US EPA

29104 

Book/Book Chapter 

Understanding photosynthetic adaptation to changing climate 

Lawlor, DW; Keys, AJ 

1993 

Chapman and Hall 

London, United Kingdom 

Plant adaptation to environmental stress 

Photosynthesis, and its response and adaptation to climate change, are important because the carbon economy of plants is a major link between the atmosphere, geosphere and biosphere. The atmospheric carbon dioxide pool is small and rapidly exchanges with other carbon pools, including those of the biosphere because of the dominant role of photosynthesis. Photosynthesis is also the basis of all ecosystem processes, including those on which human society depends. Thus the way in which photosynthesis behaves in the face of rapid and substantial changes in atmospheric chemistry and expected changes in climate is of more than academic interest (Jager and Ferguson, 1991). The rate of photosynthesis, per unit area of both leaf and ground surface, depends on suitable environmental conditions; greatest photosynthetic productivity occurs on areas of the earth's surface with mean temperatures between 5 and 25 0C, and where water and nutrients are available. Photosynthetic rate responds to environmental conditions on a time-scale ranging from almost instantaneous, in the case of light, to the slow response to seasonal changes in temperature and radiation at high latitudes. Changes in the rate of photosynthesis caused by the environment are quickly reflected in the carbon dioxide content of the atmosphere (Watson et at., 1990; Roeckner, 1992). The rate of photosynthesis also largely determines net primary productivity, which influences the production of biomass and thereby terrestrial soil carbon pools and deposition of carbon in wood and peat, all of which have short-to-medium rates of turnover, as well as in coal and natural gas which are much more slowly recycled (Schlesinger, 1991). Alterations in the global atmospheric composition (e.g. increasing carbon dioxide) and climate (e.g. rising temperature) may increase rates of photosynthesis and thus ameliorate the changes in global conditions, whereas reduced rates of photosynthesis may exacerbate the climate change. The response of photosynthesis to altered atmospheric carbon dioxide level is therefore of importance for its potential effects on global conditions and also for its consequences on the biosphere. The subject of photosynthetic adaptation to climate change has been reviewed by Stitt (1991) and Bowes (1991) from biochemical viewpoints and by Long (1991) with physiological emphasis. Aspects of plant responses to potential global climate change have been discussed by Lawlor and Mitchell (1991), Lawlor (1991) and Mousseau and Saugier (1992). The following analysis considers the concepts and information available at the interface between biochemical processes and physiological functions from which plant photosynthetic responses to changing environment may be assessed, and suggests aspects of plant function which require more attention. 

Fowden, L.; Mansfield, T.; Stoddart, J.