Supports reverting to stocking sources of wood (9)

'sources of wood' is the definition.
The definition and answer can be both man-made objects as well as being plural nouns.
Perhaps you can see an association between them that I can't see?

'supports reverting to stocking' is the wordplay.
'supports' becomes 'forests' (I am not sure about this - if you are sure you should believe this answer much more).
'reverting' is a reversal indicator.
'stocking' indicates putting letters inside ('stock' can mean 'fill').
'to' in reverse letter order is 'ot'.
'forests' placed around 'ot' is 'FOOTRESTS'.

Can you help me to learn more?