Not just trees. Grasslands as well. Which considering that includes both natural ones and man made ones via agriculture - that's a LOT of acres.

It's compounded by the seasonal cycles of tillage. Farmers tend to plow in the fall thru spring so that the old crops' plant matter will have decomposed by the time they need to plant again. That decomposition releases CO2.

But there's a cycle to it, and much will be reabsorbed once plant growth kicks back into high gear with spring's warmth.