Terminalia acuminata (Terminalia acuminata)
Mohamed bin Zayed Species project number 160512857
Back from the brink? The future of the Brazilian Guarajuba tree, declared Extinct in the Wild (EW) but recently rediscovered
Guarajuba (Terminalia acuminata), is one out of three Brazilian plants declared Extinct in the Wild by the IUCN Red List. Rediscovered in 2015, this distinctive tree survives as several discrete subpopulations within the city of Rio de Janeiro. While the rediscovery gives cause for optimism, the extant population is in urgent need of research and evidence-based action to save it from the brink of extinction.
The project focuses on its rediscovery in the wild, declared extinct in 1998 as it had not been seen in its natural habiat since 1942. The rediscovery of this enigmatic timber tree, prompted many questions which can only be addressed with sound scientific evidence.
Such questions include:
- What is the current size of the extant population?
- How its age/ size structure is formed nowadays?
- Is recruitment ongoing?
- What is the effect of the severe observed historical fragmentation of its habitat, which originally formed a continuous cover of Atlantic Rainforest?
We have already completed a 15-day expedition in Rio de Janeiro between March and April, 2016 (flowering and fruiting season). Quantitative data on population number, and size of each individual were gathered along with size leaf tissue from each individual for further investigation of the population genetic diversity and structure. During June and July 2016, DNA extractions and genetic analysis of the leaf tissue collections were undertaken at RBG Kew’s Jodrell Laboratory. Analysis of these results will help us to quantify genetic diversity and differentiation within and among sub-populations. Such data represent a significant source of evidence in the development of effective conservation strategies based on comprehensive and reliable extinction risk assessments.
Moreover, declaring the “guarajuba” to be extinct highlights its status as a putative ‘’living dead”: its population is not expected to thrive in its remaining habitat without urgent and significant human intervention. The known wild specimens are restricted to a small geographic range, and the population has suffered decline due to decades of selective logging and habitat loss. Although long-lived trees such as T. acuminata are, a priori, relatively more resistant to the effects of fragmentation, the impacts of depletion of its habitat may affects its breeding pattern, reproductive output and progeny fitness, directly compromising population viability. We hope that scientifically robust answers for all these questions will support the foundations of a feasible participatory conservation action plan to save it from the verge of extinction.
Finally, a much clearer understanding of why rediscovered species were initially declared extinct and whether rediscovered populations might be viable is urgently needed, both to inform conservation action and so checklists are accurate. Therefore, I will present my case study of this Brazilian tropical hardwood timber species in the context of a review of other rediscovered plant species in order to more clearly understand declaration of extinction and the fate of rediscovered plants.