DOI: 10.5061/dryad.vdncjsz37
title: Data from: fire in the rainforest: a 3,200-year history of fire in a West Kalimantan, Indonesia tropical rainforest

description: Despite its perceived historical rarity, fire is an important disturbance
 in tropical rainforests. Very large rainforest fires have been observed
 multiple times in recent decades, often during years of strong El
 Niño-Southern Oscillation droughts. Fire in rainforest has major
 short-term consequences for humans and wildlife by converting forest to
 fire-prone fern, shrub, and grass, but the long-term effects remain to be
 seen. Borneo’s indigenous groups have been using fire to clear land for
 centuries, yet the prevalence and spatial patterns of pre-modern fire
 across forest types in Borneo is not well understood. This research set
 out to reconstruct fire in a 1500-ha primary rainforest spanning 800 m of
 elevation in Indonesian Borneo with the goal of elucidating the role
 humans have played in rainforest fire. We found that humans played an
 important role in the occurrence of fire in recent centuries. Evidence of
 fire—charcoal &gt;2 mm—is more abundant in forest types where humans
 would be more likely to live and/or practice swidden agriculture. However,
 pyrogenic material is ubiquitous across the study area, showing that all
 forest types have experienced fire. A set of 50 radiocarbon dates showed
 that in lowland areas—where human-caused fire is most likely—fire occurred
 throughout the last 3,200 years, peaking 1300-1600 CE. The upland areas
 lacked evidence of fire before 1250 CE but otherwise had a similar pattern
 to the lowlands. The period of high fire coincides with regional
 demographic changes as well as regional droughts documented elsewhere in
 Southeast Asia. In upland areas, fires likely burned only under regional
 drought when fires could more easily spread upslope. Although forest plot
 studies at this site show little structural evidence of past fires, tree
 diversity is lower than expected in the most burned areas (alluvial
 benches). Thus, our results suggest that land clearance was a major source
 of fire, but the current intact state of these rainforests indicates that
 they were largely resilient to fires and land use hundreds of years ago.
 Recent fires mirror patterns of fire spread that occurred hundreds of
 years ago, though their severity and extent is likely much greater.
description: We collected soil samples (cores from the A horizon surface to
 20cm below the surface in 5cm increments) in the field at the coordinates
 indicated. Charcoal was isolated from the soil samples using 2mm and 0.5mm
 sieves. We collected, counted, and weighed all charcoal pieces in each
 size fraction. A subset of charcoal pieces was sent to the Woods Hole
 Oceanographic Institution National Ocean Sciences Accelerator Mass
 Spectrometry (NOSAMS) facility for radiocarbon dating (following NOSAMS
 submission guidelines, including cleaning of charcoal pieces before
 submission). Radiocarbon dates returned by NOSAMS were calibrated using
 the IntCal20 calibration curve (pre-modern dates) and the SH Zone 3 bomb
 radiocarbon calibration curve (post-modern dates). 
