Bromeliads are called air-plants because they don't need soil, just rain and run off from above.
Trees also meter their growth by available soil and water and make natural bonsais. There are trees in cliffs with a thousand years of narrow growth rings that are just 1-2 meters tall. Bonsai cliff trees are often prized for dendrochronology.
Those trees require a lot of water for the summer and are sized relative to their resources, they are northern plants like birch who's white trunk is white flexible bark which protects from cold and fast temperature changes due to frost and sun, it also reflects summer sun so that the tree stays cooler in arid times.
Photo 2/ Roots can search their environment using micron-thin rootlets the width of individual cells that propagate forwards and under patches of wet leaves or moss where they sprout in the spring time. a tree just has to find a hairline crack through the tarmac to establish a lifeline to the soil.
Photo 3/ that is a plant with big cotyledon leaves which comes from a big seed with lots of energy resources. As the seed sprouts it transforms ambient water into a taproot of 10-20-30cm that is biologicalyl designed to survive in difficult conditions, dig down, and find soil. Wet rotten wood is a perfect medium for propagation of bigger seeds, it has a PH of 4-6 after a few years, which is similar to the humic acid rich leaf humus of the forest, and is easy for the taproot to travel down 20-30cm at a rate of 1-2 cm every day, to find regular water.
Photo 1/ That roof collects a lot of water when it does rain, which can collect in pools, under cracked asphat roof linings, and can create cool damp zones in the abandoned building which last for some weeks in summer. They clearly have more soil