Ken:

Poplar/Aspen like we have here in Maine has a lot of value for the "Engineered Wood Products" industry. (The nemises of timber framing and its future, some would say).

Poplar veneer is in high demand for cabinet grade hardwood plywood substrate. Smaller logs/ tree tops are also harvested for chipping and made into OSB... the sheathing in 90% of homes today.

This company is making big money w/ poplar in northern Maine.
http://www.huberwood.com/main.aspx?pagename=advantechsheathing