Notes from the Serra de Estrela

At the end of my last post I suggested that the next time I wrote it may be from Portugal.   In reality, tiredness and, to be frank, a steady consumption of Vino Verde intervened and this post may be about Portugal but is not, alas, written from that country.   Our travels took us from Lisbon northwards to Covilhã, a town on the edge of the Serra da Estrela mountain range, then onwards to the Duoro valley and Porto, and finally back to Lisbon.   The lower part of the Duoro is the home to many of the Vino Verde vineyards, although our focus was mostly on the vineyards further upstream from which the grapes for port are grown.  I’ll write more about the Duoro in a later post but, first, I want to take you on a journey to the Serra da Estrela.

These are the highest mountains in mainland Portugal (there is a higher point in the Azores) but summit with a summit at 1993 metres at Torre.  Unusually, for the highest peak in a mountain range, there is a road all the way to the top, along with a couple of shops and a small bar/restaurant.   On the day we visited, a couple of hardy cyclists had toiled their way up from the plains but most of the visitors had driven up.   We had stopped on our route up from Covilhã to explore the granite landscape and botanise so felt that we had earned our bica and Pastéis de Nata by the time we got to the very top.

Much as I appreciate a summit that satisfies a caffeine addiction, the real interest lies elsewhere, with the road up from Covilhã passing through some dramatically-eroded granite outcrops, composed of huge boulders apparently perched precariously on top of each other.  These resemble the granite “tors” we find in Dartmoor in south-west England, and have a similar origin.   The area around the tors had distinctive vegetation that will, no doubt, be described in greater length in a post on Heather’s blog before too long.   The free-draining sandy soils that the granite landscape creates mean that there was not a lot of surface water for me to indulge my own passions, so I will have to take you to another part of the Serra da Estrela for the remainder of this post.

Granite landscapes near Torre in the Serra da Estrela Natural Park in northern Portugal, September 2018.  

We found an inviting stream as we were walking near Unhais de Serra, at the southern end of the Natural Park.  The first plants to catch our eye were a submerged Ranunculus species with finely-divided leaves and five-petelled white flowers sitting at the water surface.   As well as these, we could see shoots of patches of water dropwort (Oenanthe sp.) and, looking more closely, several of these appeared to be growing out of dark coloured patches which turned out to be a submerged moss overgrown with algae (more about which a little later).   I am guessing that, once the rains come, much of these mini-ecosystems will be washed downstream leaving just a few moss stems to be colonised again next year.

Submerged vegetation in the stream at Unhais de Serra in September 2018 (40°15’44” N 7°37’21” W).  The top photograph shows a Ranunculus species and the lower photograph shows mosses overgrown with algae (a mixture of Cyanobacterial filaments, diatoms and coccoid green algae), within which young plants of Oenanthe sp. have taken root (top photograph: Heather Kelly).

Somewhat to my surprise there were also some patches of Lemanea.   This is a red algal genus that I usually associate with late winter and spring in my own part of the world, so I had not expected to find such prolific growths at this time of year at lower latitudes.   Maybe Iberian species of Lemanea behave differently to those with which I am familiar?

The Lemanea species found in the stream at Unhais de Serra in September 2018.  The top photograph shows it growing in situ and the lower photograph is a close-up.  The filaments are about a millimetre wide.

The dark film itself contained a variety of algae, some of which I have put in a plate below.   There were some cyanobacterial filaments which looked like Oscillatoria to me but which were not moving (their life between collection and examination was less than ideal).  There were also a large number of diatoms, mostly Navicula and Surirella.  Again, both would have been moving around in a healthy sample but were static when I got around to examining them; the chloroplasts in the Surirella, in particular, were not in very good condition).  I also saw some chains of Fragilaria species and several small green algae (especially Monoraphidium, discussed in the previous post).  I’ll return to the diatoms in a future post, once I have been able to get permanent slides prepared and examined but first impression is that I am looking at a community from a low nutrient, circumneutral environment.

Some of the algae living in the dark films overgrowing mosses in the stream at Unhais de Serra in September 2018.   a. – c.: Navicula angusta; d. –g. Surirella cf. roba; h. – i. two different chain-forming Fragilaria sp.; j. – k.: Navicula cf cryptocephala; l. – m.: Oscillatoria sp.    Scale bar: 20 micrometres (= 1/50th of a millimetre). 

The diatoms, in particular, reiterate the important point that notwithstanding the huge number of new species that have been described in recent years, it is possible to peer through a microscope at a sample from anywhere in Europe and see a familiar set of outlines that, for the most part, give a consistent interpretation of environmental conditions wherever you are (see, for example, “Lago di Maggiore under the microscope”).   That same rationale applies, to some extent to other organism groups too: we have recently shown this for macrophytes in shallow lakes for example.   Likewise, the geology here was shaped by the same broad forces that created the landscape of south-west England even if local climate means that the flora surrounding the tors in the Serra da Estrela is adapted to more arid conditions than that on Dartmoor.    It is important that, when we travel, we see the differences but, perhaps even more important in this fractured age, that we see the similarities too.

References

Chapuis, I.S., Sánchez-Castillo, P.M. & Aboal Sanchero, M. (2014).  Checklist of freshwater red algae in the Iberian Penisula and the Balearic Islands.   Nova Hedwigia 98: 213-232.

Poikane, S., Portielje, R., Deny, L., Elferts, D., Kelly, M., Kolada, A., Mäemets, H., Phillips, G., Søndergaard, M., Willby, N. & van den Berg, M. (2018).   Macrophyte assessment in European lakes: Diverse approaches but convergent views of ‘good’ ecological status.  Ecological Indicators 94: 185-197.

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