"Η φύση είναι ο πλούτος αυτής της χώρας."
Μετάφραση:Nature is the wealth of this country.
I don't think so. Whenever the sentence has a generic context or is just a general statement, the article is always dropped in English, when the noun is in the beginning of the sentence. There are a few exceptions, but this is definitely not the one. And considering that nature is almost never used with an article, it would make the sentence look a bit more awkward.
Some sentences can't be translated word-to-word, especially when the english structure rules differ from the greek ones.