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)