According to CorkMasters, cork forests are indeed nearly
natural: the cork is harvested off trees without permanently
harming the trees, and no herbicides, fertilisers or irrigation
are needed. Although a cork forest must involve some meddling
with nature (keeping access roads to trees clear, perhaps even
mowing around trees, perhaps removing other kinds of trees), it
seems the WWF have no problems with this kind of agricultural
impact. This relates to Dan Simon's elucidation of the idea of
inaction as it applies to the precautionary principle. Is
"inaction" continuing to use cork forests as they've been used
for centuries? Or is "inaction" completely stopping the
"exploitation" of these forests? Ask the question again about
fossil fuel use, and it's clear that most quick answers to these
questions depend on ill-examined notions of what is natural and
what is action, and probably a lot of indoctrination about
environmental good and bad.