# The Quirky Rot Fungi: Underexploited Potential for Soil Remediation and Rehabilitation
## 1 Soil Ecology, Health, and Erosion Control
### Fire-Stricken Soils  
Forest fires are catastrophic disruptions of terrestrial ecosystems. Depending on their intensity and duration, the impact of fires can range from slight/minimal to the complete destabilization of the soil structure and its sterilization [12; 48; 49]. This loss of biodiversity can disrupt nutrient cycling, increase the risk of erosion, and hinder ecosystem recovery. Fires immediately generate a loss of biomass above the ground and create a large input of recalcitrant pyrolyzed organic matter into the soil (necromass; Figure 2). This sudden influx of organic matter requires a robust decomposition system; otherwise, it can lead to aggravated long-term soil degradation. Notwithstanding the decline in microbial activity in these affected ecosystems, the large necromass input often hinges on the rapid response and activity of decomposing organisms, particularly saprophytic fungi. Rot fungi are kickstarts that play a pivotal role in initiating and driving the process of decomposition and unlocking the essential resources necessary for the establishment of other biota. For instance, [PERSON] et al. [50] verified that seven months after a moderate-to-high wildfire severity in a semi-arid Mediterranean region, the percentage of mycorrhizal fungi decreased from 36.6% (unburnt) to 2.6%, in favor of an increase in the percentage of saprotrophs (from 41.8% to 74%). Their pioneering role is believed to arise from their ability to exploit aromatic compounds that are usually part of this organic matter as food sources and the lack of the mandatory biotrophic relationships needed by other fungi (e.g., mycorrhizae). The saprotroph _Pyronema domesticum_ successfully colonized and degraded pyrolyzed substrates (charcoal and ash) by producing specific enzymes that degrade the complex structure of aromatic compounds such as PAH and phenols. After 57 days of the experiment, the fungus could significantly break down recalctrant matter into less toxic and more bioavailable compounds, contributing to the nutrient cycle and the recovery of the soil post fire [51]. Another similar study using the same species, noted the rapid colonization of the charred substrate as a nutrient source under very poor nutritional conditions, and the dominance of saprotrophic fungi at the early stages of succession in these fire scenarios [52]. However, it is important to highlight that this fungus, _P. domesticum_, is a pyrophilous (\"a fire lower\"), but other reports on non-pyrophilous species such as _Pleurotus pulmonaris_ and _Coriolus versicolor_ provide accounts of charred biomass colonization in time frames shorter than 70 days [53]. Yet, the potential beneficial role of non-pyrophilous rot fungi should not be ignored because there is plenty of evidence of their resilience under PAH-induced stress--e.g. [32; 54; 55; 56; 57]. In fact, [PERSON] and [PERSON] [54] observed the number of fungal occurrences in a burnt area undergoing recovery over a three-year period and showed that, of the 15 species that could be used as recovery bioindicators, 13 were saprophytic fungi and/or associated with wood (for example, _Tranetes hirsuta_), without having reported a pyrophyte species. Although some studies have focused on the observation and evolution of the recovery of this group of organisms in burnt area rehabilitation scenarios, no study has focused on fundamental research into the real role of these fungi or how their biology can be optimized for fire remediation scenarios. However, the role of fungi in post-fire soil recovery is not limited to decomposition, but also contributes to soil aggregation and water retention (Figure 2). Again, the mycelial network may act in a manner similar to that previously outlined for mining-derived slags. The extension of hyphae leads to the interweaving of soil components, including minerals, organic matter, and char residues.