Data from: Charcoal analysis for temperature reconstruction with infrared spectroscopy

The duration and maximum combustion temperature of vegetation fires are
important fire properties with implications for ecology, hydrology, hazard
potential, and many other processes. Directly measuring maximum combustion
temperature during vegetation fires is difficult. However, chemical
properties of charcoal formed as a by-product of fire reflect key chemical
transformations associated with temperatures. Therefore, they could be
used indirectly to determine the maximum combustion temperature of
vegetation fires. To evaluate the reliability of charcoal chemistry as an
indicator of maximum combustion temperature, we studied the chemical
properties of charcoal formed through two laboratory methods at measured
temperatures. Using a muffle furnace, we generated charcoal from the woody
material of ten different tree and shrub species at seven distinct peak
temperatures (from 200 °C to 800 °C in 100 °C increments). Additionally,
we simulated more natural combustion conditions by burning woody material
and leaves of four tree species in a combustion facility instrumented with
thermocouples, including thermocouples inside and outside of tree
branches. Charcoal samples generated in these controlled settings were
analyzed using Fourier Transform Infrared (FTIR) spectroscopy to
characterize their chemical properties. The Modern Analogue Technique
(MAT) was employed on FTIR spectra of muffle furnace charcoal to assess
the accuracy of inferring maximum pyrolysis temperature. The MAT
modeltemperature matching accuracy improved from 46% for all analogues to
81% when including ±100 ℃. Furthermore, we used MAT to compare charcoal
created in the combustion facility with muffle furnace charcoal. Our
findings indicate that the spectra of charcoals generated in a combustion
facility can be accurately matched with muffle furnace-created charcoals
of similar temperatures using MAT, and the accuracy improved when
comparing the maximum pyrolysis temperature from muffle furnace charcoal
with the maximum inner temperature of the combustion facility charcoal.
This suggests that charcoal produced in a muffle furnace may be
representative of the inner maximum temperatures for vegetation
fire-produced charcoals. FTIR spectroscopy is a promising tool for
determining maximum fire temperature from charcoals of vegetation and
prescribed fires and may have implications for fossil charcoal from
palaeoecological records.