tag:theconversation.com,2011:/institutions/universite-dantananarivo-3098/articlesUniversité d’Antananarivo2019-11-20T15:08:00Ztag:theconversation.com,2011:article/1271322019-11-20T15:08:00Z2019-11-20T15:08:00ZThe anti-inflammatory properties of Madagascar’s Tsontso plant<figure><img src="https://images.theconversation.com/files/301938/original/file-20191115-66945-rp4e2s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Cladogelonium madagascariense, more commonly known as "tsontso" in Madagascar</span> <span class="attribution"><span class="source">Tianarilalaina Tantely, Andriamampianina</span></span></figcaption></figure><p>In rural areas of Madagascar, medicinal plants are widely used to treat illness. In remote areas, and with limited funds to pay for other health products and services, traditional medicine is essential. </p>
<p>Madagascar has a wealth of <a href="https://www.nytimes.com/2004/03/30/science/on-madagascar-a-utreasury-of-fauna-and-flora.html">flora</a>, the source of a vast range of traditional medical treatments. These plants grow throughout the island, making them widely accessible. </p>
<p>However, while traditional medicine is relatively well established in rural areas, it is <a href="http://digitalcollections.sit.edu/cgi/viewcontent.cgi?article=2651&context=isp_collection">less so in urban centres</a>. This is despite the <a href="https://hal.univ-lorraine.fr/hal-01732278/document">numerous studies</a> that show the efficacy of plants and the <a href="https://apps.who.int/iris/bitstream/handle/10665/95009/9789242506099_fre.pdf;jsessionid=7636D47B48F312B700260BBA9270AC8A?sequence=1">World Health Organisation’s global strategy</a> confirming that traditional medicine can enhance people’s health and well-being.</p>
<p>As part of this effort to promote medicinal plants, <a href="http://ijppr.humanjournals.com/wp-content/uploads/2018/02/21.Tantely-T.-Andriamampianina-Jean-Fran%C3%A7ois-Rajaonarison-Patricia-Randrianavony-Nat-Quansah-Fanantenanirainy-Randimbivololona.pdf">we began research</a> into a native Malagasy plant: <em>Cladogelonium madagascariense</em>, commonly known as “tsontso”. We wanted to find out the therapeutic value of the plant and to establish whether it was safe and effective for people to use. </p>
<h2>Madagascar’s tsontso plant</h2>
<p><em>Tsontso</em> was first identified in a <a href="https://www.persee.fr/doc/jatba_0021-7662_1968_num_15_7_2992">survey</a> conducted in northern Madagascar in 1968. Villagers used it to treat fevers, pain and swelling. Given these traditional uses, it was hypothesised that the plant may have anti-inflammatory properties, and this became the starting premise for our study. </p>
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<p>We found and isolated a molecule called D:B-friedo-olean-5-en-3α-ol (DBFO).
After several laboratory tests, it appeared that DBFO was more effective than some drugs currently available on the market used to treat symptoms of inflammation, such as <a href="https://www.doctissimo.fr/principe-actif-5718-PHENYLBUTAZONE.htm">Phenylbutazone</a> and <a href="https://www.doctissimo.fr/html/sante/mag_2003/sem01/mag0411/sa_6663_aspirine_remede_miracle.htm">Aspirin</a> </p>
<p>We also made a major discovery about the plant: it is devoid of side effects on the stomach, as commonly seen in most anti-inflammatory drugs. </p>
<h2>No side effects</h2>
<p>All pharmacological studies have to include a toxicity assessment. So we carried out two series of tests on DBFO. </p>
<p>The first one is known as an acute toxicity test. DBFO was administered at 60 times a normal effective dose on mice. The results showed that it wasn’t fatal. </p>
<p>The second one, called the chronic toxicity test, revealed that DBFO does not cause gastric ulcers, even at 15 times the normal dose on mice. </p>
<p>This was an important finding as a large number of anti-inflammatory drugs on the market cause <a href="https://www.santemagazine.fr/traitement/medicaments/anti-inflammatoires/7-choses-a-savoir-avant-la-prise-danti-inflammatoires-361891">gastric ulcers</a>. </p>
<p>We then wanted to know exactly how DBFO works and relieves inflammation. </p>
<p>By definition, inflammation is an organism’s defence mechanism against something that has harmed it. It is characterised by four symptoms: redness, heat, swelling and pain. </p>
<p>Redness and heat are caused when blood vessels dilate and there’s an increased blood flow to the site of the inflamation. Because they dilate, blood vessels become more permeable and water and plasma can get into tissues. This collection of fluid in tissues cause the swelling (or edema) surrounding the infected area. The swelling in turn compresses nerves, leading to pain. </p>
<p>White blood cells, which are part of the body’s immune system helping to fight infection and other diseases, get engaged around the infected area to combat pathogens – anything that might cause disease. They release substances, among them is TNF-α – tumour necrosis factor. Once released, TNF-α will “recruit” other defence cells in the organism. If the pathogen persists, more TNF-α are released, while continuing to bring in other defence components. This aggravates the inflammation. </p>
<p>Knowledge of the mechanisms of inflammation enables us to directly target the agents involved in the body’s inflammatory response. Since TNF-α plays such an essential role, it is an ideal target for anti-inflammatory substances. The results of tests carried out on human white blood cells demonstrated that the DBFO found in <em>tsontso</em> reduces the concentration of TNF-α. </p>
<p>In other words, DBFO stops inflammation by inhibiting or stopping the production process of TNF-α.</p>
