Oecologia

, Volume 91, Issue 2, pp 281–287 | Cite as

Density dependent interactions between VA mycorrhizal fungi and even-aged seedlings of two perennial Fabaceae species

  • N. Allsopp
  • W. D. Stock
Original Papers

Summary

The interaction of density and mycorrhizal effects on the growth, mineral nutrition and size distribution of seedlings of two perennial members of the Fabaceae was investigated in pot culture. Seedlings of Otholobium hirtum and Aspalathus linearis were grown at densities of 1, 4, 8 and 16 plants per 13-cm pot with or without vesicular-arbuscular (VA) mycorrhizal inoculum for 120 days. Plant mass, relative growth rates, height and leaf number all decreased with increasing plant density. This was ascribed to the decreasing availability of phosphorus per plant as density increased. O. hirtum was highly dependent on mycorrhizas for P uptake but both mycorrhizal and non-mycorrhizal A. linearis seedlings were able to extract soil P with equal ease. Plant size distribution as measured by the coefficient of variation (CV) of shoot mass was greater at higher densities. CVs of mycorrhizal O. hirtum plants were higher than those of non-mycorrhizal plants. CVs of the facultatively mycorrhizal A. linearis were similar for both mycorrhizal and non-mycorrhizal plants. Higher CVs are attributed to resource preemption by larger individuals. Individuals in populations with high CVs will probably survive stress which would result in the extinction of populations with low CVs. Mass of mycorrhizal plants of both species decreased more rapidly with increasing density than did non-mycorrhizal plant mass. It is concluded that the cost of being mycorrhizal increases as plant density increases, while the benefit decreases. The results suggest that mycorrhizas will influence density-dependent population processes of faculative and obligate mycorrhizal species.

