How trunks/leaves colors looks depend much on what time of the day it is and what weather it is, since that affects coloring and like you said, shaders affects colors too..
Generally Morrowind looks best in the morning around 6, at least with my .ini settings
At daytime i've always thought Morrowind looks kind of bland, haven't figured out a good weather/truebloom setting for it :/
Which leaves are too olive green btw? I just realized the other day when i was out photographing how i've kind of neglected olive/military green leaves, there are a lot of leaves out in nature with that color. But ofcourse, copying how things looks IRL isnt always the best option for games.