Medium term changes in the structure and organic matter

Abstract

To study the variations in soil structure and organic matter content of a Mediterranean soil burned repeatedly, a set of two experimental fires with different severities were conducted in the Experimental Station of La Concordia (Valencia, Spain). In June of 1995, three plots (20 x 4 m) were burned with high severity fire (T1), three with moderate severity (T2) and three plots were left unburned to be used as control (T3). In July of 2003, plots corresponding to the fire treatments were burned again, giving low fire severities. In the eight-year interval between fires, plots remained undisturbed. A period of four years after the repeated fires (July 2003 - July 2007) was considered to study the changes and the relationships among the aggregates size (mean weight diameter: MWD), their stability (SMS) and organic matter content (SOM) in a Rendzic Leptosol differentiating two environments: soil under canopy (UC) and soil between plants or bare soil (BS).