Advertisement

Plant Ecology

, Volume 164, Issue 1, pp 85–94 | Cite as

Woody invasion of grasslands: evidence that CO2 enrichment indirectly promotes establishment of Prosopis glandulosa

  • H. Wayne PolleyEmail author
  • Hyrum B. Johnson
  • Charles R. Tischler
Article

Abstract

Grasslands worldwide have been invaded by woody species during the last200 years. Atmospheric CO2 enrichment may indirectly havefacilitatedinvasion by reducing soil water depletion by grasses. We used a two-stepcorrelative approach to test this hypothesis with the invasive and native shrubhoney mesquite (Prosopis glandulosa Torr. var.glandulosa). 1) Water content to 0.15 m depthwas measured in grassland exposed to a CO2 gradient from 200 to 550μmol/mol to evaluate the prediction that CO2enrichment lessens soil water depletion by grasses. 2) Soil water content andemergence and survival of mesquite seedlings were measured in adjacentgrasslandplots from which grass roots were excluded to 0.15 m depth toreduce water depletion or that were irrigated to increase soil water levels.With these measurements, we tested the hypothesis that mesquite establishmentislimited by water.Excluding grass roots doubled emergence of mesquite and almost tripledthe fraction of emergent seedlings that survived for 12 weeks following thefirst of two plantings. Seedlings were taller, heavier, and had greater leafarea when grown without grass roots. Root exclusion did not measurably affectsoil water during the 3-week period of seedling emergence, but soilwatercontent over the 12 weeks that seedling survival was studied was higher inplotsfrom which grass roots were excluded and following an April than May planting.Survivorship of mesquite seedlings correlated positively with soil watercontent. Percentage survival of seedlings increased from 1.5% to15% and 28% at the soil water content measured in grasslandexposed to CO2 concentrations of 270 (preindustrial), 360 (current),and 550 μmol/mol (future), respectively. We infer thatrecent and projected increases in atmospheric CO2 concentration maybe large enough to increase establishment of invading mesquite seedlings ingrasslands that are severely water-limited.

