The most common and most likely answer to this crossword clue is the 5 letter word LEAFY
I've seen this crossword clue in Financial Times
L
E
A
F
Y
Buddy explains!

The straight part
We know that "abounding with trees" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case abounding with trees = leafy.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does LEAFY mean?
LEAFY adjective- Covered with leaves
- Containing much foliage
- In the form of leaves (of some material)
- Resembling a leaf
- (of a place) wealthy, middle- or upper-class