Sunset lights up the tsingy outcrop where the main population of Tahina spectabilis is found
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Revisiting the Madagascan suicide palm: a decade on

Lauren Gardiner continues the fascinating tale of Tahina spectabilis, and recounts her journey to Madagascar to see the species in the wild, ten years after the discovery of the magnificent Madagascan suicide palm.

Blog team: 
Author: 
Lauren Gardiner

 

Last week’s Kew Science blog post, ‘Revisiting the Madagascan suicide palm’, told the story of the discovery of Tahina spectabilis, Kew’s involvement in describing this new species and the impact of this discovery on the local community. 

Team Tahina return in 2016 (L>R): Alison Shapcott (University of the Sunshine Coast), David Rabehevitra (Kew Madagascar), Lauren Gardiner (RBG Kew, UK), Rockiman Letsara (PBZT/CAS, Madagascar), Roger Rajaoarison (Kew Madagascar).

Botanists return to the Tahina site eight years later

It was with some trepidation in early September that I set off with a team of botanists from Madagascar, the UK and Australia to find the remarkable palm Tahina spectabilis, in the wild, a decade after its discovery by Xavier Metz, the manager of a cashew plantation. The species had been assessed as Critically Endangered (according to the IUCN Red List categories and criteria) in 2010, and was known to be in a precarious situation. With only a tiny known population, the species is threatened by grassland fires and illegal collection of plants and seeds for horticulture.

We had received reports of more flowerings of some of the larger Tahina individuals at Antsingilava, and reports of seedlings being found nearby, but Kew researchers had not been back to visit the site since 2008. Although it was known that some local conservation efforts had been made to protect the species, we did not know exactly what we would find.

A rewarding journey

We travelled for two full days overland to the remote peninsula in northwest Madagascar, in one of Kew’s Land Rover Defenders, expertly driven by Roger Rajaonarison, Kew Madagascar’s head driver-mechanic. Our rather treacherous journey took us through devastated grassland hillsides, still smouldering after being ravaged by fires, and across narrow, rocky zebu (cattle) cart tracks, dried riverbeds, as well as sandy beaches and spiky mangrove roots – crossing in the short windows of time whilst the tides were out.

The Kew team travelled for two days, off-road, by Land Rover Defender to the remote site (Image: L. Gardiner).

Our first glimpse of Tahina in the wild was unforgettable. We pulled up a stone's throw away from the ‘tsingy’, a dark green island of vegetation and light grey rock, as the sun was setting across the grassland. We realised that the sharply-defined light green patches in the dark green island were the enormous leaves of individual Tahina crowns, emerging from between the other vegetation and the top of the ‘island’. The last of the sun’s rays turned the limestone rock orange-red and the Tahina leaves stood out even more brightly as we pitched our tents just inside the firebreak separating the tsingy island and its precious inhabitants from the inflammable grassland around it.

Sunset lights up the tsingy outcrop where the main population of Tahina spectabilis is found, surrounded by grassland (Image: L. Gardiner).

Surveys and sampling at Antsingilava

Our first task was to re-survey the known Tahina population. We were thrilled to see many seedlings and young Tahina plants in and around the tsingy outcrop, representing seedling cohorts from the various flowerings and fruitings that have taken place over the last decade. From Xavier’s records, we knew that five adult plants had died since 2008, and we found the remains of their decomposing trunks and hollows showing where these adults previously stood. Five of the juvenile plants recorded in 2008 have now grown large enough to be defined as ‘adult’, effectively replacing the five dead trees. 

Overall at Antsingilava we recorded 568 Tahina individuals (27 of which we consider to be adults as they have produced a trunk), approximately 100 individuals more than were recorded at the site in 2008. Excitingly, we managed to find the seedling site that had been reported by Xavier - approximately 1.5 km away from Antsingilava in Ambatosaromby, and comprising 170 seedlings. Local people told us that these came from an adult which they remember had flowered and died some years ago.

As of this census, the total known population of Tahina spectabilis on the peninsula is 740 individual plants.

A single large trunked Tahina spectabilis grows on the edge of a village near to the main population, here with the Kew Madagascar Land Rover Defender in front for scale (Image: L. Gardiner).

