Seeding
A Forest Regeneration Alternative

Another, and more common, form of artificial forest regeneration is planting tree seedlings. Both methods have advantages and disadvantages, depending on the particular situation. Either method offers the opportunity to introduce a new species on an area. When a site is currently occupied by undesirable species, the only way to convert the area is to eliminate the existing cover and replace it with seed or seedlings of desirable species.

Advantages of Direct Seeding

Lower Initial Cost

Easier To Use in Remote Areas

Root Systems of Trees are Natural

Timing Is Important

Sow longleaf pines in the fall (before mid-December) or in the early spring. Sow loblolly, shortleaf, and slash pines in mid and late spring. Generally, oak acorns are sown successfully at any time. One last advantage of direct seeding that relates to timing is the quick response following a fire, flood, or other natural disaster.

Disadvantages of Direct Seeding

Reduced Control of Spacing and Stocking

The opposite situation is also true, and survival may not be adequate to stock an area fully with trees. In this situation, supplemental seed sowing is required to get enough trees to occupy the site fully.

Either corrective measure costs money, and money saved in the initial costs could be lost. Even when survival rates are acceptable, the spacing of the trees is not as uniform as in planted seedling areas, and cultural operations throughout the rotation are not as easily accomplished, especially those requiring moving equipment across the area.

The problem of spacing is worse on steep slopes where seed are washed downhill after rainfall, resulting in loss of seed and highly uneven distribution. For these reasons, direct seeding is not recommended for steep slopes.

High Mortality in Droughty Soils

Longer Rotations and Lower Yields

Growing trees is much like growing most other crops in that the more money that is put into management, the bigger and better the final yield up to a certain point. However, a good crop of timber can be grown in stands that are started by direct seeding.

Appropriate Sites for Direct Seedings

The three types of areas where direct seeding has the greatest application are these: (1) remote or inaccessible sites (previously discussed), (2) poor or low productivity sites where growth of the trees would not make the cost of planting operations economically feasible, and (3) any area of land where a minimal investment is absolutely essential.

The last category is perhaps the most important because many private landowners cannot afford the cost of intensive site preparation and planting. It is better to direct seed these areas rather than to allow them to grow up "naturally," which usually results in mostly undesirable species and in brush taking over the area.

Species Selection

You must decide the goals of ownership first, since they control the choices in the other categories. If you want to grow pine timber, your list of choices is different from the landowner who wants to produce habitat for squirrels.

Geographic location and hazard potential basically state that the species should be matched to the site. Putting the species on the site where it grows best with the least danger of loss results in the most successful direct seeding efforts. This means you need a substantial amount of information on the site and the tree species, and you should get professional advice before starting.

Seed availability is the last, but not least, item to consider. You must purchase the seeds or collect and prepare them. Collecting seeds is a considerable job but not nearly as much trouble as preparing them. Pine seeds have to be de-winged, and oak acorns have to be de-capped and then the seed must be stratified. Stratification involves storing the seed at a certain cold temperature for an exact time period to promote germination.

After stratification, most seed need to be treated with an insecticide, fungicide, and animal repellent before sowing. Unless you are familiar with all these procedures, the best alternative is to purchase seed already treated and tested. The Mississippi State Forestry Commission can supply landowners with information on seed availability and purchasing procedures. After purchase, sow the seed as soon as possible. If storage is required, store stratified pine seed at a temperature between 25 and 40 degrees Fahrenheit. Store oak acorns at 35 degrees Fahrenheit.

Site Preparation

Second, some degree of competition control is highly desirable. Burning and disking reduce the initial amount of competing vegetation, although resprouting will certainly occur. If economically feasible, an application of herbicides is beneficial in areas where the competing vegetation is well established and hard to control. An added benefit from competing vegetation control is the reduced predation by animals on the seed. In areas with little competition control, small animals can eat nearly all the acorns that have been sown.

Sowing Seed

Sowing rates are influenced by various factors, including condition of the site, quality of the seed, method of seed distribution, and number of trees desired. Sowing seed by hand requires fewer seed but requires more labor and more time. A helicopter can seed 2,000 acres per day, and aerial work is the only practical way to seed areas that are inaccessible or where debris restricts ground movement. Most private landowners in the same general area can combine their work and employ aerial seeding services. Seed distribution from the air is referred to as broadcast work.

Another form of broadcasting is ground distribution with a cyclone seeder. Depending on the site conditions, one person can cover 12 to 15 acres per day. These cyclone seeders are adjustable to accommodate various seed sizes and result in uniform seed distribution across the area.

The other two forms of ground seeding are row seeding and spot seeding. Both of these methods require much less seed per acre than broadcasting. In row seeding, seeds are dropped 1 to 2 feet apart along parallel lines of travel across the area. This is slightly slower than broadcasting, since rows are usually 8 to 10 feet apart. If site conditions are unfavorable for survival, make your rows closer together to ensure better stocking on the area.

You can use spot seeding for pine and oak regeneration. In pine seeding, a fire rake is often used to clear a spot on the ground, usually 1 to 2 feet in diameter, and 5 to 8 seeds are dropped in the clearing. These spots are normally on spacings of 8 by 8 feet, but you can reduce the spacing for areas with poor survival conditions.

When spot seeding acorns, the rule of thumb is to allow 30 square feet per acorn or to sow about 1,500 acorns per acre. A spacing of 3 feet between acorns in the row and 10 feet between rows has shown good results. Since the acorn needs to be covered with soil, a metal bar or even a sharp stick should be used to make a hole in the ground for the acorn. For best results for most oaks, make holes consistently 2 inches deep. You might want to construct a hand device to make holes of consistent depths. The USDA Forest Service personnel at Stoneville, Mississippi have developed a hand tool that makes holes of a consistent depth. An added advantage to their tool is that you do not have to bend over to put the acorn in the hole.

Table 1 gives critical information on the seed and sowing rates for the major southern yellow pine species. These rates are average recommendations, and you can modify them to meet different stocking requirements and site conditions.

Table 1. Recommended sowing rates (Campbell, 1982)

Safety

Evaluation of Seeding

Regardless of the number of sample plots used, remember to distribute the plots evenly across the entire area. Map out a grid system before sampling, and locate plots according to the grid system.

Sample plots should be mil-acre (1/1000 of an acre) size for broadcast areas. This is a circular plot with a radius of 3 feet 8.7 inches, which can be measured using string from a center point or making a permanent plot by bending some stiff wire into a circle of the appropriate size.

Twenty-five is the minimum number of plots for any seeded area. On large areas, one plot per acre has been used successfully. During the inventory, count the number of seedlings in each plot and record the data separately for each plot.

To get the number of seedlings per acre on the area, a two-step procedure is involved:

1. Get an average number of seedlings per plot by dividing the total number of counted seedlings by the total number of plots.
2. Multiply the average number of seedlings per plot by 1,000 = average number of seedlings per acre.

A successful seeding operation is one that results in 1,000 to 3,000 seedlings per acre with 55 percent stocking rates. If the inventory indicates fewer than 1,000 seedlings per acre, or 55 percent stocking, wait until the end of the second growing season and take an intensive inventory before reseeding or planting. Areas with more than 2,500 seedlings per acre at the end of the first growing season should be resampled at the end of the third year to determine if a precommercial thin is necessary.

Row seeding and spot seeding require different sampling approaches for best accuracy. The mil-acre method may be used with confidence if enough samples are taken.

Summary

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Publication 1588
Extension Service of Mississippi State University, cooperating with U.S. Department of Agriculture. Published in furtherance of Acts of Congress, May 8 and June 30, 1914. RONALD A. BROWN, Director