When humans started building colonies and getting civilized their dependency on plants increased by several folds. Today plants are even more important due to their increased demand for their different uses. The study of plants is vital because they underpin almost all animal life on Earth by generating a large proportion of the oxygen and foodl that provide humans and other organisms with aerobic respiration with the chemical energy they need to exist. Plant responses to climate and other environmental changes can inform our understanding of how these changes affect ecosystem function and productivity.