To use your models
1.Open your project, then click file--append or press Shift+f1.
2.Find the PineTrees.blend file, select object folder and choose the trees you want to append.
3.Click "Append from library"
1: 336,477 faces 2: 311,505 faces 3: 311,514 faces 4: 318,951 faces
To get a brighter tree, please set Render--LightPath--Transparency to around 20.
If you have any questions, feel free to ask me.