Fieldwork in Tahiti (French Polynesia) from 2-16 october 2013

Claudine AH-PENG, Terry HEDDERSON with Olivier FLORES and Dirk KARGER (Universität Zürich, Switzerland) took part to the last transect expedition of the Moveclim project on Mount Aorai (2066 m).

Our host Jean-Yves Meyer (Délégation à la Recherche) and Ravahere Taputuarai (member of the local NGO Te Rau Ati Ati A Tau A Hiti Noa Tu) welcomed us on the island traditionally, with flowers.

Pix: Flowers' crown (Photo credit: Ah-Peng C.)

We stayed at the “Pavillon d’accueil” of IRD in Arue, North of Papeete which is the main town of Tahiti, close to the road to Mount Aorai (Belvédère).

Pix: IRD Pavillon d'acceuil sea view (Photo credit: Ah-Peng C)

The following day of the arrival (8 oct), Claudine gave a talk in the conference cycle “Savoir pour Tous” at the University of French Polynesia entitled “Islands, sentinels of climate change”.

The bryophyte flora of the Society Islands (major islands Tahiti, Raiatea, Bora Bora, Moorea and Huahine) counts to our knowledge around 398 species divided into 178 moss species (Whittier, 1976; De Sloover 1994) and 220 species of liverworts and hornworts (Bardat et al. in prep.).  The geological age of the islands ranges from 1.4 to 12 Myrs. Tahiti is the highest (2241 m) and the largest island (1045 km2) in French Polynesia. This volcanic island emerged approximately 1.4 My ago as two islands Tahiti Nui and Tahiti Iti connected by the isthmus of Taravao. The interior of Tahiti Nui is almost entirely uninhabited. Tahiti Iti has remained isolated, as its south eastern half (Te Pari) is accessible only by boat or on foot.

After the arrival of Dirk and Olivier, we started the fieldwork in Tahiti Nui for the collection of bryophytes, ferns and the set up of climatic sensors along an elevational transect on mount Aorai from 600 to 2000 m. At each elevation, two long term monitoring plots of 10 X 10 m are set up.

Pix: Map of the sampling sites on Tahiti Nui (Photo credit: O. Flores)

JY Meyer already set up the plots, which was not an easy task as the physical nature of the island especially in the highlands is mostly vertical and with abrupt crests… As a consequence, at an exception to the other transects, plots could not be set up every 200 m, and the methodology has to be adapted to the steepness of the environment. Earlier this year, JY Meyer and his team worked on fern diversity and abundance as well as the structure of the forest structure and composition, to characterize these sampling plots. 

Pix: Mountain's landscape in Tahiti Nui (Photo credit: C. Ah-Peng)

Plots at 600 m and 900 m are dominated by two invasive species Spathodea campanulata and Miconia calvescens. Since its introduction in 1937, Miconia calvescens covers 2/3 of the island (Meyer & Florence, 1996).

Pix: Miconia calvescens invader of native forests; More recently a fungal pathogen was released to attack the leaves, which slows down the expansion of the invasive populations, with main impacts on juvenils (Meyer et al. 2008), Photo credit: C. Ah-Peng

Pix: At these altitudes, on exposed soil banks, members of the Pottiaceae family are found: Weisia controversa and Anoectangium ssp.

Pix: The liverwort Trichocolea tomentella (Trichocoleaceae),  in shade and humicolous habitats (Photo credit: C. Ah-Peng (left) & Jacques Bardat (right) 

Pix: Dense corticolous population of the moss Neckeropsis lepineana (Neckeraceae) and close-up, Photo credit: C. Ah-Peng

Pix: The dendroid moss Hypnodendron samoanum present on decaying wood, humus and rocks. It can be distinguished from Hypnodendron tahiticum by the absence of tomentum (dense reddish rhizoid network), Photo credit: C. Ah-Peng

At 1200 and 1300 m, the number and cover of invasive species decreases, the montane cloud forest starts.

Pix: At 1200 and 1300 m in the cloud forest (Photo credit: O. Flores)

Some bryophyte species appear at these altitudes…

Pix: Ptychomnion aciculare (Ptychomniaceae) is member of a genus restricted to the Southern hemisphere, present in Australia, Tasmania, New Zealand, New Caledonia, Pacific islands, Chile and Patagonia. (Photo credit: C. Ah-Peng)

Pix: Corticolous Garovaglia powellii var. tahitensis, in the family Pterobryaceae, the genus was revised by H. Düring in 1977.

