Could the increase in CO2 be due to the reduction of biomass?

Deforestation: The conversion of forest to another land use or the long-term reduction of the tree canopy cover below a 10 percent threshold. Deforestation implies the long-term or permanent loss of forest cover and its transformation into another land use.

Figure 1. Area of Primary Forests in the United States

Tropical deforestation contributes as much as 90% of the current net release of biotic carbon dioxide into the atmosphere. This change may represent as much as 20% - 30% of the total carbon flux due to humans - rivaling tthe carbon release due to fossil fuel burning.

Recovery time of a forest after clearing and a burn. Note that it is only after 100+ years that forest become as they were before the cut. Forest regrowth sequesters atmospheric carbon as plant biomass.

Source: Deforestation

The increase in CO2 can be due to the reduction in biomass