The Department of Conservation is warning farmers not to graze stock on reserve lands.
It follows the department successfully prosecuting a farmer from central Hawke's Bay, who cut boundary fences to the Hiranui Scenic Reserve and put more than 60 cows on the land.
Conservation services manager Dave Carlton says the department sympathises with farmers who struggle with drought - but that does not give anyone the right to put their stock on neighbours' land without their consent.
Damage done by the cows has set the reserve back many years, as much of the lower vegetation has been destroyed and will take years to recover, he said.