may look “messy” or “weedy” the first summer or two after application but that’s okay! Actually, it’s what you want! Most of the “weeds” that come from the seed bank provide excellent cover and food for a variety of wildlife species. Just be sure to control undesirable weeds such as Canada thistle, if they appear.

For more information on how to manage NWSG or other early successional vegetation, contact your local IN-DNR wildlife biologist or NRCS office.

Additional Resources:
Herbicides to reduce NWSG density, SEAFWA
Landowner’s guide to NWSG management, TRACE
Quail Habitat – Putting the Numbers in Perspective, The Education Store
Control of Canada Thistle in CRP and Other Noncrop Acreage, The Education Store

Jarred Brooke, Extension Wildlife Specialist;
Purdue University Department of Forestry and Natural Resources

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