Prescribed burning is a tool that is frequently used for various land management objectives, mainly related to reduction of hazardous forest fuels, habitat management and ecological restoration. Given the crucial role of soil in forest ecosystem processes and functions, assessing the effects of prescribed burning on soil is particularly relevant. This study reviews research on the impacts of repeated prescribed burning on the physical, chemical and biological properties of soil. The available information shows that the effects are highly variable, rather inconsistent and generally minor for most of the soil characteristics studied, while a number of soil properties show contrasting responses. On the other hand, ecosystem characteristics, differences in fire severity, frequency of application and the cumulative effect of treatment repetition over time, have possibly made it more difficult to find a more common response in soil attributes. Our study has also revealed some limitations of previous research that may have contributed to this result, including a limited number of long-term studies, conducted at a few experimental sites, and in a limited number of forest ecosystems. Research issues concerning the effects of prescribed fire on soil are presented. The need to integrate such research into a broader interdisciplinary framework, encompassing the role of the fire regime on ecosystem functions and processes, is also highlighted.

Wildfires are becoming more frequent and severe globally, particularly in the Mediterranean Basin due to rapid climate and land-use changes. These trends threaten soil biodiversity and ecosystem functioning. In fire-prone forests, prescribed burning is increasingly used to reduce fuel loads, yet the long-term effects of repeated prescribed fires on post-wildfire soil functioning remain unclear, particularly regarding soil fauna, which has rarely been examined in this context. We assessed the effects of a wildfire that took place in 2021 affecting an area treated five times with low-intensity prescribed burns (conducted between 1984 and 2017) on soil mesofauna communities, the QBS-ar index (Soil Biological Quality-arthropods; an index based on the ecological adaptation of soil fauna), soil functions, and soil multifunctionality (SMF) in a maritime pine (Pinus pinaster Ait.) reforestation in northwestern Spain. Three fire history treatments were compared: unburned (U), wildfire only (C + W; plots used as unburned controls during the prescribed fires that were burned in 2021), and prescribed burning followed by wildfire (PF + W). Soils were sampled at three post-wildfire time points to assess mesofauna and physical, chemical, and microbiological properties used to calculate four soil functions (water regulation, fertility, climate regulation, and organic matter decomposition) and SMF. PF + W plots hosted more resilient mesofauna communities than W plots and shared several indicator taxa with unburned soils. Similarly, a principal component analyses (PCA) revealed that overall soil conditions in PF + W plots were intermediate between U and C + W. Wildfire alone had the strongest negative impact on climate regulation and decomposition, whereas water regulation and soil fertility functions were similar among treatments. Soil multifunctionality was lowest in W plots and highest in both U and PF + W plots, with fire treatment and mesofauna jointly explaining 44 % of SMF variation, and soil properties accounting for 25 %. These findings indicate that repeated low-intensity prescribed burns can precondition soils, thereby maintaining biodiversity and soil multifunctionality after a wildfire, and highlight the importance of ecological memory and soil biota in post-fire recovery.