Oecologia

, Volume 94, Issue 3, pp 446–450 | Cite as

Population fragmentation may reduce fertility to zero in Banksia goodii — a demonstration of the Allee effect

  • Byron B. Lamont
  • Peter G. L. Klinkhamer
  • E. T. F. Witkowski
Original Papers

Abstract

All individuals of all known populations of Banksia goodii were assessed for seed production. Small populations produced no or only a few seeds per unit canopy area. Effects of population size on seed production per unit area and seed production per plant were present over the whole range of population sizes, indicating that even in large populations seed production may still not be at its maximum. Resource differences could not explain this disproportionate decrease in seed production with decline in population size, because there were no differences in soil properties and understorey or overstorey cover between the small and large populations. Although plants in small and large populations were similar in size, seed production per plant was much lower in small populations. This was not because plants in small populations produced fewer cones but because the fraction of these cones that was fertile was much lower. Five of the nine smallest populations (<200 m2) produced no fertile cones over the last 10 years. The number of seeds per fertile cone did not depend on population size. The results are discussed in relation to pollination biology.

Key words

Allee effect Pollination Rare species Road verges Seed set 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Allee WC (1949) Group survival value for Philodina roseola, a rotifer. Ecology 30:395–397Google Scholar
  2. Burgman MA, Ferson S, Akçakaya HR (1992) Risk assessment in conservation biology. Chapman and Hall, LondonGoogle Scholar
  3. Collins BG, Newland C (1986) Honeyeater population change in relation to food availability in the jarrah forst of Western Australia. Aust J Ecol 11: 63–76Google Scholar
  4. Collins BG, Spicc J (1986) Honeyeaters and the pollination biology of Banksia prionotes (Proteaccae). Aust J Bot 34:175–185Google Scholar
  5. Collins BG, Briffa P, Newland C (1984) Temporal changes in abundance and resource utilization by honeyeaters at Wongamine Nature Reserve. Emu 84: 159–166Google Scholar
  6. Copland BS, Whelan RS (1989) Seasonal variation in flowering intensity and pollination limitation of fruit set in four co-occurring Banksia species. J Ecol 77:509–523Google Scholar
  7. Fuss AM, Sedgley M (1991) Pollen tube growth and seed set of Banksia coccinea R. Br. (Proteaceae). Ann Bot 68:377–384Google Scholar
  8. Jennersten O (1988) Pollination in Dianthus deltoides (Caryophyllaceae): effects of habitat fragmentation on visitation and seed set. Conserv Biol 2:359–366Google Scholar
  9. Klinkhamer PGL, Jong TJ de (1990) Plant size and pollinator visitation in Cynoglossum officinale. Oikos 54:201–204Google Scholar
  10. Klinkhamer PGL, Jong TJ de, Meelis E (1990) How to test for proportionality in the reproductive effort of plants? Am Nat 135:291–300Google Scholar
  11. Klinkhamer PGL, Meelis E, Jong TJ de, Weiner J (1992) On the analysis of size-dependent reproductive output in plants. Funct Ecol 6:308–316Google Scholar
  12. Lamont BB, Collins BG (1985) Flower colour change in Banksia ilicifolia: a signal for pollinators. Aust J Ecol 15:129–135Google Scholar
  13. Lamont BB, Connell SW, Bergl S (1991) Population and seed bank dynamics of Banksia cuneata: the role of time, fire and moisture. Bot Gaz 152:114–122Google Scholar
  14. Lande R, Barrowclough GF (1987) Effective population size, genetic variation, and their use in population management. In: Soulé ME (ed), Viable populations for conservation. Cambridge University Press, Cambridge, pp 87–123Google Scholar
  15. Lesica P, Allendorf FW (1992) Are small populations of plants worth preserving? Conserv Biol 6:135–139Google Scholar
  16. Mehroff LA (1983) Pollination in the genus Isotria (Orchidaceae), Am J Bot 70:1444–1453Google Scholar
  17. Ramsey M, Vaughton G (1991) Self-incompatibility, protandry, pollen production and pollen longevity in Banksia menziesii. Aust J Bot 39:497–504Google Scholar
  18. Rathke B (1983) Competition and facilitation among plants for pollination. In: Real L (ed), Pollination Ecology. Academic Press, New YorkGoogle Scholar
  19. Recher HF, Serventy DL (1991) Long term changes in the relative abundances of birds in Kings Park, Western Australia. Conserv Biol 5:90–102Google Scholar
  20. Schemske DW (1980) Floral ecology and hummingbird pollination of Combretum farinosum in Costa Rica. Biotropica 12:169–181Google Scholar
  21. Scott JK (1980) Estimation of the outcrossing rate for Banksia attenuata R. Br. and Banksia manziesii R. Br. (Proteaceae) Aust J Ecol 28:53–59Google Scholar
  22. Sowig P (1989) Effects of plant's patch size on species composition of pollinator communities, foraging strategies, and resource partitioning in bumblebees (Hymenoptera: Apidae). Oecologia 78:550–558Google Scholar
  23. Stock WD, Pate JS, Kuo J, Hansen AP (1989) Resource control of seed set in Banksia laricina C. Gardner (Proteaceae). Funct Ecol 3:453–460Google Scholar
  24. Taylor A, Hopper S (1988) The banksia atlas. Aust Gort Pub Serv, CanberraGoogle Scholar
  25. Wallace DD, O'Dowd DJ (1989) The effect of nutrients and inflorescence damage by insects on fruit set by Banksia spinulosa. Oecologia 79:482–488Google Scholar
  26. Whelan RJ, Goldingay RL (1986) Do pollinators infuence seed-set in Banksia paludosa R. Br. Aust J Ecol 11:181–186Google Scholar

Copyright information

© Springer-Verlag 1993

Authors and Affiliations

  • Byron B. Lamont
    • 1
  • Peter G. L. Klinkhamer
    • 2
  • E. T. F. Witkowski
    • 1
  1. 1.School of Environmental BiologyCurtin University of TechnologyPerthAustralia
  2. 2.Institute of Fvolutionary and Environmental Sciences, Research Group Ecology of Plants and HerbivoresUniversity of LeidenLeidenThe Netherlands

Personalised recommendations