Carbon pool Tansient Variable table

Hello Community, I have a question about the filling of the transient table. What does the variable “biomass-half-life” mean?. INVEST documentation says it is in integer years, but I still don’t understand what it means. Is the number of years that biomass is naturally kept as biomass?
Thank you

Hi @borochi,

Welcome to the forum! The purpose of the biomass half life variable is to approximate the rate of carbon release from biomass after a disturbance. You might find this report helpful. It’s the source of the half-life data provided in the documentation here, and it explains more about the modeling of carbon loss. From page 19,

In theory, following conversion, carbon in biomass is emitted to the atmosphere in the first few years, although organic carbon could be redistributed and redeposited to other environ-ments. Release of soil organic carbon will take longer than biomass, and the deeper the soil carbon, the slower its rate of release. In each case, emission rates are expected to be high in the years immediately after disturbance and to drop later.

We assume that the habitat is converted or damaged in year zero, and we model the release of carbon from the soil and biomass over a 25-year horizon. We use the values for biomass and soil organic carbon that were presented above. On the basis of guidance from collaborators and the scientific literature, we assign exponential decay functions and associated half-lives for biomass and for soil organic to each habitat type.

Since the release of carbon is modeled by an exponential curve, the half-life is needed as a measure of how steep the curve is. So, the biomass half-life is the time it takes for 50% of the biomass carbon to be released. This is measured as an integer number of years after the habitat disturbance happened.

I hope that helps!


Thank you Emily really helpful!!!