Seed Dispersal of the Australian Cycad Macrozamia Miquelii (Zamiaceae): Are Cycads Megafauna-Dispersed "grove Forming" Plants?

Hall, John A. and Walter, Gimme H. (2013) Seed Dispersal of the Australian Cycad Macrozamia Miquelii (Zamiaceae): Are Cycads Megafauna-Dispersed "grove Forming" Plants?. American Journal of Botany, 100 6: 1127-1136. doi:10.3732/ajb.1200115

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Author Hall, John A.
Walter, Gimme H.
Title Seed Dispersal of the Australian Cycad Macrozamia Miquelii (Zamiaceae): Are Cycads Megafauna-Dispersed "grove Forming" Plants?
Formatted title
Seed Dispersal of the Australian Cycad Macrozamia Miquelii (Zamiaceae): Are Cycads Megafauna-Dispersed "grove Forming" Plants?
Journal name American Journal of Botany   Check publisher's open access policy
ISSN 0002-9122
1537-2197
Publication date 2013-06-01
Year available 2013
Sub-type Article (original research)
DOI 10.3732/ajb.1200115
Volume 100
Issue 6
Start page 1127
End page 1136
Total pages 10
Place of publication St Louis USA
Publisher Botanical Society of America
Collection year 2014
Language eng
Formatted abstract
Premise of the Study: Plants that invest in large, heavy seeds and colorful, fleshy fruits or analogous structures seem adapted for dispersal by large vertebrates. Some such plants, like Australian cycads in the genus Macrozamia, do not disperse well, which could be explained by seed-dispersal relationships with megafauna that are rare or extinct in contemporary ecosystems. Such plants provide an opportunity to investigate the ecological consequences of low seed-dispersal distances.
Methods: We investigated seed dispersal of Macrozamia miquelii in Central Queensland by tracking the fate of marked seeds, identifying the dispersal fauna and quantifying population demography and spatial structure.
Key Results: We found that 70–100% of marked seeds remained within 1 m of maternal females (cycads are dioecious). Of the 812 seeds recovered (from 840 originally marked) only 24 dispersed >1 m from maternal females, the greatest observed dispersal being 5 m. We found an average of 2.2 seedlings and 0.7 juveniles within 1.5 m of mature females, which suggests that most seeds that remain in the vicinity of maternal females perish. Within-stand densities ranged between 1000 and 5000 plants/ha. The brushtail possum Trichosurus vulpecula was the only animal observed to move the seeds.
Conclusions: Macrozamia are adapted for dispersal by megafauna that are rare or absent in contemporary ecosystems. We argue that Macrozamia are “grove forming” plants that derive ecological benefit from existing as high-density, spatially discrete populations, the function of megafaunal dispersal adaptations being the infrequent dispersal of seeds en masse to establish new such groves in the landscape.
Keyword clumped plant distribution
cycad
extinct dispersal fauna
Macrozamia
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2014 Collection
School of Biological Sciences Publications
 
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