We used to have a lot of Poplar trees at the farm and woodlot. All of them were cut down and burned as firewood. The wood is garbage if left on the ground more than a few months. I don't miss not having them around.In my experience it goes bad very fast unless it's milled, and then dried and stored indoors... In one case an associate from the woodworkers club had trees taken down at his home and another member brought over his bandsaw mill and milled the logs into boards. They stickered, bound, and tarped the wood with air flow around the stack that was up on cement blocks. A year or so later I went over to get some. There were insects and fungus in evidence... being "close" to the ground it was too damp. I took a bunch of it home thinking I could pick through it and use the rest for kindling... it all went to kindling as boards I planed and stacked started showing bug dust piles.
In the other case a tree service cut down a bunch of poplar and put the logs aside for me... in a spot that was inaccessible for all but an excavator. When he finally moved the logs he staged them so they could be moved to his log yard on his log truck. The plan was that I was going mill them on his bandsaw mill. That too dragged on... When he finally got ready to move them they were full of insects and fungus and rot had started. He ended up running all the logs through his big tracked chipper. Complete waste as they were nice logs.
From talking to other guys in the club it seems the best course of action is to fell poplar and mill quickly. Then sticker them to dry under real cover (inside a dry building) or kiln dry the wood. The poplar doesn't like moisture at all... and insects do. Don't use it for outdoor projects as it will disappear before your eyes! You might want to take a look at the logs and at the first sign of insect tunnels or fugus walk away...