Additional shard(s) which will allow for increased drop rate of tree and/or stones. Much like the Aquifer shard you would get more sap and living wood and/or iron, mithril, jewels, silver etc...
Also a 1/3 energy return on tree and/or stone taps would be cool as well.
My gripe would mostly be about sap. As it is used in more crafting areas then any other resource (maybe not water but it has a shard) it is difficult to keep stocked. So a shard which helps that would be awesome. I am not as concerned with stone products as I have 4 mines to draw from. Sap is another story.