Plant Ecology

, Volume 164, Issue 1, pp 29–36 | Cite as

Canopy gaps are sites of reduced belowground plant competition in a productive old field

  • James F. CahillEmail author
  • Brenda B. Casper


Whether small gaps in the aboveground vegetation of productive oldfields correspond to gaps in belowground plant biomass, and whether such“root gaps” result in a reduction of competition for soil resourcesis not known. Our study in an abandoned hayfield shows that root biomass withinsmall gaps (< 0.50 m diam) is 20% of that found withinintact vegetation, similar to the findings for shoot biomass. Associated withthe decrease in root biomass was a 25% reduction in the intensity ofbelowground competition within gaps compared to the surrounding matrixvegetation. These differences could not be attributed to variation in soilproperties, as gap and matrix soils did not differ in any of the physical orchemical properties measured. These results indicate that the increased plantgrowth commonly observed within gaps may be partly due to reduced belowgroundcompetition, independent of any advantage gained from increased lightavailability. By providing areas of low belowground competitive intensity, gapsin this field could allow poor belowground competitors to exist with in oldfields,thusincreasing community diversity.

Abutilon theophrasti Favorable microsite Root competition Root gaps Succession 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Aguilera M.O. and Lauenroth W.K. 1993. Seedling establishment in adult neighbourhoods-intraspecific constraints in the regeneration of the bunchgrass Bouteloua gracilis. J. Ecol. 81: 253-261.Google Scholar
  2. Aguilera M.O. and Lauenroth W.K. 1995. Influence of gap disturbances and type of microsites on seedling establishment in Bouteloua gracilis. J. Ecol. 83: 87-97.Google Scholar
  3. Bradshaw L. and Goldberg D.E. 1989. Resource levels in undisturbed vegetation and mole mounds in old fields. Am. Midland Natural. 121: 176-183.Google Scholar
  4. Burke I., Lauenroth W., Vinton M., Hook P., Kelly R., Epstein H. et al. 1998. Plant-soil interactions in temperate grasslands. Biogeochem. 42: 121-143.Google Scholar
  5. Cahill J.F. 1997. Symmetry, Intensity, and Additivity: Belowground Interactions in an Early Successional Field. PhD Dissertation.Google Scholar
  6. Cahill J.F. 1999. Fertilization effects on interactions between above-and belowground competition in an old field. Ecology 80: 466-480.Google Scholar
  7. Cahill J.F. and Casper B.B. 2000. Investigating the relationship between neighbor root biomass and belowground competition: Field evidence for symmetric competition belowground. Oikos 90: 311-320.Google Scholar
  8. Campbell J.J., Finer L. and Messier C. 1998. Fine-root production in small experimental gaps in successional mixed boreal forests. J. Veg. Sci. 9: 537-542.Google Scholar
  9. Casper B.B. and Cahill J.F. 1996. Limited effects of soil nutrient heterogeneity on populations of Abutilon theophrasti(Malvaceae). Am. J. Bot. 83: 333-341.Google Scholar
  10. Casper B.B., Cahill J.F. and Jackson R.B. 2001. Plant Competition in Spatially Heterogeneous Environments. In: Hutchings M.J., John E. and Stewart A. (eds), Ecological Consequences of Habitat Heterogeneity. Blackwell.Google Scholar
  11. Casper B.B. and Jackson R.B. 1997. Plant competition underground. Ann. Rev. Ecol. System. 28: 545-570.Google Scholar
  12. Coffin D.P. and Lauenroth W.K. 1988. The effects of disturbance size and frequency on a shortgrass plant community. Ecology 69: 1609-1617.Google Scholar
  13. Coffin D.P. and Lauenroth W.K. 1998. A gap dynamics simulation model of succession in a semiarid grassland. Ecological Modelling 49: 229-266.Google Scholar
  14. Denslow J.S., Ellison A.M. and Sanford R.E. 1998. Treefall gap size effects on above-and below-ground processes in a tropical wet forest. J. Ecol. 86: 597-609.Google Scholar
  15. English E.I. and Bowers M.A. 1994. Vegetational gradients and proximity to woodchuck (Marmota monax) burrows in an old field. J. Mammal. 75: 775-780.Google Scholar
