The most common and most likely answer to this crossword clue is the 7 letter word QUADRAT
I've seen this crossword clue in Financial Times
Q
U
A
D
R
A
T
Buddy explains!
The straight part
We know that "ecologically significant area" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case ecologically significant area = quadrat.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 QUADRAT mean?
QUADRAT noun- An area of land, marked for studying its plants, animals, soil, natural processes, etc.
- A quad; a blank metal block used to fill space in lines of type.
- A virtual rectangular subdivision of a line or column of hieroglyphs within which a group of hieroglyphs is arranged.