Use of dendrochronological method in Pinus halepensis to estimate the soil erosion in the South East of Madrid (Spain)

The rate of soil erosion in pine forests (Pinus halepensis) located in the Southeast of Madrid has been estimated using dendrochronological analysis based on the change in ring-growth pattern from concentric to eccentric when the root is exposed. Using 49 roots spread across five inclined areas, it has been found that the length and direction of the hillsides, as well as their vegetation cover affect the rate of erosion, while the slope itself does not. The erosion rates found for the different areas studied vary between 3.5 and 8.8 mm year−1, that is between 40 and 101 t ha−1 year−1 respectively. These values are between 2 and 3 times greater than those predicted by USLE, for which this equation underestimates soil loss for Central Spainʹs Mediterranean conditions. Nonetheless, both methods (using dendrochronology to determine actual soil loss and theoretical prediction with USLE) are able to establish the same significant differences among the areas studied, allowing for the comparative estimate of the severity of the areaʹs erosion problem.