1. Silvicultural systems and biological nitrogen fixation.- 2. Morphology of nitrogen fixers in forest ecosystems.- 3. Taxonomy and distribution of non-legume nitrogen-fixing systems.- 4. Isolation and culture of nitrogen-fixing organisms.- 5. Biochemical, physiological and environmental aspects of symbiotic nitrogen fixation.- 6. Analysis of nitrogen fixation.- 7. Agricultural and horticultural systems: implications for forestry.- 8. Nitrogen fixing plants in forest plantation management.- 9. Nitrogen fixation in North American forestry: research and application.- 10. Application of biological nitrogen fixation in European silviculture.- 11. Nitrogen fixation in Southeast Asian forestry: research and practice.- 12. Biological nitrogen fixation in forestry: research and practice in Australia and New Zealand.