If You Use a Screen Reader

This content is available through Read Online (Free) program, which relies on page scans. Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Journal Article

Effect of Invasive Australian Acacias on the Regeneration, Growth and Nutrient Chemistry of South African Lowland Fynbos

C. F. Musil
Journal of Applied Ecology
Vol. 30, No. 2 (1993), pp. 361-372
DOI: 10.2307/2404637
Stable URL: http://www.jstor.org/stable/2404637
Page Count: 12

You can always find the topics here!

Topics: Habitats, Plant architecture, Seedlings, Fynbos, Plants, Vegetation, Taxa, Plant growth, Lowlands, Botany
Were these topics helpful?
See something inaccurate? Let us know!

Select the topics that are inaccurate.

  • Read Online (Free)
  • Download ($18.00)
  • Subscribe ($19.50)
  • Add to My Lists
  • Cite this Item
Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Effect of Invasive Australian Acacias on the Regeneration, Growth and Nutrient Chemistry of South African Lowland Fynbos
Preview not available

Abstract

1. Regeneration, mortality, local extinction, growth and foliar elemental concentrations of indigenous (ericoid, restioid, proteoid) and alien (acacia) plant forms and concentrations of soil elements were compared in stands of the invasive Australian Acacia saligna and in surrounding sand plain lowland fynbos vegetation after an autumn fire. 2. All indigenous forms regenerated less successfully in acacia-infested than in natural habitats. Seedling:parent ratios of proteoids were 32%, restioids 42% and ericoids 65% of those in natural vegetation. Seedling mortalities of all plant forms were not different in the two habitats. 3. Simulated probabilities of extinction, based on the measured spatial variation in seedling:parent ratios of different forms in acacia stands and in natural vegetation, showed that the risk of local extinction after fire was three to four times greater for ericoids, five times greater for proteoids and seven times greater for restioids in acacia-infested than in natural habitats. Within a 10-m2 acacia stand area, the probability of extinction of proteoids was high (99.7%) and moderate (56-57%) for ericoid and restioid forms. 4. Soil N, Ca, Mg, K, Mn and B concentrations were higher and soil Fe concentrations lower in acacia-infested than in natural habitats; but the only significant concentration increases recorded for all plant forms were in the N and K of seedling leaves in acacia stands. 5. Seedling shoot and root dry masses of all forms, except restioids which had the lowest foliar elemental concentrations, were unaffected by the higher soil nutrient concentrations beneath acacias. Increased shoot:root ratios observed among indigenous forms in acacia-infested habitats reflected responses to shading by burnt acacia parental remnants rather than soil mineral enrichment. Acacia shoot:root ratios were unaffected by the different environmental conditions in acacia stands. 6. It is concluded that the mineral enrichment of lowland fynbos soils by acacias has no detrimental effect on post-fire seedling growth and survival of indigenous taxa. The depletion of indigenous taxa, particularly obligate reseeding forms, beneath acacia stands results mainly from their poor seed regeneration success and associated increased risk of local extinction from stochastic causes in this habitat after fire.

Page Thumbnails

  • Thumbnail: Page 
361
    361
  • Thumbnail: Page 
362
    362
  • Thumbnail: Page 
363
    363
  • Thumbnail: Page 
364
    364
  • Thumbnail: Page 
365
    365
  • Thumbnail: Page 
366
    366
  • Thumbnail: Page 
367
    367
  • Thumbnail: Page 
368
    368
  • Thumbnail: Page 
369
    369
  • Thumbnail: Page 
370
    370
  • Thumbnail: Page 
371
    371
  • Thumbnail: Page 
372
    372