Fig 1.
Combined charcoal reflectance calibration curve for five experimentally charred boreal woods (Betula nana, Picea mariana, Picea glauca, Betula papyrifera, Populus tremuloides).
Mean random reflectance under oil (Romean) and standard deviations represent all species.
Fig 2.
Vegetation and pyrolysis intensities from Screaming Lynx Lake, during the Holocene, (A) birch pollen (primarily B.nana) percentages, (B) pollen percentages of main tree species referred to in the text (modified from ref. 17).
Random-effects reflectance estimates for, (C) biodegraded charcoals, and (D) undegraded charcoals (both plotted with 95% confidence intervals), (E) Proportions of biodegraded and undegraded charcoals from each 1kyr interval.
Fig 3.
Photomicrographs illustrating charcoals from ‘undegraded’ and ‘biodegraded’ categories, (A) undegraded gymnospermous woody fragment, (B) Plant tissue showing evidence of biodegradation prior to charring: the presence of cell infillings formed from biodegradation of the cell wall, distortion of cell walls, and cavity formation in secondary walls.
Photographs were taken using reflected-light microscopy with immersion oil.
Fig 4.
Total heat release curves for (A) Spruce (Picea sp.) needle litter and (B) Aspen (Populus sp.) broadleaf litter.