Photosynthetic responses to increased co₂ and air pollutants

Historical View: Plants in a Changing Environment: After centuries of relatively stable atmospheric composition, the Industrial Revolution has driven a need for plants to cope with a changing atmosphere. However, plants not only passively undergo global climatic changes but are also driving factors that may influence the course of climatic change. This is particularly true for trees and forests as they play a significant role in the global carbon cycle and in the control of CO₂ concentration in the atmosphere. The scientific community has therefore sought to assess and quantify both the response and the contribution of the ecosystems and particularly of the forests to the increase of CO₂ and air pollutants (Dixon et al., 1994; Table 17.1). If the studies on the impact of climate change on forests have environmental understanding as the main objective, the studies on crops have yield and quality of the products as main goals. Moreover studies on herbaceous plants are usually easier than those on trees and can be particularly important when we try to identify the mechanisms of response. In some cases, such as tree crops commonly planted for bioenergy, these objectives can merge and the great challenge becomes maximising future production in a changing climate, while minimising depletion of soil and water resources (Cassman et al.,