Plantation Planning and Design
Think about how your reforestation project relates to short- and long-term landowner goals. Such goals might include producing income from timber, improving habitat for specific wildlife species, restoring a natural plant community, reducing soil erosion, improving water quality or enhancing the aesthetics of the land. Remember that many goals are compatible with each other, allowing a single forest planting to serve multiple purposes.
Planning reforestation activities begins with evaluating the planting site. Knowledge of potentially limiting site factors such as climate, soils, existing vegetation, topography, insects, diseases, animals and productivity potential will aid in selecting suitable species, preparing the site and prescribing post-planting management practices.
The planting design will provide specific details for the creation and management of a planting, including acreage, species, number of trees, layout of roads and fire breaks, nursery stock type, site preparation and planting method, spacing, arrangement and any post-planting maintenance. Before planting, develop a written reforestation plan and map to help clarify all these details and facilitate any modifications prior to planting.
Contact your local DNR forester for further information on reforestation planning. A plantation map can graphically display precise planting locations, species arrangement and access roads. The planting design is directly tied to the landowner's goals and the resources and capabilities of the planting site.
Learn more by viewing the video Green Side Up: Planting Plan.
Goals and considerations
Below are examples of goals and their associated design considerations.
- Match species with area market demands and opportunities.
- Provide equipment access for thinning, pruning and harvesting.
- Include harvest roads and fire breaks.
- Add species that will create future natural regeneration opportunities.
- Leave space around power lines, underground cables and gas lines.
- Avoid steep slopes and wet areas.
- Provide closer spacing of hardwoods to improve sawtimber quality.
- Enhance biological diversity and complement habitat in the surrounding landscape.
- Offer habitats that are in locally short supply.
- Choose species that provide preferred food for desired wildlife.
- Establish or expand travel corridors to connect habitats.
- Create irregular boundaries for more habitat options.
- Enhance "interior" forest habitat by planting artificial openings, such as isolated fields.
- Plant around existing "wolf" trees (large trees that have wide-spreading crowns and inhibit or prevent the growth of smaller trees around them).
- Leave frost pockets and odd corners unplanted to improve habitat variety.
- Leave wildlife openings.
- Leave grass buffer zones near streams to prevent siltation.
- Plant trees along contours to help control runoff.
- Leave drainage pathways covered in grass.
- Concentrate trees in "problem areas."
- Plant tree species in riparian zones that have a long life expectancy.
- Plant highly erodible upland fields to decrease runoff.
- Use a wide variety of species, including wildlife shrubs.
- Use non-row plantings, curved rows and irregular edges for more natural effect.
- Plant species with desirable fall color.
- Leave openings or islands of differing size/age trees.
- Retain landmarks and distinct features.
- Create or retain scenic views.
- Locate trails or roads to take advantage of scenic quality.
Tree species selected for reforestation must be compatible with the landowner’s management goals and biologically suited to the planting site. After determining the potential advantages and limitations of the planting site, select a species or combination of species that emphasize the advantages and overcome the limiting factors. Things to consider are:
- site requirements, especially soil factors;
- climatic suitability;
- potential growth rate on site;
- sunlight requirements;
- potential competition problems;
- potential for insect and disease problems;
- wood and fiber properties and potential markets;
- compatibility with other species;
- timber, wildlife, erosion control and aesthetic values; and
- individual tree species' characteristics.
Initial spacing will affect both the productivity and the management of a plantation. The choice of spacing will depend on the species selected, the product desired, the need for and intensity of intermediate stand treatments, the expected initial survival and the cost. Consider the relative advantages and disadvantages of wide and close spacing.
Wide spacing advantages
- Planting costs are less.
- Trees attain larger diameters and become merchantable sooner.
- Trees may produce greater quantities of seed/mast at an earlier age.
- Increased understory growth will provide wildlife food and habitat.
Wide spacing disadvantages
- Increased weed competition and maintenance.
- Reduced stem quality due to greater taper and longer branch retention.
- Increased fire hazard.
- Reduced erosion control.
Close spacing advantages
- Faster crown closure resulting in less weed competition and maintenance.
- Improved stem quality (straighter boles and small, self-pruning branches).
- Large wood volumes accumulate in early years.
- Greater number of trees to select from during thinning operations.
Close spacing disadvantages
- Increased site preparation, planting and seedling costs.
- Early timber stand improvement may be needed to reduce crown competition.
- Access during initial thinning operations may be difficult.
Height growth can be reduced at extremely high or low densities. Fortunately, the most commonly used tree planting densities fall within a range that does not reduce dominant tree height (Table 1).
Generally, for quality hardwood tree production, choose a closer spacing to encourage straight boles and small lower branches that self-prune easily. Hardwood plantings for wildlife purposes can use wider spacing to encourage crown development and earlier seed production. Note: Plantation spacing requirements may be specified by some cost-sharing and tax law programs.
Planting arrangement refers to the pattern or distribution of tree and shrub species across a planting site. The arrangement of species may be varied to match topographic features, changing soils or site conditions. For example, a mixed hardwood plantation may concentrate black walnut seedlings on the deeper topsoils of the lower slope and place red and white oak seedlings near the ridge tops and convex slopes. The arrangement should also consider the growth characteristics and compatibility of species planted next to each other. For example, due to the fast juvenile growth of green ash, an alternating pattern with white oak may result in suppression of the oak. One solution is to group the species within the planting to minimize problems associated with very different juvenile growth rates.
Recently, conifer and hardwood mixtures have been recommended for afforestation in Wisconsin. The benefits of these conifer-hardwood mixtures include:
- conifers assist in early crown closure and capturing the site;
- cost of plantation establishment is less than for a pure hardwood plantation;
- conifers improve the quality of hardwoods by shading out lower branches and forcing hardwoods to grow straight; and
- conifers provide wind protection and offer an easy alternative for a first thinning.
