A thick stand of cactus, such as a Saguaro forest, can migrate onto or off of a patch of southwestern desert in little as 100 years.

• 郁郁葱葱的仙人掌树丛，比如巨树仙人掌从林，可以在短短不到100年之内迁进或迁出西南部的小块沙漠地带。