<p>While these results are very satisfying, our research on <em>Cladogelonium madagascariense</em> does not stop there. There is much left to discover, in particular the likely effect of DBFO on immune system substances other than TNF-α, the possible presence of pure molecules other than DBFO in the plant and their respective mechanisms. </p>
<p>The fact remains that the journey from plant to drug is long. In the meantime, tsontso is available as a decoction called “tambavy” in Madagascar. It is often served in small, overflowing glasses. Here’s to your health! </p>
<p><em>Translated from the French by Alice Heathwood for <a href="http://www.fastforword.fr/en">Fast ForWord</a>.</em></p><img src="https://counter.theconversation.com/content/127132/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Tianarilalaina Tantely, Andriamampianina ne travaille pas, ne conseille pas, ne possède pas de parts, ne reçoit pas de fonds d'une organisation qui pourrait tirer profit de cet article, et n'a déclaré aucune autre affiliation que son organisme de recherche.</span></em></p>Unlike a large number of anti-inflammatory drugs on the market, “tsontso” doesn’t cause stomach ulcersTianarilalaina Tantely, Andriamampianina, Enseignant-chercheur en pharmacologie, Université d’AntananarivoLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1262872019-11-07T19:29:25Z2019-11-07T19:29:25ZLes vertus anti-inflammatoires et sans effet secondaire du « tsontso », une plante locale malgache<figure><img src="https://images.theconversation.com/files/300330/original/file-20191105-88394-vlrobx.jpg?ixlib=rb-1.1.0&rect=7%2C7%2C1191%2C790&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">La flore malgache est un trésor biologique à préserver. </span> <span class="attribution"><span class="source">Rijasolo/AFP</span>, <span class="license">Author provided</span></span></figcaption></figure><p>À Madagascar, l’utilisation des plantes médicinales pour le soin des maladies est une pratique largement répandue en milieu rural. Au-delà de la simple coutume ou de la transmission d’un art ancestral, cette méthode de soin, connue sous l’appellation de « médecine traditionnelle », apparaît comme une vraie pratique vitale pour la population là où l’éloignement géographique et la limite du pouvoir d’achat ne permettent pas l’accès aux services et produits de santé.</p>
<h2>La flore malgache, un trésor biologique</h2>
<p>C’est indéniable, Madagascar est doté d’une <a href="https://www.nytimes.com/2004/03/30/science/on-madagascar-a-treasury-of-fauna-and-flora.html">flore riche</a> et luxuriante, à l’origine de la vaste panoplie de soins en médecine traditionnelle qu’elle offre. La présence de ces plantes sur l’ensemble de l’île assure aussi une grande accessibilité.</p>
<p>Cependant, si en milieu rural la médecine traditionnelle est assez bien implantée, elle l’<a href="http://digitalcollections.sit.edu/cgi/viewcontent.cgi?article=2651&context=isp_collection">est moins dans les centres urbains</a>. Pourtant, de <a href="https://hal.univ-lorraine.fr/hal-01732278/document">nombreuses recherches</a> ont déjà démontré l’efficacité de ces plantes. Qui plus est, la <a href="https://apps.who.int/iris/bitstream/handle/10665/95009/9789242506099_fre.pdf;jsessionid=7636D47B48F312B700260BBA9270AC8A?sequence=1">stratégie mondiale de l’OMS</a>, vient davantage confirmer la contribution que la médecine traditionnelle peut apporter à la santé et au bien-être des individus.</p>
<h2>Le « tsontso », plus efficace que les anti-inflammatoires actuels</h2>
<p>Dans la continuité de ces efforts en faveur de la promotion des plantes médicinales, nous avons entamé des travaux de recherche sur une plante endémique à Madagascar, le <em>Cladogelonium madagascariense</em>, plus communément appelé « tsontso » par la population locale. Les objectifs étaient de valoriser les ressources du pays, d’apporter des évidences scientifiques sur les vertus thérapeutiques de la plante et d’établir des références pour une utilisation sure et efficace.</p>
<p>Le « tsontso » a été recensé lors d’une <a href="https://www.persee.fr/doc/jatba_0021-7662_1968_num_15_7_2992">enquête ethnopharmacologique</a> dans la partie nord de Madagascar. Les villageois l’utilisent pour soigner notamment les fièvres, douleurs et enflures. Vu ces utilisations traditionnelles, l’hypothèse d’une probable activité anti-inflammatoire a été émise, ce qui a constitué le postulat de départ de nos travaux. Après purification, nous avons isolé une molécule qui s’appelle D :B-friedo-olean-5-en-3α-ol (DBFO).</p>
<p>Les résultats ont dévoilé que la molécule DBFO est plus efficace que certains médicaments déjà présents sur le marché et utilisés dans le traitement de l’inflammation, notamment la <a href="https://www.doctissimo.fr/principe-actif-5718-PHENYLBUTAZONE.htm">Phénylbutazone</a>, l’<a href="https://www.doctissimo.fr/html/sante/mag_2003/sem01/mag0411/sa_6663_aspirine_remede_miracle.htm">aspirine</a> et le <a href="https://www.doctissimo.fr/principe-actif-7222-TRAMADOL.htm">Tramadol</a>.</p>
<h2>Sans effet secondaire</h2>
<p>Par ailleurs, toute étude pharmacologique devant passer par un test de toxicité, DBFO a été soumis à deux séries de tests. Sur la première, dite test de toxicité aiguë, DBFO a été administré jusqu’à 60 fois sa dose normale d’efficacité. Les résultats ont montré que DBFO ne provoque pas la mortalité. Sur la seconde, dite test de toxicité chronique, les résultats ont montré que DBFO ne provoque aucune lésion au niveau de l’estomac, même administré à une dose égale à 15 fois sa dose normale d’efficacité.</p>
<p>Cela marque un jalon important dans nos travaux de recherche car bon nombre de médicaments anti-inflammatoires actuellement en vente sur le marché présentent tous le <a href="https://www.santemagazine.fr/traitement/medicaments/anti-inflammatoires/7-choses-a-savoir-avant-la-prise-danti-inflammatoires-361891">même effet secondaire</a> : ils provoquent des ulcères gastriques.</p>
