Forests in sub-Saharan Africa account for roughly a quarter of total tropical forest carbon, according to a comprehensive assessment of the world’s carbon stocks published in the journal Proceedings of the National Academy of Sciences (PNAS).
The study, based on remote sensing data and field surveys of 75 calibration plots, came up with estimates of forest cover and carbon storage based on varying definitions of what constitutes forest. Using the broadest definition of 10 percent tree cover, forests cover 775 million hectares, or 36 percent, of sub-Saharan Africa. Using a 30 percent tree cover cutoff, sub-Saharan Africa’s forest extent amounts to 447 million hectares, or 21 percent.
The researchers estimate sub-Saharan Africa’s forests contain 44-66 billion tons of carbon, depending on how forests are defined. Nearly 80 percent of the carbon is stored in aboveground biomass or vegetation consisting of leaves, branches, and tree trunks.
Unlike other tropical forest regions, nearly three-quarters of Africa’s forests are distributed in woodland savannas and dry forests that contain less than 100 tons of carbon per hectare. Extremely carbon-dense forests, which store more than 350 tons of carbon in aboveground biomass per hectare, account for 8.7 percent of sub-Saharan Africa’s total stored carbon.
Overall, African forests store the least amount of carbon per hectare of any region, averaging 69-117 tons per hectare. Asia is the highest, averaging 125-174 tons per hectare per hectare, followed by the tropical Americas, which averages 87-132 tons per hectare.
Unsurprisingly, the forests of the Democratic Republic of Congo are the most extensive and store the most carbon of any African country, accounting for 26-37 percent of forest cover (depending on how forest is defined) and 38-56 percent of carbon. Three other Congo Basin countries — Cameroon, Republic of Congo, and Central African Republic — follow.
The new carbon data indicate that deforestation in Africa produces proportionately fewer emissions than estimated by the Food and Agriculture Organization of the United Nations (FAO).
FAO estimates are based on the assumption that African forests store one-third of tropical forest carbon and accounted for 30 percent of deforestation between 2000 and 2005. By comparison, the PNAS study, combined with remote sensing work by Matt Hansen of South Dakota State University, which put Africa’s share of tropical deforestation at less than 6 percent from 2000-2005, suggests that Africa’s forest loss is a considerably smaller driver of climate change than conventionally thought.
CITATION: Sassan Saatchi et al (2011). Benchmark map of forest carbon stocks in tropical regions across three continents.” PNAS June 3, 2011.
Mean biomass estimate for sub-Saharan African nations using a 25% forest cover definition
|Aboveground forest carbon stocks
|Belowground forest carbon stocks
|Total forest carbon stocks
|Avg Carbon Density
|Rep. of Congo||24||3,015||802||3,817||160|
New global carbon map for 2.5 billion ha of forests
(05/31/2011) Tropical forests across Latin America, Africa, and Southeast Asia stored 247 gigatons of carbon — more than 30 years’ worth of current emissions from fossil fuels use — in the early 2000s, according to a comprehensive assessment of the world’s carbon stocks. The research, published in the journal Proceedings of the National Academy of Sciences by an international team of scientists, used data from 4,079 plot sites around the world and satellite-based measurements to estimate that forests store 193 billion tons of carbon in their vegetation and 54 billion tons in their roots structure. The study has produced a carbon map for 2.5 billion ha (6.2 billion acres) of forests.
Temperate forests store more carbon than tropical forests, finds study
(07/17/2009) Temperate forests trump rainforests when it comes to storing carbon, reports a new assessment of global forest carbon stocks published July 14th in Proceedings of the National Academy of Sciences (PNAS). The findings have important implications for efforts to mitigate climate change by protecting forests. Sampling and reviewing published data from nearly 100 forest sites around the world, Heather Keith, Brendan G. Mackey, and David B. Lindenmayer of Australian National University found that Australia’s temperate Eucalyptus forests are champions of carbon storage, sequestering up to 2,844 metric tons of carbon per hectare, a figure that far exceeds previous estimates. These forests, located in the Central Highlands of Victoria in southeastern Australia, are dominated by giant Mountain Ash (Eucalyptus regnans) trees, which can reach a height of 320 feet and live for more than 350 years. They are also favored by the timber industry. Mountain Ash forests have been widely logged across Australia, with only limited old-growth stands remaining.
How satellites are used in conservation
(04/13/2009) In October 2008 scientists with the Royal Botanical Garden at Kew discovered a host of previously unknown species in a remote highland forest in Mozambique. The find was no accident: three years earlier, conservationist Julian Bayliss identified the site—Mount Mabu—using Google Earth, a tool that’s rapidly becoming a critical part of conservation efforts around the world. As the discovery in Mozambique suggests, remote sensing is being used for a bewildering array of applications, from monitoring sea ice to detecting deforestation to tracking wildlife. The number of uses grows as the technology matures and becomes more widely available. Google Earth may represent a critical point, bringing the power of remote sensing to the masses and allowing anyone with an Internet connection to attach data to a geographic representation of Earth.