Temperate forests store more carbon than tropical | PNAS
A study published in PNAS by Heather Keith, Brendan Mackey, and David Lindenmayer, "Re-evaluation of forest biomass carbon stocks and lessons from the world’s most carbon-dense forests," finds that moist temperate forests store more carbon that any other forest type.
(I'm a few months behind on the study, which came out in July and was reported in Mongbay.com and Treehugger.)
From Matt McDermott at Treehugger:
Researchers at the Australian National University looked at 100 forest sites around the world and found that temperate moist forests stored an average of 377 tons of carbon per hectare in above ground biomass; subtropical moist forests, 294 tC/ha; cool dry temperate forests, 176 tC/ha; and, tropical rainforests, 171 tC/ha.
Of the sampled sites, the forests with the highest amount of stored carbon per hectare were found to be in Australia: Southern Tasmania, with about 750 tC/ha stored in above ground biomass; and, central Victoria, with slightly under 600 tC/ha. For comparison, the tropical lowland forests in Borneo and the forest along Oregon's coast stored similar amounts of carbon: Approximately 430 tons per hectare.
The findings diverge significantly from the default values for estimating carbon stocks used by the Intergovernmental Panel on Climate Change (IPCC). The IPCC Special Report on Land Use, Land-Use Change, and Forestry found, for example, 155 tC/ha for above ground biomass in temperate moist forests and 146 tC/ha in tropical rainforests.
In the publication, "Green Carbon: The role of natural forests in carbon storage," Mackey, Keith, Lindenmayer, and Sandra Berry elaborate:
How can we explain the difference in total carbon between our estimates and the IPCC default values? The answer lies in the fact that current approaches to carbon accounting have been designed to estimate carbon stocks and flows in industrialized forests, including plantations. That is, they are designed to measure what we call brown carbon, not green carbon. As we discussed earlier, current approaches generally use field data from forestry mensuration plots. These plots are designed to provide estimates of growth rates in regenerating trees of commercial importance, which store much less carbon than unlogged natural forests. This is the main reason why carbon accounting methods that are calibrated using field data from industrialized forests significantly underestimate a landscape’s carbon carrying capacity. There is also the problem of definition of forest and how different average values are compared. ...
Green carbon accounting tools for natural forests need to be calibrated using ecological field data obtained from sites that have not been disturbed by intensive human land-use activity, especially commercial logging. We made a special effort to find such ecological field data for our study region so that our estimates of carbon stocks were calibrated appropriately to represent the landscape’s carbon carrying capacity.
