Evidence grows daily of the rapid changes in climate due to human activities and their impact on plants and animals. Plant function is inextricably linked to climate and atmospheric carbon dioxide concentration. On the shortest and smallest scales the climate affects the plant’s immediate environment and thus directly influences physiological processes. On longer and larger time and space scales climate influ- ences species distribution and community composition and determines what crops can be viably produced in managed agricultural, horticultural and forestry ecosys- tems. Plant growth also influences the local, regional and global climate through the exchanges of energy and gases between the plants and the air around them