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Mauritian tree rediscovered
Abstract
The Dombeya mauritiana, an endemic Mauritian tree previously thought to be extinct in the wild, was found by Cláudia Baider and the chair of the Mascarenes Plant Specialist Group, in the Black River Gorges National Park, Mauritius, in April 2009. The species was previously known from a single 10 m tall plant discovered in 1976 in a dry native forest in the Black River District. It was described by Francis Friedmann in 1981 as a new Mauritius endemic. Despite further survey efforts in the area, no other plant had been found. In a paper by Wyse-Jackson et al. in 1989 it was reported that 89 cuttings were taken of the plant; all the cuttings failed. Further cuttings were taken and some were successful. In 1994 the single wild plant was dead and it was declared Extinct in the wild. The exact cause of ‘extinction’ of the species in the wild is not fully understood. It is reported that the plant got ‘sick’ and died despite attempted treatment. However, what is known is that the ‘sickness’ appeared after the huge number of cuttings were taken in 1989. The cause of decline (at the level of the whole species) appears to be a combination of habitat destruction, with 95% of the natural habitats of Mauritius transformed into agriculture or urban areas, and the impacts of invasive alien species. The site where the species has been relocated is highly invaded with alien plants, particularly the strawberry guava Psidium cattleianum. The forest habitat is however very rich, with about a 100 species of native or endemic flowering plants so far recorded. These include some very rare species like the Mascarenes endemic Dombeya populnea of which eight plants were found, resulting in more than a doubling of its known wild population for Mauritius. Further field visits to the area have failed to locate other D. mauritiana plants, but the search continues. None of the seeds collected from the plant and sown three months ago have germinated. The National Parks and Conservation Services are interested in controlling invasive alien weeds in the vicinity of the plant, and the Mascarenes Plant SG is planning to raise funds to restore the habitat of the plant and try propagation and augmentation in the wild.
... Florens offered several examples for illustrating 'unfavourable sampling' with dramatic consequences for conservation. Two of these examples concerns endemic and critically endangered Dombeya species from Mauritius, that is, Dombeya sevathianii Le Péchon et Baider [2] and Dombeya mauritiana Friedmann [3], which are currently represented in the wild by eight specimens and one specimen, respectively [2,4]. According to Florens, specimens of both species died because of infection. ...
... We are therefore accused of indirectly killing the specimen type of this critically endangered taxon [1]. For D. mauritiana, despite previously admitting 'the exact cause of extinction of the species in the wild is not fully understood' [4], Florens argued that the disease is a consequence of 89 cuttings sampled [1]. ...
... As a consequence, conservation actions and research using perfectly efficient practices could be stopped or restricted while these works in the field are absolutely necessary to preserve and safeguard critically endangered species. For example, the taxonomical recognition of D. sevathianii and the study of its wood anatomy [2,4] directly contribute to its conservation [10]. Given the important threats on its natural distribution, the likelihood of the success of the in situ conservation programme for D. mauritiana was null and the cuttings ensured its ex situ conservation. ...
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... (Cheke & Hume, 2008), as well as plants like Strawberry guava (Psidium cattleyanum) (Lorence & Sussman, 1986) which constitute the dominant species in even the best preserved and protected moist to wet native forest areas . This combination of factors has resulted in high rates of extinction and endangerment of the island's native biota (Cheke & Hume, 2008;Florens, 2013), which also comprise both the rarest species worldwide (Florens, 2015b) and the rarest species in the wild (Florens, 2009). ...
Human-wildlife conflicts (HWC) pose a growing threat to biodiversity worldwide and solutions can be as sound as the understanding of the HWC itself. Conservation biologists therefore must carefully examine their local situations to inform on which approach and strategies may be best. In this context, Mauritius implemented what may be the first mass-culls of an already threatened native species when it culled the flying fox (Pteropus niger) in 2015 and 2016 to try increase fruit producers’ profits. Although the Red List category of the species consequently worsened to ‘Endangered’ and fruit production dropped substantially, a third mass-cull was decided in 2018. A critical analysis is important to draw lessons that may help to prevent recurrences particularly that HWC involving Pteropus spp. are common and set to worsen. We synthesized the best literature available locally and also elsewhere in relevant situations, to critically appraise the setting, nature, timeline of events and outcome of both completed mass-culling campaigns to explore why and how they happened so as to help towards devising better approaches to such conflicts. The idea to cull P. niger originated around 2002 and a small cull was done in 2006. The first mass-cull started immediately after Mauritius’ biodiversity protection law was weakened in 2015 primarily to legalize culls of threatened native species, but still breached the law in place then. The 2016 mass-cull was recommended in line with the law, but was not evidence-based and consequently did not result in improved profits of fruit producers. Appeals supported by best scientific evidence from local and international organizations and conservationists to the effect that culls will not increase fruit production, but instead further endanger the species, were ignored. To forestall recurrences here and elsewhere, it matters to recognize their precursor signs and the conditions that favoured them including why the mass-culls were not stopped. The events provide a rare opportunity to explore the strategy that was used by conservationists and open the way to propose impactful alternatives or additional actions instead. The situation also exemplifies an eroding commitment towards biodiversity conservation, eased by withdrawal from evidence-based policy that suit short term goals of election cycles at the expense of longer term environmental interests.
... Authorised sampling of critically endangered species for research and conservation in particular should be carefully planned and carried out, but is often not. For example, large numbers of cuttings were taken from the then last-known individual of a small endemic tree, which died shortly after [6,7]. More recently, the type specimen of a newly described critically endangered endemic tree known from only three adults [8] had its wood tissue sampled [9] and died from infection emanating from the untreated injury. ...
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... Pedicels glabrous. Surprisingly it grows sympatrically with another rare Dombeya: D. mauritiana Friedmann (1981: 439), a species thought to be extinct in the wild, but was recently rediscovered but is known only from a single wild adult (Florens 2009). ...
Dombeya sevathianii, a new endemic species from Mauritius, is described and illustrated. Based on its morphology, D. sevathianiibelongs to the section Assonias defined by Arènes and is closely related to D. populnea, endemic to La Réunion and Mauritius. These affinities are confirmed by a previous molecular study. The morphological diagnostic features for D. sevathianii are the cupuliform and entire epicalyx, and the absence of staminodes within the androecium. Given its known restricted distribution and small population, the species should be considered Critically Endangered (CR) as per the Red List Criteria of the International Union for the Conservation of Nature.
Laurance [1] posited that research may safeguard protected areas while highlighting the need for an improved understanding of the advantages and limitations of field research for aiding protected areas and their biodiversity. I discussed some of these advantages and limitations [2]. Now, Boura et al. [3] are challenging two of the several examples that I have used.
They claimed that I ‘did not provide any analyses or results for justifying that both specimens died from infection, neither the link. . .between the injuries. . .and the
putative infection’. In fact, contrary to their assertion, I linked injury with infection in only one case. I did not expand further to avoid distracting details and to remain
within the required word limit for a Letter. Observation on the dead plant revealed symptoms of a fungal infection spreading from the wood-coring injury including axial
cambial decay (e.g., [4]). This decay was present before the plant’s death, as seen in the species description paper, in which the plant was already reported to be dying (Figure 2D in [5]). An examination of the injury in 2012 revealed ....
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