# Integrated monitoring in the tropical lowland forest of Mare Longue, Réunion Island

Claudine Ah-Peng, Saioa Ricou-Dreneuc, Antoine Becker Scarpitta, Raphaël Aussenac, Robin Pouteau, Rodolphe Rougerie, Lucas Sire, Pierre Staménoff, Magali David, Yoan Benoit, et al.

► To cite this version:

Claudine Ah-Peng, Saioa Ricou-Dreneuc, Antoine Becker Scarpitta, Raphaël Aussenac, Robin Pouteau, et al. Integrated monitoring in the tropical lowland forest of Mare Longue, Réunion Island. ARPHA Conference Abstracts, 2025, 8, pp.1-3. 10.3897/aca.8.e156720. hal-05127085

HAL Id: hal-05127085

https://hal.inrae.fr/hal-05127085v1

Submitted on 24 Jun 2025

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# Integrated monitoring in the tropical lowland forest of Mare Longue, Réunion Island

Claudine Ah-Peng<sup>‡,§</sup>, Saioa Ricou-Dreneuc<sup>¶</sup>, Antoine Becker Scarpitta<sup>¶</sup>, Raphaël Aussenac<sup>¶</sup>, Robin Pouteau<sup>#</sup>, Rodolphe Rougerie<sup>¶</sup>, Lucas Sire<sup>¶</sup>, Pierre Staménoff<sup>§</sup>, Magali David<sup>§</sup>, Yoan Benoit<sup>§</sup>, Olivier Magand<sup>§</sup>, Victor K/Bidi<sup>§</sup>, Bhavani Benard<sup>¶</sup>, Dominique Strasberg<sup>¶</sup>, Laurent Michon<sup>¶</sup>, Olivier Flores<sup>^</sup>

‡ UMR PVBMT, University of La Réunion, Saint-Pierre, France

§ OSU-R, University of La Réunion, Saint-Denis, France

| UMR PVBMT, Cirad, Saint-Pierre, France

¶ Forests and Societies, Cirad, INP-HB, Department of Forest, Water and Environment, Yamoussoukro, Cote d'Ivoire

\# UMR AMAP, IRD, Saint-Pierre, France

□ UMR 7205, ISYEB, MNHN, CNRS, EPHE-PSL, SU, UA, Paris, France

« UMR7154, IPGP, Laboratoire Géosciences, University of La Réunion, Saint-Denis, France

» UMR PVBMT, University of La Réunion, La Réunion, France

^ UMR PVBMT, University of La Réunion, Saint-Denis, France

Corresponding author: Claudine Ah-Peng (claudine.ahpeng@univ-reunion.fr)

Received: 23 Apr 2025 | Published: 02 Jun 2025

Citation: Ah-Peng C, Ricou-Dreneuc S, Becker Scarpitta A, Aussenac R, Pouteau R, Rougerie R, Sire L, Staménoff P, David M, Benoit Y, Magand O, K/Bidi V, Benard B, Strasberg D, Michon L, Flores O (2025)
Integrated monitoring in the tropical lowland forest of Mare Longue, Réunion Island. ARPHA Conference

Abstracts 8: e156720. https://doi.org/10.3897/aca.8.e156720

## Abstract

Tropical volcanic islands are biodiversity hotspots where the Critical Zone still remains poorly studied. In such steep topographic environments associated with extreme climatic events (cyclones), deployment and maintenance of monitoring equipment is challenging. While a few Critical Zone Observatories are located in tropical volcanic regions, none of them includes a Tropical Lowland Rainforest. We present here the set-up of an observatory from the French network of Critical Zone observatories (OZCAR) located in an insular tropical and volcanic context, integrating permanent plots in a lowland rainforest. This multidisciplinary observatory is located in the southern part of Réunion island (Indian Ocean) on a 364 years old lava flow which hosts the lowland rainforest of Mare Longue, the last preserved lowland forest in the Mascarene archipelago (Indian Ocean). This forest constitutes the only land-to-sea corridor on the island between 0-2600 m, with uninterrupted vegetation and where the human impact is recent (since the
island's colonization in 1665). In the native forest 3 ha permanent plots have been monitored (MALO1 since 1990, MALO2 since 1999 and MALO3 since 2003) where all trees (dbh > 1cm) are inventoried, tagged and measured for their diameters every 5 years. A climatic station in the native forest at 250 m has been operating since 2015, and this was recently complemented by an understory climatic station. Since 2018, five litter traps have provided monthly information for litter biomass and physico-chemistry along with LAI measurements. Within the framework of the BIOSCAN project, a Malaise trap was added to the set-up in 2024, using DNA metabarcoding to monitor (biweekly) the diversity of flying insects. This integrated monitoring is deployed with the collaboration of local biodiversity managers, notably for the tree census, and has collected a multidisciplinary dataset with a constant improvement of the instrumentation over time. This dataset consists of continuous time series variables related to meteorology and biology. The absence of soil and perennial rivers in this forest prevents surveys on soil, ground and stream water monitoring. Despite the frequent maintenance of the monitoring sites, several data gaps exist due to the remote location of some sites and instrument destruction by cyclones. This observatory is a unique research site in an insular volcanic tropical environment offering a window of observation for the study of Critical Zone processes through vegetation dynamics in response to extreme climatic events (world records for precipitation, cyclones) and their respective evolution under changing climatic conditions. In the closest town, the field research forest station of Mare Longue is welcoming researchers and students for their scientific stay on the island with all needed facilities.

**Keywords**

forest dynamics, permanent plots, Field Research station, biosphere, tropical lowland forest

**Presenting author**

Claudine Ah-Peng

**Presented at**

POSTER

**Acknowledgements**

We thank our colleagues from the Office National des Forêts, Parc National de la Réunion, Conservatoire Botanique National de Mascarin for continuously contributing to the forest dynamics measurements. The Observatory of the Critical Zone of Réunion in charge of this integrated monitoring of the Mare longue Forest is funded by the Institut
National des Sciences de l'Univers (CNRS INSU), the University of La Réunion (UR), Météo France, The Insitut de Recherches pour le Développement (IRD), the Observatoire des Sciences de l'Univers (OSU-Réunion) and the French network of critical zone observatories (OZCAR). We acknowledge the funding of the Biodiversa project, Biomonl (Biodiversity Monitoring of Island Ecosystems) and the BIOSCAN-FR project.

Conflicts of interest

The authors have declared that no competing interests exist.