  16. Goldberg D.E. 1987. Seedling colonization of experimental gaps in two old-field communities. Bull. Torrey Bot. Soc. 114: 139-148.Google Scholar
  17. Goldberg D.E. and Gross K.L. 1988. Disturbance regimes of midsuccessional old fields. Ecology 69: 1677-1688.Google Scholar
  18. Goldberg D.E. and Werner P.A. 1983. The effects of size of opening in vegetation and litter cover on seedling establishment of goldenrods (Solidagospp.). Oecologia 60: 149-155.Google Scholar
  19. Gross K.L. and Werner P.A. 1982. Colonizing abilities of "biennial" plant species in relation to ground cover: Implications for their distributions in a successional sere. Ecology 63: 921-931.Google Scholar
  20. Hobbs R.J. and Mooney H.A. 1985. Community and population dynamics of serpentine grassland annuals in relation to gopher disturbance. Oecologia 67: 342-351.Google Scholar
  21. Howard T.G. and Goldberg D.E. 2001. Competitive response hierarchies for germination, growth, and survival and their influence on abundance. Ecology 82: 979-990.Google Scholar
  22. Joslin J.D. and Wolfe M.H. 1999. Disturbances during minirhizotron installation can affect root observation data. J. Soil Sci. Soc. Am. 63: 218-221.Google Scholar
  23. King T.J. 1977. The plant ecology of ant-hills in calcareous grasslands i. Patterns of species in relation to ant-hills in southern England. J. Ecol. 65: 235-256.Google Scholar
  24. Koide R.T., Huenneke L.F. and Mooney H.A. 1987. Gopher mound soil reduces growth and affects ion uptake of two annual grassland species. Oecologia 72: 284-290.Google Scholar
  25. McConnaughay K.D.M. and Bazzaz F.A. 1987. The relationship between gap size and performance of several colonizing annuals. Ecology 68: 411-416.Google Scholar
  26. McIntyre S., Lavorel S. and Tremont R.M. 1995. Plant life-history attributes: Their relationship to disturbance response in herbaceous vegetation. J. Ecol. 83: 31-44.Google Scholar
  27. Morgan J.W. 1998. Importance of canopy gaps for recruitment of some forbs in Themeda triandra-dominated grasslands in southeastern Australia. Austral. J. Bot. 46: 609-627.Google Scholar
  28. Ostertag R. 1998. Belowground effects of canopy gaps in a tropical wet forest. Ecology 79: 1294-1304.Google Scholar
  29. Pickett S.T.A. and White P.S. 1985. The Ecology of Natural Disturbance and Patch Dynamics. Academic Press, London, p 472.Google Scholar
  30. Platt W.J. 1975. The colonization and formation of equilibrium plant species associations on badger disturbances in a tall-grass prairie. Ecol. Monog. 45: 285-305.Google Scholar
  31. Sanford R.L.J. 1990. Fine root biomass under light gap openings in an Amazon rain forest. Oecologia 83: 541-545.Google Scholar
  32. Silver L.W. and Vogt K.A. 1993. Fine root dynamics following single and multiple disturbances in a subtropical wet forest ecosystem. J. Ecol. 81: 729-738.Google Scholar
  33. Spencer N.R. 1984. Velvetleaf, Abutilon theophrasti, history and economic impact in the united states. Econ. Bot. 38: 407-416.Google Scholar
  34. Tilman D. 1989. Competition, nutrient reduction, and the competitive neighborhood of a bunchgrass. Function. Ecol. 3: 215-219.Google Scholar
  35. Twolan-Strutt L. and Keddy P.A. 1996. Above-and belowground competition intensity in two contrasting wetland plant communities. Ecology 77: 259-270.Google Scholar
  36. Whendee L.S. and Vogt K.A. 1993. Fine root dynamics following single and multiple disturbances in a subtropical wet forest ecosystem. Journal of Ecology 81: 729-738.Google Scholar
  37. Wilczynski C.J. and Pickett S.T.A. 1993. Fine root biomass within experimental canopy gaps: Evidence for a below-ground gap. J. Veg. Sci. 4: 571-574.Google Scholar
  38. Wilson J. 1988. Shoot competition and root competition. J. Applied Ecol. 25: 279-296.Google Scholar
  39. Wilson S.D. and Tilman D. 1991. Components of plant competition along an experimental gradient of nitrogen availability. Ecology 72: 1050-1065.Google Scholar

Copyright information

© Kluwer Academic Publishers 2003

Authors and Affiliations

  1. 1.Department of BiologyUniversity of PennsylvaniaUSA

Personalised recommendations