This I did not know.Also, forested tiles on non fresh water hills actually provide more food for Irq for the same hammers that the standard alternative.
forest hill 1/1 -> (chopped and mined) 0/3 -> (with Chemistry) 0/4
forest hill 1/1 -> (long house built & lumbermill) 1/3 -> (with Sci Theory) 1/4
While the same number of trade routes increases food the same raw amount, it helps low food starts a lot more since it represents a higher percentage. (The gap in population from a percentage basis is a lot less from a low food start on turn X compared to normal food start is a lot less than in used to be.)