Posters were put up around Knettishall Heath in Suffolk on 1 April, claiming work was ongoing to reintroduce wolves.
Suffolk Wildlife Trust said it had received messages of concern "amid continuing coverage" on spoof sites.
"Just to be clear, there are no plans to introduce wolves anywhere in Suffolk," a park ranger said.
It is not known who was behind the hoax.
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The realistic-looking signs, which advised visitors to carry flare guns and not to enter the heath after dark, were removed by rangers as soon as they were spotted.
The hoax claimed the wildlife trust was working in partnership with the UK Wolf Conservation Trust to reintroduce a pack of wolves to the site by the end of the month.
Ranger Sam Norris said the heath was an "ancient place" which the trust was "delighted" to be restoring "to the kind of wild landscape that our Bronze Age ancestors would have recognised".
"However, I can categorically say that this definitely does not involve re-introducing wolves," she added.
Knettishall Heath, near the border with Norfolk, is made up of heath, grassland and woodland, and the trust said it was "clearly not a suitable place in which to re-introduce what was one of the UK's biggest apex predators" because of its proximity to human populations.
A wildlife trust has reassured visitors there are no plans to bring wolves back to the area after an April Fool's joke refused to disappear.