<p>Nos travaux se sont par la suite concentrés sur une analyse plus approfondie du mécanisme de fonctionnement de DBFO. Une inflammation est par définition une réaction de défense de l’organisme à la suite d’une agression. Elle est caractérisée par quatre symptômes : rougeur, chaleur, tumeur, douleur. La rougeur est provoquée par la dilatation des vaisseaux sanguins à proximité de la zone lésée, accompagnée par la chaleur due à l’augmentation de la perméabilité des capillaires. Ces derniers, étant perméables, laissent échapper de l’eau et du plasma des vaisseaux sanguins, formant la tumeur ou œdème qui limite la lésion. Ce gonflement vient compresser les nerfs et fait apparaître en cascade la douleur.</p>
<p>Les globules blancs du sang sont aussi recrutés au niveau de la lésion pour combattre les agents pathogènes. Ils libèrent des substances, dont le TNF-α (de l’anglais <em>tumor necrosis factor</em> ou facteur de nécrose tumorale). Ce TNF-α, une fois libéré, va « recruter » d’autres cellules de défense de l’organisme. Si l’agent pathogène persiste, le TNF-α va entretenir sa propre libération et, en même temps, continuer à « recruter » indéfiniment d’autres éléments de défense : ainsi, l’inflammation s’aggrave.</p>
<p>Cette connaissance du mécanisme de l’inflammation permet de cibler directement les acteurs de la réaction inflammatoire. Comme le TNF-α y joue un rôle essentiel, il constitue une cible idéale pour les substances anti-inflammatoires. Les résultats des tests effectués sur des globules blancs du sang humain ont montré que DBFO diminue la concentration de TNF-α. Ces résultats ont permis de déduire que l’activité anti-inflammatoire de DBFO isolé de <em>Cladogelonium madagascariense</em> est due à l’inhibition de la synthèse ou de la libération de TNF-α.</p>
<p>En conclusion, les données empiriques sur l’utilisation du « tsontso » sont donc bien fondées et vérifiées scientifiquement. De plus, une découverte majeure a été faite sur une propriété de la plante : elle est démunie d’effets secondaires, contrairement aux anti-inflammatoires sur le marché.</p>
<p>Bien que ces résultats soient réellement satisfaisants, ils ne clôturent pas pour autant nos recherches sur le <em>Cladogelonium madagascariense</em>. Beaucoup en effet reste à découvrir, notamment l’effet probable de DBFO sur les substances du système immunitaire autres que le TNF-α, la présence de molécules pures autre que DBFO dans la plante ainsi que leurs mécanismes respectifs, etc. </p>
<p>Toujours est-il que de la plante au médicament, le chemin est encore long. En attendant, le « tsontso » est disponible en décoction, « tambavy » comme on l’appelle dans le pays. Il est souvent servi dans des petits verres bien remplis. Le toast prendrait alors tout son sens. Santé !</p><img src="https://counter.theconversation.com/content/126287/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Tianarilalaina Tantely, Andriamampianina ne travaille pas, ne conseille pas, ne possède pas de parts, ne reçoit pas de fonds d'une organisation qui pourrait tirer profit de cet article, et n'a déclaré aucune autre affiliation que son organisme de recherche.</span></em></p>Les données empiriques sur l’utilisation du « tsontso » ont montré que cette plante malgache est plus efficace que les médicaments anti-inflammatoires. Qui plus est, elle n’a pas d’effet secondaire.Tianarilalaina Tantely, Andriamampianina, Enseignant-chercheur en pharmacologie, Université d’AntananarivoLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/909462018-04-08T10:13:10Z2018-04-08T10:13:10ZMeasuring the economic impact of cyclones in Madagascar<figure><img src="https://images.theconversation.com/files/209917/original/file-20180312-30961-1d2kcrc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Cyclone Ava caused hundreds of millions of dollars worth of damage in Madagascar.</span> <span class="attribution"><span class="source">deruneinholbare/Flickr</span></span></figcaption></figure><p>Madagascar, Africa’s largest island, is naturally prone to cyclones. Earlier this year it was hit by one named <a href="https://www.aljazeera.com/news/2018/01/cyclone-ava-kills-29-madagascar-180109184951149.html">Ava</a> – a category three cyclone that killed at least 50 people, displaced over 50,000 and caused huge damage. And just this month <a href="https://www.aljazeera.com/news/2018/03/tropical-cyclone-triggers-flooding-madagascar-180305084750402.html">another</a> cyclone triggered flooding in the north of the country.</p>
<p>This is not unusual for the island which gets hit by an average of three to four of these aggressive storms each year.</p>
<p>Known as typhoons in the Pacific, cyclones are characterised by storms, torrential rain and strong winds. They <a href="https://sciencing.com/types-cyclones-8572905.html">vary</a> in intensity and can be categorised into <a href="http://www.bom.gov.au/cyclone/about/intensity.shtml">five</a> strengths – one being the weakest (with a wind speed between 119 - 153 km/h) and five the strongest (wind speed of at least 250km/h).</p>
<p>The impact, both short and long term, is devastating. A great deal of the population and economy <a href="http://www.new-ag.info/en/country/profile.php?a=2888">relies</a> on agriculture which, most of time, gets destroyed in cyclones. The majority of the country’s population, <a href="https://tradingeconomics.com/madagascar/rural-population-percent-of-total-population-wb-data.html">more than</a> 65%, also live in rural areas which become inaccessible when the storms hit and destroy the weak infrastructure.</p>
