Access

You are not currently logged in.

Access your personal account or get JSTOR access through your library or other institution:

login

Log in to your personal account or through your institution.

Seedling Dynamics over Thirty-Two Years in a Tropical Rain Forest Tree

Joseph H. Connell and Peter T. Green
Ecology
Vol. 81, No. 2 (Feb., 2000), pp. 568-584
Published by: Wiley
DOI: 10.2307/177449
Stable URL: http://www.jstor.org/stable/177449
Page Count: 17
  • Download ($42.00)
  • Subscribe ($19.50)
  • Cite this Item
Seedling Dynamics over Thirty-Two Years in a Tropical Rain Forest Tree
Preview not available

Abstract

We examined patterns of seedling recruitment and their underlying mechanisms in a population of Chrysophyllum sp. nov. (Sapotaceae), a shade-tolerant canopy species in mature tropical rainforest in Queensland, Australia. We considered spatial scales ranging from 1 m2 to 1 ha, and temporal scales ranging from 1 to 32 yr. Over the 32-yr study period there were six episodes of very high seedling recruitment (masts) at intervals ranging from 4 to 10 yr. Less than 2% of new recruits were found in the nine censuses in other years. We found no significant correlations between the numbers of seedlings per census and either seasonal or annual rainfall, number of dry months per year, or El Nino Southern Oscillation (ENSO) events but found two correlations with mean seasonal air temperatures in the years preceding flowering. There were long-term changes in abundance in both time and space. In 1965 there were 163 seedling-sized plants in two dense patches, whereas in 1996, there were 4000 in 15 patches. Once a new patch became established, seedlings recruited there in each succeeding mast episode. Adult trees varied in their production of seedlings. Only 25% of the trees in the sample analyzed participated in all mast years; others had few seedlings for up to 28 yr before beginning to produce many seedlings. Seedlings were shade tolerant. They grew extremely slowly in the shaded understory, mean height only doubling in 27 yr. They were also quite long-lived; 6% of seedlings recruited in 1969 were still alive 27 yr later. There was little effect of natural enemies on seeds or seedlings. We found weak positive and negative effects of density on seed germination, seedling mortality, and growth. Mortality rates of Chrysophyllum seedlings did not show any trends with time, nor with distance from conspecific adults. These results suggest that abundance of older stages is determined by recruitment as well as subsequent growth and mortality. Mortality rates of seedlings of species other than Chrysophyllum decreased with distance from adult Chrysophyllum trees. Under present conditions, the Chrysophyllum population may be increasing in relation to that of other species, perhaps leading to a reduction in tree diversity in this tropical rainforest.

Page Thumbnails

  • Thumbnail: Page 
568
    568
  • Thumbnail: Page 
569
    569
  • Thumbnail: Page 
570
    570
  • Thumbnail: Page 
571
    571
  • Thumbnail: Page 
572
    572
  • Thumbnail: Page 
573
    573
  • Thumbnail: Page 
574
    574
  • Thumbnail: Page 
575
    575
  • Thumbnail: Page 
576
    576
  • Thumbnail: Page 
577
    577
  • Thumbnail: Page 
578
    578
  • Thumbnail: Page 
579
    579
  • Thumbnail: Page 
580
    580
  • Thumbnail: Page 
581
    581
  • Thumbnail: Page 
582
    582
  • Thumbnail: Page 
583
    583
  • Thumbnail: Page 
584
    584