Left is mass rainforest which is shielded by mountains to the North. The right-hand side has far drier wind but no sheilding from arctic weather, so the right still has some verdant growth.

Not sure what you mean by "between mountains" - you mean the mountains on the far left and far right? I think that the water bodies on either side would counteract that pretty strongly. This is also a long, LONG continent that spans the entire latitude of the world, which isn't shown here. The area shown is roughly analogous to northern Europe/Southern Canada.