Plant Ecology

, Volume 168, Issue 1, pp 107–120 | Cite as

Growth and biomass allocation of shrub and grass seedlings in response to predicted changes in precipitation seasonality


Anthropogenic emissions contribute to an annual 0.5% increase in atmospheric CO2. As global CO2 levels increase, regional precipitation patterns will likely be altered. Our primary objective was to determine whether a reduction in summer precipitation or an increase in winter/spring precipitation, predicted by global climate change models, will favor the establishment of C4 grasses or C3 shrubs in southern savannas. Our secondary objective was to determine how defoliation and microsite light availability interact with altered precipitation regimes to influence grass and shrub seedling growth and biomass allocation patterns. Seedlings of 3 shrub species (Prosopis glandulosa var. glandulosa, Acacia berlandieri, and A. greggii var. wrightii) and 3 grass species (Aristida purpurea var. wrightii, Setaria texana, and Stipa leucotricha) were watered based on probable changes in precipitation in a CO2 enriched atmosphere (0.6, 0.8, and 1.0 current ambient summer precipitation and 1.0, 1.15, and 1.30 current winter/spring precipitation). Seedlings were defoliated at 3 levels (non-defoliated, single defoliation, and repeated defoliation) within 2 levels of microsite light availability (100 and 50% ambient). Defoliation significantly reduced total shrub and grass seedling biomass. Reducing light availability decreased shrub seedling root:shoot ratio, but total biomass was not significantly affected. Grass seedling biomass and root:shoot ratio decreased when light availability was reduced. Changing the seasonality of precipitation by reducing summer rainfall or increasing winter/spring rainfall did not significantly influence growth or biomass allocation of grass and shrub seedlings in a semiarid savanna. Microsite variations in defoliation intensity and light availability influence seedling growth and biomass allocation more than changing seasonality of precipitation. Shrub and grass seedling establishment and growth on semiarid rangelands are already limited by summer precipitation, so a further reduction as proposed by climate change models will have a limited impact on seedling dynamics.

