In the centre of our city

there´s an old destructed industrial area which nowadays is called Steppeland. There are some people without somewhere to live camping. There are some old scateboard ramps and it´s a place for Graffiti painters. Shot this on my way to work.
Went home early today and found three trees of the same species but three different colours. I thought the colour was due to different soils, different light or different humidity, but these three are living under same circumstances so...
I don´t understand.