[cmrdporcupine]

Temperate forests sequester carbon over millions of years by leaving a layer of carbon rich top soil beneath them through leaf and other litter fall.

Soil can hold a _lot_ of carbon per square foot. Carbon that is partially lost to the atmosphere when it is plowed.

But my understanding is that tropical forests tend to have fairly carbon poor soils on the forest floor.

[DenisM]

The only way it could work is for the top soil to grow thicker by the year, reaching huge depths over tens of millions of years. As I recall my temperate forests, the topsoil is skin-deep, relatively speaking.

[cmrdporcupine]

If you take a core sample from an established forest it's often got at least 5-6 feet of heavy dark carbon rich soil beneath. That's the case on my property anyways. I had some trees moved with a giant tree spade some years back. Sandy soil, but the top 5 feet was nice and dark. The area would have been forest and marsh only about 50-100 years ago.

[DenisM]

Amazon has been around for 55 million years. Do you think we will find the topsoil to be 55,000,000 / 100 * 5 feet thick? I wager it went up to like 20 feet max in the first million years and hasn’t changed since then.