TREE PLANTING

Trees contribute to their environment over long periods of time by providing oxygen, improving air quality, climate amelioration, conserving water, preserving soil, and supporting wildlife. During the process of photosynthesis, trees take in carbon dioxide and produce the oxygen we breathe.

In silviculture, the activity is known as reforestation, or afforestation, depending on whether the area being planted has or has not recently been forested. It involves planting seedlings over an area of land where the forest has been harvested or damaged by fire, disease, or human activity. Tree planting is carried out in many different parts of the world, and strategies may differ widely across nations and regions and among individual reforestation companies. Tree planting is grounded in forest science, and if performed properly can result in the successful regeneration of a deforested area. Reforestation is the commercial logging industry's answer to the large-scale destruction of old-growth forests, but a planted forest rarely replicates the biodiversity and complexity of a natural forest.

Because trees remove carbon dioxide from the air as they grow, tree planting can be used as a geoengineering technique to remove CO
2 from the atmosphere.

Determining Planting Objective(s)

Determining objectives for planting is important because it will often dictate the species and number of seedlings needed. Objectives for planting are numerous and varied and include:

Improving wildlife habitat-food and/or cover
Producing future timber/investment
Providing a privacy screen or windbreak
Restoring a woodland
Reintroducing a tree species
Controlling erosion/improving water quality
Reforesting an old field
Special uses such as Christmas trees, sugarbush, nuts, or energy crops

Try answering the following questions to help you determine your objectives:

What purpose(s) do you want the planting to serve?
Why do you want to plant trees?
With some thoughtful planning and decision making, the trees you plant will meet your objectives and provide numerous environmental benefits as well.

Assessing the Planting Site

Not all tree species are suited to all sites. Observing and learning about the planting site a year or more before planting will provide useful insights. Consider the following:

Soil type (drainage, fertility, and texture)
Periodic flooding
Amount of available sunlight
Existing plant competition
Exposure/aspect/orientation of the terrain (north and east slopes generally have better growing conditions, while south and west slopes are generally hotter and drier)

These site factors influence species selection. Some site conditions such as soil moisture, soil texture, and exposure are inherent to the site and not easily changed. It is important to select tree species that can thrive under given conditions. For example, aspen, black cherry, larch, red pine, and black walnut are shade-intolerant species. These trees will not tolerate even moderate levels of shade. If the site already has tree cover, shade-tolerant trees such as eastern hemlock, black gum, red spruce, or sugar maple would be better choices.

Soil acidity or alkalinity (pH) is another key factor in determining which trees will grow best on a given site. Most tree species prefer neutral or slightly acidic soils. Also important is soil structure. Soils that are too tightly compacted will resist root penetration, slow the passage of water and nutrients, and inhibit the free movement of oxygen and carbon dioxide. Hardwood (broadleaf deciduous) trees tend to grow best in loamy soils, a mixture of sand, silt, and clay. Many conifers do just fine in heavy clay or well-drained sandy soils and can tolerate dry southern exposures better than most hardwoods. As a rule, conifers can withstand adverse conditions better than hardwoods.

If a nearby but similar site already has trees, those trees may be a good indicator of the existing site and soil conditions and what species may do well on your site. For example, speckled alder does well on moist, heavy clay; sugar maple prefers fertile, moderately well-drained soils; and American sycamore prospers in periodically flooded soils along stream banks and in bottomlands.

Another way to determine the soil type on your site is to consult the U.S. Department of Agriculture's Soil Survey Maps, which are available at your local conservation district office or online. Soil samples can also be brought to your local Penn State Extension office where, for a nominal fee, they are sent out to assess soil fertility and pH.

Primary factors that limit tree planting success

Soil drainage: excessively drained or poorly drained
Existing competing vegetation: grasses, weeds, and invasive plants
Exposure/aspect: wind, sun, and shade
Wildlife: deer, bear, voles, and other small mammals

Selecting Tree Species

The likelihood of project success greatly improves with clearly identified planting objectives and a selection of tree species that meet objectives and are compatible with site conditions. The goal is to plant the right trees in the right location. In other words, plant tree species that will meet objectives and grow well under the given site conditions.

The choice of tree species for planting in the northeastern hardwood region is extensive. There are dozens of species to choose from. Since tree planting is somewhat permanent, carefully consider your choices. Selecting a diversity of native species that have no major pest problems and are adapted to the site is important. The use of exotic species is discouraged today because many have become invasive and now cause damage to native plant and animal communities. Because choosing the best tree species for a particular site is so important, consider seeking advice from a knowledgeable natural resource professional or forester before ordering.