In the plots 1700, 1800 and 2000 m, the forest is dominated by tree ferns (Cyathea spp), Weinmania parviflora, and the native trees Ilex anomala and Metrosideros collina. The canopy is lower 6-8 m, with many high dbh tree on the ground.

Pix: Metrosideros collina (Photo credit: C. Ah-Peng)

Pix: Colony of  Pyrrhobryum spiniforme (Rhizogoniaceae) on decaying wood, Photo credit: C. Ah-Peng

Pix: One of the favorite moss of the team on this trip: Spiridens reinwardtii on Cyathea sp., gametophyte length sometimes reaches 30 cm. Cladocarpous moss (sprophytes are on short lateral branches).

Pix: Epiphytic liverwort Mastigophora diclados (Mastigophoraceae), same habit as Réunion island in the cloud forest, (Photograph credit: C. Ah-Peng).

A total of 695 ecological specimens (50 cm²) of bryophytes were collected for this transect, and 350 floristic samples. This transect was set up with a western orientation, as in the eastern side, the access to the mountain would have required land owners authorization, which could have delayed this expedition. In the future, it would be interesting to set up an eastern transect, as local climate can vary prominently over a few km or on a different slope of the mountain, to compare the diversity pattern. As an element of comparison for this first Tahitian transect, in the South Pacific ocean, three transects for epiphytic bryophytes were surveyed in Fiji by Mereia Katafono (Ms student) from the University of the South Pacific and Matt von Konratt's team with the same sampling methodology but restricted to epiphytic communities on a Calophyllum sp and tree ferns species. We are looking forward to this bryological collaborative work.

Pix: Olivier is setting a Madgetech climatic sensor, which records hourly relative humidity and temperature. In front Asplenium's  leaf. Jean Yves and Rava will be collected the climatic data every six months at each studied altitude. Photo credit: C. Ah-Peng

Pix: Group's picture after the fieldwork, from left to right: Rava, Claudine, Olivier, Terry, Dirk and in the middle Jean-Yves.

During our stay we had the opportunity to explore Mount Marau and bryologizing for one day.

Pix: The cameraman Matahi Tutavae interviewed the team for the evening news  of Tahiti Nui Television, on a crest at 1400 m,  Photo credit: JY Meyer

Pix: With Elie Poroi from the NGO Te Rau Ati Ati at Mount Marau, Photo credit: JY Meyer

During our stay, the former president of the NGO, Henry Jaÿ, invited us at his house for diner with members of the active NGO for nature protection “Te Rau Ati Ati”. Henri knows very well the tahitian mountains, he is one of the first person to open hiking trails in Tahiti and bring scientists up the mountains. Claudine gave a brief presentation of the Moveclim project and on some Tahitian bryophytes in front of an attentive audience.

Pix: Moveclim presentation from Te Rau Ati Ati, Photo credit: JY Meyer

Pix: The presentation was followed by a lovely tahitian supper, at Henri Jaÿ's home, made of fresh coconut fish, féi (cooked banana), taro, rice, prawn and fish curry,  wild pig cooked in the underground traditional polynesian oven (hima'a), accompanied by some ukulele music from Mrs Poroi, upper left, Paul Niva (anthropologist, Tuihana), "Zaza" Poroi (Te Rau Ati Ati), Claudine et Terry (Photo credit: JY Meyer)

For the last two days of this field trip, we went to the close island Moorea by ferry, and meet up with another bryologist B. Mishler who was giving a field course to Berkeley University lucky students. We enjoyed our stay at the Gump field station and had the chance to explore the island.

Pix: The Gump field station of the University of Berkeley (left up),  with our host B. Mishler. Views of Moorea

Pix: Island of Moorea (French Polynesia), photo credit: C. Ah-Peng

Pix: Cook's bay in Moorea, Photo credit: C. Ah-Peng

It has been a lovely journey to the Pacific islands, the warmth welcoming, the beautiful landscapes and untouched highlands, the interesting bryoflora and plant diversity make this journey unforgettable and one to come visit again. Although a moss flora was produced in 1976, the author himself mentioned that the "true flora is far from thoroughly known"... This bryophyte flora of the Society islands archipelago was produced primarily from collections from Tahiti and Moorea (about 2000 numbered specimens of both mosses and hepatics). Many islands in French Polynesia (area> 35 km2) with altitude (>600 m) as Bora Bora, Huabine and Tahaa in the Society islands archipelago and Fatu Iva, Tahuata, Ua Pou, Ua Huka in the Marquisas islands archipelago are still unexplored for their bryoflora with for some of them not any one bryophyte record. 