<p>This is extremely damaging to Madagascar as it’s <a href="http://uk.businessinsider.com/the-25-poorest-countries-in-the-world-2017-3?IR=T">one of</a> the poorest countries in the world. Though it has huge marine, mineral and tourism potential, it’s very dependent on primary resources, <a href="https://www.cia.gov/library/publications/the-world-factbook/geos/print_ma.html">like</a> fishing and forestry, and has suffered <a href="http://www.worldbank.org/en/news/press-release/2017/03/21/poverty-in-madagascar-recent-findings">from</a> political crises, rises in global food prices and climate shocks.</p>
<p>Despite the frequency and damages caused by the cyclones, very <a href="https://www.researchgate.net/publication/288063702_Advancing_disaster_risk_governance_in_madagascar_The_role_of_higher_education_institutions">little</a> has been done to track and understand their economic impact.</p>
<p>For about 30 years the government of Madagascar has <a href="https://reliefweb.int/report/madagascar/madagascar-cyclone-tropical-ava-rapport-de-situation-conjoint-no-1-17-janvier-2018">studied</a> the impact of cyclones. But these tend to look at the cost of physical damage for immediate relief needs without taking the loss of services or livelihoods into consideration. This has meant that the full impact of cyclones on the economy aren’t estimated.</p>
<p>We set out to highlight the full impact that cyclones have on Madagascar’s economy. We’re the only <a href="http://www.riskreductionafrica.org/partners-and-programmes-1/university-of-antananarivo-antananarivo-madagascar.html">centre of research</a> in the country that is working on what we call an “economic risk atlas”. This is a tool that examines a hazard, and its intensity or magnitude, and gives the economic cost information of vulnerable assets.</p>
<p>By using this economic risk atlas model, policymakers can know the economic benefits of different assets in advance – and therefore where to invest in disaster risk reduction. The main advantage is that, if resources are limited, the model provides information on which vulnerable assets are a priority.</p>
<p>Before this model, total loss assessment had only been done once, in 2008. This was carried out by the Global Facility for Disaster Reduction and Recovery, World Bank and UN. The evaluation was done in a “Damage and Losses Assessment” (DaLA) framework. But, we’re using different techniques. Damage and losses assessment is based mainly on accounting costs of assets whereas we’re using economic valuation tools – taking into account other impacts, like health or environment. It’s a tool that could be used for other islands or any countries trying to implement disaster risk reduction, whatever the hazard.</p>
<p>According to our research cyclone Ava has caused about USD$ 130 million of damage and USD$ 156 million in losses. This <a href="https://data.worldbank.org/country/madagascar">accounts</a> for 2.9% of the country’s 2017 GDP. Considering the national GDP growth averages about 2.5% GDP each year, this is very high. All the economic growth made over a year is blown away by one disaster.</p>
<h2>Damages and losses</h2>
<p>Coastal areas are the first areas to get hit and the impact is immediately felt as homes are mostly built <a href="https://www.britannica.com/place/Madagascar/Local-government">using</a> local, cheap material – like wood, woven mats, mud or metal sheets. These building techniques <a href="https://reliefweb.int/report/madagascar/madagascar-cyclone-leaves-100000-homeless">can make</a> hundreds of thousands homeless if the cyclone is category two or higher. But they can also be <a href="https://pdfs.semanticscholar.org/1579/1edc38364c880918815428723cc8d06409e0.pdf">considered</a> as a local adaptation strategy. Because of the low cost and access to these materials, homes can be rebuilt in less than a week.</p>
<p>After the initial strike, other problems, like health issues, start to crop up. For example, because most households use open well as water sources in rural areas, it’s easy for them to become contaminated. As a result illnesses like <a href="https://www.theguardian.com/global-development/2017/may/16/after-cyclone-enawo-madacasgar-village-forging-new-life-from-ruins">dysentery</a> often follow cyclones. Environmental hazards also follow as the rains can <a href="http://www.linfo.re/ocean-indien/madagascar/715278-madagascar-un-glissement-de-terrain-tue-huit-personnes">cause</a> landslides.</p>
<p>Then there are the longer-term losses.</p>
<p>Flooding which can severely damage key infrastructure, like roads and bridges. Cyclone Ava caused damage which prevented <a href="https://reliefweb.int/report/madagascar/flash-update-5-tropical-cyclone-ava-hits-madagascar-10-january-2018">road access</a> to some south-eastern and south-western parts of the country. This prevents people from moving around, slows trade and production slows down all over the country.</p>
<p>The cyclone’s strong winds cause significant damage to infrastructure like electricity. Power cuts can last for days. Cyclone Ava destroyed 90% of the port city of Toamasina’s electricity infrastructure. This kind of damage causes huge losses to livelihoods and the local economy.</p>
<p>One of the biggest, and most important, losses is the temporary or permanent loss of jobs. In Madagascar, the informal sector <a href="http://www.linfo.re/ocean-indien/madagascar/madagascar-le-secteur-informel-favorise-par-le-chomage">accounts</a> for more than 80% of jobs and this sector is heavily affected when cyclones strike. Cyclone Ava caused a job loss of 40%, of which 90% were from the informal sector.</p>
