African forests store 25% of tropical forest carbon

mongabay.com
June 22, 2011



Sign warning that a rainforest tree has been spiked to discourage illegal logging in Indonesian Borneo

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.

Forest carbon by region
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
CountryForest Area
(mln ha)
Aboveground forest carbon stocks
(Mt C)
Belowground forest carbon stocks
(Mt C)
Total forest carbon stocks
(Mt C)
Avg Carbon Density
(t C/ha)
Angola501,7925472,33947
Benin062829
Botswana11241619
Burundi01541964
Cameroon303,3619064,268142
Central
African
Republic
422,1456312,77666
Chad12062631
Côte d'Ivoire640611652285
DR Congo17717,8054,85722,662128
Equatorial
Guinea
231082393160
Ethiopia1353616169853
Gabon222,8207483,568164
Gambia0.040.30.10.412
Ghana32256328894
Guinea836510947357
Guinea-Bissau138125037
Kenya2862611154
Lesotho11341719
Liberia99902661,257147
Madagascar178932611,15470
Malawi251166740
Mali0.28931244
Mozambique351,1243481,47242
Namibia0.0510.2116
Nigeria745012957983
Rep. of Congo243,0158023,817160
Rwanda0.331952473
Senegal11141426
Sierra Leone52998638583
Somalia021234
South Africa102177028828
Sudan1343313356745
Swaziland0.491241632
Tanzania1758517976445
Togo0.1972949
Uganda41885524465
Zambia311,0273171,34443
Zimbabwe61284117030














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CITATION:
mongabay.com (June 22, 2011).

African forests store 25% of tropical forest carbon.

http://news.mongabay.com/2011/0622-africa_forest_carbon.html