We would like to thank Jean-Yves, Rava, Téa and the members of the NGO Te Rau Ati Ati, for their contribution to this memorable fieldwork, the IRD team for accommodating us (many thanks to Lysette and Mama Rose), and Brent Mishler for organizing our stay at the Gump station in Moorea.

It was a nice coincidence to discover while we were in Tahiti, that a famous novelist recently published a book, about the adventures of a bryologist to Tahiti during the Darwin's era and captain Cook expeditions’, perfect reading at this time... “The signature of all things” from Elisabeth Gilbert.

Claudine, Olivier and Terry.

Cited references

Bardat J., R. Gradstein, Hagborg A. & Söderström L. (in preparation). Checklist of the liverworts and hornworts of French Polynesia,

Meyer J.-Y. (1998).
Meyer J.-Y.  and Florence (1996) J. Tahiti’s native flora endangered by the invasion of Miconia calvescens DC. (Melastomataceae).” Journal of Biogeography 23 (6): 775-781. 

Witthier H.0. (1976) Mosses of the Society Islands, The University Presses of Florida, Gainesville, 410 pp.

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Mid Course Meeting, 2-6 September 2013, Réunion (Mascarenes)

The meeting held in La Réunion on the South Campus of La Réunion University was a good opportunity to discuss data, results, progress and collaborative papers.

Left to right: At the lowland forest of Mare Longue (Réunion): Nicholas Wilding, Claudine Ah-Peng, Etienne Leveneur, Jean-Yves Meyer, Terry Hedderson, Juana Gonzalez Mancebo, Raquel Hernandez Hernandez, Jacques Bardat, Julio Leal Perez, Hervé Magnin.

Jean Yves Meyer (Tahiti partner) on his blog (link below) illustrated this meeting made of talks, posters presentations, workshops and field excursions:

http://www.jymeyer.com/pages/2013_26_sept_Moveclim_Midcourse_Meeting_Le_Tampon_amp_fieldtrips_ile_de_La_Reunion-8756857.html

A newspaper article from "The Journal de L'île de La Réunion" (10.09.2013)  can be read in the Press section of this blog.

Picture of the Moveclim team, in front of the Caldeira of the Piton de La Fournaise volcano (from left to right, first row: Nicholas Wilding, Jacques Bardat, Juana Gonzalez Mancebo, Claudine Ah-Peng, Terry Hedderson; from left to right, second row: Jean-Yves Meyer, Julio Leal Perez, Raquel Hernandez Hernandez and Olivier Flores)

The Moveclim final meeting in La Palma (Canarias) is proposed by Juana Gonzalez Mancebo and her team for early 2015.

Program of the mid course meeting:

Crédit photographique: Jacques Bardat

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From the shore to the summit and from the "Moss" to the "Tree" on La Reunion island

We, Lolita and Lisa, conducted complementary studies on the eastern side of  Piton des Neiges in the National Park of La Réunion. Our hypotheses were built up on the data set from their first inventory in 2008. In the frame of our two master studies we, both, try to find explanations about the distribution of the plant species they found and therefore visited the plots together. However, our thesis are based on two different perspectives in ecology.

Lolita focuses on the large scale distribution of the three major plant groups (Bryophytes, Pteridophytes and Angiosperms) and investigates the effect of water use efficiency on their altitudinal distribution in La Réunion for her master at the University of Zürich.  

Lisa is doing her master thesis (Paris 6) on ecological factors affecting the vertical distribution of corticolous (=bark living organisms) bryophytes along an elevational gradient.  The hypothesis is that bryophytes have specific microhabitat determined by various abiotic factors (temperature, interception of sunlight and exposure of the area) and biotic (bark rugosity, tree species). Under the guidance of Claudine Ah-Peng we spent 14 days in the field from mid May to mid June 2013. It was a learning journey, discovering La Réunion in a deeper manner. We had a closer look on plant diversity and on plant distribution along an elevational gradient. Each altitude has its own characteristics, not only concerning the species composition but also vegetation structure.

 We stayed at Gite de la Bélouve few nights and at La Caverne Dufour for a couple of nights. Also, we climbed up the Piton des Neiges (3070 m) for our work as the highest plot is at 2950 m!

