This is the skirt finished the way the tutorial explains, it's darling, but I wanted to add a couple more ruffles. And that's where the next part of this post comes in- I discovered a couple tricks for gathering long strips of fabric that may come in handy if you're ever making something like this. Normally you would run a gathering stitch the entire length of the strip you are going to gather, people will have you do two rows of stitching in case one thread breaks. (I know about the tension way of gathering on your machine, but I used it, and now my machine has major tension problems so I'm a little gun-shy to try it again)
So, here's my trick. I had four sections of fabric sewn together to make the long strip I was going to ruffle. At each seam, I stopped stitching, pulled out some thread from the machine and clipped the thread. Then I started stitching again. Now you have sections of thread instead of one long thread to gather along. (even if you have more than four sections of fabric and you can't use the seams as a guide, you can divide the length of your strip in quarters and mark them with pins, then do the same thing.)
Next, I found the four quarter positions on my tree skirt and lined up the quarter marks on my ruffle. Starting at the center point, you will pin the ruffle fabric to the base fabric. Then, take the end threads and anchor them around the pin (as shown in this picture), this will keep you from pulling out the thread as you gather it. Gather the fabric to the desired length and pin in place. Repeat with the remaining three sections, then stitch in place. I found it was much easier to keep my gathers even and it didn't shred the edge of the fabric as much as gathering the entire length of the ruffle.