The Green Pact applies to Bosmer wherever they go, not just in Valenwood. So you have to figure out if your character obeys the Pact. If he was born in Valenwood, he almost surely does. If he was born outside of Valenwood, it's possible he doesn't. It depends on how Imperialized he is. How many generations has his family lived outside of Valenwood?
http://uesp.net/wiki/Lore:Green_Pact
Key words 'of Valenwood'. So, by my understanding, a Wood Elf can follow the Green Pact and still use plants and wood etc,
as long as it didn't originate from Valenwood. So OP would still be lore friendly to pick plants from Cyrodiil.
Also, other Races seem to be allowed to build and use plants/wood. However, the last sentence is a bit confusing. I
think it means that nobody can harm plant life from Valenwood.
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I hope that TES:VI is set in Valenwood (and Elsweyr, those to provinces would be o for awesome), because I want to see how BGS would implement the Green Pact, if at all.