Interestingly not all lichens respond to meeting another member of their species in this way, rather they fight for their own individuality. This also occurs between different species and you can often see a mosaic of lichens on a rock all sharply defined by black lines where they individual borders are demarcated. In theory then some lichens are immortal, and some famous Ascomycetes hold to the truth of this theory. Certainly they can live for a long time and their lives can often be measured in hundreds rather than tens of years. Lichens live all across the world, in Antarctica they can be found living just below the surface of rocks, in deserts, providing there is a permanent substrate they can be found surviving the hottest sun, they can also be found in rock pools on the sea shore and on the roofs of our buildings.
Lichens survive an extremely wide range of temperatures.
Going to the other extreme they can also survive temperatures as high as 100C if they are dried out, and even when moist temperatures of 40C-50C do not worry them. However because they depend on their Algal partners to photosynthesise in order to obtain energy for growth all lichens need light. There are therefore no subterranean of deep cave dwelling lichens. Generally speaking lichens like areas where their is plenty of light such as the exposed surfaces of alpine rocks etc. Like all plants lichens like water, and most of them like a regular supply of it.