<p>Recovering from these losses is very challenging. People don’t have insurance to claim on damage that is done to crops, goods or livestock. For those in the informal sector there is no government support to fall on if they lose their jobs.</p>
<p>Madagascar needs to invest more, and strategically, in prevention and in disaster risk governance to decrease the costs of future disasters. The economic risk atlas is a scientific tool which would be useful in assisting in this process.</p><img src="https://counter.theconversation.com/content/90946/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Tiana Mahefasoa Randrianalijaona does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Madagascar gets hit by an average of four cyclones each year but their full impact is still being tracked.Tiana Mahefasoa Randrianalijaona, Director of the Multidisciplinary Disaster and Risk Management Master’s programme, Université d’AntananarivoLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/796462017-06-18T19:56:15Z2017-06-18T19:56:15ZLes palmiers malgaches victimes de leur succès local et mondial<figure><img src="https://images.theconversation.com/files/174308/original/file-20170618-28797-19jz0eg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Le _Dypsis decipiens_, un des palmiers malgaches les plus vulnérables. </span> <span class="attribution"><span class="source">Mijoro Rakotoarinivo</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span></figcaption></figure><p>Madagascar constitue un « point chaud » de biodiversité pour les palmiers. <a href="https://stateoftheworldsplants.com/2017/report/SOTWP_2017_6_country_focus_status_of_knowledge_of_madagascan_plants.pdf">98 %</a> des 204 espèces connues aujourd’hui ne se trouvent en effet que sur cette grande île de l’océan Indien située au large du Mozambique.</p>
<p>Une telle variété s’explique par le fait que le territoire malgache a connu une longue période d’isolement <a href="http://evolution.berkeley.edu/evolibrary/news/091001_madagascar">après s’être détaché</a> du super continent Gondwana. Ses forêts humides du nord-est concentrent la plus grande diversité de palmiers ; on peut y trouver pas moins de <a href="http://rspb.royalsocietypublishing.org/content/280/1757/20123048">45 espèces</a> différentes au kilomètre carré !</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/174314/original/file-20170618-28802-1cxmcn1.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/174314/original/file-20170618-28802-1cxmcn1.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/174314/original/file-20170618-28802-1cxmcn1.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=483&fit=crop&dpr=1 600w, https://images.theconversation.com/files/174314/original/file-20170618-28802-1cxmcn1.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=483&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/174314/original/file-20170618-28802-1cxmcn1.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=483&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/174314/original/file-20170618-28802-1cxmcn1.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=606&fit=crop&dpr=1 754w, https://images.theconversation.com/files/174314/original/file-20170618-28802-1cxmcn1.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=606&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/174314/original/file-20170618-28802-1cxmcn1.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=606&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="attribution"><span class="source">Google</span></span>
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<p>Mais cette situation exceptionnelle ainsi que la présence dominante de ces arbres dans l’écosystème malgache en ont fait une des ressources végétales les plus courantes et les plus exploitées de l’île. Les palmiers servent en effet à des <a href="https://www.amazon.com/Palms-Madagascar-J-Dransfield/dp/0947643826">usages très variés</a> : pour les toits de chaume, la construction, la vannerie, l’alimentation et même la médecine.</p>
<h2>Attention, cœur fragile</h2>
<p>La situation des palmiers malgaches est aujourd’hui si préoccupante que dans sa dernière liste rouge des espèces menacées, l’Union internationale pour la conservation de la nature a estimé que <a href="http://www.iucnredlist.org/news/madagascars-palms-near-extinction">83 %</a> des espèces locales étaient en danger.</p>
<p>C’est ainsi le cas du <em>Tahina spectabilis</em>, dont on sait qu’il n’existe plus que <a href="http://www.iucnredlist.org/details/195893/0">30 individus</a> matures. Il s’agit là d’une espèce particulièrement fragile, même si elle peut vivre jusqu’à 50 ans ; elle ne fleurit d’autre part qu’une seule fois dans sa vie.</p>
<p>Les palmiers sont essentiels aux communautés humaines des zones rurales qui en dépendent pour leur subsistance quotidienne. Elles <a href="http://reliefweb.int/report/madagascar/possible-palm-extinction-threatens-livelihoods">utilisent ces arbres</a> pour bâtir leurs maisons, fabriquer des outils – à l’image des balais, des cordes ou des manches de couteaux – et se nourrissent de leurs cœurs. Les populations rurales les utilisent également pour leurs propriétés médicinales en vue de <a href="http://qualquant.org/wp-content/uploads/ethnoecology/2001%20Byg951-970.pdf">soulager</a> la toux ou les problèmes digestifs. Mais ces multiples usages sont souvent fatals aux arbres, car extraire le cœur des palmiers les fait périr.</p>
<h2>Une demande mondiale croissante</h2>
