How "green" is biomass?

Climate change standards seem to assume that burning biomass (e.g. wood) is carbon neutral, but that isn't really the case:

[A] report, done by Manomet Center for Conservation Sciences, makes it very clear that most forest biomass is not carbon neutral. In fact, the report finds that burning whole trees to make power would leave the atmosphere 3% more polluted between now and 2050 than burning coal over that same period." "Under a best-case scenario for sourcing and forest management, the study finds that 40 years of wood-derived power could actually be 11% better than 40 years of coal. This is still very far from 100% better, which is what carbon neutral implies

- Source: Magically carbon neutral biomass, evil EPA rules and other myths

Burning leftover woodchips from processing lumber might be reasonable, but growing trees solely for the purposes of burning may be unhelpful.