Blog

June 2023 - Congratulations to Quentin

Quentin has successfully defended his MSc project entitled “Spatializing endemism, extinction risk and phylogenetic diversity of woody plants in Reunion Island”. He showed that hotspots of endemism, extinction risk and phylogenetic diversity are not overlapping, which calls for new conservation approaches accounting for the multiple facets of biodiversity. 

June 2023 - Congratulations to Lyse

Lyse has successfully defended her MSc project entitled “Do native and alien trees from Reunion Island have different CSR ecological strategies?”. She found a convergence of strategies between native and alien trees, which suggests a predominant effect of environmental filters.

July 2023 - Margaux Rojat has joined us as PhD Student

Margaux holds a master degree in ecology and conservation from the University of La Réunion. She will explore competitive exclusion and other multi-species interactions between alien and native plants in La Réunion based on forest inventories, community models and pot experiments, and under the supervision of Raphaël Pélissier, Ghislain Vieilledent, Mark van Kleunen and Robin Pouteau. Welcome to the team! ©Margaux ROJAT

October 2023 - LiDAR campaign

With the Observatory of Universe Sciences of La Réunion (OSU-R), we welcomed colleagues from University of Cherbourg and their Matrix 300 UAV for LiDAR measurements over our forest plots. They got a taste of the challenging environmental conditions associated with montane tropical forests. ©Robin POUTEAU

November 2023 - Field work campaign started

We collected ecological data on the last populations of (top to bottom): the vulnerable shrub Dombeya acutangula subsp. acutangula var. acutangula, the endangered endemic trees Obetia ficifolia and Polyscias cutispongia and the critically endangered woody plants Abutilon exstipulare, Polyscias aemiliguineae, Tabernaemontana persicariifolia  and Volkameria heterophylla. A lot of invasive alien plants, showers but also fun! ©Robin POUTEAU, Anaëlle REGEN, Sarah ROUSSEL & Dominique STRASBERG

January 2024 - The cyclone season is open!

Because of the tropical cyclone Belal, the tropical storm Candice and other major meteorological events that caused significant human losses and material damage in Mascarene Islands, our field work campaign has been slowed (only five days this month). ©Météo-France & Robin POUTEAU

February 2024 - 2024 is off to a good start

We discovered that a population of the small tree Dombeya acutangula first described in 2009 as made of 20 individuals has doubled since then. This is thanks to a high number of seedlings and juveniles at the foot of a steep cliff where a highly productive 'mother tree' found refuge (lying tree in the middle picture). Nice to see that this species is still regenerating in a few places. Dombeya acutangula is considered vulnerable in Réunion and critically endangered in Mauritius and Rodrigues.  We also noted that a population of two individuals of the endangered archipelago endemic shrub Fernelia buxifolia remains stable since 2009, and that one of them is even flowering and producing fruits! ©Robin Pouteau

February 2024 - Pot experiment coming soon...

For her PhD, Margaux is setting up an ambitious pot experiment that aims to better understand interactions between endemic threatened trees and alien invasive plants. This experiment, designed with the help of Mark van Kleunen (Konstanz University) and managed with the help of Henri Hoarau (CBNM), will be hosted in one of the shade houses of the project partner CBNM in Saint-Leu (a big thank you goes to them!). Below are:

• the tunnel where the experiment will take place;

• Margaux and Henri caring for the babies;

• flowers of the Reunion endemic CR small tree Indigofera ammoxylon in the CBNM arboretum;

• a flowering individual of the Mascarene endemic CR tree Foetidia mauritiana;

• seedlings of the Mascarene endemic CR tree Terminalia bentzoe.

©Robin POUTEAU

March 2024 - A nice example of management efforts

We made two inventories in one of the last relicts of semi-dry forest (it is thought that only 1% of the original ecosystem remains) in Cap Francis, northwest of Réunion. This site hosts an exceptional richness in threatened endemic trees. It is jointly managed by ONF (French national forest office) and the Conservatoire du littoral (coastal protection agency). Conserving such sites can have an enormous impact in securing the endemic flora of Réunion. Below are:

• a view on the river Grande Chaloupe;

• Elise and Rémi-Paul with the rock Cap Francis in the background;

• the highly invasive alien wine Hiptage benghalensis, sometimes forming impenetrable thickets over native vegetation and causing breakage of supporting trees, has been cut;

• the invasive alien tree Albizia lebbeck has been debarked, allowing light reaching the forest understory;

• seedling of the Mascarene endemic EN tree Scolopia heterophylla;

• seedling of the Mascarene endemic CR tree Foetidia mauritiana;

• young fruit of the Mascarene endemic CR tree Foetidia mauritiana;

• ripe fruit of the Mascarene endemic VU shrub Erythroxylum hypericifolium. We measured hundreds of them;

• a flowering individual of the Réunion endemic CR shrub Croton mauritianus;

• a flowering individual of the Mascarene endemic VU shrub Dombeya acutangula subsp. acutangula var. acutangula;

• the Mascarene endemic CR tree Ruizia populnea;

• female of the alien chameleon Furcifer pardalis.