FIELDWORK

Lolita Ammann:

Liverworts, mosses, ferns and angiosperms have their diversity maxima at different elevations. The older the stem group, the higher lies its diversity maximum on the elevational gradient. In this study I test how much this pattern is determined by water use efficiency by making up three hypothesis:

-Water use efficiency should become higher in lower elevations considering the decrease in water availability towards lower elevations,

- Comparing humid and arid sides of mountains, the decrease of overall diversity on the arid side is more pronounced for groups with lower water use efficiency, 

On the sentier de la Rivière, Bélouve forest

- Comparing humid and arid sides of mountains, diversity patterns of the major plant groups are shifted upwards on the arid side because of higher cloud condensation levels and the increasing importance of low temperatures in determining environmental humidity.

Three approaches/methodologies should help me to assess the questions: for carbon isotope ratio (δ¹³C), samples of the 5 most representatives of the three stem groups are collected for both terricolous and epiphytic habitats, LICOR 6400 (gas exchange measurements, i.e., uptake of CO₂ and release of water) these tests will be conducted in controlled greenhouse conditions, so collected plants needed to be transferred alive to Zürich, and finally comparison of the diversity pattern of fern and angiosperm species between the western and eastern transect.

Lisa Margot Couet:

We are currently aware that landscape feature creates microclimate. Therefore, we can suppose that bryophytes, being small organisms and living in a wide range of substrat have particular microhabitats. As any plants, bryophyte species have different light and temperature requirements. My work  focuses on factors affecting the corticolous microhabitats for bryophytes.

The hypothesis is that there is a smaller scale distribution and assemblage of species along the phorophyte.

Lisa measuring the temperature of the moss colony

In the field, I recorded data on three or four species of bryophytes at each altitude. We chose 15 trees per altitude which hosted at least one of the species studied and represented well the ecosystem. For each tree, I measured the size (length, width, thickness) of each colony, the temperature and the sunlight intercepted in each of the 3 microhabitats (0-0,5m; 0,5-1 m; 1-2 meters). I also recorded the tree species and their morphology (DBH, Height, Bark rugosity) in order to evaluate the influence of the substrat on the distribution.  

The leafy liverwort, Mastigophora diclados

I collected data for the following species: Mastigophora diclados (Brid. ex F.Weber) Nees), Pyrrhobryum spiniforme (Hedw.) Mitt., Dicranoloma billardierei (Brid.) Paris, Pleurozia gigantea (F. Weber) Lindb., Holomitrium borbonicum Besch., Herbertus dicranus (Taylor ex Gottsche, Lindenb. & Nees) Trevis., Leucophanes angustifolium (Renauld & Cardot ) and the two gender Bazzania and Radula.

luxmeter

   Describing ecological niches of corticolous bryophytes is a particular matter as some are referred as biological indicators. Knowing if a species is a generalist or a specialist across ecosystem can help to investigate on the impact of climate change at different scales. Also, as a complementary on bryophyte niches, I investigated the assemblage of a few common species and their distribution along the elevational gradient.

We had a great time exploring the montane tropical forests. Local botanists and ecologists who are involved in project within the park came to give us a hand in the field for the collection and the identification of plants. Furthermore, we were part of the team to set up the new transect in the Western side, at La Forêt des Makes, where sensors of temperature and relative humidity were set up every 200 m from 1150 to 2350 m. Many thanks to Jacques, Pierre, Olivier, Dominique S, Dominique H and in particularly Claudine Ah-Peng who take us in the field and take care of the organization of the field work.

Lolita, Lisa and Dominique H, Takamaka viewpoint

From left to right, Lisa, Claudine, Jacques and Lolita, 7^th of June 2013, Bélouve forest

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Preliminary bryological results from la Soufrière Transect (Guadeloupe)

A total of 649 samples of 50 cm² of bryophytes were collected along La Soufrière transect and my task was to determine the collections for these two lowland elevations: 350 m (107 samples) and 450 m (107 samples).

From August 2012 to May 2013, I stored the samples in paper envelopes as described in Bryolat/Moveclim Methodology (Com. Pers. Claudine Ah-Peng) and I could sort out one quarter of the samples collected at  each level with the identification of species. Also I was taking photos of almost every species.

I visited two national herbaria, to access reference collections:

- The National Muséum of Natural History (PC) in Paris in December 2012, where I could check especially Plagiochila specimens

- The New York Botanical Garden (NY) in March 2013, hosted by B. Buck where my research focused on the Lejeuneaceae especially some species also collected by Duss in the beginning of the 20^th century in Guadeloupe.

New York Botanical Garden, March 2013

I chose to process the samples so that we can have already some indications about the bryodiversity in these areas. So to start, I studied approximately the same number of samples collected at each altitude and in all types of supports.

