Skip to main content

Seasonal and inter-annual photosynthetic response of representative C4 species to soil water content and leaf nitrogen concentration across a tropical seasonal floodplain

  • K. B. Mantlana (a1) (a2) (a3), A. Arneth (a4) (a5), E. M. Veenendaal (a2) (a6), P. Wohland (a4) (a7), P. Wolski (a6), O. Kolle (a1) and J. Lloyd (a7)...

We examined the seasonal and inter-annual variation of leaf-level photosynthetic characteristics of three C4 perennial species, Cyperus articulatus, Panicum repens and Imperata cylindrica, and their response to environmental variables, to determine comparative physiological responses of plants representing particular microhabitats within a seasonal tropical floodplain in the Okavango River Delta, Botswana. Five measurement campaigns were carried out over a period of 2 y which covered two early rainy seasons, two late rainy seasons and one dry season. For all three species, light-saturated net photosynthetic rates (Asat) and stomatal conductance (gsat) decreased with decreasing soil water content with a seasonal range for Asat of approximately 5–45 μmol m−2 s−1, and for gsat of 0.03–0.35 mol m−2 s−1. The species representing the wettest microhabitat (Cyperus) had the highest gsat at low leaf-to-air vapour pressure deficits (Dl), the highest ratio of intercellular to ambient CO2 concentration (Ci/Ca), as well as the highest degree of variation in Ci/Ca from season to season. We interpret this as being indicative of its adaptation to a moist growth environment allowing for non-conservative water use strategies as soil moisture is usually abundant. For all three species there was significant variation in photosynthetic fluxes from one year to another that was related to variation in leaf nitrogen and phosphorus. This study shows that when assessing the role of savanna stands in large-scale carbon balance models, the remarkable inter-annual variation in leaf photosynthesis reported in this study should be taken into account.

