I was wondering the other day what the origin of the tree skirt was. My google search got me lots of patterns and opportunities to buy skirts, but little in the way of information about tree skirts. One site speculates that the tradition dates back from the use of candles on trees. The notion being that a cloth was put under the tree to catch wax drips from the candles.
According to Wikipedia, since candles were used to light trees until electric bulbs came about, a mat (UK) or “skirt” (US) was often placed on the floor below the tree to protect it by catching the dripping candle wax, and also to collect any needles that fall. Even when dripless candles, electric lights and artificial trees have been used, a skirt is still usually used as a decorative feature: among other things, it hides the tree stand, which may be unsightly but which is an important safety feature of home trees. What began as ordinary cloth has now often become much more ornate, some having embroidery or being put together like a quilt.
Generally, the difference between a mat and skirt is simply that a mat is placed under the tree stand, while a skirt is placed over it, having a hole in the middle for the trunk, with a slot cut to the outside edge so that it can be placed around the tree (beneath the branches) easily. A plain mat of fabric or plastic may also be placed under the stand and skirt to protect the floor from scratches or water.
We know that in the early part of last century, a nativity scene, model train, or putz (Christmas village) may have been placed on the mat or skirt. Christmas presents were generally placed underneath the tree on the tree skirt (depending on tradition, all Christmas gifts, or those too large to be hung on the tree). Modern day Christmas tree skirts are usually color coordinated with the Christmas tree decorations on a tree decorated with a theme, or it may be adorned with characters, animals, flowers, or holiday prints.