Key words

Vesicular-arbuscular mycorrhizas Densitydependence Plant population dynamics Resource depletion Phosphorus 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Addicott JF (1986) On the population consequences of mutualism. In: Diamond J, Case TJ (eds) Community Ecology. Harper and Row, New York, pp 425–436Google Scholar
  2. Bååth E, Hayman DS (1984) Effects of soil volume and plant density on mycorrhizal infection and growth response. Plant Soil 77: 373–376Google Scholar
  3. Benjamin LR, Hardwick RC (1986) Sources of variation and measures of variability in even-aged stands of plants. Ann Bot 58: 757–778Google Scholar
  4. Chiarello N, Hickman JC, Mooney HA (1982) Endomycorrhizal role for interspecific transfer of phosphorus in a community of annual plants. Science 217: 941–943Google Scholar
  5. Clark JS (1990) Integration of ecological levels: individual plant growth, population mortality and ecosystem processes. J Ecol 78:275–299Google Scholar
  6. Engelbrecht MC, Smit WA, Knox-Davies PS (1983) Damping-off of rooibos tea, Aspalathus linearis. Phytophylactica 15: 121–124Google Scholar
  7. Field C, Mooney HA (1986) The photosynthesis-nitrogen relationship in wild plants. In: Givnish TJ (ed) On the economy of plant form and function. Cambridge University Press, Cambridge, pp 25–55Google Scholar
  8. Firbank LG, Watkinson AR (1990) On the effects of competition: from monocultures to mixtures. In: Grace JB, Tilman D (eds) Perspectives on plant competition. Academic Press, San Diego, pp 165–192Google Scholar
  9. Föhse D, Claassen N, Jungk A (1988) Phosphorus efficiency of plants I. External and internal P requirement and P uptake efficiency of different plant species. Plant Soil 110: 101–109Google Scholar
  10. Francis R, Finlay RD, Read DJ (1986) Vesicular-arbuscular mycorrhizas in natural vegetation systems IV. Transfer of nutrients in inter- and intra-specific combinations of host plants. New Phytol 102: 103–111Google Scholar
  11. Hara T (1988) Dynamics of size structure in plant populations. TREE 3: 129–133Google Scholar
  12. Harley JL, Smith SE (1983) Mycorrhizal symbiosis. Academic Press. LondonGoogle Scholar
  13. Hunt R (1978) Plant growth analysis. Edward Arnold, LondonGoogle Scholar
  14. Jackson ML (1958) Soil chemical analysis. Prentice Hall, New JerseyGoogle Scholar
  15. Jeffrey DW (1967) Phosphate nutrition of Australian heath plants J. The importance of proteoid roots in Banksia (Proteaceae). Aust J Bot 15:403–411Google Scholar
  16. Koide RT (1985) The nature of growth depressions in sunflower caused by vesicular-arbuscular mycorrhizal infection. New Phytol 99:449–462Google Scholar
  17. Koide RT (1991) Density-dependent response to mycorrhizal infection in Abutilon theophrasti Medic. Oecologia 85:389–395Google Scholar
  18. Mitchell DT, Brown G, Jongens-Roberts SM (1984) Variations of forms of phosphorus in the sandy soils of coastal fynbos, southwestern Cape. J Ecol 72:575–584Google Scholar
  19. Murphy J, Riley JP (1962) A modified single solution method for the determination of phosphate in natural waters. Anal Chim Acta 27:31–36Google Scholar
  20. Phillips JM, Hayman DS (1970) Improved procedures for clearing and staining parasitic and vesicular-arbuscular mycorrhizal fungi for rapid assessment of infection. Trans Br Myc Soc 55: 158–160Google Scholar
  21. Shaw RG, Antonovics J (1986) Density-dependence in Salvia lyrata, a herbaceous perennial: the effects of experimental alteration of seed densities. J Ecol 74:797–813Google Scholar
  22. Smith BH (1983) Demography of Floerkea prosepinacoides, a forest-floor annual I. Density-dependent growth and mortality. J Ecol 71: 391–404Google Scholar
  23. Smith SE, Gianinazzi-Pearson V (1990) Phosphate uptake and arbuscular activity in mycorrhizal Allium cepa L.: effects of photon irradiance and phosphate nutrition. Aust J Plant Physiol 17:177–188Google Scholar
  24. Smith VR (1980) A phenol-hypochlorite determination of ammonium-nitrogen in kjeldahl digests of plant tissue. Commun Soil Sci Plant Anal 11:709–722Google Scholar
  25. Stock WD, Allsopp N (1992) Functional perspectives of ecosystems. In: Cowling RM (ed) The ecology of fynbos. Oxford University Press, Cape Town, pp 241–259Google Scholar
  26. Stock WD, Lewis OAM (1986) Soil nitrogen and the role of fire as a mineralizing agent in a South African coastal fynbos ecosystem. J Ecol 74:317–328Google Scholar
  27. Stock WD, Pate JS, Delfs J (1990) Influence of seed size and quality on seedling development under low nutrient conditions in five Australian and South African members of the Proteaceae. J Ecol 78: 1005–1020Google Scholar
  28. Weiner J, Solbrig OT (1984) The meaning and measurement of size hierarchies in plant populations. Oecologia 61:334–336Google Scholar
  29. Weiner J, Thomas SC (1986) Size variability and competition in plant monocultures. Oikos 47:211–222Google Scholar
  30. Yoda K, Kira T, Ogawa H, Hozumi K (1963) Self-thinning in overcrowded pure stands under cultivated and natural conditions. (Intraspecific competition among higher plants XI). J Biol, Osaka City Univ 14:107–129Google Scholar
  31. Zar JH (1984) Biostatistical Analysis. Prentice-Hall, New JerseyGoogle Scholar

Copyright information

© Springer-Verlag 1992

Authors and Affiliations

  • N. Allsopp
    • 1
  • W. D. Stock
    • 1
  1. 1.Department of BotanyUniversity of Cape TownRondeboschSouth Africa

Personalised recommendations