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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Fascinating research on the role of bryophytes in biogeochemical cycles and their role on climate!!

In this recent paper (Biogeosciences discussion: 10, 3735-3847, 2013) « Estimating global carbon uptake by lichens and bryophytes » P. Porada (Institute for Biogeochemistry in Jena) and co authors present the first process-based model to estimate the Net Carbon uptake by bryophytes and lichens at a global scale, and consequently assessing their role in biogeochemical cycles.

(See http://www.biogeosciences-discuss.net/10/3735/2013/bgd-10-3735-2013.html)

Elbert et al (2012) in “Contribution of cryptogamic covers to the global cycles of carbon and nitrogen” (Nat Geosci, 5: 459-462) suggest that cryptogamic plants as lichens and bryophytes contribute largely to biogeochemical cycles, from field and lab experiments they estimate for global net Carbon uptake amounts to 7% of terrestrial net primary productivity (NPP), the derived value of nitrogen fixation corresponds to around 50 % of the terrestrial uptake, significant impact on the global nitrogen cycle.

Lenton et al. (2012) in their paper entitled “ First plants cooled the Ordovician” (Nat. Geosci, 5: 86-89) focus on the effects of the predecessors of modern bryophytes on atmospheric CO₂ concentration during the Ordovician. They showed that these early non-vascular land plants could have caused a considerable drawdown in atmospheric CO₂ levels via the silicate weathering feedback and consequently a decrease in global surface temperature. The release of phosphorus from the weathered rocks into the oceans could have led to rise in marine productivity and therefore to further cooling...

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Une mission au Sommet/One expedition at the summit

Here is a newspaper article from the MOVECLIM expedition at the summit of Mount Aorai in Tahiti!

In the page "Press" on this blog, look at the video of the expedition!!!

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Notes on field work in La Palma, Canarias.

From April 25th to 30th, I visited the Moveclim monitoring plots on the island of La Palma, Canaries, Spain. The collecting on the bryophytes has already mostly been done a couple of weeks before, and so I joined the research team of Juana, Raquel and Julio while installing data loggers and sampling the bryophytes at two remaining sites.

Vanderporten et al. (2007) list 53 of fern species for the Canary islands, of which about 35 may be found on La Palma. Within the plots of the project, I found in total 13 species, of which Asplenium onopteris and Dryopteris oligodonta have been the most frequent species and found in almost the half of the plots.

Figure 1  Photographs of selected plots from each elevation. Plot number and elevation is given. 

Species richness trend with elevation is as expected: at shady sites with Laurus canariensis, Ocotea foetens and other laurel species (monteverde) species richness is highest, creating the well known hump around 800 m (see photos of plots 400-1000 m in Fig. 1). This is also favoured by the fact that plots are situated in a deep erosion gully (barranco) with almost perennial running water. Towards lower and higher elevations, fern richness, as well as number of individuals per plot is reduced for similar reasons: drought. Below, at the hot and dry sites of the succulent vegetation and at the transition to monteverde-forest  (photo from 50 m in Fig. 1) with numerous Euphorbia-species and Opuntia, and at the transition to monteverde-forest (photo from 200 m in Fig. 1) only drought resisting species like Adiantum reniforme, Cheilanthes pulchella, and Davallia canariensis could be found sheltered between rocks in deeper shade. Above monteverde-forests, in Pinus-forests  (photos from 1400 m and 1600 m in Fig. 1), increasingly thick carpets of pine needles up to 20 cm and reduced ambient humidity prevent raise of most fern species, here as well restricted to sheltered situations between rocks (Asplenium adiantum-nigrum, Cystopteris diaphana) or as indicator after burning with subterranean rhizomes, Pteridium aquilinum susp. aquilinum (photo from 1400 m, with ca. 10-years-burned Pinus and Myrica faya). Asplenium adiantum-nigrum and Cystopteris diaphana are the only two species found at and above treeline in open habitats, again only between rocks in shrub-vegetation dominated by Adenocarpus viscosus. Photos of most species may be found in Fig. 3.

Juergen Kluge, University of Marburg (Germany)

Figure 2  Photographs of selected species from study plots. First row: Cheilanthes pulchella,  Adiantum reniforme, Davallia canariensis, Asplenium hemionitis, Cystopteris diaphana; mid row: Dryopteris oligodonta, Diplazium caudatum, Woodwardia radicans; bottom row: Asplenium onopteris, Polystichum setiferum, Pteridium aquilinum.

References

Vanderpoorten, A., Rumsey, F.J., Carine, M.A. 2007. Does Macaronesia exist? Conflicting signal in the bryophyte and pteridophyte floras. Am J Bot 94:625-639.

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Revisiting the Piton des Neiges transect

A team of four people, O. Flores, P. Stamenoff who kindly joined the project for the occasion and two friendly volunteer assistants, A. Déléage and N. Gueroni, climbed the Piton des Neiges volcano beginning of April 2013. 