Corresponding author
1Corresponding author, at Global Change Research Group address; Email:
Hide All
ABD EL-GHANI M. M. & FAHMY A. G. 2001. Analysis of aquatic vegetation in islands of the Nile Valley (Egypt). International Journal of Ecology and Environmental Sciences 27:111.
ALMENDROS G., KGATHI D., SEKHWELA M., ZANCADA M., TINOCO P. & PARDO M. 2003. Biogeochemical assessment of resilient humus formations from virgin and cultivated northern Botswana soils. Journal of Agricultural and Food Chemistry 51:43214330.
ANTEN N. P. R., WERGER M. J. A. & MEDINA E. 1998. Nitrogen distribution and leaf area indices in relation to photosynthetic nitrogen use efficiency in savanna grasses. Plant Ecology 138:6375.
ARCHER S., COUGHENOUR C. D., FERNANDEZ G. W., HAY J., HOFFMAN W., KLINK C., SILVA J. F. & SOLBRIG O. T. 1996. Savanna biodiversity and ecosystem properties. Pp. 207224 in Solbrig O. T., Medina E. & Silva J. F. (eds.). Biodiversity and savanna ecosystem processes: a global perspective. Springer Verlag, Berlin.
BARUCH Z. 1996. Ecophysiological aspects of the invasion by African grasses and their impact on biodiversity and function of neotropical savannas. Pp. 7993 in Solbrig O. T., Medina E. & Silva J. F. (eds.). Biodiversity and savanna ecosystem processes: a global perspective. Springer Verlag, Berlin.
BARUCH Z. & BILBAO B. 1999. Effects of fire and defoliation on the life history of native and invader C4 grasses in a Neotropical savanna. Oecologia 119:510520.
BARUCH Z., LUDLOW M. M. & DAVIS R. 1985. Photosynthetic responses of native and introduced C4 grasses from Venezuelan savannas. Oecologia 67:338393.
BEALE C. V., MORISON J. I. L. & LONG S. P. 1999. Water use efficiency of C4 perennial grasses in a temperate climate. Agricultural and Forest Meteorology 96:103115.
BONYONGO M. C., BREDENKAMP G. J. & VEENENDAAL E. 2000. Floodplain vegetation in the Nxaraga Lagoon area, Okavango Delta, Botswana. South African Journal of Botany 66:1521.
BONYONGO M. C. & MUBYANA T. 2004. Soil nutrient status in vegetation communities of the Okavango Delta floodplains. South African Journal of Science 100:337340.
BRYSON C. T. & CARTER R. 2004. Biology of pathways for invasive weeds. Weed Technology 18:12161220.
BUNCE J. A. 1998. Effects of environment during growth on the sensitivity of leaf conductance to changes in humidity. Global Change Biology 4:269274.
CAUSTON D. R. & DALE M. P. 1990. The monomolecular and rectangular hyperbolas empirical models of the response of photosynthetic rate to photon flux density, with applications to three Veronica species. Annals of Botany 65:389394.
COMSTOCK J. & EHLERINGER J. 1993. Stomatal response to humidity in common bean (Phaseolus vulgaris): implications for maximum transpiration rate, water-use efficiency and productivity. Australian Journal of Plant Physiology 20:669691.
DE LUCIA E. H., WHITEHEAD D. & CLEARWATER M. J. 2003. The relative limitation of photosynthesis by mesophyll conductance in co-occurring species in a temperate rainforest dominated by the conifer Dacrydium cupressinum. Functional Plant Biology 30:11971204.
EDWARDS G. E. & WALKER D. A. 1983. C3, C4: mechanisms, and cellular and environmental regulation of photosynthesis. Blackwell Scientific Publications, Oxford. 542 pp.
EDWARDS G. E., KU M. S. B. & MONSON R. K. 1985. C4 photosynthesis and its regulation. Pp. 289327 in Barber J. & Baker N. R. (eds.). Photosynthetic mechanismsm and the environment. Elsevier Science Publishers B.V., Amsterdam.
EHLERINGER J. R., CERLING T. E. & HELLIKER B. R. 1997. C4 photosynthesis, atmospheric CO2 and climate. Oecologia 112:285299.
ELLERY W. N. & MCCARTHY T. S. 1994. Principles for the sustainable utilization of the Okavango Delta ecosystem, Botswana. Biological Conservation 70:159168.
FIELD C. & MOONEY H. A. 1986. The photosynthesis-nitrogen relationship in wild plants. Pp. 2555 in Givnish T. J. (ed.). On the economy of plant form and function. Cambridge University Press, Cambridge.
GIBBS RUSSELL G. E., WATSON L., KOEKEMOER M., SMOOK L., BARKER N. P., ANDERSON H. M. & DALLWITZ M. J. 1991. Grasses of Southern Africa. Botanical Research Institute, Pretoria. 437 pp.
HEINL M., FROST P., VANDERPOST C. & SLIVA J. 2007. Fire activity on drylands and floodplains in the southern Okavango Delta, Botswana. Journal of Arid Environments 68:7787.
HIKOSAKA K. 2004. Interspecific difference in the photosynthesis-nitrogen relationship: patterns, physiological causes, and ecological importance. Journal of Plant Research 117:481494.
JIA Y. & GRAY V. M. 2004. Influence of phosphorus and nitrogen on photosynthetic parameters and growth in Vicia faba L. Photosynthetica 42:535542.
JONES M. B. 1988. Photosynthetic responses of C3 and C4 wetland species in a tropical swamp. Journal of Ecology 76:253262.
KGOPE B. S. 2004. Differential photosynthetic responses of broad- and fine-leaved savanna trees to elevated temperatures. South African Journal of Botany 70:760766.
KNAPP A. K. 1993. Gas exchange dynamics in C3 and C4 grasses: consequences of differences in stomatal conductance. Ecology 74:113123.
LAWLOR D. W. 2001. Photosynthesis. (Third edition). Bios Scientific Publishers, Oxford. 386 pp.
LE ROUX X. & MORDELET P. 1995. Leaf and canopy CO2 assimilation in a West-African humid savanna during early growing season. Journal of Tropical Ecology 11:529545.
LLOYD J. & FARQUHAR G. D. 1994. C-13 discrimination during CO2 assimilation by the terrestrial biosphere. Oecologia 99:201215.
