Color difference for Biomes on cartography Maps

I find it frustrating that maps only have one colour of green for all the trees in Minecraft, i.e. spruce, oak, acacia. I can't tell on a map the difference between a spruce biome or an oak forest, which makes the map a bit useless if it's displayed on my wall. Please could you improve the maps to make them more useful by making the colours on the map reflect the biome on the ground? Thank you so much.