Ruderates
Ruderates is a term for the redundant areas, which come to exist in connection with building projects, but which are not actually used and thus are left to themselves. And they are swarming with life!
They are often areas with nutrition poor soil that mainly consists of sand, rocks and mites. This causes the plants which grow in the area to not grow very tall. This makes room for many plant species as no plant type takes all the sunlight. Very often, there will also be several areas consisting only of dirt, which makes way for new plants in the areas.
An open vegetation with soil as rich in sand and stones as these often mean that the microclimate is very warm. And this, in addition to the low, open plantation and rocks, makes it ideal for many insects. Spiders, beetles, ants, earth bees and many other species thrive in ruderates.