For twenty years, Louis Roussel continues, with great skill and method, the study of natural radiation and their influence on the forest environment. The first publication of his work dates back to 1952. It was the presentation of the thesis he argued November 5, 1952 for the degree of Doctor of Engineering. Since then, he has written numerous articles in various technical journals, including the Bulletin de la Societe Forestiere de Franche-Comte, which has met several in a pamphlet published in 1968.

Early in its work, taking the following tentative tests conducted by the Forest Research Station then attached to the Ecole Nationale des Eaux et Forêts, Nancy, Louis Roussel concentrated his studies on the two trees that are most important Haut Jura: fir and spruce.

A little later, he extended the hardwoods of the Haute-Saone and Champagne.

This book is both a summary of all of its work and development of modern ideas on these issues as they arise in contemporary French publications and foreign. In this brief introduction, I will not detail the many issues raised by the study of natural radiation and their effect on the life of the forest environment. I just want to stress the importance and practicability of this work: a new science is created, using the most varied disciplines. Already some interesting results were obtained, allowing, for example, to define with some precision the old fundamentals, rather vague, as the distinctions between "shade-tolerant" and "trees of light", the brightness necessary to Birth of seedlings in natural regeneration, and growth at different ages, etc. ...

Gradually as they grow, these studies provide ecologists and foresters well documented, and help give these fields a more scientific and, in practice, to improve production.

The work of Louis Roussel, very clear and documented plans new light on the requirements of plant life and deserves undoubtedly retain the attention of all those who for various reasons, are interested in these issues.