The monograph summarizes the results of many years of research by the author, summarizes Soviet and foreign works on this problem, develops a new doctrine on forest pathology and environmental regulation in forests in order to create biological stability of plantings. Modern methods of research and material processing are involved, schemes of mathematical methods for solving individual issues and approaches to the use of computers are given. The book provides a definition of a healthy and diseased forest, considers the reasons that violate the normal state of the forest, the classification of "diseased" plantations, the reasons for the drying out of spruce, oak and pine forests on the Russian Plain, etc. Prediction of pathological phenomena in forests, modeling of individual processes associated with the development of pathological phenomena are given. Methods of ecological regulation of forest ecosystems through forestry measures are described. Methods of accounting for pathological phenomena and pathological diagnostics are described. The methodology for drawing up zonal systems of forest protection measures is given, the doctrine of forest protection regimes is developing. The economic justification of forest protection measures is given. The book is designed for scientists, forest managers, foresters, geographers, ecologists, specialists in nature conservation and forest protection.