What is the difference between carbon sink and reservoir？

[Kior]

I am trying to figure out the difference between a carbon sink and a carbon reservoir. The definition for a carbon sink from wikipedia is that “carbon sink is a natural or artificial reservoir that accumulates and stores some carbon-containing chemical compound for an indefinite period. ” And the definition for carbon reservoir is “ Carbon-storing natural feature (such as a forest or the land mass) that exchanges carbon with other reservoirs." My textbook says that mature forests are carbon reservoirs but they are not carbon sinks. So what is the difference between a carbon sink and a carbon reservoir on earth?

 

[paisiello2]

I think it's given right in your definition: one accumulates and the other exchanges (which can be same as releases?). I assume a mature forest is one that is not growing very fast and therefore does not accumulate any more carbon but simply inhales it during the day and releases it back at night? But that is just a guess on my part.

 

[Dr. Courtney]

I agree. A C sink tends to store carbon. A C reservoir will both store and release.