It suggests that trees may have some kind of hive intelligence in their roots and through the fungal networks they can communicate and share resources. It isn't something that I've investigated in a ton of detail but the ideas seem scientifically informed.
It describes some experiments which can be interpreted as plants "remembering" and "predicting" things.
Here's a recording of a (~1 hour) presentation I saw her give: https://www.youtube.com/watch?v=SZFKon7kook
I don't know what to make of this, but it's certainly made me think differently...
The answer probably lies somewhere in the middle. Rather than viewing trees as a hive intelligence, I think it’s plausible that we’ve been missing the forest as a whole organism. Perhaps “ecosystem” just means “an organism that is bigger than any one of us.”