Biological legacies facilitate post-fire active management by improving the micro-sites

Forest restoration is often advocated after natural disturbances to guarantee prompt ecological recovery and the provision of ecosystem services. Sowing and transplant of seedlings are the main techniques, and ecological facilitators (biological legacies, abiotic features) may promote artificial regeneration by enhancing the microenvironment. In this study, three types of Quercus pubescens L. propagules (1-year seedlings, acorns with, and without shelter) were used in a burnt forest in Central Italy. The effect of four ecological facilitators (shrubs, downed logs, branches, and micro-terraces) on regeneration survival and growth was monitored for the first two growing seasons. In addition, sensors for air temperature and illuminance were deployed during the first year near the artificial regeneration to investigate the effect of ecological facilitators on the surrounding microclimate. Results show a clear positive effect of biological legacies on regeneration survival and a reduction of near-ground air temperature and insolation. The trend was consistent along the dry summer season, and similar across propagule types. Branches were the best ecological facilitator in terms of reduction of air temperature (-7.9 degrees C than control), solar radiation (-38.9 %), and propagules survival (52-75 % after one year and 12-33 % after two years), while regeneration performance and microclimate conditions were the same on micro-terraces and in control positions. Branches and shrubs may also have discouraged wildlife pressure on propagules. The outcomes confirm the beneficial role of ecological facilitators on forest regeneration, and suggest that locating propagules near ecological facilitators is more important than choosing propagule types in forest restoration.