Our national forests

by Richard H. D. Boerker

Seed extraction is usually done most economically by experienced Forest officers. It requires drying by exposure to natural or artificial heat to open the cones; threshing to separate the seed from the scales and woody portions of the cone; and cleaning or fanning to remove chaff and dirt. Much of the extraction has hitherto been done in small quantities at a large number of stations and with very simple home-made appliances. In view of the large amount of seed which must be handled each year the cost of extraction has been materially reduced and seed of higher average fertility has been obtained by concentrating the major part of the work at central seed-extracting plants equipped with improved machinery.

A problem of great importance from the standpoint of final results is that of having seed available at the season of the year when it is needed. Past experiments have shown that fall sowing is essential to success in most parts of the West where extensive seeding projects will be conducted. Experience has also shown that seed on a large scale cannot be extracted in time for use in the same season. Moreover, every year is not a good seed year, so that Forest officers must take advantage of the good years to collect large quantities and store them for use during years of seed shortage. Purchased domestic or foreign seed cannot be used to advantage to make up these deficiencies because it is sometimes of poor quality and not adapted to the climatic conditions in which it must be sown. For these reasons methods had to be devised for storing large quantities of seeds for several years at a time and in such a manner that their vitality would not be impaired. Many storage tests have been made by the Forest Service to determine the best way of storing seeds. The tests showed that the sealed glass jar is the best container and that seed must be stored either in air-tight receptacles or at low temperatures to be kept for any considerable period without loss of fertility.

Probably the greatest obstacle encountered in reforestation by direct seeding is the destruction of the seeds by rodents. The failure of many direct seeding projects has been due primarily to loss from this cause. Failure has occurred on areas of practically every character regardless of the time of the year the seed was sown. Success has been encountered only where recent burns had largely eliminated the animals either by outright destruction or by the loss of food supply. The rodents which are most destructive to tree seeds are the ground squirrels, the chipmunks, the mice, and the gophers. It is not strange that they should seek out the seed that has been carefully sown by the Forest officers. In many cases these seeds are their natural food and they are wonderfully diligent and expert in searching it out.

In coöperation with the Biological Survey, the Forest Service has worked on the problem of destroying the rodents. Many methods have been tried out in the field. The free use of grain poisoned with strychnine has thus far produced the best results and has reduced the loss from rodents sufficiently to secure satisfactory germination. The successful elimination of such injury appears to lie in the thorough poisoning by this method of areas to be seeded, once or oftener in advance of sowing.

With successful germination assured by the collection of good seed and the protection of it after it has been sowed from rodents, the next problem lies in cheap methods of cultivation and sowing. This will enable the young seedling to develop its root system early enough and rapidly enough to withstand the first annual drought, the dominant feature of the climate of all the western National Forests.

Figure 25. One of the large Forest Service nurseries where the young trees are given the utmost care before they are large and strong enough to endure the rigorous climate of the National Forests. McCloud Nursery, Shasta National Forest, California.

There are numerous methods used in sowing tree seed on the National Forests. Three general methods are used in most of the work. Broadcast sowing is practiced in the fall and spring or upon the snow in the winter, both on ground that has not been prepared and on soil that has been scarified by rough brush drags, harrowing, disking, or partial or complete plowing. In seed-spot sowing the seed is planted at regular intervals in small spots where the soil is cleared of vegetation and worked up loose to a depth of from 5 to 6 inches. When corn planting or dibbling is practiced the seed is thrust into the soil by a hand corn-planter, or, in the case of large nuts, pressed into holes made with a pointed stick. The corn-planter method is often combined with the preparation of seed spots or the plowing of single furrows, in order to plant the seed in loose soil free from vegetation.

On a large majority of the Forests broadcast seeding on unprepared ground has not succeeded. As a rule satisfactory stands have been secured from broadcasting only after an expensive preliminary cultivation which would be impracticable in extended operations and which would exceed the cost of planting with nursery stock. But broadcasting on prepared strips and upon recent burns has given some success. The seed-spot method has been most successful if done at the proper season. Late summer and early fall sowing has produced better results than sowing in spring or winter. As a whole direct seeding has not succeeded, especially when the results and costs of the work are compared with the planting of nursery stock. Planting has thus far yielded better results, especially on the less favorable areas. Furthermore, from the standpoint of final results attained, planting has actually been cheaper than seeding, in spite of the greater initial cost of planting. While the major emphasis in reforestation work is placed upon planting, considerable seeding is being done, but it is confined to the most favorable localities and sites.

Planting on the National Forests. Reforestation by planting young trees has received much attention during the last few years principally because it has produced better results. Much still remains to be said for both methods and future experiments alone can decide which method to use in a specified region and under given conditions of climate and soil. Usually direct seeding has been tried first in any given locality where reforestation work was to be done. In fact the policy of the Forest Service in artificial reforestation on the National Forests has been, first, to conduct experiments to find out what can be done and what is the best way to do it; second, to reforest by direct seeding wherever this is feasible; and third, to plant nursery seedlings where direct seeding has been found too uncertain.