Fixing soil pH with plants

Hello Permaculture Friends,

I live in the Andes, and there we have a lot of ferns, I guess because of the acid soil caused by all the rain.
We already put limestone to increase the pH.

Some Farmers here say that the ferns making the soil even more acidic. Can that be true?
Are there Plants that make soil more alkaline?

Thank you for your advice.

The Rainbow Community