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Pix 4: Plot in the Laurel forests in Barranco de Los Tilos
Text and Photographs: Juana María González-Mancebo
A trip to La Palma Island took place this month to work along the elevational gradient that is located in the eastern slope of the island. The team was composed by Pr. Dr. Juana María González Mancebo, Raquel Hernández Hernández and Julio Leal Pérez that is the collaborator of La Laguna Bryologists group.
Pix: La Palma's team during the field work of october 2012, from left to right, Raquel Hernández-Hernández, Julio Leal and Juana María González-Mancebo
The transect includes 24 plots from 40 to 2200 m a.s.l., among them 18 plots were made in this expedition.
Here it is a brief description and some pictures of the plots that were sampled.
40 m – Fajana de La Galga
Vegetation is mainly composed by coastal shrubs like Peripoloco laevigata, Euphorbia canariensis and Rumex lunaria. Bryophytes were more frequent in soil and rocks, although the cover was very reduced. The dominant species were Tortella nitida, Bryum spp. and Frullania ericoides.
Pix 2: Raquel and Julio working in Fajana de la Galga
200 m- Barranco del Cubo de La Galga
The dominant tree species at this elevation were Apollonias barbujana and Visnea mocanera, so thermophilous laurel forest trees. Canopy is quite closed, so we found a higher bryophyte cover and species like Homalia webbiana, Radula lindenbergiana, Eurhynchium meridionale.
Pix 3: Raquel and Juana María working at 400 m in the first forests along the elevational gradient
400 m- Cubo de La Galga
The canopy at this elevation was mainly dominated by Laurus novocanariensis and Persea indica. Some exotic herbaceous species were also present and unfortunately relatively abundant like Ageratina adenophora. Bryophytes were way more abundant in rocks (75%) than in other microhábitats.
600 m- Cubo de La Galga
Laurel forest dominated by Persea indica and Ocotea foetens. Bryophytes cover increases highly respect the previous elevational plots. The most common species were the Iberian-Macaronesian endemic Heteroscyphus denticulatus and a widespread species in the laurel forest, Isothecium myosuroides, mainly in rocks.
800m- Barranco de Los Tilos
Forest dominated by Persea indica and Laurus novocanariensis. Total canopy cover reaches 95%. Dominant bryophytes were: Rhynchostegium megapolitanum, Saccogyna viticulosa and Frullania tamarisci.
1000m- Pista del Mulato (Barranco de Los Tilos)
Laurel forest composed mainly by Laurus novocanariensis, but there were also presence of Persea indica, Morella faya and Ilex canariensis. Some of the species we found were Saccogyna viticulosa, Isothecium myosuroides and the Macaronesian endemic Leptodon longisetus.
1200m- Under the “Casa del Monte” (Barranco de Los Tilos)
Laurel forest in which Laurus novocanariensis is the dominant species together with some individuals of Erica arborea and Ilex canariensis and with a narrow closed canopy. Bryophytes cover on rocks raised 80%.
1400m- Casa del Monte (Barranco de Los Tilos)
Mixed pine forest dominated by Pinus canariensis, Morella faya and Erica arborea and Pinus canariensis. The total canopy cover is 80%. Bryophytes very scarce and only present on soil under the pine litter.
1800m- Topo Mosquito
This correspond with the highest plot with pine forest in our transect. At this elevation the schrub Adenocarpus viscosus was quite abundant. Bryophytes relatively abundant (45%) on rocks, but absent on soils and very scarce as epiphytes (only Dicranoweissia cirrata and Orthotrichum sp. On rocks Grimmia trichophylla was the most common species.
Pix 5: The highest level for the pine forest in La Palma is around 2000 m a.s.l.
2000m- Fuente Vizcaína
Schrub-land vegetation dominated by Adenocarpus viscosus, with presence of other species like Erysimum scoparium and some graminae species. Bryophytes only present on rocks.
Pix 6: High montane vegetation in La Palma at 2000 m a.s.l.
Some additional work
In this island two additional transects are being studied at the same altitudinal level. Both are transects with a different degree of disturbance as part of the thesis of the PhD of Raquel Hernández-Hernández, in which we are trying to analyse the influence of disturbance along the elevation gradient on both, biodiversity and functional traits of bryophytes.