Algodoo

The only solution that lets you harvest the trees as well!

Keys: left/right to drive, up/down to move the blade, `n` to lower the blade, `m` to move it up.

Instructions: drive forwards. When you have the trees, press UP and `m` simultaneously and release LEFT. Drive slowly to the truck and stop just next to it. Release `m` and press `n` to dump your load.

Yes, it it tricky to operate.