Dog walkers are letting their pets leave almost ten tonnes of faeces in the New Forest every day, a study by the Forestry Commission claims.
There are about 27,000 dog-owning households in the New Forest
The commission says that means the same weight as 240 double decker buses is being left behind every year.
It has launched a campaign to encourage dog owners to clear up after the pets.
Forestry Commission spokeswoman Emma Stevens told the BBC website the mess could have a serious effect on the forest environment.
"As far as the environment goes, dog waste does not decompose very quickly in the same way as that of New Forest ponies and cattle," she said.
"It just stays put and pulls in foreign nutrients into the forest so that alone is not a good thing.
"Also if a dog has not been wormed regularly there's the possibility of disease in the waste.
"In terms of wildlife, if a bird smells the scent of the waste it could think a predator is close by, which can frighten it away from the nest."
Six areas of the forest shown by the study to be favourite dog-walking spots will all now be kitted out with special bins in which waste can be deposited.
They are Wilverley, Godshill Cricket, Deerleap, Longslade Bottom, Linford Bottom and Dibden Inclosure.
A survey revealed there are about 27,000 dog-owning households in the area, with an estimated 37,000 dogs.
The bins have been introduced after residents surveyed raised concerns that they had nowhere to dispose of their dogs' waste.
Phil Buckley, external affairs manager of the Kennel Club, welcomed the commission's introduction of bins.
He said: "The Kennel Club is aware that dog faeces is a major issue for the non-dog owning public with regard to complaints to local authorities."