Competition Emergence Seedling survival Southwestern U.S. Water relations Woody plant invasion 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Agresti A. 1996. An introduction to categorical data analysis. John Wiley & Sons, New York.Google Scholar
  2. Archer S. 1989. Have southern Texas savannas been converted to woodlands in recent history? American Naturalist 134: 545- 561.Google Scholar
  3. Archer S. 1994. Woody plant encroachment into Southwestern grasslands and savannas: rates, patterns and proximate causes. In: Vavra M., Laycock W.A. and Pieper R.D. (eds), Ecological implications of livestock herbivory in the West. Society for Range Management, Denver, pp. 13-68.Google Scholar
  4. 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
  5. Bahre C.J. and Shelton M.L. 1993. Historic vegetation change, mesquite increase, and climate in southeastern Arizona. Journal of Biogeography 20: 489-504.Google Scholar
  6. Belsky A.J. 1984. Role of small browsing mammals in preventing woodland regeneration in the Serengeti National Park, Tanzania. African Journal of Ecology 22: 271-279.Google Scholar
  7. Berg W.A. and Sims P.L. 1995. Nitrogen fertilizer use efficiency in steer gain on old world bluestem. Journal of Range Management 48: 465-469.Google Scholar
  8. Bond W.J. and Midgley G.F. 2000. A proposed CO2-controlled mechanism of woody plant invasion in grasslands and savannas. Global Change Biology 6: 865-869.Google Scholar
  9. Brown J.H., Valone T.J. and Curtin C.G. 1997. Reorganization of an arid ecosystem in response to recent climatic change. Proceedings National Academy of Science, USA 94: 9729-9733.Google Scholar
  10. Brown J.R. and Archer S. 1989. Woody plant invasion of grasslands: establishment of honey mesquite (Prosopis glandulosavar. glandulosa) on sites differing in herbaceous biomass and grazing history. Oecologia 80: 19-26.Google Scholar
  11. Brown J.R. and Archer S. 1990. Water relations of perennial grass and seedling vs adult woody plants in a subtropical savanna, Texas. Oikos 57: 366-374.Google Scholar
  12. Brown J.R. and Archer S. 1999. Shrub invasion of grassland: recruitment is continuous and not regulated by herbaceous biomass or density. Ecology 80: 2385-2396.Google Scholar
  13. Brown J.R., Scanlan J.C. and McIvor J.G. 1998. Competition by herbs as a limiting factor in shrub invasion in grassland: a test with different growth forms. Journal of Vegetation Science 9: 829-836.Google Scholar
  14. Burkhardt J.W. and Tisdale E.W. 1976. Causes of juniper invasion in southwestern Idaho. Ecology 57: 472-484.Google Scholar
  15. Bush J.K. and Van Auken O.W. 1990. Growth and survival of Prosopis glandulosaseedlings associated with shade and herbaceous competition. Botanical Gazette 151: 234-239.Google Scholar
  16. Davis M.A., Wrage K.J. and Reich P.B. 1998. Competition between tree seedlings and herbaceous vegetation: support for a theory of resource supply and demand. Journal of Ecology 86: 652-661.Google Scholar
  17. Field C.B., Lund C.P., Chiariello N.R. and Mortimer B.E. 1997. CO2 effects on the water budget of grassland microcosm communities. Global Change Biology 3: 197-206.Google Scholar
  18. Harrington G.N. 1991. Effects of soil moisture on shrub seedling survival in a semi-arid grassland. Ecology 72: 1138-1149.Google Scholar
  19. Jeltsch F., Milton S.J., Dean W.R.J. and van Rooyen N. 1997. Analysing shrub encroachment in the southern Kalahari: a gridbased modelling approach. Journal of Applied Ecology 34: 1497-1508.Google Scholar
  20. Johnson H.B. and Mayeux H.S. 1990. Prosopis glandulosaand the nitrogen balance of rangelands: extent and occurrence of nodulation. Oecologia 84: 176-185.Google Scholar
  21. Johnson H.B., Polley H.W. and Whitis R.P. 2000. Elongated chambers for field studies across atmospheric CO2 gradients. Functional Ecology 14: 388-396.Google Scholar
  22. Johnston M.C. 1963. Past and present grasslands of southern Texas and northeastern Mexico. Ecology 44: 456-466.Google Scholar
  23. Kirkham M.B., He H., Bolger T.P., Lawlor D.J. and Kanemasu E.T. 1991. Leaf photosynthesis and water use of big bluestem under elevated carbon dioxide. Crop Science 31: 1589-1594.Google Scholar
  24. Knoop W.T. and Walker B.H. 1985. Interactions of woody and herbaceous vegetation in a southern African savanna. Journal of Ecology 73: 235-253.Google Scholar
  25. McPherson G.R. 1997. Ecology and management of North American savannas. University of Arizona Press, Tucson.Google Scholar
  26. McPherson G.R., Boutton T.W. and Midwood A.J. 1993. Stable carbon isotope analysis of soil organic matter illustrates vegetation change at the grassland/woodland boundary in southeastern Arizona, USA. Oecologia 93: 95-101.Google Scholar
  27. Mayeux H.S., Johnson H.B. and Polley H.W. 1991. Global change and vegetation dynamics. In: James L.F., Evans J.O., Ralphs M.H. and Child R.D. (eds), Noxious range weeds. Westview Press, Boulder, pp. 62-74.Google Scholar
