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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