World’s Soil Resources

Figure 4.5 Maps of change in soil carbon due to
land use change and land management from
1860 to 2010 from three vegetation models.
Pink indicates loss of soil carbon, blue indicates
carbon gain. The models were run with historical
land use change. This was compared to a
model run with only natural vegetation cover
to diagnose the difference in soil carbon due to
land cover change. Both model runs included
historical climate and CO 2
change. Source: Smith
et al. (in press).
Panel (a) of Figure 4.5 shows cropland and pasture coverage in 2003. The model was run with historical land
use change. This was compared to a model run with only natural vegetation cover to diagnose the difference
in soil carbon due to land cover change up to year 2003 as shown in Panel (b). Both model runs included
historical climate and CO 2
change. Pink indicates loss of carbon due to land use, blue indicates areas of carbon
gain.
Model Tropical Temperate Boreal Global
LPJ-GUESS 12.63 15.01 0.37 29.85
LPJmL 34.86 25.99 0.05 61.86
ISAM 17.24 37.83 5.28 60.35
Mean 21.57666667 26.27666667 1.9 50.68666667
Table 4.1 Soil carbon lost globally due to land use change over the period 1860 to 2010 (PgC)
Data are from three vegetation models ISAM (Jain et al., 2013; El-Masri et al., 2013; Barman, Jain and Liang,
2014 a, b); LPJ-GUESS (Smith et al., 2001; Pugh et al., 2015); and LPJmL (Bondeau et al., 2007; Schaphoff et al.,
2013). Each model is run with and without historical land use change data and the difference between the ‘with
land use change’ and ‘no land use change’ runs gives the loss due to land use change. The runs also included
historical climate and CO 2
and cover the period from 1900 to 2010.
Impacts of land management and degradation
Logging and fire are the major causes of forest degradation in the tropics (Bryan et al., 2013). Logging removes
nutrients. Logging operations also cause soil disturbance affecting soil physical properties and nutrient levels
(soil and litter) in tropical (e.g. Olander et al., 2005; Villela et al., 2006; Alexander, 2012) and temperate forests
(Perez et al., 2009). Many physical, chemical, mineralogical, and biological soil properties can be affected by
forest fires depending on fire regime (Certini, 2005). Increased frequency of fires contributes to degradation
and reduces the resilience of the biomes to natural disturbances
Status of the World’s Soil Resources | Main Report Soils and Humans
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