SARTURUS - Ulthui - Map landscape drawing question

[TaylorH]

Hello, all. I've been working on this map for a while now. I've written lore over nearly a decade with a few friends and I've decided to put it to cartography. This map shows most, but not all, of the continent of Ulthui, with its distinct political boundaries and some geography. I know it looks rough. This is all just planning for now.



My question is, how would I convey dense unbroken forest? The region to the north is mountainous and below that are uplands of hills, plateaus and moorland, which transitions to heavy forest in the center and in the south. My question is, since I'm used to making "physical geography satellite" maps with colour, how would I convey this massive region as entirely covered by forest? Obviously since this is a continent and an extremely zoomed out view, it wouldn't work to have patches of forest that can be identified by eye. The entire central region and most of the south is covered in forest, so should I just represent it by covering the lands with a large block and "texturing" it, like this?



The problem I have with this method is I want a gradual transition from forest to uplands, but I'm not sure how to draw that, really. It shouldn't be a hard boundary. I guess my question is rather how do I draw a soft boundary?