Effects of prescribed fire for pasture management on soil organic matter and biological properties: A 1-year study case in the Central Pyrenees

Prescribed burning has been readopted in the last decade in the Central Pyrenees to stop the regression of subalpine grasslands in favour of shrublands, dominated among others by Echinospartum horridum (Vahl) Rothm. Nevertheless, the effect of this practice on soil properties is uncertain. The aim of this work was to analyse the effects of these burnings on topsoil organic matter and biological properties. Soil sampling was carried out in an autumnal prescribed fire in Buisan (NE-Spain, November 2015). Topsoil was sampled at 0-1 cm, 1-2 cm and 2-3 cm depth in triplicate just before (U), similar to 1 h (B0), 6 months (B6) and 12 months (B12) after burning. We analysed soil total organic C (TOC), total nitrogen (TN), microbial biomass C (C-mic), soil respiration (SR) and ss-D-glucosidase activity. A maximum temperature of 438 degrees C was recorded at soil surface while at 1 cm depth only 31 degrees C were reached. Burning significantly decreased TOC (-52%), TN (-44%), C-mic (-57%), SR (-72%) and ss-D-glucosidase (-66%) at 0-1 cm depth while SR was also reduced (-45%) at 1-2 cm depth. In B6 and B12, no significant changes in these properties were observed as compared to B0. It can be concluded that the impact of prescribed burning has been significant and sustained over time, although limited to the first two topsoil centimetres. (c) 2017 Elsevier B.V. All rights reserved.