Humus buildup (C sequestration) rates in forest ecosystems : a regional level

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Berg, Björn ; Akselsson, Cecilia ; Gundersen, Per ; Meentemeyer, Vernon:
Humus buildup (C sequestration) rates in forest ecosystems : a regional level.
2004

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Abstract

Using the forested area of Sweden as an example we made an upscaling of carbon (C) sequestration rates in the humus layers on top of the mineral soil. The forested area encompassed 23 * 106 ha ranging from about 55oN to 69oN, with boreal climate north of ca 60 o N and temperate climate from ca 55 to 60 oN. For the upscaling we used 5 * 5 km grids, i.e. 17 000 grids covering the forested area of Sweden. For each grid, data of forested area and main species composition was available and average annual actual evapotranspiration (AET) was estimatedThe C sequestration rate was calculated using the limit value method, which combines quantitative litter fall with data on the remaining recalcitrant fraction of foliar litter, namely that part that becomes soil organic matter (SOM).Using the limit value approach we obtained a value of 4.8* 106 tons of C annually sequestered in SOM in forest soils in Sweden, with an annual average of 180 kg C ha-1. There is a clear gradient in C sequestration over the country with the highest values (410 kg C ha-1 yr-1 ) in southwest, and the lowest (ca 40 kg C ha-1 yr-1) in the northern parts, mainly corresponding to the gradient in litter fall.We distinguished differences among species. Thus, Norway spruce forests accumulated on the average 200 kg C ha-1 annually as SOM on top of the mineral soil. Scots pine and the two dominant 2 birch species had an average of 150 kg C ha-1. In a group with beech and oak, which is limited to south Sweden, the C sequestration rate was around 400 kg ha-1 yr-.http://kuk.uni-freiburg.de/hosted/eurosoil2004/full_papers/id181_Berg_full.pdf