Forest inventory in theory and practice
Forest inventory, by F. Loetsch, F. Zöhrer and K.E. Haller. Vol. 2. Translated from German into English by K.F. Panzer. Munich, BLV Verlagsgesellschaft, 1973. 493 p., 153 illustrations, 53 tables. DM 195.
The increasing need for faster, more reliable and detailed information about large forest areas, combined with progress in aerial photography, statistical knowledge and electronic data processing have brought about rapid advances in forest inventory in the past 20 years. The authors began a challenging, comprehensive treatment of this subject with Volume 1 of Forest inventory in 1965. It dealt primarily with the use of statistics and aerial photo-interpretation in forest inventory. Volume 2 picks up from there.
The outstanding feature of this book is its well-balanced combination of condensed theory and indicative examples. It reflects the long and varied experience of the senior author and his co-workers both in research and in field work in temperate and tropical forests. For the same reasons the authors are in a position to point out the details which may seem trivial but are fundamental for proper inventory work, for example, correct diameter measurement or strict avoidance of biased observations and recordings. Another noteworthy feature of this book is that appraisal problems involving social benefits of forests are well treated. The authors thus succeed in presenting forest inventory in theory and practice as an indispensable tool for solving in the broadest sense complex problems of management and utilization of forest resources. For all these reasons this work is likely to become a widely used standard reference for professionals engaged in research, teaching and field operations.
Volume 2 begins with a treatment of inventory data collected by terrestrial measurements and observations. Principles and units of measurements are explained and accompanied by some useful conversion tables. A summary of instruments and methods of terrestrial surveys and area determination is followed by a short, well-presented section on tree species identification, one of the key problems in tropical forest inventories. When dealing with methods, problems and instruments for diameter and basal area measurements, recent findings expressing diameter distributions by mathematical functions are emphasized. Opportunities offered by angle-count instruments and other optical measuring devices are also described in detail. How to measure bark and height, as well as volume of stumps, stands and higher area categories are included.
The section on assessment of timber quality and value in temperate and tropical forests is a comprehensive summary of present knowledge in this extremely difficult and complex sector. It points to the need for further research. The presentation of basic aspects ends with considerations regarding determination of time-intervals in forest inventories, such as age, time required for passing through diameter-classes, or age of stumps for assessing former wood-removals.
The book presents some relevant methods and techniques for calculation of growing stock and determination of its increment, an area of fundamental importance for management and general forest sector planning. The authors also deal with the increasingly important forest inventory objective of providing information about forest sites, past removals and prediction of future cuts, infrastructure, accessibility of the surveyed areas and collection of data for characterizing nontimber benefits of forests.
A chapter on data processing provides an easily understandable, comprehensive review of basic principles and present techniques for this important, complex and fast-growing field. The need for further work on simulation and operations research is underlined.
Almost one quarter of Volume 2 is devoted to a discussion of problems of forest inventory methodology. The determination of type, size and shape of sampling and record units and the special cases of borderline units are explained in detail. The presentation of principles and methods for the application of point-sampling, distance methods in regeneration surveys and methods of sampling with probability proportional to size (PPS-sampling) or proportional to prediction (PPP-sampling) is well and clearly written.
The description of relatively new methods of list-sampling with unequal probabilities and use of a-priori-lists and a-posteriori-lists is of specific interest for those concerned with temperate forests where there is a long management tradition, and a good knowledge of stand structure.
The concluding chapter is a synopsis. It summarizes the criteria to be observed when planning, conducting, controlling and evaluating forest inventories. It is of particular value for those actively engaged in field work. Much experience gained by organizations dealing with large forest inventory operations, such as FAO and certain government forest services, has been incorporated.
EBERHARD GÄRTNER (Hessische Forstliche Versuchsanstalt, Hann. - Münden, Federal Republic of Germany)
