Saltcedar is an exotic introduced from Eurasia at the turn of the 20th Century.
As seen in the photo, it secretes salt which inhibits the growth of native vegetation. It also is an enormous consumer of water "drinking" up to 200 gallons a day. Studies have shown birds don't really like the saltcedar and the seeds and leaves are too small to be a food source for other animals.
Efforts are being made to eradicate them but it's proving to be very difficult.
The salty creek beds are a common sight here in southwest Arizona.