(text copied from my DA page - also, as usual, I had to reduce the size of the picture for Elfwood, so the DA pic is slightly bigger)
Here is my best attempt at explaining this:
The yggdrasil reference is to the Norse myth, in which the tree represents the world(s). There are elements of that in there (the 'tree', the snake creature on the bottom, the eagle head, and the hawk/falcon on top). There are more elements than those in the myth, and obviously (I think it's obvious), they don't look like this (although the serpent is more closely based on actual references). I also designed it to look somewhat like both a dreamcatcher and a chalice (the snake on the bottom being the ‘base’, and the half circle of the dreamcatcher-like section the ‘glass’ part. The feathers hanging from it are from different birds - hawk, pheasant, eagle and others (the eagle feather I had to base off of pictorial references, the others I have). The only really important feathers that I specifically picked out for their meanings are the eagle(right) and the hawk(left), which are believed to be messengers of the gods in some religions, especially Native American. Actually, depending on the story, the hawk can have almost opposite (negative) symbology as the eagle (so they can sort of represent good and evil), but usually they are associated with the same thing, although the eagle is usually considered more important (here, interpreting it either way works). The fact that the eagle on the top of the tree is represented by just the skull - and the fact that the tree itself is based on skeletal elements was not really intended to mean that 'the tree/world is dead', or 'spirituality is dead' (although it can be interpreted that way) rather it was more a way to unify the concepts of life and death, spirituality and material things, etc. In the Norse myth, the serpent on the bottom gnaws on the roots of the tree, trying to kill it, so I thought it would be very interesting to actually have the snake *become, the rose (I think that part is a little subtle, but is noticeable if you look). The rose is about (sort of) where the heart would be, given that I based the 'tree' on an organic animal like design, connecting the forces that strive for death and destruction to the same ones that sustain life and vitality (if you look at the chalice aspect of the design, the rose can also appear to be held within it). There are other rebirth/life/duality references within the picture - the ribs and the vertebrae become birdlike in some places, the red color of the rose, stylized sun/moon symbols, a keystone that, well, actually has a keyhole in it, and the totem image supporting the dream-catcher element. Someone commented that it also looked like it was trapped/hung-up/imprisoned in it. This wasn't purposely intended when I started the picture - it was just supposed to look like it was holding it - but is an excellent way to look at it too.