Book Review

Abstract

Renée 1997. The soil seed banks of North West Europe: methodology, density and longevity. 276 pp. Cambridge University Press, Cambridge. ISBN 0-521-49519-9 (hardcover). Price: USD 120.-.Seed bank dynamics offers highly valuable information for researchers with an interest in plant population ecology. Work in this area is extensive and based on a variety of methods which makes it difficult to generalize and draw valid conclusions. The authors of this book have completed the huge task of putting together the results of seed bank studies for 1189 species belonging to the northwest European flora. The book consists to a large extent (80 %) of a very comprehensive data base which is elucidated by four chapters with background information and discussion on seed-ecological items. The data base comprises 21 071 records from 275 publication. It is not only available in the printed version but also provided on an enclosed 3.5 inch disk.Chapter 1 explains how the data base was built up. It also deals with the problem of classification of seed banks as regards the longevity of seeds, and presents the classification criteria used by the authors. A key is given to the seed bank types employed, i.e. transient, short-term persistent, long-term persistent and present.Chapter 2 presents the principal features of the data with remarks on the origin of the publications used, the period covered and the methods used. Four summary tables present information on the number of species and records per seed bank type for each family, the top 100 species ranked by number of records, the top 25 species ranked by average density, and the top 100 species ranked by maximum longevity.Chapter 3 discusses the various methods of seed bank analysis in use, including seed separation methods, seedling emergence methods and sample size, volume and statistics. Standardized methods for seed bank sampling are proposed. Species in the data base are listed family-wise and in alphabetical order within families. Additional information includes authority, seed bank type, number of records, longevity, seeds/ m 2 (minimum, maximum and mean), depth of sampling, method code (seven categories) and source code.A critical remark concerns the restriction of the authors' approach in that the data base fails to take into account the differences between seed banks in arable land and those under natural vegetation. While the dichotomous key to the seed bank types works well when dealing with seed banks under natural vegetation, it does not do so in arable land. Characterizing persistence of the seed bank by comparing the frequency in different soil layers is not relevant if the soil is frequently ploughed or disturbed in another way. In addition, it is well known that frequent disturbance of the soil causes a faster turnover of the seed bank. So it is likely that seed longevity will be underestimated in such environments. Since more than 15 % of the data base refers to species of arable land this is an important issue.Another remark concerns the role of germination biolog...