The natural world talks by simply being itself. It speaks by moving, doing what it has to do. Thoreau and Dillard listened through their eyes, ears, tongues, and hands with the lens of science and, from there, responded through poetry.
But the natural world does not understand the language of man. It does not understand poetry. It only understands the language of action. So when Thoreau and Dillard heard nature and responded through poetry, they were not really talking back to nature. They were talking to their own kind.
Nature then is perhaps Deaf. It does not speak words. It speaks through signs. Its language is visual. It makes sounds, but looking at it is enough to get what it is saying. A flower blooms, and you know soon its seeds will burst. It wants to give birth, to continue life. And nature comprehends signs, too, comprehends kindness.
You can talk about conserving nature nonstop, but nature won’t understand you until you strike a stick to the ground to support a dying plant. Nature talks through actions, listens through actions.