September 1987, the Faculty Biology of the Vrije Universiteit, Amsterdam commemorated the fact that Prof. Dr. Wilfried Hans Otto Ernst had been active as a scientist for 25 years. This period of 25 years of scientific research started at the Institut flir Angewandte Botanik (Institute of Applied Botany) of the University of Munster, FRG. In 1965 he completed his Ph. D. thesis, entitled "Untersuchungen der Schwermetallpflanzengesellschaften Mitteleuropas unter Einschluss der Alpen. " He was appointed full Professor at the Department of Ecology of the Vrije Universiteit, Amsterdam in 1973. On the occasion of his 25th anniversary as a scientist, a promise was made, though in covert terms, which we could not redeem at that time. The promise held to offer Prof. Ernst a book, in which his former and present staffmembers, Ph. D. students and colle ages should write a review about their specialism concerning a central theme. Now, at the beginning of 1990 we consider the chapters of "Ecological Responses to Environmental Stresses" to be completed. The book reflects the wide range of research approaches that has been initiated and organized by Wilfried Ernst. The editors hope to have attained the primary aim of the production of the book of friends, that is to gather relevant papers of staff-members and colleagues of Wilfried Ernst. The title of the book "Ecological Responses to Environmental Stresses" covers the majority of the chapters included.

1. Stress tolerance in plants - the evolutionary framework.- 2. Heavy metal resistance in higher plants: biochemical and genetic aspects.- 3. Free radicals and heavy metal tolerance.- 4. Physiological responses of higher plants to soil contamination with metals.- 5. Arsenic in water, sediment and vegetation of the Jales gold mine, North Portugal.- 6. Ecophysiological adaptations of higher plants in natural communities to waterlogging.- 7. Effects of inundation stress on salt marsh halophytes.- 8. Water as a stress factor in the coastal dune system.- 9. Natural and man-made environmental stresses in coastal wetlands.- 10. Economic uses of salt marshes.- 11. Occurrence and function of mycorrhiza in environmentally stressed soils.- 12. Contamination of coastal wetlands with heavy metals: factors affecting uptake of heavy metals by salt marsh plants.- 13. Population ecology of plant species in disturbed forest and grassland habitats.- 14. Ecological responses of macro- and microphytic algae to water pollution.- 15. Common reed.- 16. The impact of oil pollution on salt marsh vegetation.- 17. Effects of air pollution on plants and vegetations.- 18. Air pollution and reproductive processes in natural plant species.- 19. Developments and present status of terrestrial ecotoxicology.- 20. Global change, the impact of the greenhouse effect (atmospheric CO2 enrichment) and the increased UV-B radiation on terrestrial plants.- 21. The genetics and ecology of variation in secondary plant substances.- 22. Phenolic substances in forest leaf litter and their impact on plant growth in forest vegetations.- 23. Plant responses to human activities in the tropical savanna ecosystem of Botswana.- 24. Agricultural problems of saline arable land in Pakistan.- 25. Genetic variability inOrobanche (broomrape) and Striga (witchweed) and its implications for host crop resistance breeding.