**5. Conclusions**

The main purpose of this study was to measure and analyse the immediate e ffect of fire on forest Haplic Luvisol. This was carried out using representative small scale fire plots that enables fire e ffect on soil to be measured without damaging large areas of land. These experimental fires carried out on soil matter in Damak Forest, North East Hungary, produced significant changes to the Haplic Luvisol organic matter and chemical properties. Increased changes were most obvious in exchangeable Ca, followed by available P and exchangeable Mg, with pH only significant in the high intensity fire treatment. Significant decrease was observed in all the fire intensities for exchangeable K. This is a key finding of this study, as it is one of the few studies that have found losses in exchangeable K post-fire. This contrasts with the general behaviour of exchangeable K in soils [2,46]. As expected, a higher intensity fire resulted in a greater change in nutrient levels, with the exception of Mg.

Another relevant finding of this study is the increase of pH, which was significant in the high intensity fires. Through leaching, the Haplic Luvisol will likely have a much higher pH, which can directly a ffect pH sensitive vegetation (e.g., native rare species such as *Quercus frainetto* Ten.).

This study indicates that there are potential negative e ffects on soil fertility based on the decrease of potassium in the experiment. Potassium is a key nutrient for the ion transport within vegetation. Any loss of this from the soil would have major influences on the agricultural sector of the Hungarian economy. With an increased forest fire risk across Europe, from the 2041–2070 A1B emission scenario [61], nutrient rich soil, such as Haplic Luvisol, will be adversely a ffected by losses in K. As such, this study provides a reference point for further investigation into the e ffect of fire intensity on Haplic Luvisol and for any soil type that could be subject to burning. To enable stronger conclusions to be drawn in future investigations, we recommend conducting a larger scale of experimental burning, to follow burned soils over a recovery period and to evaluate impacts on productivity. Nevertheless, we believe our findings provide useful evidence for Haplic Luvisol changes under fire disturbance, while also supporting the maintaining of the current Hungarian fire prevention policy.

**Author Contributions:** Conceptualisation, J.M.B. and G.P.P.; methodology, J.M.B. and G.P.P.; formal analysis, J.M.B.; investigation, J.M.B., G.P.P. and N.C.; writing—original draft preparation, J.M.B., G.P.P. and N.C.; writing—review and editing, J.M.B., G.P.P., and N.C.; visualisation, J.M.B.; supervision, G.P.P. and N.C.; project administration and funding acquisition J.M.B.

**Funding:** GPP's contribution to this work was supported by NERC's Newton Fund RCUK project Towards a Fire Early Warning System for Indonesia (ToFEWSI).

**Acknowledgments:** We thank János and Katalin Tóth, who granted permission for the experiment to be carried out on their land. We are grateful to Roxána Filetóth for facilitating the arrangemen<sup>t</sup> and in particular for her help with the fieldwork. Ian Saunders in the DGES Laboratory at Aberystwyth University who helped with the analysis of the soil samples. Andrew Thomas is acknowledged for insightful discussions on the manuscript.

**Conflicts of Interest:** The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.
