That depends. If I take a forest which stores X amount of carbon, and replace it with farmland which has .1X the carbon. The remaining .9x carbon would have gone in the atmosphere. But now I can take that .1x carbon, put it into some cows, and grow another .1x on the farm, and now we're at .2x carbon (.1x in some cows + .1x in the plants on the farmland). I can do this and grow the population of cows, and eventually have a denser store of carbon than the forest alone originally had, but also eventually hit a sustainable limit.

But what I'm really saying is: focusing on stuff like this is not what we should be doing, as it's negligible and doesn't address the root of the problem. We need to look at the bigger picture. Which is: where is the problematic carbon ultimately coming from? Changing forests into farmland? Okay that can be easily changed in 100 or so years (and nature naturally does it for us). Burning a tank of gas in a few minutes? It takes millions of years for nature to reverse that... (not to mention that oil is an even denser store of carbon than trees).