Variation in Gas Exchange Characteristics Among Desert Plants
387
18.7 Conclusions
Desert environments are characterized by both low precipitation inputs and
high year-to-year variability in soil moisture inputs. In response to this
environmental variation, there is significant variation in plant gas exchange
characteristics. While C4 and CAM photosynthesis are associated with
deserts, they do not constitute the dominant photosynthetic pathways and
most of the gas-exchange variation occurs in C 3 photosynthesis. These patterns include substantial variations in the intercellular CO2 concentrations of
leaves and in the photosynthetic tissue type (leaves, twigs, and stems).
Variation in the fractions of winter versus summer precipitation and of a
species' ability to use summer moisture are also associated with variations in
the intercellular CO2 concentrations of C3 plants. These environmental
constraints and unpredictability of year-to-year precipitation may be the
major selective force for the high life-form diversity that characterizes desert
vegetation.
Acknowledgments. The support of the Ecological Research Division at the Office of
Health and Environmental Research at the US Department of Energy is very much
appreciated.
References
Balding FR, Cunningham GL (1974) The influence of soil water potential on the perennial
vegetation of a desert arroyo. Southwest Nat 19: 241-248
Beatley JC (1974a) Effects of rainfall and temperature on the distribution and behavior of
Larrea tridentata (creosote-bush) in the Mojave Desert of Nevada. Ecology 52: 245-261
Beatley JC (1974b) Phenological events and their environmental triggers in Mojave
Desert ecosystems. Ecology 55: 856-863
Bender GL (ed) (1982) Reference handbook on the deserts of North America. Greenwood
Press, Westport, Connecticut
Bender MM (1968) Mass spectrometric studies of carbon 13 variations in com and other
grasses. Radiocarbon 10: 468-472
Bloom AJ, Troughton JH (1979) High productivity and photosynthetic flexibility in a
CAM plant. Oecologia 38: 35-43
Bowers MA, Lowe CH (1985) Plant-form gradients on Sonoran Desert bajadas. Oikos
46: 284-291
Bowman WD, Hubick KT, von Caemmerer S, Farquhar GD (1989) Short-term changes
in leaf carbon isotope discrimination in salt- and water-stressed C 4 grasses. Plant
Physiol 90: 162-166
Brown GW Jr (ed) (1968) Desert biology, vol 1. Academic Press, New York
Caldwell MM (1985) Cold desert. In: Chabot BF, Mooney HA (eds) Physiological
ecology of north American plant communities. Chapman and Hall, New York, pp
198-212
Caldwell MM, White, RS, Moore RT, Camp LB (1977) Carbon balance, productivity,
and water use of cold-winter desert shrub communities dominated by C 3 and C 4
species. Oecologia 29: 275-300
387
18.7 Conclusions
Desert environments are characterized by both low precipitation inputs and
high year-to-year variability in soil moisture inputs. In response to this
environmental variation, there is significant variation in plant gas exchange
characteristics. While C4 and CAM photosynthesis are associated with
deserts, they do not constitute the dominant photosynthetic pathways and
most of the gas-exchange variation occurs in C 3 photosynthesis. These patterns include substantial variations in the intercellular CO2 concentrations of
leaves and in the photosynthetic tissue type (leaves, twigs, and stems).
Variation in the fractions of winter versus summer precipitation and of a
species' ability to use summer moisture are also associated with variations in
the intercellular CO2 concentrations of C3 plants. These environmental
constraints and unpredictability of year-to-year precipitation may be the
major selective force for the high life-form diversity that characterizes desert
vegetation.
Acknowledgments. The support of the Ecological Research Division at the Office of
Health and Environmental Research at the US Department of Energy is very much
appreciated.
References
Balding FR, Cunningham GL (1974) The influence of soil water potential on the perennial
vegetation of a desert arroyo. Southwest Nat 19: 241-248
Beatley JC (1974a) Effects of rainfall and temperature on the distribution and behavior of
Larrea tridentata (creosote-bush) in the Mojave Desert of Nevada. Ecology 52: 245-261
Beatley JC (1974b) Phenological events and their environmental triggers in Mojave
Desert ecosystems. Ecology 55: 856-863
Bender GL (ed) (1982) Reference handbook on the deserts of North America. Greenwood
Press, Westport, Connecticut
Bender MM (1968) Mass spectrometric studies of carbon 13 variations in com and other
grasses. Radiocarbon 10: 468-472
Bloom AJ, Troughton JH (1979) High productivity and photosynthetic flexibility in a
CAM plant. Oecologia 38: 35-43
Bowers MA, Lowe CH (1985) Plant-form gradients on Sonoran Desert bajadas. Oikos
46: 284-291
Bowman WD, Hubick KT, von Caemmerer S, Farquhar GD (1989) Short-term changes
in leaf carbon isotope discrimination in salt- and water-stressed C 4 grasses. Plant
Physiol 90: 162-166
Brown GW Jr (ed) (1968) Desert biology, vol 1. Academic Press, New York
Caldwell MM (1985) Cold desert. In: Chabot BF, Mooney HA (eds) Physiological
ecology of north American plant communities. Chapman and Hall, New York, pp
198-212
Caldwell MM, White, RS, Moore RT, Camp LB (1977) Carbon balance, productivity,
and water use of cold-winter desert shrub communities dominated by C 3 and C 4
species. Oecologia 29: 275-300