<p>Les bons résultats de ces arbres en horticulture constituent une autre menace. Si cette exploitation a démarré dès les premières explorations botaniques dans l’île, le succès des palmiers comme arbres d’ornementation a conduit à la croissance exponentielle de leur culture ces <a href="https://books.google.mg/books?id=STrAt8uYb-QC&pg=PT122&lpg=PT122&dq=dypsis+cultivation&source=bl&ots=sySer-mGZi&sig=Qe6e5l7Yt0s0UMBLaFGc7sN5W9s&hl=fr&sa=X&ved=0ahUKEwic7OC6rKzUAhVCOxoKHTZ_AhQQ6AEIYTAM#v=onepage&q=dypsis%20cultivation&f=false">trente dernières années</a>. Conséquence de cet insatiable appétit mondial, le prélèvement toujours plus intense de leurs graines en milieu naturel.</p>
<p>Cette récolte de graines n’est cependant pas toujours conduite de façon durable. Beaucoup de prélèvements s’accompagnent ainsi de troncs coupés qui condamnent les arbres. Aujourd’hui, la majorité des espèces de palmiers malgaches sont vendues à l’international et la majorité de leurs graines <a href="https://portals.iucn.org/library/efiles/documents/1996-025.pdf">sont prélevées</a>.</p>
<p>Et <a href="http://www.kew.org/science/news/madagascar%E2%80%99s-palms-near-extinction">ces prélèvements</a> se font souvent aux dépens de la régénération naturelle de l’espèce. On a ainsi constaté qu’il restait <a href="https://www.cites.org/eng/cop/15/prop/E-15-Prop-32.pdf">peu d’individus matures</a> du <em>Beccariophoenix madagascariensis</em> dans son habitat d’origine, dans les régions de Mantadia et de Fort-Dauphin. Le ravénéa des berges (<em>Ravenea rivularis</em>) a également vu sa population décliner <a href="http://www.kew.org/science/news/madagascar%E2%80%99s-palms-near-extinction">à cause</a> de sa popularité internationale et du prélèvement de ses graines.</p>
<p>La régénération est d’autre part cruciale pour ces espèces victimes de la <a href="http://www4.ncsu.edu/%7Etlbolton/world_forestry/">déforestation</a> massive qui touche Madagascar depuis la fin du XIX<sup>e</sup> siècle, le pays <a href="http://www.eoi.es/blogs/guidopreti/2014/02/04/deforestation-in-madagascar-a-threat-to-its-biodiversity/">ayant perdu 80 %</a> de ses forêts d’origine.</p>
<h2>Condamnés loin des forêts humides</h2>
<p>Les palmiers sont des arbres <a href="http://onlinelibrary.wiley.com/wol1/doi/10.1111/j.1095-8339.2006.00520.x/full">à croissance lente</a> et leur chance d’atteindre la maturité dépend souvent de l’opportunité de recevoir la lumière <a href="http://www.tropenbos.org/publications/growth+and+survival+of+tropical+rain+forest+tree+seedlings+in+forest+understorey+and+canopy+openings.+implications+for+forest+management.">traversant la canopée</a>. La perte d’individus matures comporte ainsi des conséquences irréversibles pour leurs populations.</p>
<p>Il faut ajouter qu’une fois prélevés, il est difficile de garder ces arbres en vie. Les plantules survivent en effet rarement dans des habitats secondaires. Car 90 % des palmiers malgaches se trouvent <a href="http://rspb.royalsocietypublishing.org/content/280/1757/20123048">dans les forêts humides</a> et tout changement affectant leur niche écologique primaire <a href="https://www.amazon.com/Palms-Madagascar-J-Dransfield/dp/0947643826">réduit dramatiquement</a> leur chance de survie.</p>
<h2>De quoi vont se nourrir les lémurs noirs ?</h2>
<p>Les menaces qui pèsent sur les palmiers affectent également les écosystèmes malgaches, ces arbres y jouant un rôle écologique essentiel. La perte de diverses espèces aura de façon évidente des conséquences néfastes sur la faune et la flore de l’île. Car les fruits des palmiers sont indispensables à nombre d’espèces d’oiseaux pour se nourrir tandis que leurs palmes et leurs couronnes servent souvent de nids pour les oiseaux, les insectes, les reptiles ou les amphibiens.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/174313/original/file-20170618-28759-d48t7q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/174313/original/file-20170618-28759-d48t7q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/174313/original/file-20170618-28759-d48t7q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=472&fit=crop&dpr=1 600w, https://images.theconversation.com/files/174313/original/file-20170618-28759-d48t7q.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=472&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/174313/original/file-20170618-28759-d48t7q.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=472&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/174313/original/file-20170618-28759-d48t7q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=593&fit=crop&dpr=1 754w, https://images.theconversation.com/files/174313/original/file-20170618-28759-d48t7q.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=593&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/174313/original/file-20170618-28759-d48t7q.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=593&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Lémur noir de Madagascar.</span>
<span class="attribution"><a class="source" href="https://fr.wikipedia.org/wiki/L%C3%A9mur_noir#/media/File:Eulemur_macaco_female_01.jpg">Brocken Inaglory/Wikipedia</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
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<p><a href="http://www.palms.org/principes/1994/vol38n4p204-210.pdf">Des travaux</a> ont montré par exemple que les <a href="http://lemur.duke.edu/discover/meet-the-lemurs/common-black-lemur/">lémurs noirs</a> passaient une grande partie de leur temps à se nourrir des fruits du <em>Dypsis madagascariensis</em>. Il est évident que la disparition de ces arbres <a href="http://greentumble.com/how-does-deforestation-affect-animals/">entraînera</a> inéluctablement celles des êtres vivants qui en dépendent : sans palmier, ils verront disparaître une source de nourriture, un abri, un lieu où se reproduire.</p>
<h2>La nécessité d’inventorier pour protéger</h2>
