Home and garden retailer The Range is shedding 300 jobs after deciding to move its distribution centre in Mitcheldean, in the Forest of Dean, to near Doncaster "to improve efficiency".
But workers representative Mike Grindle said they wanted PM David Cameron "to sit up and listen to put work back in the Forest."
Grindle said: "It's going to have a massive impact on the foresters and the future of the young people finding work, their livelihoods, work, mortgages. It's a bad thing. We just hope that in the future there will be something else in the Forest for the young people."
The Range said it was holding a consultation process over the cuts and would redeploy as many staff as possible.