Okay so...
You need to have an object that you can test for when touching. My guess is that would be the tree. Second you need an object to the left of the tree. that is invisible. Create a variable called touchdt.
When you touch the tree, set touchdt to 0
everytick add dt to touchdtt
If touch overlaps the object on the left and touchdt < some value (0.3 seconds?) then play the animation.
You could also do this by tracking touch location, adding up the change in position over x amount of time and if the change in position after touching the tree is greater than x, call it a swipe so long as the player never stopped touching the screen during the add up.