Preface

When people first cultivated trees, they walked the land, sowing seed the way they sowed crops. Later, as foresky became more sophisticated, seeds were germinated in nursery beds and seedlings transplanted to the field. This method required less seed, enhanced seedling survival rates, made tree growing more reliable, and gave trees a healthier start. Moreover, because the seedlings could be properly spaced, transplanted seedlings produced more-uniform forests and an increased growth rate.

Today, however, this planting technique seems not to fulfill all the demands for reforestation, especially in the poorer nations of the tropics and dry areas. In those regions, forests are being destroyed on an unprecedented scale. In 1973, for example, the annual rate of forest destruction in the Philippines was conservatively placed at 172,000 hectares, while reforestation was a mere 16,300 hectares. It was estimated that more than 5 million hectares of deforested land were then awaiting planting, of which 1.4 million were located on critical watersheds subject to serious erosion, and that reforesting just these denuded watersheds would take more than 60 years at the existing rate (Glory, A., cited in Dalmacio, M. V., and Barangan, F. 1976. Direct-seeding of Pinus kesiya. Philippine Forest Research Journal 1 (3): 215-222).

If even a fraction of such forest areas is to be restored, existing planting techniques should be supplemented with methods that require less organization, less infrastructure, less capital investment, and that enable rapid reforestation over vast areas.

One possibility may be the "primitive" practice of sowing seed directly on the site to be forested. This method is known to foresters as direct seeding, broadcast seeding, or broadcast sowing. The availability of chemicals for coating seeds to repel birds, rodents, and insects has made this a practical and more reliable method of reforestation.

This report discusses reforestation in which the seed is broadcast from a plane or helicopter. It relies mainly on experiences in Australia, New Zealand, Canada, and the United States. It is not a textbook nor a practical guide to aerial seeding: details of the operations and techniques can be found in the selected readings, Appendix B. Our purpose here is to show administrators and foresters that this fast and often economical technique can be successful on appropriate sites, at least in temperate climates. The panel hopes that the report will stimulate trials with, and research into, direct seeding (with or without the use of aircraft). In particular, trials are neededin the tropics where deforestation is most severe, to see if it can become a successful weapon in the war on tropical deforestation-a war now being lost.

Aerial seeding is unproven in the tropics. The panel's purpose is not to recommend it over conventional reforestation techniques but to suggest trials of aerial seeding as a possible supplementary tool.

The panel that produced this report met from November 7 to 9,1979, in Birmingham, Alabama, and Pineville, Louisiana, to examine pine forests that had been aerially seeded 20 years before. In Alabama, they toured mine-spoil banks once devoid of all vegetation but now densely forested as a result of aerial seeding. In Louisiana, they toured direct-seeded pine forests occupying former grasslands and cutover pine lands.

The panel members are indebted to Ivan Kronberg, Howard Baxendale, and J. E. Smith of United States Steel Corporation, and to Harry Murphy of Resource Management Services, Inc., for their hospitality and efforts in organizing the Alabama visit. The members are also grateful to the staff of International Paper Company and the T. L. James & Company, Inc., for conducting visits to their forests in Louisiana, and to Thomas E. Campbell of the U.S. Forest Service who coordinated these tours and made available the U.S. Forest Service photographs.

The final draft was edited and prepared for publication by F. R. Ruskin.

The Advisory Committee on Technology Innovation of the Board on Science and Technology for International Development, National Research Council , is assessing scientific and technologlcal advances that might prove especially applicable to problems of developing countries. This report is one of a series that explores promising areas of plant science that heretofore have been unknown, neglected, or overlooked. Other titles include:

· Underexploited Tropical Plants with Promising Economic Value (1975)
· Products from Jojoba: A Promising New Crop for Arid Lands (1975)
· The Winged Bean: A High-Protein Crop for the Tropics (1975)
· Making Aquatic Weeds Useful: Some Perspectives for Developing Countries (1976)
· Guayule: An Altemative Source of Natural Rubber (1977)
. Tropical Legumes: Resources for the Future (1979)
. Firewood Crops: Shrub and Tree Species for Energy Production (1980)
. The Potential for Alcohol Fuels in Developing Countries (in preparation)
· Producer Gas: A Little-Known Fuel for Motor Transport (in preparation)
· Vegetable Oils as Diesel Fuel (in preparation)

For information on obtaining copies.

These activities are supported largely by the U.S. Agency for International Development (AID). This study was sponsored by AID's Office of Science and Technology.