Simple colour ramp material for anime style tree render. You can see this style of tree in Makoto Shinkai's old film like 5cm per second.
Good! I like your art!
for those who are using new version just go to materials , in place of untitled nodes on the left side of color ramp use diffuse bsdf with shader to rgb nodes and connect to color ramp and then at the other side us material output, do this for all of them and it will be done!