<p>Pour préserver <a href="https://www.iucn.org/theme/species/publications/species-action-plans">ce patrimoine naturel unique</a>, il faut élaborer rapidement un plan d’action. Les efforts de conservation se doivent d’impliquer les communautés locales, en insistant sur une meilleure connaissance et une mise en œuvre des conditions de survie pour les différentes espèces. C’est pour cette raison que les travaux de recherche et les initiatives de conservation doivent chercher les moyens d’améliorer les capacités de germination des graines ; il convient également d’intégrer les savoirs locaux dans la gestion durable des palmiers.</p>
<p>Comparée à d’autres travaux conduits sur des plantes charismatiques, comme les <a href="http://press.uchicago.edu/ucp/books/book/distributed/F/bo9113764.html">orchidées</a>, la recherche sur les palmiers a connu ces vingt dernières années de <a href="https://www.researchgate.net/publication/257325637_The_history_of_palm_exploration_in_Madagascar">remarquables progrès</a>. Mais les expéditions conduites dans des sites <a href="https://link.springer.com/article/10.1007%2Fs12225-010-9210-7">très peu explorés</a> révèlent fréquemment l’existence de nouvelles espèces, soulignant la nécessité de poursuivre l’exploration et la classification.</p>
<p>Depuis la parution de l’ouvrage <a href="https://www.amazon.com/Palms-Madagascar-J-Dransfield/dp/0947643826"><em>Palms of Madagascar</em></a> en 1995, 34 nouvelles espèces <a href="https://stateoftheworldsplants.com/2017/report/SOTWP_2017_6_country_focus_status_of_knowledge_of_madagascan_plants.pdf">ont été découvertes</a>, dont un <a href="http://onlinelibrary.wiley.com/doi/10.1111/j.1095-8339.2007.00742.x/abstract">nouveau genre</a> totalement inconnu (<em>Tahina</em>) en 2007.</p>
<p>Établir cet inventaire botanique robuste du palmier deviendra un plus défi toujours plus important, compte tenu des pertes auxquelles l’écosystème malgache est aujourd’hui confronté.</p><img src="https://counter.theconversation.com/content/79646/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Mijoro Rakotoarinivo ne travaille pas, ne conseille pas, ne possède pas de parts, ne reçoit pas de fonds d'une organisation qui pourrait tirer profit de cet article, et n'a déclaré aucune autre affiliation que son organisme de recherche.</span></em></p>Madagascar concentre la majorité des espèces de palmiers connus sur la planète. Mais ces arbres, très demandés sur le marché horticole mondial, sont de plus en plus vulnérables.Mijoro Rakotoarinivo, Lecturer, Université d’AntananarivoLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/786222017-06-11T08:39:46Z2017-06-11T08:39:46ZThe loss of Madagascar’s unique palm trees will devastate ecosystems<figure><img src="https://images.theconversation.com/files/172900/original/file-20170608-32339-ueumhe.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Dypsis decipiens - a highly threatened palm of Madagascar.</span> <span class="attribution"><span class="source">Mijoro Rakotoarinivo</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Madagascar is a crucial diversity hot spot for palm tree species. <a href="https://stateoftheworldsplants.com/2017/report/SOTWP_2017_6_country_focus_status_of_knowledge_of_madagascan_plants.pdf">98%</a> of the currently 204 known species do not occur anywhere else.</p>
<p>This high diversity is because the island – and its palms – had a long period of isolation <a href="http://evolution.berkeley.edu/evolibrary/news/091001_madagascar">following</a> the break up of the ancient super continent of Gondwana. The humid northeastern forests of Madagascar have the richest species diversity, there can be up to 45 different palm species in <a href="http://rspb.royalsocietypublishing.org/content/280/1757/20123048">one square kilometre</a>. </p>
<p>Unfortunately, their uniqueness and prominence throughout Madagascar’s ecosystems have turned them into one of the most used and exploited plants on the island. Palms have <a href="https://www.amazon.com/Palms-Madagascar-J-Dransfield/dp/0947643826">multiple uses</a> including; thatching, construction, for basket weaving, food and even medicine.</p>
<h2>Threats to the palm</h2>
<p>The situation is so severe that the latest IUCN redlist of threatened species estimated <a href="http://www.iucnredlist.org/news/madagascars-palms-near-extinction">that 83%</a> of the native species are threatened and on the verge of extinction. In the case of the <em>Tahina spectabilis</em>, for example, <a href="http://www.iucnredlist.org/details/195893/0">only</a> 30 mature individuals are known to exist in the wild. It’s a particularly vulnerable species as, though it can live up to 50 years, each individual can produce flowers only once.</p>
<p>Palms are vital to rural people whose daily subsistence depends heavily on natural resources. They <a href="http://reliefweb.int/report/madagascar/possible-palm-extinction-threatens-livelihoods">use palms</a> to build their housing, for daily tools – such as brooms, strings or knife sleeves – and they also eat the palm heart. The palm is also valued by rural communities for its medicinal properties which can be used <a href="http://qualquant.org/wp-content/uploads/ethnoecology/2001%20Byg951-970.pdf">to treat</a> coughs or digestion problems. Unfortunately, many of these uses are lethal to the palm trees. For instance, extracting the palm heart kills the tree. </p>
<p>Another threat is the introduction and success of Madagascar’s palms in horticulture. It started during botanical explorations of the island but, because of their ornamental value, the harvesting of palms for the international market has really exploded <a href="https://books.google.mg/books?id=STrAt8uYb-QC&pg=PT122&lpg=PT122&dq=dypsis+cultivation&source=bl&ots=sySer-mGZi&sig=Qe6e5l7Yt0s0UMBLaFGc7sN5W9s&hl=fr&sa=X&ved=0ahUKEwic7OC6rKzUAhVCOxoKHTZ_AhQQ6AEIYTAM#v=onepage&q=dypsis%20cultivation&f=false">over the last 30 years</a>. This has resulted in a huge amount of seeds being extracted from the natural habitat. </p>
