The author of this book was one of the leading geographers of the Soviet Union, whose scientific work left a profound mark on the academic community. David Lvovich Armand was a scholar of exceptional erudition and broad scientific and social interests. He was engaged in research on geographical theory, particularly landscape science, and made a major contribution to applying geography to the needs of the national economy. He tirelessly sought effective methods for combating erosion, protecting nature, and ensuring the rational use of natural resources. To a certain extent, this volume reflects the scientist’s contribution to both the theoretical and applied problems of Soviet geography. Naturally, it was not an easy task to select from D. L. Armand’s rich scientific legacy those works that were both the most important and still relevant today. Several specialists familiar with the author and with his published and manuscript materials participated in this selection. Responsibility for reviewing and preparing the various sections of this volume for publication was undertaken by K. V. Zvorykin (articles on the rational use of nature), N. I. Makkaveyev (articles on water and wind erosion), Yu. K. Yefremov (articles on nature conservation), S. V. Zoni (materials on the design of shelterbelts), and G. D. Richter (articles on methodological and theoretical questions). We express our sincere gratitude to all of them for their assistance and attention. The contemporary significance of these works by D. L. Armand is beyond doubt. The themes of the first seven articles directly correspond to the task of geography and geographers actively serving the national economy. For many years, D. L. Armand persistently studied the complex and often contradictory problems of natural resource utilization and conservation. Among his many publications on this subject, only a selected portion has been included in the present volume. These articles most vividly demonstrate the author's creative achievements in addressing these issues, and their importance remains undiminished. Among the subsequent articles devoted to theoretical and methodological questions is a paper on landscape science. This is no coincidence, as D. L. Armand always attached great importance to problems of landscape geography. In 1975, his monograph Landscape Science was published, in which he summarized his views on landscape science as the foundation of modern physical geography. D. L. Armand’s articles On the Theory of Radiation Boundaries and On the Law of the Intensity of Physical-Geographical Processes were written in connection with Academician A. A. Grigoryev’s investigations into theoretical problems of physical geography. While fully recognizing the great scholar’s contributions to solving key scientific problems in the Soviet Union, D. L. Armand criticized certain individual aspects of A. A. Grigoryev’s views during the latter’s lifetime. For example, immediately after the publication of A. A. Grigoryev’s article The Law of the Intensity of Physical-Geographical Processes (1943), D. L. Armand communicated his comments directly to the author. In his subsequent writings, he critically analyzed both this law and the theory of radiation boundaries. The concept of radiation boundaries as indicators for the comparative analysis of natural characteristics across different latitudes had been proposed by A. A. Grigoryev approximately forty years earlier. Since then, much has been learned about the role of solar radiation and radiation balance in the life of our planet. Nevertheless, the transcript of D. L. Armand’s report On the Theory of Radiation Boundaries, representing the result of a major original investigation, continues to attract interest today. Moreover, this transcript, published for the first time in this volume, provides a vivid illustration of the scientist’s creative laboratory and working methods, involving meticulous calculations, the search for factual evidence, and the development of logical solutions. One of A. A. Grigoryev’s major achievements was the introduction of advances in geophysics into physical geography. D. L. Armand continued along this productive path and achieved considerable success in many respects. His article Certain Tasks and Methods of Landscape Physics (1967) provides clear evidence of this. In it, he set forth his views on a new direction in physical geography with exceptional clarity. Further details on this subject are provided in the concluding essay, which outlines the author’s scientific interests and his complex life path as an active public figure and passionate advocate of nature conservation. G. V. Armand-Tkachenko, A. L. Armand, A. V. Drozdov, and G. V. Kushnaryova participated in preparing the works of D. L. Armand for publication.