Interstellar explorers have discovered what looks like a very suitable planet for human colonization. The climate is good, there are no pathogens, and a beautiful forest grows abundantly. A charming aspect of the flora is that leaves can detach themselves and fly off like flocks of multicolored butterflies. When they land on humans, the fliers take a tiny genetic sample as a sort of hello. Some of the biologists at the research station are disturbed that this idyllic scene will soon be plowed under.
To make the planet ready for settlers, an island has been cleared of native vegetation and inroads are being made on the mainland as well. But the forest that covers the mainland resists mightily, creating solid rings of wood around cleared areas that are planted with terrestrial vegetation. And it's hard to keep an area cleared when the trees can distributed themselves as flying leaves. The woody rings can be blasted open to allow terrestrial plants a foothold, but more rings form, and from the air the scars are very evident.
The forest is really all one organism. Eventually a pair of characters finds it possible to communicate chemically with this world-straddling forest. In the process, they become symbiotic with it.
I probably read (and reread) this story in an English-language anthology during the 70s, a time when ecologic concepts were becoming widespread in science fiction.