Short-term effects of post-fire mulching with straw or wood chips on soil properties of semi-arid forests

Few studies have compared the variability of soil properties using different types of mulches in semi-arid forests. This study evaluated the changes in physico-chemical soil properties in a semi-arid forest of Central Eastern Spain, where straw and pine wood chips were distributed as mulch three months after a wildfire. Soils were sampled under burned and unmulched and burned and mulched plots three and nine months after the treatments. The data was processed using Principal Component Analysis (PCA) and Analytical Hierarchical Cluster Analysis (AHCA). Mulching with straw or wood chips did not have any significant effects on the texture and chemical properties of burned sites few months after the treatment. In contrast, significant changes are expected over time in organic matter, nutrients and many ions. There were no significant differences in soil properties between the two mulches. These low changes were confirmed by PCA coupled with AHCA, which did not show a clear distinction among the three soil conditions. However, a noticeable and significant variability of many of these properties over time was evident. This study shows that mulching does not degrade of soil properties in the short-term after a wildfire and after post-fire treatments, and thus helps protect semi-arid forest ecosystems against the negative impacts of high-severity fires.