Fire-related features of wood anatomy in a sweet chestnut (Castanea sativa) coppice in southern Switzerland

Explorative wood anatomical analysis was conducted on a Castanea sativa stand in southern Switzerland, where a moderate-intensity surface fire burned in April 1997. Cross-sections were sampled at multiple heights from 20 scarred shoots, 20 apparently intact shoots, along with cores taken from 20 reference trees outside the fire area. Thin sections were prepared from uphill and downhill locations on the circumference for up to 5 years preceding and following the event year. The thin sections were visually observed in order to identify a response to the known fire event preserved in the wood anatomical structure. Anatomical features were observed at the uphill and downhill locations on both scarred and intact (unscarred) cross-sections, and they occurred in a subset of the observed samples. The features observed in both scarred and intact cross-sections were an apparent increase in vessel density and a decrease in lumen area of the second row of earlywood vessels, along with tyloses formation in the first row of earlywood vessels. Furthermore, the scarred region exhibited a zone of delayed cambial death following the fire, and the onset of woundwood was often initiated later in the season or the following year. Using the type of features and their location around the circumference, we inferred that the observed features may have formed in response to local heating of the cambium, and likely formed in response to canopy damage.