The phrase "a large forest" is correct and usable in written English.
You can use it when describing the size of a forest in a general context or in a specific narrative.
Example: "The hikers ventured deep into a large forest, surrounded by towering trees and the sounds of nature."
Alternatives: "a vast woodland" or "an expansive forest".
On the cookie sheet, they looked like the droppings of a large forest animal.
Nowhere in the U.S. below Alaska is there such a large forest with virtually no structures.
Imagine different tribes living around the edge of a large forest.
When last August, a freshly killed cutia – a large forest rodent – was left, villagers surmised it was a present.
I know of a large forest landowner in the Brewster area who actively manages her forest well within view of Routes 684 and 84.
A magnifying glass showed the types of insects and animals that might inhabit a large forest plant while a gorilla nest was open for tryouts.
The Rocky Mountains consist of four million acres of beetle-killed pinewood, which poses a large forest-fire risk.
Taman Negara contains some of the oldest rain forest in the world and sprawls over 1,676 square miles; it is part of a larger forest complex and has almost all of Asia's large mammals, including sun bears, gaur, tigers, elephants and tapirs.
One of the loveliest sights, halfway through a film soaked in loveliness, is a travelling shot of the Bois de Boulogne; it marks the climax to a short speech in which we learn that the Bois forms the remnant of a larger forest that encrusted Paris when, as Lutetia, it was invaded by Julius Caesar.
We all correctly identified the right trees to examine and climb, but in that exploration, the majority of us weren't able to see those trees together as part of a larger forest until it was too late.
The study supports the formation of a larger forest reserve encompassing both PPSRNP and the adjacent Cleopatra's Needle Mountain Range, which also has two recently discovered endemic Begonia (Hughes et al. 2010), and doubtless many other endemic plant species awaiting description.
