Hi @joanabana ,
Thanks for writing in with your question. Which version of InVEST did you run?
Please search this forum for similar posts, such as this one, to find your answers. We recently updated this model, changing raster results from tons/pixel to tons/hectare, so the answer depends on which version you used. Always refer to the InVEST User Guide for clarity on units of measurement and all model details.
The results are directly derived from the values users enter in the Carbon Pools input CSV table, so if the resulting values seem low, you should review the parameters you entered. Are you differentiating densities between the different pools?
-Jesse