One disadvantage to this mixture is that once established the options for chemical release of the plantation are more limited than pure conifer plantings. Initial site preparation treatments are critical for successful conifer-hardwood plantations. In addition, alternate row plantings may necessitate the removal of all conifers during the first thinning, unless other thinning methods are designed into the plantation.
Interplanting is the practice of planting new seedlings "between" or "among" existing forest growth. Sometimes forests fail to regenerate as expected after a harvest and interplanting provides a way to supplement natural regeneration. The planting arrangement in this situation will depend on an evaluation of the number, size and spatial distribution of desirable advanced reproduction. Do not forget to factor in the contribution of stump or root sprouts to fill all or part of the reproduction deficiency. Interplanting is almost always accomplished by hand planting. Interplanted trees will be in competition with other vegetation so their success can be measured against the growth of dominant competing vegetation. Generally, larger sized seedlings (e.g. 2-0 or 3-0 hardwoods and 3-0 or transplant conifers) are needed to compete with the advanced reproduction and sprouts. These types of plantings generally require some type of release early in the establishment phase.
Planting stock age classes: What the numbers mean
Bare root stock is often sold using an age class designation, such as 1-0, 2-0, 3-0 or 2-1. The first numeral refers to the number of years spent in a seedbed. For example, a 2-0 designation means the tree spent two years in a seedbed. The second numeral refers to the number of years spent in a transplant bed. For example, a 2-1 designation means the tree spent two years in a seedbed and one year in a transplant bed (transplanting improves root development).
Direct seeding vs. seedlings
One of the initial planning decisions is whether to plant seeds or seedlings. Each method has advantages and disadvantages in terms of ecology, operation and expense.
- Less expense for conifer plantings or small areas.
- Quick establishment of tree cover to "capture" the site.
- Applicable on difficult terrain or shallow soils.
- Good root development with no transplant shock.
- More uniform stocking than a naturally regenerated stands.
- Improved hardwood stem quality in high-density plantings.
Direct seeding often is not successful, many times because of improper planning. Multiple factors influence seed germination, making careful planning critical in highly variable field environments.
- Necessity for intensive site preparation and follow-up weed control.
- Difficulty controlling stand density.
- Greater costs for hardwoods depending on the quantity of seed used.
- Small planting areas may be subject to heavy seed predation.
- Hardwood seed is difficult to obtain in most years and does not store well.
Proper seed collection, handling and storage are critical to establishing direct seeded plantations. Seed collected during an abundant seed year is usually higher quality, especially if mature seeds are collected just before or simultaneously with seed fall. Always consider seed source by collecting from quality trees that are within 100 miles of the planting site or from sources that have proven performance through genetic testing. Properly store, stratify and treat seed to maximize germination rates.
Seed source selection
Seed source is an often overlooked but critical component in a successful reforestation program. Selecting appropriate seed sources will improve the overall productivity of the plantation since the trees will be adapted to the environment of the planting site. Appropriate seed source selection will also reduce catastrophic plantation losses due to poorly adapted genetic material. Poorly adapted seed sources can survive and grow for many years, until an environmental event, such as an early frost or extremely cold winter, results in catastrophic losses.
Local seed sources (e.g. Wisconsin) are the most appropriate unless proven otherwise through genetic testing. For example, genetic testing has revealed that southern Ontario white spruce sources are well adapted to Wisconsin’s environmental conditions and also offer improved growth rates over local sources. Tree improvement efforts continue to examine seed source performance across Wisconsin in order to identify appropriate sources and seed zones (Figure 1). Advanced tree improvement practices include the establishment of seed production areas to facilitate the collection of seed from quality native stands, the establishment of progeny tests where individual families are tested and selected for high performance and seed orchards for the production of high quality seed with superior genetic potential.
Stock type selection
How the planting site will influence seedling establishment and early growth is important in selecting the best nursery stock type for a given situation. Consider the relative advantages and disadvantages of containerized vs. bare root stock in order to select seedlings that will meet the landowner’s goals and overcome any limiting factors of the planting site.
Containerized stock is usually less than 1-year-old and is grown, shipped and planted in a soil "plug" of peat, perlite (or vermiculite) and sand. Its use in the Great Lakes states has been restricted primarily to conifer seedlings, but recent advances in pot sizes have allowed some production of containerized hardwoods. Seedlings from containerized stock can be grown in six to 15 weeks. They have high survival rates, superior initial height growth, more uniform size and good plantability, especially on rocky sites where it may be difficult to open a large hole for bare root seedlings. In addition, these seedlings are less likely to experience transplant shock since the tree is planted in the rooting medium and the process makes more efficient use of seed. Finally, containerized stock extends planting seasons and seedlings can perform well on adverse sites. Containerized seedlings also are more resistant to heat and drying stress, so transportation and storage are less problematic. Containerized stock, however, is more expensive than bare root stock, more bulky to transport and handle, less able to compete with weeds, susceptible to deer browse, prone to frost heaving when planted on bare mineral soil and often smaller in size.
Bare root stock is seeded and grown in nursery beds for one to three years and may be moved to a transplant bed to improve root development. Conifer seedlings should have a 4-6 mm caliper and a 2:1 shoot/root ratio. Hardwood seedlings should have good lateral root development with a minimum of five primary lateral roots (>1 mm in diameter) for optimal seedling survival and growth. Advantages of bare root stock include lower costs, ease of transportation and storage, better weed competitor, less susceptibility to deer browse and faster root regeneration. Bare root stock, however, takes longer to grow, can dry out quickly due to exposed roots, is prone to root damage and deformity during planting operations and may require special planting considerations due to the larger seedling size.