"at the forest" is correct and usable in written English.
You could use it to describe a location. For example: "We went for a hike at the forest and enjoyed the peacefulness of nature."
Her first play, David, was produced at the Forest Theatre in Carmel, California, in 1910.
Thomas Hirschhorn, "Gramsci Monument" at the Forest Houses, in the Bronx.
Often these projects are aimed at protecting small communities at the forest edge.
By Peter Schjeldahl Visitors to the installation at the Forest Houses, in the South Bronx.
The perspective of being away from something lets you look at the forest.
Dove's memorial took place at the Forest Lawn Ceremony in Glendale.
ES goals were distinguished at the forest- and stand-level spatial extents.
At the forest-averaged level, we found that mortality increased with increasing radiation (Fig. 1D).
Diminishing forested habitats and the progression of savannah might have facilitated a niche displacement at the forest-savannah ecotone.
But I do take issue with his description of the first concert after Newport, at the Forest Hills tennis stadium.
I have just found out that the Beatles will be at The Forest Hills Stadium (Not the World's Fair).
