Seed bank status and dynamics of Acacia saligna at two sites in the Western Cape, South Africa
Date
2010-09-23Author
Strydom, M.
Esler, K.J.
Wood, A.R.
Date Created
2009Format Extent
196608 bytes154071 bytes
Rights
copyrightMetadata
Show full item recordAbstract
Acacia saligna is the most damaging invasive species in the coastal lowlands of the south-western Cape.
The gall rust fungus, Uromycladium tepperianum, has been highly successful as a biological control agent
for A. saligna populations in South Africa and has effectively reduced the density, canopy cover and seed
production of the tree. However, there are still concerns about the soil-stored seed bank and knowledge
of seed bank status and dynamics is crucial for effective management. This study evaluated the
effectiveness of two different sampling methods in assessing the status of the seed bank, how the seed
bank of A. saligna at two different sites varies over time and how these findings compare to findings of
other seed bank studies of A. saligna across southern Africa. Even with the reduction in seed production
caused by biological control, numbers of seeds in the soil seed bank are high enough to maintain high
levels of recruitment after management or natural disturbances. Both sampling methods (grid and random
sampling) attempted were effective in assessing the vertical distribution of the seed bank and estimated
the size of the seed bank to be within the same order of magnitude. However, random sampling will be
more effective in assessing the seed bank size as it was found that the seeds have a clumped horizontal
distribution. The vertical distribution of seeds in the seed bank was found to be influenced by soil
properties. The largest portion of the seed bank is situated in the upper 0-10 cm of the soil and declines in
size with depth.