The Backyard Forest
As a more in-depth article from the previous "Forest Habitat Gardening", this article is going to go over some of the basics of forest composition and forest maintenance.
Layers of the Forest
The decidious forests of Eastern North America are generally made up of various "layers" - The Canopy, Subcanopy, Understory, Shrub Layer and Herb Layer.
The forest canopy is the uppermost layer of the woods - Typically, the canopy is made up of tall, long-lived hardwood trees. In some forests in the Northeast and the Appalachians, there may be a conifer component of white pine, spruce and/or hemlock. Canopy species are usually the "Climax" forest species - These are the tree species that dominate in old-growth forests in the region. In Second-growth forests, which are forests that have grown back since the land was first cleared, faster-growing pioneer trees make up the canopy, with climax species more common in the sub-canopy.
Like the canopy, the subcanopy is usually made up of long-lived trees - These trees will often be saplings of climax trees, or they can be shorter-growing, shade-tolerant trees such as elms. When a canopy-layer tree dies, a subcanopy tree will usually take over the open spot.
The Understory layer is comprised of lower-growing trees, as well as saplings of the canopy trees. The understory layer is usually the most floriferous, with trees such as flowering dogwood, witch hazel and redbud.
The Shrub Layer
Shrub layers are variable in woodlands - They mostly exist in mesic (moist) conditions and more open woodlands. In drier woodlands, the shrub layer will be nearly non-existant; in mesic forests, shrub layers may be very lush and thick. Shrubs are, in general, much shorter than even understory trees, growing around 6-10 feet tall. Common shrubs in the deciduous forest are bladdernut, spicebush, viburnums and hazelnut.
The Herbaceous Layer
The Herbaceous layer is usually the most species-rich component of the forest. Made up of ferns, mosses, grasses and wildflowers, the groundcover layer is usually very diverse. Some of the more common plants in the ground layer are trilliums, bluebells, trout lillies, and asters and goldenrod. Often, the bulk of the plants will disappear by summer as the canopy leafs out; however, there are some wildflowers that will persist throughout the summer. Careful planning will help the forest look less "empty" in the summer months.
Planting Your Forest
When planting, aim for a good mixture of tree species, blending canopy and subcanopy species. For canopy and subcanopy trees, an initial 8x8 foot spacing is ideal, as it keeps trees close enough to prompt upright growth. Space the trees somewhat randomly so they aren't perfectly lined up in rows, and make every 4th or 5th tree a subcanopy tree. In between the trees, plant understory trees and shrubs. Using RootMaker Plug Seedlings, within 3 years, you'll have a dense forest that shades the weeds out completely.
Maintaining a Forest
As mentioned previously, there isn't a whole lot of maintenance in a forest garden. Some pruning may be necessary at first to keep trees growing straight - Remove dual leaders on tree saplings, and remove any branches that form tight angles against the trunk, as these will cause problems with snow and ice as the trees get on in age.
One of the most important things to do when trees are first planted is to protect them from weed competition and browsing from animals. If you have a lot of deer, nothing short of a 5-foot tall wire cage will keep them away. In our area, rabbits are a huge concern, and any trees we plant have a tree tube around them. We prefer to use 2-foot tall tubes, as this keeps rabbits away while providing shelter when the trees are really young. A weed mat is a good investment, too, and we like to use our biodegradable fabric mat for this purpose. A 3-foot ring of weed-free soil will help tree seedlings grow quickly, and a little mulch is good to keep the mat held down.
Fertilizer isn't completely necessary, but fertilizing your plantings helps the trees grow quickly when young. A handful of rich, organic fertilizer around each tree is all you need - We like to use composted chicken manure here at the nursery. Most of the Epsoma Plant-Tone fertilizers work very well, and they are readily available at most retail garden centers.
With weed control, mulching and fertilizing, trees planted as RootMaker seedlings will grow 3-5 feet per year depending on species, and fill in within 3 years.
As trees mature, they will create their own mulch in the form of fallen leaves. Let the leaves stay where they fall - Don't bother raking. As the leaves decompose, they will add nutrients back into the soil, and the organic matter will make the soil rich and loose, allowing for shrubs and wildflowers to really flourish. Begin seeding or planting wilflowers in the 3rd year, once the branches begin to touch - If the trees were planted 8 feet apart, their branches should begin touching in 3 years.