Drawcalls = (Instanced Separate meshes x materials per Mesh)
Drawcalls is per Instanced meshes, you think that the Instanced Mesh is that the engine draw in the screen.
100 = 100 times same tree x 1 material.
Dinamic shadows and some other prosprocess duplicated drawcalls.
Funny stats:
Ps3 and vita we have problem with more of 150 drawcalls framerate over 30.
Ps4 we can move more of 1500.