  28. Meyer R.E. and Bovey R.W. 1982. Establishment of honey mesquite and huisache on a native pasture. Journal of Range Management 35: 548-550.Google Scholar
  29. Morgan I.A., LeCain D.R., Read J.J., Hunt H.W. and Knight W.G. 1998. Photosynthetic pathway and ontogeny affect water relations and the impact of CO2 on Bouteloua gracilis(C4) and Pascopyrum smithii(C3). Oecologia 114: 483-493.Google Scholar
  30. Neilson R.P. 1986. High-resolution climatic analysis and southwest biogeography. Science 232: 27-34.Google Scholar
  31. Niklaus P.A., Spindler D. and Körner C. 1998. Soil moisture dynamics of calcareous grassland under elevated CO2. Oecologia 117: 201-208.Google Scholar
  32. O’Connor T.G. 1995. Acacia karrooinvasion of grassland: environmental and biotic effects influencing seedling emergence and establishment. Oecologia 103: 214-223.Google Scholar
  33. Owensby C.E., Coyne P.I., Ham J.M., Auen L.A. and Knapp A.K. 1993. Biomass production in a tallgrass prairie ecosystem exposed to ambient and elevated CO2. Ecological Applications 3: 644-653.Google Scholar
  34. Owensby C.E., Ham J.M., Knapp A.K., Bremer D. and Auen L.M. 1997. Water vapour fluxes and their impact under elevated CO2 in a C4-tallgrass prairie. Global Change Biology 3: 189-195.Google Scholar
  35. Polley H.W., Johnson H.B., Mayeux H.S. and Tischler C.R. 1996a. Are some of the recent changes in grassland communities a response to rising CO2 concentrations? In: Körner C. and Bazzaz F.A. (eds), Carbon dioxide, populations, and communities. Academic Press, San Diego, pp. 177-195.Google Scholar
  36. Polley H.W., Johnson H.B., Mayeux H.S., Tischler C.R. and Brown D.A. 1996b. Carbon dioxide enrichment improves growth, water relations and survival of droughted honey mesquite (Prosopis glandulosa) seedlings. Tree Physiology 16: 817-823.Google Scholar
  37. Polley H.W., Mayeux H.S., Johnson H.B. and Tischler C.R. 1997. Viewpoint: Atmospheric CO2, soil water, and shrub/grass ratios on rangelands. Journal of Range Management 50: 278-284.Google Scholar
  38. Polley H.W., Tischler C.R., Johnson H.B. and Pennington R.E. 1999. Growth, water relations, and survival of drought-exposed seedlings from six maternal families of honey mesquite (Prosopis glandulosa): responses to CO2 enrichment. Tree Physiology 19: 359-366.Google Scholar
  39. Schlesinger W.H., Reynolds J.F., Cunningham G.L., Huenneke L.F., Jarrell W.M., Virginia R.A. et al. 1990. Biological feedbacks in global desertification. Science 247: 1043-1048.Google Scholar
  40. Scholes R.J. and Archer S.R. 1997. Tree-grass interactions in savannas. Annual Review Ecology and Systematics 28: 517-544.Google Scholar
  41. Sims P.L. and Dewald C.L. 1982. Old World bluestems and their forage potential for the Southern Great Plains:Areview of early studies. ARM-S-28, USDA, ARS, New Orleans.Google Scholar
  42. Stock W.D., Wienand K.T. and Baker A.C. 1995. Impacts of invading N2-fixing Acaciaspecies on patterns of nutrient cycling in two Cape ecosystems: evidence from soil incubation studies and 15N natural abundance values. Oecologia 101: 375-382.Google Scholar
  43. Tischler C.R., Polley H.W., Johnson H.B. and Mayeux H.S. 1996. Effects of elevated concentrations of carbon dioxide on seedling growth of mesquite and huisache. In: Barrow J.R., McArthur E.D., Sosebee R.E. and Tausch R.J. (eds), Proceedings: Shrubland ecosystem dynamics in a changing environment. Intermountain Research Station, Forest Service, USDA, Ogden, pp. 246-248.Google Scholar
  44. Topp G.C., Davis J.L. and Annan A.P. 1980. Electromagnetic determination of soil water content: measurements in coaxial transmission lines. Water Resources Research 16: 574-582.Google Scholar
  45. Turner R.M. 1990. Long-term vegetation change at a fully protected Sonoran desert site. Ecology 71: 464-477.Google Scholar
  46. Ueckert D.N., Smith L.L. and Allen B.L. 1979. Emergence and survival of honey mesquite seedlings on several soils in West Texas. Journal of Range Management 32: 284-287.Google Scholar
  47. Van Auken O.W. and Bush J.K. 1997. Growth of Prosopis glandulosain response to changes in aboveground and belowground interference. Ecology 78: 1222-1229.Google Scholar
  48. Weltzin J.F., Archer S. and Heitschmidt R.K. 1997. Small-mammal regulation of vegetation structure in a temperate savanna. Ecology 78: 751-763.Google Scholar
  49. 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
  50. 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
  51. Wilson S.D. and Tilman D. 1995. Competitive responses of eight old-field plant species in four environments. Ecology 76: 1169-1180.Google Scholar

Copyright information

© Kluwer Academic Publishers 2003

Authors and Affiliations

  • H. Wayne Polley
    • 1
    • 1
    Email author
  • Hyrum B. Johnson
    • 1
  • Charles R. Tischler
    • 1
  1. 1.Grassland, Soil and Water Research LaboratoryU.S. Department of Agriculture, Agricultural Research ServiceTempleUSA

Personalised recommendations