Hey, first off, welcome to the guild! I figured someone other than Toff should chime in. Second, it's a very nice map, a unique style to use the wood grain, though I must agree with Toff that it's not working well in quadrants. Maybe one grain to represent plains. Being Red-Green deficient myself (the most common form of color-blindness, as I understand it) I was thinking of trying alternates to colored height-fields, but I've been trying to learn more basic steps in digital cartography before moving into 'my own voice', so to speak. You seem well on your way, look forward to seeing more or different solutions to the color issue. Have some rep for a nice and unusual styled map for your first post. Cheers, and Happy Mapping!
(Yeah, I see blue, dark, but blue.)