Aims
The aim of this methodology is to determine the capacity of soil-erosion regulation according to the land-use changes, within the framework of global change. This calculation gains meaning when the values are compared within the same territory for two different temporal references, enabling us to analyse the trends in providing this service.
Method and effort
To evaluate the capacity of the ecosystem to regulate soil erosion, we use an indirect indicator. We cannot assess the magnitude of the erosion at the scale of Sierra Nevada but we can estimate the potential erosion of a specific area and compare it with what would occur in different scenarios of land use and agricultural practices. In this way, we can ascertain the quantity of potential erosion that is being avoided or that is being provoked as a surrogate of the regulation capacity. To calculate the potential erosion, we use the methodology known as R.U.S.L.E., a revised U.S.L.E. (Universal Soil Loss Equation), published in 1962 and widely used in the scientific literature. The equation that defines the potential erosion is:
A = R x K x L x S x C x P (t/ha/year)
where:
A= is the soil loss per unit of surface area and time; R= rainfall erosivity; K= soil erodibility; L= slope length; S= slope gradient; C= soil use; P= management practices;
RUSLE is calculated in the same way, although modifications and improvements have been made in the way to calculate the different variables. Thus, for the factor R, new isovalue maps have been calculated; K takes into account the possibility of freezing; L and S are estimated jointly with GIS tools; C includes new classifications; and, for P, new typologies of agricultural practices have been included.
Periodicity
The periodicity of these studies is subject to the availability of information on soil uses and management practices.
Results
References
Martín-Fernández, L., and Martínez-Núñez, M. 2011. An empirical approach to estimate soil erosion risk in Spain. Sci. Total Environ., 409(17): 3114-23.
Moreno Llorca, R., Navarro González, I. and Bonet García, F.J. 2011. Evolution of ecosystem services in intensive and extensive Agricultural Systems. En: 12th European Ecological Federation. Congress. Responding to rapid environmental change. Ávila, Sep 2011.
Wischmeier, W.H. y Smith, D.D. 1962. Soil loss estimation as a tool in soil and water management planning. Pp. 148-159. En: Symposium of Bari, Oct. 1962. Commission on Land Erosion. IAHS Publ. nº 59.
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