Ecology, Plants(Producers)?

Question

I was wondering if plants or producers vary a little or a lot in their efficiency at producing joules for human consumption? And could you suggest reasons for this variation?

Answer 1

Um, I am not sure how clarify this question. That is why it is confusing me.

But just out of experience would you say that plants vary a little or a lot in their efficiency at producing joules for human consumption. And could you suggest reasons for the variation?

Answer 2

I mean what