Cryptogam, lichens and moss

These are pictures of lichens growing on one of the maple trees along the street. I believe even the fuzzy one that looks like moss is not actually moss but a lichen. We have a lot of rocks strewn around the yard mainly as borders but also as focus of interest which I wish would be covered with lichen by now but despite my painting it with yogurt a supposed treatment to attract lichen spores(?) and to hasten the growth of any microscopic ones already on the rocks, none have shown any sign of lichens.

Why would they grow readily on the bark of the maple and not on the rocks? I guess I'll have to do some research on how lichens grow.

I've noticed that in the past few years, mosses seem to be growing very well if not vigorously. A well trodden path around a cache basin and water tower are covered with moss and even the cracks in the sidewalk are filled with lush velvet moss. I wonder if this is due to climate change?

I'm experimenting with re-sizing the photos to see if they would upload faster and it does but not by much. These are originally about 5mp photos 2560 x 1920 pixels reduced to 1024 x 768 pixels. I'll be interested to see how they are displayed on the blog and when the photo is clicked. The preview function on Blogger doesn't always display the juxtaposition of the text to the photos accurately but it looks ok.

Found this great website on lichens and this is a quote on how lichens form:

'Lichens are composite, symbiotic organisms made up from members of as many as three kingdoms.

The dominant partner is a fungus. Fungi are incapable of making their own food. They usually provide for themselves as parasites or decomposers.

"Lichens are fungi that have discovered agriculture"-- lichenologist Trevor Goward.

The lichen fungi (kingdom Fungi) cultivate partners that manufacture food by photosynthesis. Sometimes the partners are algae (kingdom Protista), other times cyanobacteria (kingdom Monera), formerly called blue-green algae. Some enterprising fungi exploit both at once.'

So not easy to actually grow some unless you have many conditions simultaneously conducive for growth of fungus, algae and bacteria!