Climate change Defoliation Light Microsite Shade 


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  1. Aerts R., Boot R.G.A. and van der Aart P.J.M. 1991. The relationship between above-and belowground biomass allocation patterns and competitive ability. Oecologia 87: 551–559.Google Scholar
  2. Archer S. 1994. Woody plant encroachment into southwestern grasslands and savannas: rates, patterns and proximate causes.In: Vavra M., Laycock W. and Pieper R. (eds), Ecological Implications of Livestock Herbivory in the West. Society for Range Management, Denver, pp. 13–68.Google Scholar
  3. Archer S. 1995. Tree-grass dynamics in a Prosopis-thornscrub savanna parkland: reconstructing the past and predicting the future. Ecoscience 2: 83–99.Google Scholar
  4. Archer S. and Detling J.K. 1984. The effects of defoliation and competition on regrowth of tillers of two North American mixed-grass prairie graminoids. Oikos 43: 351–357.Google Scholar
  5. Archer S., Schimel D.S. and Holland E.A. 1995. Mechanisms of shrubland expansion: land use, climate or CO2? Climatic Change 29: 91–99.Google Scholar
  6. Auld T.D. 1995. Seedling survival under grazing in the arid perennial Acacia oswaldii. Biological Conservation 72: 27–32.Google Scholar
  7. Bilbrough C.J. and Richards J.H. 1993. Growth of sagebrush and bitterbrush following simulated winter browsing: mechanisms of tolerance. Ecology 74: 481–492.Google Scholar
  8. Briske D.D., Boutton T.W. and Wang Z. 1996. Contribution of flexible allocation priorities to herbivory tolerance in C4 perennial grasses: an evaluation with 13C labeling. Oecologia 105: 151–159.Google Scholar
  9. Brown J.H., Valone T.J. and Curtin C.G. 1997. Reorganization of an arid ecosystem in response to recent climate change. Proceedings of the National Acadademy of Sciences of the United States of America 94: 9729–9733.Google Scholar
  10. Bush J.K. and Van Auken O.W. 1987. Light requirements for growth of Prosopis glandulosa seedlings. The Southwestern Naturalist 32: 469–473.Google Scholar
  11. Canham C.D., Berkowitz A.R., Kelly V.R., Lovett G.M., Ollinger S.V. and Schnurr J. 1996. Biomass allocation and multiple resource limitation in tree seedlings. Canadian Journal of Forest Research 26: 1521–1530.Google Scholar
  12. Canham C.D., Kobe R.K., Latty E.F. and Chazdon R.L. 1999. Interspecific and intraspecific variation in tree seedling survival: effects of allocation to roots versus carbohydrate reserves. Oecologia 121: 1–11.Google Scholar
  13. Cohen S., Miller K., Duncan K., Gregorich E., Groffman P., Kovacs P. et al. 2001. North America. In: McCarthy J.J., Canziani O.F., Leary N.A., Dokken D.J. and White K.S. (eds), Climate Change 2001: Impacts Adaptation and Vulnerability. Cambridge University Press, pp. 745–784.Google Scholar
  14. Coughenour M.B., Detling J.K., Bamberg I.E. and Mugambi M.M. 1990. Production and nitrogen responses of the African dwarf shrub Indigofera spinosa to defoliation and water limitation. Oecologia 83: 546–552.Google Scholar
  15. Fay P.A., Carlisle J.D., Knapp A.K., Blair J.M. and Collins S.L. 2000. Altering rainfall timing and quantity in a mesic grassland ecosystem: design and performance of rainfall manipulation shelters. Ecosystems 3: 308–319.Google Scholar
  16. Giorgi F., Mearns L.O., Shields C. and McDaniel L. 1998. Regional nested model simulations of present day and 2 × CO2 climate over the central plains of the US. Climatic Change 40: 457–493.Google Scholar
  17. Gould F.W. 1975. The Grasses of Texas. Texas A & M University Press, College Station.Google Scholar
  18. Harrington G.N. 1991. Effects of soil moisture zon shrub seedling survival in a semi-arid grassland. Ecology 72: 1138–1149.Google Scholar
  19. Harper J.L. 1977. Population Biology of Plants. Academic Press, London.Google Scholar
  20. Hatch S.L., Kancheepuram N.G. and Brown L.E. 1990. Checklist of the Vascular Plants of Texas. MP-1655. Texas Agricultural Experiment Station, College Station.Google Scholar
  21. Jones P.D. and Wigley T.M.L. 1990. Global Warming Trends. Scientific American 263: 84–91.Google Scholar
  22. Kattenberg A., Giorgi F., Grassl H., Meehl G.A., Mitchell J.F.B., Stouffer R.J. et al. 1996. Climate models–projections of future climate. In: Houghton J.T., Filho L.G.M., Callander B.A., Harris N., Kattenberg A. and Maskell K. (eds), Climate Change 1995: The Science of Climate Change. Cambridge University Press, Cambridge, pp. 287–357.Google Scholar
  23. Kemp P.R. and Williams G.J. 1980. A physiological basis for niche separation between Agropyron smithii (C3) and Bouteloua gracilis (C4). Ecology 61:846–858.Google Scholar
