Fig 3. Fire proxy records of Lake Czechowskie, northern Poland.

A) Raw macrocharcoal (CHAR, n = 82) and MA (LVG, MAN, GAL, n = 75) influx records. CHAR_sum is the summed record of all charcoal particles >150 μm. Black lines and gray polygons are medians and interquartile ranges of robust influx calculations, respectively (Methods). Influxes calculated using the classical mean age-depth model are in red. B) Fire proxy background component. Black lines and gray polygons are medians and Q10–Q90 ranges, respectively, of 1,000 random LOESS fits of the standardized median of the robust influx records (black lines in A) with varying window widths. C) Fire proxy peak components. Black lines and gray polygons are medians and Q10–Q90 ranges, respectively, from subtracting the LOESS-fits of B from the standardized median records of A (black lines). Crosses and colored shaded areas (yellow to orange) mark major positive peaks indicating source area- and temperature-specific fire episodes (FEs1–7, Table 1). Black crosses in brackets mark tentative peaks that were above average only for some window widths. Red crosses mark peaks from decomposition of the mean influx record.