From mulching to greenhouses, the air space between the cover and the soil surface is the key to the classification of climates under cover. The same mechanism governs environments produced by the various covers. This book describes and analyses all the different environments from mulching to greenhouses. The relationship between plants and environment is another important topic in the book. Stress is placed on the link between quantitative phenomena and qualitative analyses. Most phenomena involved are nonlinear and non-steady-state. An approach called System Dynamics is used, and simulation models developed in the simulation language CSMP are fully used. The subjects covered are of relevance to graduate students, to scientists and researchers in agriculture and biological sciences and, of course, to agricultural organizations in both the developing and developed countries.