©Robin POUTEAU

April 2024 - Three days in La Montagne, Reunion

We went on a three day-field trip in the north-east of the island. There, the invasive alien liana Hiptage benghalensis is causing dramatic changes to forest habitats and endemic trees often remain aggregated in tiny relict patches. It was a tiring but exhilarating adventure. Below:

• the Mascarene endemic CR tree Ceodes lanceolata known in Réunion from only five individuals distributed among three sites lost in a dense matrix made of the invasive alien tree Syzygium jambos;

• Margaux and the Mascarene endemic CR tree Foetidia mauritiana sometimes forming populations of several individuals including juveniles;

• flower of the Mascarene endemic CR tree Hibiscus columnaris;

• Arnaud climbing on the Réunion endemic EN tree Polyscias cutispongia to collect leaves;

• discovery of a new population of the Mascarene endemic EN liana Hugonia serrata;

• the team in Ravine à Malheur with a majestic Polyscias cutispongia in the background;

• Elise, Margaux and Rémi-Paul measuring leaf traits in the kitchen after a hard day's work. 

©Robin POUTEAU & Arnaud RHUMEUR

May 2024 - One week on the east coast, Reunion

We received the visit of Jean-Yves Meyer (Research Department, Government of French Polynesia) for one week of intense field work on the east coast of Reunion with Rémi-Paul Grondin (Univ Reunion), Robin Pouteau (IRD-AMAP), Christophe Larvergne (CBNM), Olivier Flores (Univ Reunion), Dominique Strasberg (Univ Reunion) and Arnaud Rhumeur (CBNM). We revisited plots established more than 10 years ago and set up a few new ones. In this part of the island, the most problematic invasive alien plants are undoubtedly the strawberry guava Psidium cattleyanum and the rose-apple Syzygium jambos. We also visited Henri Hoarau at CBNM to see the progress on the ex situ experiment.

©Jean-Yves MEYER

May 2024 - Congratulations to Anaëlle

Anaëlle has successfully defended her MSc project entitled “The effect of invasive alien plant species richness on the regeneration of threatened endemic woody species on Reunion Island”. She demonstrated that the impact of invasive alien plant species richness on the regeneration of threatened endemic woody species was highly species-dependent, with those whose regeneration decreases the most with the number of invasive alien plant species being also typically affected by the extinction of their native seed dispersers.

June 2024 - Congratulations to Cassandra

Cassandra has successfully completed her first year of MSc with a project entitled “Estimating extinction risk of five trees and shrubs restricted to the semi-dry forests of Reunion Island”. Her simulations led either to extinction within a few decades or to population size at which extinction becomes inevitable by the end of the century, which urges local conservation stakeholders to make every possible effort both on site and ex situ to prevent the imminent extinction of this unique flora.

June 2024 - Mafate expedition

From 10 to 13 June, we went to one of the most remote places in La Réunion, the Cirque de Mafate, to collect data (plant inventories, forest structure measurements, functional traits). The four plots that we set up there were moderately to highly invaded by various species including Hiptage benghalensis, Lantana camara, Furcraea foetida and Hedychium gardenarium (foreground in second picture). We discovered one population of Obetia ficifolia (third picture) and two of Dombeya populnea that were not recorded in databases yet. Elise Adrien (MSc student, University of Geneva), Olivier Flores (Lecturer, University of La Réunion), Rémi-Paul Grondin (Research Assistant, University of La Réunion), Margaux Rojat (PhD student, IRD-AMAP lab) and Yohan Simon (BSc student, University of Montpellier) took part of this field trip.

©Elise ADRIEN, Olivier FLORES, Yohan SIMON 

August 2024 - Babies are growing well

As part of the WP2 of the project, we are conducting a one-year pot experiment to assess the interactions between invasive alien species and threatened endemic species at the seedling/juvenile stage. The first phase leaded by Yohan Simon with the assistance of the CBNM nursery manager Henri Hoarau involves producing large quantities (thousands) of seedlings of endemic species, like Croton mauritianus (picture 1) and Poupartia borbonica (picture 2), both categorised CR, and invasive alien species like Hiptage benghalensis (picture 3) and Leucaena leucocephala (picture 4). Yohan is also measuring several parameters to better understand the biology of these species including germination rates and seedling allometries.

©Yohan SIMON 

September 2024 - Field trip in Mafate

We went to Cirque de Mafate with our partners from CBNM (Arnaud Rhumeur) and ONF (Léa Marie) (pictures 1-3) to monitor the fruit production of the last individuals of the Mascarene endemic CR tree Terminalia bentzoe subsp. bentzoe that have been weeded in 2022 (pictures 4-7). This species is particularly threatened by the invasive alien high-climbing liana Hiptage benghalensis (picture 8). We also collected fruits of a newly discovered population of the Mascarene endemic CR shrub Volkameria heterophylla for inclusion in the CBNM arboretum.

©Robin POUTEAU

October 2024 - Pot experiment is underway

Over the past weeks, Margaux, Henri and 18 volunteers have carefully set up our experiment, which aims at studying the interactions between threatened endemic trees and invasive alien plants. A total of 27 threatened-invasive pairs have been selected and >2,000 plants have been planted into 700 pots, each pot containing either one or two species. Every individual plant has been measured and will be measured again in about one year to assess changes in performance when growing alone, with heterospecific competitors, or with conspecifics. The goal is to quantify and compare the competitive ability of each species and, ultimately, to assess the threat posed by the aliens. Hopefully, this research could help design future conservation strategies. A special thanks to the volunteers who helped out! 

©Margaux ROJAT