PARENT SESSION
Poster Session #42: Carbon Storage.
Thursday, August 9, 2001. Presentation from 3:30 PM to 5:00 PM. Exhibition Hall
143
The effect of land use change on the belowground carbon stock of the Miombo Woodlands.
Walker, Sarah1, Desanker, Paul1, 1
ABSTRACT- In the Miombo Woodlands Region of south-central Africa, an estimated 35-55% of the total system′s carbon stock is found belowground. Human population pressure, with rising demand for productive soils causes increasing deforestation and land degradation. We studied belowground carbon stocks within the miombo woodlands region to understand alterations in soil carbon levels caused by each dominant land use: woodland, agriculture, Eucalyptus plantation, and fallow. At 35 sites, soil and root samples were collected in 4 1m2 pits (depth of 150cm) at 6 depth intervals. Roots were cleaned, dried and weighed. Samples were analyzed using an automated CN analyzer. Soil carbon (SOC) levels varied considerably in the top 10cm even within the same land use type. Soil carbon levels were very similar in the woodlands and Eucalyptus sites (1.7-2.8% at the surface). Agricultural soil carbon was depressed (0.7-1.1% at the surface), however the majority of the reduction in SOC occurred within the first years of farming. Due to land pressures ′fallow′ areas are also used for grazing and firewood collection and this use has kept SOC levels degraded. Root biomass levels were very variable, but declined with increasing age of the agricultural field. By linking satellite imagery with these values of belowground carbon stocks, changes in soil carbon stocks due to land cover change can be estimated over regional scales.
KEY WORDS: Soil carbon, Land Use Change