Okay, so you may have heard about setting the time forward to get tree food. It works right? Wrong! When you set the time back to normal the critters are messed up and won't make food until the date or time that you had set your device to. Well there is a way to make that not happen! To make this simple, set the date forward by 1 day at a time. Get all the tree food you want but don't summon critters, and when you want to set the date back to normal, do this: set the date 1 more day forward so all your critters are ready to have their tree food harvested. Do not harvest the tree food and set the date back to normal. All your critters will have their food ready to be harvested and will not be frozen. It really works, I've tried it myself! Hope this helped!
If you wait until your animal gives tree food and then repeatedly click on the bottom left hand corner of the screen being careful not to click on any other animals your animal will be forced to give you more tree food.