Woody plants occupy dominant vegetation in forest ecosystem. They play an important role in reducing carbon load from the atmosphere and store them as biomass and carbon as sources of energy. Forest trees are sources of timbers, various domestic uses, medicinal purposes, forest products, and sources of animal nutrition. At this juncture, there is a great necessity to save forest trees for life security and effective management and maintain an ecobalance to save earth from the clutch of pollution. To fulfill these objectives, a clear understanding of the biology of trees and its applications is an essential prerequisite for effective management and its application. No such book is available to undergraduate and graduate students and teachers. It discusses experimental biology to study the various aspects of tree biology from a practical stand point guide. This deals with general concepts of plant, soil and environments, the vegetation and biodiversity, morpho-anatomical and ecophysiological traits phenological events and plasticity, branching pattern and branching density functioning as solar panel for capture of solar radiation for productivity, diversity of leaves morphological and biochemical traits such as pigments, epicuticular wax, leaf macronutrients necessary for the growth and development and animal nutrition, wood anatomical traits related to timber quality and utility. A special emphasis has been given in the selection of tree species with high ecophysiological traits. The book deals with advances in research and includes our original research results.