LONG S. 1985. Leaf gas exchange. Pp. 453499 in Barber J. & Baker N. R. (eds.). Photosynthetic mechanisms and the environment. Elsevier Science Publishers B.V. Amsterdam.
MACDONALD G. E. 2004. Cogongrass (Imperata cylindrica) – biology, ecology, and management. Critical Reviews in Plant Science 23:367380.
MAHERALI H., JOHNSON H. B. & JACKSON R. B. 2003. Stomatal sensitivity to vapour pressure difference over a subambient to elevated CO2 gradient in a C3/C4 grassland. Plant Cell and Environment 26:12971306.
MAROCO J. P., PEREIRA J. S. & CHAVES M. M. 2000. Growth, photosynthesis and water-use efficiency of two C4 Sahelian grasses subjected to water deficits. Journal of Arid Environments 46:119137.
MCCARTHY T. S. & ELLERY W. N. 1994. The effect of vegetation on soil and ground water chemistry and hydrology of islands in the seasonal swamps of the Okavango Fan, Botswana. Journal of Hydrology 154:169193.
MIDGLEY G. F., WAND S. J. E. & PAMMENTER N. W. 1999. Nutrient and genotypic effects on CO2-responsiveness: photosynthetic regulation in Leucadendron species of a nutrient-poor environment. Journal of Experimental Botany 50:533542.
MIRANDA A. C., MIRANDA H. S., LLOYD J., GRACE J., FRANCEY R. J., MCINTYRE J. A., MEIR P., RIGGAN P., LOCKWOOD R. & BRASS J. 1997. Fluxes of carbon, water and energy over Brazilian cerrado: an analysis using eddy covariance and stable isotopes. Plant Cell and Environment 20:315328.
MORISON J. I. L. & GIFFORD R. M. 1983. Stomatal sensitivity to carbon dioxide and humidity. Plant Physiology 71:789796.
MOTT J. J., WILLIAMS J., ANDREWS M. H. & GILLISON A. N. 1985. Australian savanna ecosystems. Pp. 5682 in Tothill J. C. & Mott J. J. (eds.). Ecology and management of the world's savannas. Australian Academy of Science, Canberra.
OLIVARES E., VIZCAINO D. & GAMBOA A. 2002. Mineral nutrition of three aquatic emergent macrophytes in a managed wetland in Venezuela. Journal of Plant Nutrition 25:475496.
OREN R., SPERRY J. S., KATUL G. G., PATAKI D. E., EWERS B. E., PHILLIPS N. & SCHAEFER K. V. R. 1999. Survey and synthesis of intra- and interspecific variation in stomatal sensitivity to vapour pressure deficit. Plant, Cell and Environment 22:15151526.
PIEDADE M. T. F., JUNK W. J. & LONG S. P. 1991. The productivity of the C4 grass Echinochloa polystachya on the Amazon floodplain. Ecology 72:14561463.
PIEDADE M. T. F., JUNK W. J. & LONG S. P. 1997. Nutrient dynamics of the highly productive C4 macrophyte Echinochloa polystachya on the Amazon floodplain – are the high-potential rates associated with the C4 syndrome realized under the near-optimal conditions provided by this exceptional natural habitat? Functional Ecology 11:6065.
REICH P. B., ELLSWORTH D. S. & WALTERS M. B. 1998. Leaf structure (specific leaf area) modulates photosynthesis-nitrogen relations: evidence from within and across species and functional groups. Functional Ecology 12:948958.
REICH P. B., BUSCHENA C., TJOELKER M. G., WRAGE K., KNOPS J., TILMAN D. & MACHADO J. L. 2003. Variation in growth rate and ecophysiology among 34 grassland and savanna species under contrasting N supply: a test of functional group differences. New Phytologist 157:617631.
SAGE R. F. & PEARCY R. W. 1987. The nitrogen use efficiency of C3 and C4 plants. II. Leaf nitrogen effects on the gas exchange characteristics of Chenopodium album L. and Amaranthus retroflexus L. Plant Physiology 84:959963.
SAGE R. F., PEARCY R. W. & SEEMANN J. R. 1987. The nitrogen use efficiency of C3 and C4 Plants. III. Leaf nitrogen effects on the activity of carboxylating enzymes in Chenopodium album (L) and Amaranthus retroflexus (L). Plant Physiology 85:355359.
SCHOLES R. J. & WALKER B. H. 1993. An African savanna: synthesis of the Nylsvlei study. Cambridge University Press, Cambridge.306 pp.
SIMIONI G., LE ROUX X., GIGNOUX J. & WALCROFT A. S. 2004. Leaf gas exchange characteristics and water- and nitrogen-use efficiencies of dominant grass and tree species in a West African savanna. Plant Ecology 173:233246.
TAUB D. R. & LERDAU M. T. 2000. Relationship between leaf nitrogen and photosynthetic rate for three NAD-ME and three NADP-ME C4 grasses. American Journal of Botany 87:412417.
THOMPSON K. 1985. Emergent plants of permanent and seasonally-flooded wetlands. Pp. 43107 in Denny P. W. (ed.). The ecology and management of African wetland vegetation. Junk Publishers, Dordrecht. 344 pp.
TOOTH S. & MCCARTHY T. S. 2007. Wetlands in drylands: geomorphological and sedimentological characteristics, with emphasis on examples from southern Africa. Progress in Physical Geography 31:341.
VON CAEMMERER S. 2000. Biochemical models of leaf photosynthesis. CSIRO Publishing, Collingwood. 165 pp.
WAND S. J. E., MIDGLEY G. F. & STOCK W. D. 2001. Growth responses to elevated CO2 in NADP-ME, NAD-ME and PCK C4 grasses and a C3 grass from South Africa. Australian Journal of Plant Physiology 28:1325.
Recommend this journal

Email your librarian or administrator to recommend adding this journal to your organisation's collection.

Journal of Tropical Ecology
  • ISSN: 0266-4674
  • EISSN: 1469-7831
  • URL: /core/journals/journal-of-tropical-ecology
Please enter your name
Please enter a valid email address
Who would you like to send this to? *



Full text views

Total number of HTML views: 1
Total number of PDF views: 7 *
Loading metrics...

Abstract views

Total abstract views: 101 *
Loading metrics...

* Views captured on Cambridge Core between September 2016 - 19th January 2018. This data will be updated every 24 hours.