I have an area in the back corner of my yard that is nicely shaded by the branches of a mature elm, and which I would like to make into a shady garden "room".

It is, however, an area with a lot of problems. It was once the site of a shed and utility area. Groundhogs took up residence under the shed (or at least have an entrance there -- there is probably another down the slope in the woods). The 12x18 area is now quite uneven, and needs some serious leveling, as well as tree roots to avoid and a groundhog problem to deal with or work around.

My first thought had been to fill with gravel to level, and then top with 24" concrete pavers. (Let's see the groundhogs move THAT, says I...) But my arborist has urged me to rethink this, as even if I just build up and don't cut into roots, the pavers will cut off water to about 25% of the root system of the elm. Dirt (which would be needed for grass or any groundcover alternative), she stressed, would be even worse for the roots. So she recommended a raised deck, or if I had to do something on the ground, crushed stone or pea gravel.

So I'm wondering:

- What is your advice on using gravel and stone around mature tree roots?

- Does anyone have experience that leads to alternative suggestions on how to turn this kind of area with these particular problems into a pleasant and useful area? WIthout endangering the tree, that is. The tree is more important to me than the surface underneath it.

- My assumption is that the deck option would be far more expensive than the gravel option, though perhaps I'm wrong. Does anyone know if the presence of woodchucks in the vicinity is likely to compromise the integrity of deck piers? I've seen lots of discussion of woodchucks and foundations, but not of decks.

- Am I just foolish to try anything in an area with an established woodchuck burrow? From what I can tell, even if you relocate them (not legal here) or drive them off, you're just likely to get a new set of tenants. I had hoped that the compactor and the gravel truck would make them think twice about using that part of the tunnels, and perhaps collapse that entrance, and that large pavers would prevent a new point of entry there. But I doubt gravel alone would do that. I've seen suggestions for keeping woodchucks out of gardens with 3" wire mesh, and it occurs to me that this could be laid under the gravel horizontally, but I've never seen this suggested. (And I can see that it might make any future work on the patio area much harder.)