Friday, 26 October 2012

Field trip in Canarias, La Palma island in October 2012

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.

Pix 4: Plot in the Laurel forests in Barranco de Los Tilos

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.  

Text and Photographs: Juana María González-Mancebo

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Monday, 15 October 2012

On the use of "elevation" and "altitude"

In a recent paper Vicar & Körner (2012) in  Oecologia (doi:10.1007/s00442-012-2416-7)  clarified the use of elevation, altitude and height that have been used with confusion in literature. Here, I report from their note the definition of these terms, which sometimes have been misused from translations between Romanic languages.

Elevation is the vertical distance between  a point on the land surface and a reference point, usually taken to be the mean sea level.
Altitude is the vertical distance between an object (e.g., a bird, aircraft, or parcel of air) and a reference point or stratum, where the object is not in direct contact with the reference point/stratum.
Height is the vertical distance between the top of an object and the land surface, where the object is in direct contact with the ground.

I thought some of you will be interested...
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Monday, 1 October 2012

Field trip in Azores, Terceira island: 25-28th september 2012

An expedition in Terceira island (Azores)  along an elevational gradient took place between the 25th and 28th of September 2012. The team was composed by Pr. Dr. Rosalina Gabriel, Márcia Coelho, Raquel Hernández, Débora Henriques and by Fernando Pereira.
This study of this gradient in the Azores is carried out in the framework of Débora’s PhD (University of Azores). Raquel (PhD student in Canaries) joined the Azorean team to be trained on the collecting methodology of the Moveclim project.
The weather was good, allowing the fieldwork to proceed within 4 days. Six altitudes were sampled along the gradient from 40 to 1000 m. This transect was set up along the western side of the island.
We briefly describe here the sampling sites and illustrate the gradient with some photographs:
40 m – Serreta lighthouse
Vegetation is composed of shrubs (scrubland). Bryophytes are more abundant on rocks, the canopy is low < 2m. The vascular flora is dominated by Erica azorica and Myrica faya.

Pix: Vegetation type of the lowland (M. Coelho)

200 m – Canada das Covas – Serreta
The forest was unfortunately dominated by non-native Pittosporum undulatum, but also by native trees like Erica azorica and Myrica faya
Pix: Bryophytes were there mainly recorded on the rocks ( R. Gabriel)

400 m – Pico Carneiro - Serreta
Forest system, the canopy is higher (maximum of 6 m). Vegetation is dominated by Pittosporum undulatum (70%). Erica azorica, Juniperus brevifolia and Myrica faya were also present but in lower quantities (25-30%).
Pix: Raquel on the field in Pico Carneiro-Serrata (R. Gabriel)

600 m – Pico da Lagoinha – Serreta
Forest vegetation dominated by Laurus azorica (40%), Juniperus brevifolia (30%) and Ilex azorica (30%). Cover of bryophytes is predominant on the soil (100%) but also very significant in trees (75%).

800 m – Trail to Lagoa do Pinheiro - Serreta
Forest system with trees up to 4 m high. Juniperus brevifolia and Ilex azorica were the most frequent trees composing the native vegetation together with Laurus azorica and Vaccinium cylindraceum. Bryophytes were more common in the trees (95%) and in the soil (75%).
Pix: Sphagnum sp in Lagoa do Pinheiro-Serrata (M. Coelho)
1000 m –Serra de Santa Bárbara
Serra de Santa Bárbara is a Natural reserve of 1863 ha with the highest peak at 1021 m. The vegetation is dominated by scrubland; bryophyte cover is predominant on the soil and schrubs. Vascular species are < 2 m high. Juniperus brevifolia and Calluna vulgaris dominate the plant composition, Hymenophyllum sp. is also abundant.
Pix: Bazzania azorica and filmy ferns (R. Gabriel)

Pix: Vegetation type in Serra de Santa Barbara (M. Coelho)

Three other islands of the Azores will be explored along an elevational gradient in the framework of Débora's PhD thesis, the rest of the field work will take place in mid 2013. Samples of the Pico and Terceira gradients are now being curated and processed for analysis at the University of Azores.

Text and Photographs: Dr. Rosalina Gabriel, Márcia Coelho, Débora Henriques, Raquel Hernández.

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