It all starts with a single seed from the Lower East Side. If there is enough resources trees grow based on their lifetime. After a certain age they start shrinking again until they die eventually. Middle aged they spread seeds around them carried by the current wind direction. Every generation has a little color mutation they pass on to their kids. Then lumberjacks land at Battery Park, walk around lumbering wood and found a first base camp. There little lumberjacks are born that, just like their parents, go outside the city lumbering wood, returning to their home every night. With the population of a given city rising appartments get more expensive increasing the chance for artists leaving to look for cheaper places in Brooklyn and New Jersey in turn pushing back the native tree population.