EXCLUSIVE

8:22 AM PT -- A rep for MTV tells TMZ ... "Given Shain's tragic passing and essential presence on the show, we felt it was not appropriate to continue without him."

The rep adds, "Instead, we are working on a meaningful way to pay tribute to his memory on our air and privately."

MTV says ... this weekend, it will have a "day of programming dedicated to Shain in which we will air the entire first season of 'Buckwild'."

MTV is pulling the plug on "Buckwild" -- canceling the reality series that was rocked just 8 days ago by the death of cast member Shain Gandee ... TMZ has learned.

Sources connected to the show tell us MTV decided to stop production in the middle of the second season of the show ... which followed the lives of young people in a rural West Virginia town.

We're told MTV didn't give the cast and crew any specific reason for the cancellation. An official announcement is expected Wednesday morning.

Gandee died of carbon monoxide poisoning in his Bronco last week ... when the vehicle got trapped in mud during an off-road excursion.

There were other issues since the show debuted in January -- the arrests of 2 other cast members ... Salwa Amin for drug possession and Michael Burford for DUI.