In this study, the «temperature benefit» per unit of afforestation in tropical regions was around three times greater than that in northern - temperate or boreal regions. (bitsofscience.org)
He also says that any program that provides carbon credits for afforestation projects take soil carbon into account. (scientificamerican.com)
This is somewhat offset by our greatly reduced adoption of afforestation in the Land Use Sector, compared to the IPCC and others. (drawdown.org)