Tree Mystery

Yesterday a crew of guys came over and dug big moats around our trees. I don't know why...and they didn't try very hard to explain so we just let them go about their business. Now our yard looks like crap. They even wrapped some fabric around the root balls...are they taking our trees away? They are 3 healthy looking big trees...not sure why they would want to remove them?! Any ideas? I'm interested to see what happens next. If you can't tell...it has been a boring weekend. :-)