Old-growth forests remove carbon dioxide from the atmosphere1, 2 at rates that vary with climate and nitrogen deposition3. The sequestered carbon dioxide is stored in live woody tissues and slowly decomposing organic matter in litter and soil4. Old-growth forests therefore serve as a global carbon dioxide sink, but they are not protected by international treaties, because it is generally thought that ageing forests cease to accumulate carbon5, 6. Here we report a search of literature and databases for forest carbon-flux estimates. We find that in forests between 15 and 800 years of age, net ecosystem productivity (the net carbon balance of the forest including soils) is usually positive. Our results demonstrate that old-growth forests can continue to accumulate carbon, contrary to the long-standing view that they are carbon neutral. Over 30 per cent of the global forest area is unmanaged primary forest, and this area contains the remaining old-growth forests7. Half of the primary forests (6 
108 hectares) are located in the boreal and temperate regions of the Northern Hemisphere. On the basis of our analysis, these forests alone sequester about 1.3 
0.5 gigatonnes of carbon per year. Thus, our findings suggest that 15 per cent of the global forest area, which is currently not considered when offsetting increasing atmospheric carbon dioxide concentrations, provides at least 10 per cent of the global net ecosystem productivity8. Old-growth forests accumulate carbon for centuries and contain large quantities of it. We expect, however, that much of this carbon, even soil carbon9, will move back to the atmosphere if these forests are disturbed.
Old growth forest are still able to acumliate carbon dioxide as well as new forest. Agenencies dont protect theses trees because they don't think they hold carbon dioxide. These trees are located in the Northern Hemisphere. The trees provide at least 10 percent of the global net.
I think that people should protect these trees until there dead or dying. They shouldn't get rid of them. Also they could take more samples of the older trees to tell wich one's hold the most carbon dioxide.