Continuing community-based in situ conservation – and an ex situ site too?

A major aim of the trip was to determine what in situ conservation measures have been undertaken for Tahina, and how well they are working. Essential to this is the engagement of local people in conservation activities, and the concept of community-based conservation (CBC). We were extremely pleased to see that VERAMA (the cashew plantation) and the local community at Antanamarina had been working well together since Tahina was discovered, and the funds raised from the sale of Tahina seeds have facilitated this. A new school and water well for the village were built early on from the seed sales. The funds also pay for the annual maintenance of the firebreak around the main tsingy site at Antsingilava, and the building of fences to stop zebu getting too close to the population and trampling the young plants.

Antanamarina has an active COBA (community-based association) which includes a specific committee to protect Tahina, called the Committee de Gestation de Tahina (CGT). We discussed current and future work at length with both VERAMA and the COBA. The manager of VERAMA, Alain Andrianandraina, confirmed the company’s continued interest and support in conserving Tahina. VERAMA employee Manitra Razafinahatratra is specifically assigned to work with communities in the area on environmental management and conservation. During our visit, Manitra and members of the CGT learnt how to survey Tahina so we can monitor the population in the future.

A local team from the community based association (COBA) and the cashew plantation nearby, were trained to monitor the population in the future (Image: L. Gardiner).

On our return journey we visited an exclusive ‘fly-in’ ecoresort further along the peninsula, called Anjajavy. The manager, Cedric de Foucault wanted to discuss his plan to create an ex situ Tahina spectabilis population at the site: a seven-hectare private reserve made up of dry deciduous forest, mangroves and tsingy vegetation, nestled between white sand beaches. Hopefully more seed will be collected in the future from Tahina flowerings at Antsingilava and these will be used to create a field gene bank of Tahina individuals here, with continued, assured protection from both human interference and stochastic effects of having such a small population.

Next steps for Tahina spectabilis

Back at Kew now, we are working on a conservation management plan for Tahina spectabilis based on our findings, ready for discussion with other stakeholders in Tahina’s survival. The plan will contain recommendations for work at the in situ site at Antsingilava and nearby seedling population at Ambatosaromby, and the planned ex situ site at Anjajavy.

In Australia, Alison Shapcott will soon be adding the new DNA samples to the main population genetics data set, analysing the demographic data from the census and running population viability analyses and new species distribution models. Hopefully, by understanding the population growth and development of Tahina better, and correlating the infrequent flowering events with climatic variables, we can adapt the management plan to best protect the species in the future.

Overall, we feel that the future for Tahina spectabilis is far more secure than we feared it might be. The funding from the Mohammed bin Zayed Species Conservation Fund allowed us to undertake this remote, difficult trip and to really engage with stakeholders at the in situ site as well as to visit the possible future ex situ site. Community engagement at Antsingilava is very positive and remaining funds will be spent on environmental education materials for the local community to encourage their continued awareness of and commitment to protecting Tahina. Even with the community actively protecting Tahina, with such a small population and site where the plants are found on the peninsula, the species is still at risk of being wiped out in an alarmingly short space of time.

- Lauren -

Lauren Gardiner with the population of Tahina spectabilis seedlings found a few kilometres away from the main population (Image: L. Gardiner).


Acknowledgements

Generous support from the Mohammed bin Zayed Species Conservation Fund made this expedition and the follow-up work possible.

Individual thanks go to:

The Kew Madagascar team, especially Helene Ralimanana, David Rabehevitra and Roger Rajaonarison; Alison Shapcott (University of the Sunshine Coast, Queensland, Australia); Rockiman Letsara (Parc Botanique et Zoologique de Tsimbazaza and Californian Academy of Sciences); Kew Madagascar’s Research Leader, Stuart Cable; Head of Conservation Science, Colin Clubbe; Alain Andrianandraina and Manitra Razafinahatratra from VERAMA (part of UNIMA group); Cedric de Foucault from Anjajavy Resort; Joseph from the COBA of Antonibe; and Theophile Rajaonilaza from Association Europeenne pour l’Etude et la Conservation des Lemuriens (A.E.E.C.L.).