Steps to repro:

1. Open Unity;
2. Create new project;
3. Extract attached package and open 'scene' scene;
4. Build the scene on Android or iOS;
5. Launch the project;
6. Press Toggle button;
7. Observe SpeedTree rendering.

Actual result:
Horizontal white lines appear on transition between SpeedTree LOD levels (see attached actual_behavior.mp4 video).

Expected result:
Transition between LOD levels should happen without artifacts on mobile platforms (see attached expected_behaviour.gif).
Expected behaviour could be found in Editor's Play mode.

Notes:
- Reproducible in 5.4.0f1, 5.5.0a3;
- Reproducible on both Android 6.0 (Samsung Galaxy s7 Edge) and iOS 9.2.1 (iPhone 5s).