Lichens

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Conchiolin
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Lichens

Post by Conchiolin » Fri Apr 27, 2007 5:53 pm

I really admire nature especially when it comes to symbiotic relationships. From nitrogen fixation in leguminous plants to Lichens. Lichens are the result of a symbiosis of a fungus and a plant. When we talk about lichens we are normally refering to those yellow-coloured stains (usually wall xanthoria) on rocks but remember there are 200 species of lichens on this island.

This is the Karst Cladonia (Cladonia convoluta) which is a lichen is that a bit more conspicous since it forms a carpet on the soil. People have the nasty habit of peeling of these poor lichens so to decorate their cribs. Ok maybe they are common but still... We need to appreciate those more. When we go on hikes we normally observe plants and flowers but hey what about lichens?

My question is the plant "part" in lichens provides the fungus "part" with necessary carbohydrates but what exactly does the fungus part do?? Otherwise this could not be called symbiosis but parasitism!

Oh nearly forgot to say that they are good indicators of pollution.

(Naf li hafna jafuha din pero biex inkunu cari)

Symbiosis is when 2 creatures 'live' together so that both benefit from each other. Example a bee pollinates the flower and the flower provides bee with nectar. (That's symbiosis right? :-D)

I took the photo in a garigue near dingli cliffs area. (BTW the Pyramidal Orchids are in flower so... hurry up insomma.)
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Karst Cladonia
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wolf
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Post by wolf » Fri Apr 27, 2007 7:11 pm

ive heard about this indicator of pollution but can you explain a bit ?
do they die out or disappear if pollution occurs ?

wolf

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Conchiolin
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Post by Conchiolin » Fri Apr 27, 2007 8:02 pm

Since lichens absorb the rain-water, they act as bio-indicators the rain water may contain pollutants these are absorbed by lichens. If concentration reaches certain levels they die.

They are sensitive especially for sulphur dioxide which is present in car effluent due to sulphur impurities in the fuel. (this explains desluphruization plants in oil refineries).

It's very curious lichens can live in extreme conditions but then there comes the man and they're done.
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Conchiolin
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Post by Conchiolin » Sat Apr 28, 2007 10:32 am

I hope i've answered your question wolf. The only way by which lichens can disappear is by dying :cry: . Different lichens tolerate different amounts of pollution. You can go on a hike and search for lichens and say:
Ha there lots of healthy lichens here! No pollution or smog.
There are lots of dead lichens here! This place is crap.

Dead lichens peel off easily. When the yellow lichens (wall xanthoria) die they turn to a pale greyish colour.

Scientist use lichens a lot to determine the level of pollution in cities or in country-side.
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wolf
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Post by wolf » Tue May 01, 2007 4:46 pm

thanks - that does answer my question very well

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