Notes: This is my first observation at this place, a line of sand dunes on the Portuguese coast. I was a little disappointed with the small variety of lichens found here. In addition to Xanthoria, one or two species, and one species of Cladonia just found the species of this topic, which I think is Collena tenax.
There was a (for me) non-expected amount of specimens of this species here. I saw dozens of them, many of them growing directly from the sand with no vegetation nearby and others with some moss around. The first indication of their presence was given by the presence of a cyanobacteria, of the genus Nostoc, that in some places accumulated.
There aren’t many species of Collema growing in soil. The best known is undoubtedly Collema tenax having a number of varieties. For the specimens of this observation the data seem to point to this species. The only alternative, given the form of the lobes, could be Collema bachmanianum. Apparently, in a superficial analysis of the photographs (see photographs attached), it appears that the margins of the apothecia are crenate and with small lobules, but a detailed analysis shows that the lobules develop from the base of the apothecia and not from the margin. In addition the data obtained for the average size of spores:
Me = 19.8 × 6.7 µm ; Qe = 3 (N=21)
are consistent with those of C. tenax and are shorter than those of C. bachmanianum.
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This place is subject frequently to morning fog. On the other hand, it is a bit windy. So, as you explain, this combination is such that only few lichen can survive. I looked very carefully the bases of shrubs, and many of them have a Xanthoria developing on it, but nothing else. The shrubs didn’t present crustose lichen on the bark, not even lirellae.
You’re right on the coast, so humidity, light and nutrients (from salt spray from ocean) should all be high. This is potentially perfect habitat for lichens. If there is something to grow on. The little shrubs I see in the photos might provide habitat if the bark doesn’t shred too easily. (You can always look at dead twigs instead, if the bark flakes too easily for lichens to esatblish.) Another factor that will reduce abundance and diversity is wind-blown sand. I’ve seen deserts completely scoured clean of all lichens — essentially sand-blasted clean. In such cases, check the bases of the shrubs, well-sheltered from wind, and you can generally find at least a few.
But in similar habitat in southern California, especially a little farther back from the ocean where in the dwarf oak and chaparral forest, you can find an astonishing diversity and abundance of lichens. Soil is also a very good place to look in these habitats. Look for mossy undisturbed low-angle slopes, preferrably with the underlying bedrock exposed in places. Dunes, on the other hand, shift too quickly to allow any but the fastest-growing Cladonia to establish. If moisture is insufficient (too high winds, or ocean temperatures too warm — cold water causes more morning fog, such as in California) will result in no Cladonia.
present the same lack of biodiversity in what lichens are concerned?
This was my first experience in this kind of place and, as I said in the notes, I was a bit disappointed.
Wow, does that look just like southern California.
Created: 2011-09-12 20:41:29 CEST (+0200)
Last modified: 2011-09-12 20:41:30 CEST (+0200)
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