The workbook is based on the concept of ecosystem, the structural and functional unit of ecology. The main contention of the author to provide better understanding and evaluation of the flow of energy and cycling of water and minerals to the three major plant ecosystems viz. grass, forest and freshwater. The exercises are given separately for each of the three ecosystems. During their exercise the are likely to reveal the biological basis of organic productivity. The exercise presented in the workbook will lead to better comprehension of the concept of ecosystems. First practice of the exercise on grassland and the laboratory which is likely to equip the worker with knowledge and confidence to move on to the forest or the freshwater areas for study. The other corresponding topics of the three ecosystems has the advantage of comparing and bringing the structural and functional differences between the ecosystems. The work book is useful for under graduates, post graduate students and researcher of Ecology, Botany, Zoology and Environmental Studies.