  24. Körner C.H. 1991. Some often overlooked plant characteristics as determinants of plant growth: a reconsideration. Functional Ecology 5: 162–173.Google Scholar
  25. Milliken G.A. and Johnson D.E. 1989. Analysis of Messy Data: Nonreplicated Experiments. Vol. 2. Chapman & Hall, New York.Google Scholar
  26. Mitchell J.F.B., Manabe S., Meleshko V. and Tokioka T. 1990. Equilibrium climate change and its implications for the future. In: Houghton J.T., Jenkins G.J. and Ephraums J.J. (eds), Climate Change: The IPCC Scientific Assessment. Cambridge University Press, Cambridge, pp. 131–172.Google Scholar
  27. Muthuchelian K., Paliwal K. and Gnanam A. 1989. Influence of shading on net photosynthetic and transpiration rates, stomatal diffusive resistance, nitrate reductase and biomass productivity of a woody legume tree species (Erythrina variegata Lam.). Proceedings of the Indian Academy of Sciences Plant Sciences, pp. 539–546.Google Scholar
  28. Neilson R.P., King G.A. and Koerper G. 1992. Toward a rule based biome model. Landscape Ecology 7: 27–43.Google Scholar
  29. North G.R. 1995. Global climate change. In: North G.R., Schmandt J.S. and Clarkson J. (eds), The Impact of Global Warming on Texas. University of Texas Press, Austin, pp. 4–23.Google Scholar
  30. Olff H., Van Andel J. and Bakker J.P. 1990. Biomass and shoot/ root allocation of five species from a grassland succession series at different combinations of light and nutrient supply. Functional Ecology 4: 193–200.Google Scholar
  31. Owens M.K. and Norton B.E. 1992. Interactions of grazing and plant protection on basin big sagebrush (Artemisia tridentata ssp. tridentata) seedling survival. Journal of Range Management 45: 257–262.Google Scholar
  32. Owens M.K., Wallace R.B. and Archer S.R. 1995. Landscape and microsite influences on shrub recruitment in a disturbed semiarid Quercus-Juniperus woodland. Oikos 74: 493–502.Google Scholar
  33. Paruelo J.M. and Lauenroth W.K. 1996. Relative abundance of plant functional types in grasslands and shrublands of North America. Ecological Applications 6: 1212–1224.Google Scholar
  34. Pierson E.A., Mack R.N. and Black R.A. 1990. The effect of shading on photosynthesis, growth, and regrowth following defoliation for Bromus tectorum. Oecologia 84: 534–543.Google Scholar
  35. Polley H.W. 1997. Implications of rising atmospheric carbon dioxide concentration for rangelands. Journal of Range Management 50: 561–577.Google Scholar
  36. Richards J.H. 1984. Root growth response to defoliation in two Agropyron bunchgrasses: field observations with an improved root periscope. Oecologia 64: 21–25.Google Scholar
  37. Rosenthal J.P. and Kotanen P.M. 1994. Terrestrial plant tolerance to herbivory. Tree 9: 145–149.Google Scholar
  38. SAS Institute Inc. 1996. Version 6.12., Cary, North Carolina.Google Scholar
  39. Schierenbeck K.A., Mack R.N. and Sharitz R.R. 1994. Effects of herbivory on growth and biomass allocation in native and introduced species of Lonicera. Ecology 75: 1661–1672.Google Scholar
  40. Schneider S.H. 1993. Scenarios of global warming. In: Kareiva P.M., Kingover J.G. and Huey R.B. (eds), Biotic Interactions and Global Change. Sinauer Associates, Incorporated, Sunderland, pp. 9–23.Google Scholar
  41. Schweitzer J.A. and Larson K.C. 1999. Greater morphological plasticity of exotic honeysuckle species may make them better invaders than native species. Journal of the Torrey Botanical Society 126: 15–23.Google Scholar
  42. Stubbendieck J., Hatch S.L. and Butterfield C.H. 1992. North American Range Plants. University of Nebraska Press, Lincoln.Google Scholar
  43. Tilman D. 1985. The resource-ratio hypothesis of plant succession. The American Naturalist 125: 827–852.Google Scholar
  44. Vines R.A. 1960. Trees Shrubs and Woody Vines of the Southwest. University of Texas Press, Austin.Google Scholar
  45. Weltzin J.F., Archer S.R. and Heitschmidt R.K. 1998. Defoliation and woody plant (Prosopis glandulosa) seedling regeneration: potential vs realized herbivory tolerance. Plant Ecology 138: 127–135.Google Scholar
  46. Williams K. and Hobbs R.J. 1989. Control of shrub establishment by springtime soil water availability in an annual grassland. Oecologia 81: 62–66.Google Scholar
  47. Wilson J.R. 1990. The eleventh hypothesis: shade. Agroforestry Today 2: 14–15.Google Scholar
  48. Zitzer S.F., Archer S.R. and Boutton T.W. 1996. Spatial variability in the potential for symbiotic N2 fixation by woody plants in a subtropical savanna ecosystem. Journal of Applied Ecology 33: 1125–1136.Google Scholar

Copyright information

© Kluwer Academic Publishers 2003

Authors and Affiliations

  1. 1.Texas Agricultural Experiment StationUvaldeUSA

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