23rd Pacific Science Congress, Academia Sinica, Taipei, 16 June 2016

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1 Long-term study of forest dynamics and monitoring of the impacts of plant invasions and climate change in the islands of Tahiti and Moorea (French Polynesia) Jean-Yves MEYER 1, Ravahere TAPUTUARAI 2 & Méryl JORDAN 3 1 Délégation à la Recherche, Government of French Polynesia, Tahiti 2 NGO «Te Rau Ati Ati a Tau a Hiti Noa Nu», Tahiti, French Polynesia 3 Université de Montpellier 2, Montpellier, France

2 French Polynesia (South Pacific) 4,000-8,000 BP AD 900? 2,000-3,000 BP POLYNESIA 1,000 BP? AD 900 AD 1200 (Trejaut et al PLoS Biology 3(8); Soares et al Am. J. Human Genetics 88)

3 23rd Pacific Science Congress, Academia Sinica, Taipei, 16 June 2016 French Overseas Territory EEZ = 5 million km² 120+ oceanic islands M yrs old MOOREA BORA BORA Land area = 3,500 km² Population (2015)= 270,000 TAHITI

4 23rd Pacific Science Congress, Academia Sinica, Taipei, 16 June 2016 Flora of French Polynesia Native flora Total Indigenous species Endemic species Endemism rate % (Florence et al. 2007) Psychotria (27 endemic species) Cyrtandra (25 endemic species) Metrosideros collina (native) Alien flora Fitchia (endemic genus) Cultivated Naturalized Invasive > 2000 > 590 > 70 Apetahia (endemic genus) (Fourdrigniez & Meyer, 2008)

5 Main goals: Study of island forest ecosystem composition, structure and dynamics with local & global changes Plant diversity and abundance (native vs alien species) Species distribution along elevation gradients ( habitat types) Impacts of anthropogenic disturbances (incl. invasive species) on forest dynamics(e.g. seedling recruitment) Potential future effects of climate change (incl. global warming) Native montane cloud forest, Mt Aorai, Tahiti Miconia invaded forest, Tahiti Mt Marau ridge (1,493 m), Tahiti

6 Other common objectives Comparisons between small high volcanicpacific islands (Micronesia, Melanesia & Polynesia) A contribution to the Pacific-Asia Biodiversity Transect on- goingproject & network (9th PSI Taipei 1998, 19th PSC Sydney 1999) TAHITI island topography (Ferry, 1988) PABITRA sites (Mueller-Dombois, 1998)

7 Moorea study sites Col des Trois Cocotiers-Mt Mouaroa transect ( m) 10 sites (set up in 2005/2006) Ten 20x20 m plots (divided in four 10x10 m plots) in low-to mid- elevation rainforests Moorea (140 km², 1207 m) Vaianae plot (Moorea)

8 Tahiti study sites Belvédère-Mt Aorai transect ( m):8 sites (set up in 2013) Mt Marau transect ( m):2 sites Two 10x10 m permanent plots in gulch forests Belvédère-Mt Aorai transect 900 m 600 m 1400 m 2,200 m 1,700 m Tahiti (1045 km², 2241 m)

9 Method All woody species(native & alien) above 1.3 m tall stem density (mean number/m²) All DBH (> 1 cm) total basal area (cm²/m²) 20 quadrats (2x2 m) randomly selected in each 10x10 m plot seedling density (mean number/m²) Edge Slope

10 Environmental monitoring (micro-climate) climate) Temperature & humidity Dataloggers (1h/2yrs) (MagTech RHTemp 1000 in Tahiti, Hobo Pro v2 in Moorea)

11 Resultsin Tahiti: forestcomposition Mt Aorai elevational transect ( m)

12 Resultsin Tahiti: foreststructure structure AOR = Mt Aorai ; MAR = Mt Marau

13 Resultsin Tahiti: alienplant invasions Aorai plot, 900 m Miconia calvescens (Melastomataceae) African tulip treespathodea campanulata (Bignoniaceae)

14 Resultsin Tahiti: forestdynamics Rhus tahitensis (Anacardiaceae) Rubus rosifolius (Rosaceae) (NATIVE) (ALIEN)

15 Resultsin Moorea: foreststructure structure OPU = Opunohu valley ; VAI = Vaianae valley ; MOU = Mt Mouaroa

16 Resultsin Moorea: forestdynamics Pittosporum tahitense Spathodea campanulata (ENDEMIC) (ALIEN)

17 Conclusion & Discussion High vulnerability to invasion of tropical rainforests at low and mid elevation(below 1,200 m) in Tahiti and Moorea Significant decrease of alien species diversity, stem density and seedling recruitment with elevation (except for the pioneer alien Rubus rosifolius!) Low seedling recruitment(on the ground) of native woody species at high elevation (> 1,200 m) Miconia calvescens «the green cancer» Relative resilience of native island forests at high elevation? Rubus rosifolius at Mt Tohiea (1,200 m) in Moorea

18 The potentialimpacts impacts of global warming 14,000 ha of cloudforest& subalpine vegetation(> 1800 m) +1.4 C in 2050 / +3.1 C in m shift in 2050 / +490 m in 2100 to 6,500 ha in 2050 / 1,500 ha in 2100 Future extinction of a unique habitat and endemic plants? (Pouteau et al ) Mt Orohena (2,240 m), Tahiti Grammitis sp. nov. (Grammitidaceae)

19 Summary & Future prospects First comprehensive study on vascular plant diversity, abundance and altitudinal distribution in Tahiti and Moorea ( zero point ) Series of permanent plots set up along elevation gradients in Tahiti and Moorea (to be increased) Ecological comparisons with other Pacific islands and at a more global level!

20 The MOVECLIM Project MOntane VEgetations as listening posts for CLIMate change Net-Biome Biodiversity research program ( ) 2015) Sponsored by Europe (ERANET) and funded by France (ANR) First collaboration between European Overseas Island Regions & Territories: La Réunion (Indian Ocean), Guadeloupe (Caribbean Sea), Tahiti (Pacific Ocean), Azores & Canaries (Atlantic Ocean) + South Africa, Malaysia, Germany, Switzerland, France Focus on mosses (Bryophytes) & ferns (Pteridophytes)

21 多謝感謝撈力 Mauruuru roa, merci beaucoup, many thanks! Ravahere, Julie, Marie & Robin Base camp at 2,200 m Marie & Julie botanist Jacques Florence (retired in January 2016) Méryl «Te Rau Ati Ati a Tau a Hiti Noa Tu» NGO Pauline & Maruiti