The objectives were : (i) recover the data collected by the climatic sensors in the upper part of the transect (1750 - 2950 m), (ii) bring the sensors back to the lab to assess the need for recalibration and recalibrate them in case, and (iii) re-set two sensors up. Indeed, during a former mission, we sadly discovered that one had been damaged and another stolen... 

 We started with a nice weather on Thursday morning at about 1500 m and collected data of four sensors on the way up. After an early wake-up, we then climbed the last part of the transect above 2500 m in a cold and rainy weather, but eventually succeeded in setting the upper sensors up and keeping all our fingers alive.

The new data will complete the description of climate on the sampling sites. We've noticed however some noise in the collected data, which could be due to low battery or drift after a too long period without calibration. Further enquiry required...

On the (steep) way up

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News from the field...

        Despite three months of almost continuous rains between January and March 2013 in Tahiti, we were able to conduct several field surveys between 900 and 1400 m elevation in dense montane cloudforest with my assistant Maruiti TEROROTUA (Délégation à la Recherche de la Polynésie française) to find suitable locations to set up a series of 10 x10 m permanent plots. Because of the rough topography at that elevation range, with often steep slopes and deep narrow gulches, it was not feasible to set up larger plots (e.g. 20 x 20 m), and the choice of two 100 m² plots (one located in the upper part of the gulch, the other in the lower part) appeared to be the best option.

Photo 1: a view of a gulch in montane cloud forest between 1200 and 1300 m elevation

With the recent (the 17^th of March) arrival of Pauline BLANCHARD, a graduate student (Master 2 Recherche) from the Université Pierre et Marie Curie of Paris 6, our small team started the following measurements in this series of permanent plots:

(1)  a complete inventory of all vascular plants, according to three main vegetation strata (canopy or tree layer > 5 m, understorey or shrub layer between 1-5 m and herbaceous layer < 1 m), including fern species found in different microhabitats (terrestrial on the ground, dead wood and logs, rocks; and epiphytes below 2 m, above 2 m, and found in the canopy),

(2)  the basal area of all woody species (diameter at breast height of all stems above 1,3 m) to describe the forest structure and composition, and assess the dominance of native (endemic and indigenous) versus alien naturalized woody shrubs and trees.

We have also decided to set up 2x2m quadrats around the 10x10 m permanent plots (for a total of 24 quadrats) to estimate the abundance of fern species by counting the number of individuals (or patches) per species and estimating their ground cover (%) in each quadrat. This protocol has both the advantage to prevent human disturbances inside the permanent plot, and increases our sampling area for fern diversity from 200 m² to 392 m² in each site.

 Photo 2: Pauline and Maruiti assessing fern diversity and abundance in 2x2 m quadrats (delimited by 2 m long woody sticks) located around the 10x10 m permanent plot (delimited by measuring tapes) set up at about 600 m in a Miconia invaded rainforest.

The most difficult part will be to set up similar plots above 1400 m (two hours hike both way) up to the summit of Mt Aorai at about 2000 m (overnight camping) !

Jean-Yves MEYER

Délégation à la Recherche de la Polynésie française

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IUCN Red List of Bryophytes in islands

Bryophytes as small-sized plants are usually neglected by conservation efforts. The number of regional IUCN Red lists for bryophytes is also low compared to vascular plants. There is an increasing awareness that the vast majority of extinctions go unnoticed because they occur within small, highly neglected organisms despite representing the highest proportion of currently described species (Cardoso et al., 2011).

In her recent paper, Juana González-Mancebo (Moveclim Partner) and co-authors discussed the application of IUCN criteria to bryophytes in small and highly environmental diverse island systems and reported the first Red List for bryophytes of the Canaries which comprises 105 species. They concluded that the priority conservation should be given to freshwater habitats and cloud forests because both environments together contain 63 % of the endangered (EN) bryophytes in the Canaries.

González-Mancebo et al. 2012. Applying the IUCN Red List criteria to small-sized plants on oceanic islands: conservation implications for threatened bryophytes in the Canary Islands. Biodiversity and Conservation 21:3613–3636

Claudine Ah-Peng (Moveclim co-coordinator) and co-authors provided early this year the first IUCN Red List for Réunion (Mascarenes) liverworts and hornworts, 39 taxa of liverworts are threatened of near threatened with one species considered as regionally extinct. In Réunion, the threats that the bryoflora encounters are mainly due to human population growth leading to urbanization, habitat degradation, destruction and loss, clearing of native forest for cattle farming in the uplands and more recently moss harvesting for horticultural purposes.

Ah-Peng et al. 2012. Bryophyte Red List of Réunion (Mascarene archipelago): liverworts and hornworts. Phytotaxa 68:1-23

Based on these two recent initiatives,  a solid ground in the methodology of creating regional Red List for bryophytes is provided, which should be propagated to other oceanic islands and archipelagoes across the oceans, as IUCN Red List remain a practical tool for conservation efforts and native island systems are endangered. Locally in each archipelago, it is hoped that biodiversity managers will make use of these regional Red lists and will include bryophytes for setting the next conservation priorities.

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