Wildfires are a driving factor of forest soils and their biota, especially in fire-prone ecosystems. Fire effects on soil microbial community are complex and still largely unknown. Greater knowledge is needed as fire frequency is expected to increase with human-induced climate change. This study aims at assessing the effects of a single moderately severe wildfire on microbial community diversity and activity in a Mediterranean forest soil by DNA molecular screening (polymerase chain reaction–denaturing gradient gel electrophoresis). For this purpose, the soil of a burned area was sampled 3 days and 10 months after the fire and compared with the soil of an unburned contiguous area. For the DNA fingerprinting, we analyzed both extracellular and intracellular DNA fractions of the soil metagenome. The fire impact on soil was also rated in terms of selected enzyme activities, as reliable bioindicators of biogeochemical cycles. An immediate fire-induced general decrease in enzyme activities and more durable changes in the bacterial and fungal communities structure were found, although microbial biomass was not significantly affected. Litter layer was completely turned to char and ash by the fire, but after 10 months, it showed a fair amount of DNA, a structured microbial community, and a good enzymatic activity. Overall, such relatively fast recovery was likely caused by the microbial biomass that survived the fire, which evidently adapted to the new soil conditions.

野火是森林土壤及其生物群的驱动因素，尤其是在易火灾的生态系统中。火灾对土壤微生物群落的影响很复杂，而且在很大程度上仍然未知。需要更多的知识，因为预计火灾频率会随着人类引起的气候变化而增加。本研究旨在通过 DNA 分子筛选（聚合酶链反应-变性梯度凝胶电泳）评估单一中度严重野火对地中海森林土壤中微生物群落多样性和活性的影响。为此，在火灾发生 3 天和 10 个月后对燃烧区域的土壤进行了取样，并与未燃烧的邻近区域的土壤进行了比较。对于 DNA 指纹，我们分析了土壤宏基因组的细胞外和细胞内 DNA 部分。火灾对土壤的影响也根据选定的酶活性进行评级，作为生物地球化学循环的可靠生物指标。尽管微生物生物量没有受到显着影响，但发现立即引起火灾引起的酶活性普遍降低以及细菌和真菌群落结构发生更持久的变化。垫料层在大火中完全变成炭灰，但10个月后，它显示出相当数量的DNA、结构化的微生物群落和良好的酶活性。总体而言，这种相对较快的恢复可能是由在火灾中幸存下来的微生物量造成的，这显然适应了新的土壤条件。和良好的酶活性。总体而言，这种相对较快的恢复可能是由在火灾中幸存下来的微生物量造成的，这显然适应了新的土壤条件。和良好的酶活性。总体而言，这种相对较快的恢复可能是由在火灾中幸存下来的微生物量造成的，这显然适应了新的土壤条件。