The effect of low-intensity prescribed burns in two seasons on litterfall biomass and nutrient content

摘要

Litterfall production and composition, fall pattern and nutrient content were studied in a mixed stand ofPinus nigraandPinus pinaster(El Pozuelo), as well as in a pure stand ofPinus nigra(Beteta) in the Cuenca Mountains in order to determine the effect of two-season prescribed burning treatments. Needles were the most abundant fraction. Pinecone fraction decreased after burning in the mixed stand and the opposite occurred in the pure stand. The inflorescence fraction showed a decrease in the spring-burned plots at El Pozuelo and Beteta. Bark, branch and miscellaneous fractions were affected mainly by meteorological events. Low-intensity prescribed burning was not found to cause significant perturbations. The perturbation was mitigated over the years. An immediate effect of prescribed burning in spring was seen at El Pozuelo and Beteta, although it was more significant for the pure stand. The effect of prescribed burning in autumn at Beteta had a delayed response. As regards nutrient contents, no differences in carbon concentrations were detected. Overall, an increasing trend in N, P, K concentrations in needles after the burning treatment was found. Calcium was not a limiting factor. Magnesium content exhibited no clear trend.