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Pre-dispersal seed-predation affects fruit crop and seed fitness in a highly fragmented savanna tree

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posted on 2024-02-07, 05:48 authored by Simon HeyesSimon Heyes, John MorganJohn Morgan, SJ Sinclair, ZC Walker, Susan HoebeeSusan Hoebee
Context. Silver banksia (Banksia marginata) savannas of south-eastern Australia were formerly widespread but are now largely cleared and fragmented, with small populations often showing recruitment limitation. Which may, in part, be due to seed predation by yellow-tailed black cockatoos (Zanda funerea), which have been observed foraging for seed. Aims. The study aimed to investigate the impact of pre-dispersal seed predation by yellow-tailed black cockatoos on fruit crop between early development and seed release. Additionally, we wanted to assess seed fitness from partially damaged and discarded cones. Methods. The study quantified silver banksia infructescence removal at four populations between early December and seed release in March. We also quantified seed mass and germinability of seeds from cones removed in December, February and March. Key results. All populations experienced significant seed predation (>50%), with almost complete removal of cones from some populations. Early removal limits seed release from cones (only 18% of early removed follicles released seed). Further, early removal also significantly reduced seed mass and germination. Conclusions. Pre-dispersal seed predation by cockatoos is likely to act as a strong filter for recruitment limitation in silver banksia, by negatively affecting annual seed crop size, seed fitness and germinability. Implications. Our study showed the potential impact fragmentation can have on antagonistic plant–animal interactions. Small, isolated B. marginata populations are likely to continue to decline without active strategies to remedy seed predation such as large-scale restoration.

Funding

This study was funded by the Hamilton branch of the Australian Native Plants Society and with in-kind support from the Friends of the Forgotten Woodlands.

History

Publication Date

2023-08-28

Journal

Australian Journal of Botany

Volume

71

Issue

8

Pagination

9p. (p. 434-442)

Publisher

CSIRO

ISSN

0067-1924

Rights Statement

© 2023 The Author(s) (or their employer(s)). Published by CSIRO Publishing. This is an open access article distributed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND).

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