hi i am interested please look to see if i have anything you would be interested in

If the cut off bits have a clean cut like a sharp scissors, that is rabbits. Ground squirrels or gophers are other possibilities. Gophers will come up out of their burrows at night and eat things. You can put a cylinder of wire fencing around the tree for a while--that protects well. 2' tall is enough, unless your rabbits are jackrabbits then go taller. I pin down the cylinder with landscaping staples.

Palo verde trees do best in gravelly soil with superb drainage. Neither the mulch nor organic matter will provide that. Consider creating a mound with boulders and gravelly soil and planting the tree in that. You don't say where you are, but the kiss of death for a PV tree is to be wet and cold at the same time, hence the need for superb drainage. Give them that and they are bullet-proof.

the reason i ask is that new transplants suffering from shock due to such.. can show all kinds of problems... related to being transplants .... my first thought is whether you are watering properly for a transplant ... and then whether the reflected and retained heat of the rock .... is messing with the watering.. and the tree itself ... but.. once fully established ... they can take on the traits of mature plants ,. such as drought resistance ... etc .... it really has nothing to do with what rock.. but what the rock is doing or creating .... plant culture wise ... i note.. you planted it in may.. which i presume is late for your area .... and i presume it did not have an easy summer.. as a transplant .... ken