Seed Bank Dynamics in Mimosa pigra, an Invasive Tropical Shrub

• Published in: The Journal of applied ecology 1988-12, Vol.25 (3), p.963-976
• Main Authors: Lonsdale, W. M., Harley, K. L. S., Gillett, J. D.
• Format: Article
• Language: English
• Subjects: Agricultural soils; Agrology; Animal, plant and microbial ecology; Applied ecology; Biological and medical sciences; Forest soils; Fundamental and applied biological sciences. Psychology; Half lives; Seed banks; Seeds; Soil depth; Soil ecology; Soil seed banks
• ISSN: 0021-8901; 1365-2664
• DOI: 10.2307/2403758

(1) The dynamics of the seed bank of the tropical weed Mimosa pigra were investigated in two regions of northern Australia by monitoring changes in the seed populations beneath mature stands, by a seed burial experiment, and by measuring the seed output of populations. (2) Seed populations were generally very high compared to the range expected for secondary tropical vegetation. For example, in 1986 they varied from 8500 m-2in one region to nearly 12 000 m-2in another. (3) In the seed burial experiment, viability declined with time. The rate of loss declined with increasing depth of burial, and differed between the two regions, with exponential half-lives ranging from 99 weeks at 10 cm depth in a light clay to 9 weeks at 1 cm depth in a heavier black cracking clay. These seed loss rates were within the range reported in the literature. (4) The measured seed banks broadly agreed with the values predicted by a simple model based on the rates of seed loss found in the burial experiment. (5) Although the decline in viability of M. pigra seeds can be fairly rapid, it is argued that, because of the large soil seed population, rigorous control of seedlings would have to be maintained for some years after the eradication of mature plants.