Effects of Burning on Chaparral Soils: I. Soil Nitrogen

Abstract Undisturbed moist or dry soil slabs collected from beneath chaparral plants were burned at different intensities in the laboratory. Inorganic and organic nitrogen levels were measured before and after burning. An intense burn over dry soil slabs decreased KCl‐extractable NH 4 + ‐N in the litter but increased it in the underlying soil. In contrast, NO 3 ‐ ‐N was decreased in both soil and litter during an intense burn over dry soil. Little change in NO 3 ‐ ‐ and NH 4 + ‐N occurred when litter and soil were moist. About 67% of the total N in the litter and soil was lost during the intense burn over dry soil, but less than 25% was lost when the soil and litter were moist. Amino acids were particularly sensitive to heating and were almost destroyed in dry litter during the intense burn. Almost 75% of the hexosamines in the litter and soil were also destroyed by the intense burn over dry soil.