The Handbook of Vegetation Science is growing. After the first volumes und er my editorship have appeared the interest of the scientific community has been revived and many new volume editors have started their work. The present volume wasjointly designed by Drs. J. White and W. Beeftink. Due to unforseen developments Dr. White signs now as the sole editor. The development of this volume within the series had a special history as Dr. White pointsout in his preface. Adding to this I need only to state that I found it essential to include the topic of this volume into a Hand book of Vegetation Science. lt was included therefore in my first revised Iist of topics to be included in the Handbook when I took over from Dr. Tüxen. It is a great pleasure for me to see this volume appear. Having read through the many contributions to this volume I can certainly congratu late Drs. White and Beeftink for their success in generating so much interest in this volume among their colleagues. The cooperation on this volume is forme the first sign that the new concept of the Handbook has been understood by the generation of scientists which I have to address. The influence this volume will have on the field ofplant population studies only time can teil. It appears to me, however, that this volume will become a standard resource for some future. Dr. White asked me to have this volume dedicated to Dr. Rabotnov.