Plan A: Direct Tree Seeding in Creek Valley

Summary

Controlling the Reed Canary Grass (RCG) with a combination of prescribed burning, herbicide application, mowing and tillage, followed by a direct seeding using nuts, acorns and seeds of a diverse mix of bottomland hardwoods and shrubs, supplemented by planting tree seedlings is the procedure we are using in this research area. This plan uses the techniques of a direct tree seeding, but with longer and more intense weed control to prepare the site, due to the competitiveness of the RCG. The area direct seeded with tree seeds in 2007 is about 1 ½ acres, and the tree seedlings will be planted in the spring of 2008 in this same area.

Details

A prescribed burn was completed in April of 2006 in Research Area A06. This removed a layer of thatch to make the herbicide application more effective. The site was sprayed with Sethoxydim herbicide in late May of 2006 to kill only the grasses, including RCG. Sethoxydim does not kill broadleaf plants or sedges. Using this selective grass herbicide gives the sedges and forbs a chance to return in areas were they are still present but suppressed by the RCG. These open areas will remain in this cover and add diversity to the creek valley. The areas where native sedges and forbs are no longer present were designated as tree planting areas. A second burn was planned for the spring of 2007, but a late winter flood deposited a layer of mud on the site preventing us from burning. In April of 2007, Box Elder trees were removed from the area to facilitate site preparation and direct seeding. Box Elder trees are native to Minnesota and are a pioneer species in old fields and former pastures.  However, they have little wildlife or economic value and when growing in a dense stand will shade out most understory growth, making the soil subject to erosion from flooding. All of Area A06 was treated with Sethoxydim herbicide in early June. Areas designated for direct tree seeding were mowed in late June and treated with Glyphosate herbicide in late August to kill all the plants in the areas to be direct seeded. The herbicide treatments appear to have killed most of the RCG. The site was mowed and tilled in mid September and direct seeded to a mixture of Burr Oak, White Oak, Swamp White Oak, Black Walnut, Butternut, Bitternut Hickory, Kentucky Coffee Tree, Ohio Buckeye, Chokecherry, Wild Plum, dogwood, Redbud, Ninebark and False Indigo seeds in late September and early October. Seed was thrown out onto the tilled ground by a person in the back of a trailer towed by a tractor. Refer to the Minnesota DNR Direct Seeding website for recommended tree species and seeding rates. We seeded 15 bushels of walnuts and 5 bushels of acorns per acre and lesser amounts of the other species listed above based on the site and seed availability. One bushel equals four gallons in volume. The larger seeds were disked in, followed by the smaller seeds and oats, and finished with a cultipacker. Warm wet weather allowed the oats to grow well, hopefully minimizing the affects of creek flooding. When tree seedlings become available in the spring of 2008, willow, cottonwood and Tamarack seedlings will be planted. Silver Maple seeds will be sown on the area when those seeds are ripe, in June of 2008.

Suggestions

If collecting your own seeds, prepare your seed storage early, as seed collection times can vary from year to year. We use a chest freezer modified with an override thermostat to convert it to a refrigerator and store the early collected seeds at 40 degrees. Oak, dogwood, Choke Cherry, Wild Plum and other early maturing seeds may need to be collected up to 6 weeks before the later maturing seeds are ready.  Since some of the larger seeds, including the walnuts, mature later but need to be planted first in a direct seeding, the earlier collected seeds will need proper storage.  Scout out seed trees ahead of time. When the acorns and later walnuts begin to fall, you will be in a race with deer, squirrels, lawnmowers and desiccation to gather seeds. Seeds need to be kept moist and cool to maintain viability. Soak acorns in cold water prior to storing to chill and hydrate them. If using a freezer modified to work as a refrigerator, set the thermostat at 60 degrees (or 10 degrees less than the temperature of the acorns if lower than 60 degrees) and lower it 10 degrees each day until you reach 40 degrees. This will allow the cold to spread from the walls of the freezer to the middle where the thermostat sensor is located without freezing the acorns next to the freezer walls. Look for the freezer/refrigerator override thermostat where wine and beer making supplies are sold.

We use a tool called a Nut Wizard to collect acorns, hickory nuts, butternuts and walnuts. The Nut Wizard saves considerable time and effort compared to picking by hand or raking and it is available in several sizes for various sized nuts. It works best on mowed areas, and we found a good supply of acorns and walnuts on lawns, golf courses and cemeteries. Most people are glad to give you their acorns and nuts if you pick them up.

If your planting is near an existing forest, squirrels may view your direct seeding as an easy food source. To avoid the loss of planted seeds, provide an even easier food supply by making several piles of walnuts around the edge of the planting. Hopefully the squirrels will take these and leave your planted tree seeds in the ground.