Plant populations change over time by growing in size and diversity. They generally are the first part of an ecosystem after lichens (the pioneer species) and cause an ecosystem to flourish and allow for animals to move in. I don't know if this is the answer you were looking for but it should give you somewhat of a base.
The depression was caused by a number of serious weaknesses in the economy. ... America's "Great Depression" began with the dramatic crash of the stock market on "Black Thursday", October 24, 1929 when 16 million shares of stock were quickly sold by panicking investors who had lost faith in the American economy.
It looks like a war that happened back when Romeo and Juliet was taking place
Back in the day japan started it in 1980