<p>Unfortunately, seed harvesting is not always done in a sustainable way. Many collectors cut the palm trunk, killing the palm, for the whole head of fruit. Today, most of Madagascar’s palm species are sold in international markets and most of the seeds <a href="https://portals.iucn.org/library/efiles/documents/1996-025.pdf">still come</a> from the wild. </p>
<p>The high demand for the palms also mean that too many seeds are being exported. Collectors will often take most of the <a href="http://www.kew.org/science/news/madagascar%E2%80%99s-palms-near-extinction">available fruits</a> without a thought about the natural regeneration of the species. For example, <a href="https://www.cites.org/eng/cop/15/prop/E-15-Prop-32.pdf">few mature</a> trees of <em>Beccariophoenix madagascariensis</em> now exist in its traditional areas – Mantadia and Fort-Dauphin. Or the majestic palm, <em>Ravenea rivularis</em>, this has seen a decline in its population <a href="http://www.kew.org/science/news/madagascar%E2%80%99s-palms-near-extinction">because</a> of its international popularity and seed harvesting.</p>
<p>And their regeneration is crucial. Palms are also victims of the massive <a href="http://www4.ncsu.edu/%7Etlbolton/world_forestry/">deforestation</a> that has plagued Madagascar since the end of the 19th century. The country <a href="http://www.eoi.es/blogs/guidopreti/2014/02/04/deforestation-in-madagascar-a-threat-to-its-biodiversity/">has lost</a> about 80% of its original forests. </p>
<p>Palms are <a href="http://onlinelibrary.wiley.com/wol1/doi/10.1111/j.1095-8339.2006.00520.x/full">slow growth plants</a>. They’re ability to reach maturity often depends on the opportunity to reach the light after <a href="http://www.tropenbos.org/publications/growth+and+survival+of+tropical+rain+forest+tree+seedlings+in+forest+understorey+and+canopy+openings.+implications+for+forest+management.">a gap in the canopy</a> becomes available from the death of another tree. Therefore, the loss of mature palm trees constitutes an irreversible act for the population. </p>
<p>And when they are taken, it’s hard to keep them alive. Seedlings will rarely survive in disturbed or secondary habitats. In fact, 90% of Madagascar’s palms are <a href="http://rspb.royalsocietypublishing.org/content/280/1757/20123048">restricted to humid forests</a> and the change of the ecological niches from this primary vegetation type <a href="https://www.amazon.com/Palms-Madagascar-J-Dransfield/dp/0947643826">dramatically reduces</a> their survival rate. </p>
<p>Their loss would be devastating as palms play a vital ecological role in Madagascar’s ecosystems. The loss of several species will undoubtedly have a huge negative impact on both the fauna and flora of the island. Their fruits are eaten by many animals, their leaves and crown are often used as nests for birds, insects, reptiles or amphibians. <a href="http://www.palms.org/principes/1994/vol38n4p204-210.pdf">Studies</a> for example show that the <a href="http://lemur.duke.edu/discover/meet-the-lemurs/common-black-lemur/">black lemur</a> spend big parts of their feeding time eating fruits of the <em>Dypsis madagascariensis</em> when these are available. This illustrates how the absence of a particular palm species could lead to the <a href="http://greentumble.com/how-does-deforestation-affect-animals/">extinction</a> of animals dependent on it – whether due to the loss of adequate food, shelter or breeding habitat.</p>
<h2>What must be done</h2>
<p>To save this natural legacy, as <a href="https://www.iucn.org/theme/species/publications/species-action-plans">stated</a> by the IUCN, an action plan needs to be urgently set up. Conservation efforts must include local communities in the activities and be focused on raising awareness and increasing the species survival rate. For example, more research and projects need to look at how to improve the germination rate of seeds and how local knowledge can be integrated for their sustainable management.</p>
<p>Compared to other charismatic plants, such as <a href="http://press.uchicago.edu/ucp/books/book/distributed/F/bo9113764.html">orchids</a>, <a href="https://www.researchgate.net/publication/257325637_The_history_of_palm_exploration_in_Madagascar">research on palms</a> has made remarkable progress in the last two decades. Nevertheless, <a href="https://link.springer.com/article/10.1007%2Fs12225-010-9210-7">expeditions in under-explored sites</a> often reveal new groups emphasising the need to continue taxonomic – classification – investigations. Since the publication of the book <a href="https://www.amazon.com/Palms-Madagascar-J-Dransfield/dp/0947643826">Palms of Madagascar</a> in 1995, about 34 new species have been <a href="https://stateoftheworldsplants.com/2017/report/SOTWP_2017_6_country_focus_status_of_knowledge_of_madagascan_plants.pdf">discovered</a>, these include a completely new genus (<em>Tahina</em>) <a href="http://onlinelibrary.wiley.com/doi/10.1111/j.1095-8339.2007.00742.x/abstract">discovered in 2007</a>. </p>
<p>Creating a solid botanical inventory of the palm will become an even bigger challenge with the huge natural ecosystem loss facing the island today.</p><img src="https://counter.theconversation.com/content/78622/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Mijoro Rakotoarinivo does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>International and local demand have brought Madagascar’s palm species to the brink of extinction.Mijoro Rakotoarinivo, Lecturer, Université d’AntananarivoLicensed as Creative Commons – attribution, no derivatives.