Brief description of the study sites:

The plots 350 m are in a rainforest partially modified by human activities. Large boulders occur there. This forest is out of the National Park, near flower plantations or other open areas.

The plots 450 m are located in the rain forest on relatively flat area bordered by two rivers. Although it was never cut off, this forest was somewhat modified and made vulnerable because of some human-induced degradations as the severe erosion of the trail :

 

Information on the bryophyte samples from La Soufrière Transect (June 2012)

A total of 41 liverworts (21 genera, 6 families) and 24 mosses (16 genera, 10 families) are so far identified. Twenty-one other species were identified at a genus level.

There was no terricolous species at both levels, neither humicolous species at 350 m, nor rupicolous species at 450 m. At the elevation of 350 m, 26 species (13 liverworts and 13 mosses) were identified and 11 liverworts are identified at the genus level. At the elevation of 450 m, 46 species (33 liverworts and 13 mosses) were identified and 7 liverworts and 3 mosses are determined at the genus level.

7 species are common for these two lower elevations (350 and 450 m): Ceratolejeunea laetefusca, Lejeunea asperrima, Lejeunea controversa, Telaranea nematodes, Radula kegelii, Vesicularia vesicularis var rutilans and Lepidopilum scabrisetum

Among the liverworts, the Lejeuneaceae is the most speciose family in the recorded samples.

Four of the six Cyclolejeunea cited to Guadeloupe archipelago (Lavocat Bernard & Schäfer-Verwimp 2011) were found at 450 m particularly on leaves. Cyclolejeunea convexistipa seems to be a predominant species that is forming large patches as epiphyllous (on living leaves).

Seven species (5 genera) of Lepidoziaceae and 2 Cephaloziaceae (Cephalozia crassifolia, Odontoschisma longiflorum) were found at 450 m in corticoulous and humicolous samples. 

Some other liverworts of the genus  Plagiochila, Radula, Riccardia and Metzgeria are currently being identified.

The moss family Pilotrichaceae is well represented in plots 350 m with 3 species of Callicostella (C. belangeriana, C. depressa, C. pallida), Hypnella pallescens, Pilotrichum evanescens and 2 species of Lepidopilum (L. scabrisetum and L. polytrichoides). 

Lepidopilum scabrisetum is the most frequent species in corticolous and rupicolous samples and was found at both levels, but much more abundant in plots 350 m with often a large bryophyte cover in dense populations.

Hypnella pallescens, Callicostella belangeriana and Callicostella depressa were not recently observed in Guadeloupe.

The Neckeraceae is represented in plots 350 m by Neckeropsis undulata in discrete patches on corticolous samples and by Neckeropsis disticha , a rather mesophylic species common in lowland forests, very abundant especially on lianas.

In plots 450 m the species Homaliodendron piniforme is very abundant on corticolous samples with dense and compact populations. 

Among the Calymperaceae one species was identified in plots 350 m: Calymperes afzelii and 4 species at 450 m: Calymperes lonchophyllum, Syrrhopodon ligulatus, S. lycopodioides and S. prolifer var scaber

One species of Thuidiaceae, Thuidium tomentosum is forming dense mats in rupiculous samples at 350 m.

These so far collected data could already give an idea about the composition of the bryoflora and the bryodiversity. Thought I only treated a quarter of the samples, I had a brief look on almost all other samples, and  the taxonomic and ecological trend will be confirmed in the final results.

A New record to Guadeloupe

During this field trip, we also collected with National Park collecting permit some bryophytes in areas closed to the plots. Among the specimens I collected at elevation 1250 m in highland low shrubs (Col de l’Échelle), I discovered a new record for Guadeloupe: Mytilopsis albifrons Spruce, a very small and delicate species (confirmed Det by S.R. Gradstein with photos). This species was reported to Jamaica, Guyana Highland, northern Andes (Venezuela to Peru), Brazil (Gradstein et Costa 2003) and more recently to Costa Rica (Dauphin 2005).

The identifications of the remaining samples of La Soufrière Transect will probably result in more new records for Guadeloupe, and increase the knowledge of the ecology of bryophytes.

Elisabeth Lavocat Bernard

National Botanical Conservatory of Guadeloupe

All Rights on the Photographs : Elisabeth Lavocat Bernard 

References

Lavocat Bernard E., Schäfer-Verwimp A. 2011. Checklist of the bryophytes of the Guadeloupe archipelago and Martinique (French West Indies)

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