Freezing and thawing makes soils more permeable after fires
Congratulations to Katya Rakhmatulina, whose first PhD paper Freeze Thaw Processes Degrade Post-Fire Water Repellency in Soils was published in Hydrological Processes. Katya heated soils to simulate the effects of fires - preventing water droplets on their surface from infiltrating - a problem called hydrophobicity that contributes to flooding and erosion after big fires.
Katya wet and dried these soils, simulating the effect of rainy and dry periods. She also froze and thawed the soils. After each round of wetting/drying or freezing/thawing, she measured how easily water could enter the soil, finding that it was faster each time. She showed that freezing and thawing was as effective as wetting and drying in reducing hydrophobicity. She also showed that it's likely that in mountain areas, winter freeze/thaw is the most important factor helping soils recover after fire. Check out the paper here!
You can learn more about Katya's work and field sites in this gorgeous video:
And read about it in more detail in this feature article.