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NEW(-ish) PAPER: Understanding recruitment limitations in a critically endangered species: The story of the iconic Cape cedar (Widdringtonia wallichii)
Open Access: http://doi.org/10.1016/j.gecco.2020.e01062
Open Access: http://doi.org/10.1016/j.gecco.2020.e01062
The Clanwilliam cedar has been in steady decline for over a century ( http://doi.org/10.1186/s12898-016-0108-6), with most of the extensive research on this species being placed on the mortality of long-lived adults. Our approach was to view the cedar as any other obligate reseeder.
As in most fire-prone ecosystems, such as Fynbos, obligate reseeders may experience localised adult mortality, but rely on adequately recruiting post-fire to sustain populations.
Photo: Leucadendron laureolum seedlings post-fire
Photo: Leucadendron laureolum seedlings post-fire
We show that the cedar's large wingless seeds are dispersed by the scatter-hoarding small mammal Acomys subspinosus, burying seeds in safe sites ~2 cm deep. But this mutualism appears disrupted, as only sites with dense cedar stands had effective dispersal.
After a large fire ripped through a century old, dense cedar plantation, we found many seedlings in the burned portion, with few seedlings in the non-burned portion. Together with germination trials, this showed the cedar seeds benefit from fire-cues for effective germination.
Using the brilliant @JasperSlingsby & Peter Slingsby dataset ( http://doi.org/10.7717/peerj.7005) on cedar tree distributions combined with the @CapeNature1 historical fire data we were able to delve into details of the cedar's seed fall phenology and the Cederberg's fire history.
We found that fires tend to occur 'early' before the seeds mast, which presents two problems: 1) small mammal populations tend to crash immediately post-fire, meaning seeds are not dispersed and 2) seeds don't receive a fire-cue to help synchronize germination to ideal conditions
Filling these key demographic knowledge gaps provides important new directions to the cedar's conservation/restoration. Primarily monitoring small mammal populations (conserving) and broadcasting pre-treated seeds in dense patches post-fire (restoring).
This has been a long-haul passion project that budded ±7 years ago and I'm incredibly grateful to the several collaborators and field researchers on this project who all helped get it to print!
@BernardScience @OTSSouthAfrica @BioSciUCT
http://doi.org/10.1016/j.gecco.2020.e01062
@BernardScience @OTSSouthAfrica @BioSciUCT
http://doi.org/10.1016/j.gecco.2020.e01062
