Though we are not sure of the year this photo was taken, we can be fairly sure of its location based on the alignment of the building on the far right. What we see is a common and expected occurrence of plants (in this case willows and balsam poplar) recolonizing exposed lands, whether they are cleared by humans, burnt by fire, swept clean by water, or revealed from landslide. Given time, and lack of repeated disturbance, vegetation will grow back though perhaps in a different structure or composition than it grew before.