Old growth trees, have the capacity to greatly increase their growing rate, when there is a lot of carbon dioxide in the air. This has been found, in a study by the University of Birmingham. This is important, as in many places around the world, an area of destroyed natural forest, is considered to be replaceable by a similar area of planted trees, but what is clear, is that in order to merely keep up with the absorption of the original trees, several multiples more of trees need planting. What is worse, is that this is not worrying about the huge amount of carbon that is stored in the trees that are cut down, or within its roots system and the surrounding soil.
To put this in perspective, at the current time, it is estimated that a football pitch of primary forest is lost every 6 seconds.
This experiment was done, by piping extra carbon dioxide into a forest area and monitoring its growth. Unfortunately, this does reinforce the conservationist point of view, that simply planting a similar area of woodland for each bit lost, is not good enough.