description: # Data from: fire in the rainforest: a 3,200-year history of fire in a
 West Kalimantan, Indonesia tropical rainforest
 [https://doi.org/10.5061/dryad.vdncjsz37](https://doi.org/10.5061/dryad.vdncjsz37) This dataset supports the manuscript ("Fire in the rainforest: A 3,200 year history of fire in a West Kalimantan, Indonesia tropical rainforest”). In this study, we examined fire history across an elevational gradient spanning seven distinct forest types in Gunung Palung National Park, West Kalimantan, Indonesia. We collected soil samples from all forest types and assessed the quantity and age of charcoal in each soil sample to determine the influence of human vs. lightning-ignited fire on paleofire patterns at this site. The data contained in these files includes the coordinates of sampling sites, macro-charcoal counts and masses for each sample, and raw radiocarbon results for a subset of samples. We isolated macrocharcoal from each soil sample using sieving at two size fractions: 2 mm and 0.5 mm. Each piece of macrocharcoal in each size fraction (&gt;2 mm and 0.5-2 mm) was counted, collected, and weighed. We calculated bulk density using an oven-dried parallel core for each sample and then used the bulk density to calculate macrocharcoal per gram of soil. A subset of charcoal pieces were cleaned and then submitted to the Woods Hole Oceanographic Institution National Ocean Sciences Accelerator Mass Spectrometry (NOSAMS) Facility for radiocarbon dating. We used the IntCal20 calibration curve to calibrate the results of radiocarbon dating. The contents of this folder correspond to the article: Hendricks, L.B., Anshari, G.Z., Gavin, G.G. (2024) Fire in the rainforest: A 3,200 year history of fire in a West Kalimantan, Indonesia tropical rainforest. Ecosphere. Comments and requests should be addressed to Lauren Hendricks ([laurenbhendricks@gmail.com](mailto:laurenbhendricks@gmail.com)). ## Sample Naming Schema Every sampling site was assigned an alphanumeric code based on the nearest point in the trail system/grid previously established at Cabang Panti Research Station (e.g., CH08). The first two letters indicate the trail name, and the numbers indicate position along the trail. This is the site ID. Six parallel cores, assigned a letter from A-F, were collected in pairs (A/B, C/D, and E/F), with pairs spaced approximately 20 m apart, at each site; cores in a pair were collected within 10 cm of each other. Cores A, C, and E were used to calculate bulk density; cores B, D and F were wet-sieved to isolate charcoal. Each core was collected in 5 cm increments: 0-5 cm, 5-10 cm, 10-15 cm, and 15-20 cm. Each increment is considered a sample. We collected large charcoal fragments from cores processed with either method for potential radiocarbon dating; radiocarbon date sample IDs indicate exactly which core the charcoal was found within. We used the volume of each sample (determined by the sampling device, 90.59 cm3) and the bulk density of each sample to calculate the mass of charcoal in milligrams per gram of soil. Example: CH08 C/D 5-10 cm indicates that this sample was collected around CH08, is in the second group of cores for that site (C/D), and is from 5-10 cm below the surface of the A horizon. ## **File List and Description** *CPRS_site_info.csv* – this file contains the coordinates (WGS84) of each sampling site, as well as which forest type, forest group, and zone the site is within. This file can be joined with the other two files to analyze the macrocharcoal and radiocarbon data by forest type, forest group, and/or zone. * "Site ID" is the general position that the sample was collected within the trail system; see above description of sample naming schema. * "Latitude" contains the latitude of each sample in WGS84.  * "Longitude" contains the longitude of each sample in WGS84.  * "Forest Type" records which of the seven forest types found within the study area the sample belongs to. See associated manuscript for descriptions of forest types; forest types of the study area are also described in Cannon and Leighton 2004, Paoli et al. 2006, and Cannon et al. 2007.  * "Forest Group" records which of the three forest type groups the sample belongs to. (1) Lowland is comprised of alluvial bench and lowland sandstone forest types; (2) upland is comprised of lowland granite, lowland sandstone, and montane forest types; and (3) inundated is comprised of freshwater swamp and peat forest types. * "Zone" records which of the three spatial zones we defined within the study area that the sample belongs two. We defined three spatial zones based on the study area topography. The study area contains two distinct parallel ridges that run roughly west to east; these are described as "North ridge" and "South ridge." Sites that were not located on either ridge were defined as "other." *CPRS_macrocharcoal.csv* – this file contains both the counts (number of pieces) and masses (mg per gram of soil) of charcoal present in each sample, divided into the &gt;2 mm and 0.5-2 mm size fractions. The bulk density of each sample is also included. * "Site ID" is the general position that the sample was collected within the trail system; see above description of sample naming schema. * "Core Pair" describes which of the three sets of parallel cores (A/B, C/D, or E/F) the sample belongs to; see above description of sample naming schema. We collected additional parallel cores at three sites; therefore, those sites have additional core pair labels (e.g., G/H).  * "Depth" refers to the depth segment from which the sample was collected; see above description of sample naming schema. Depths are measured in centimeters from the surface of the A horizon.  * "Sample ID" combines the information in the previous three columns into a single label/identification code for each sample.  * "Bulk Density" is the bulk density of each sample in grams per cubic centimeter.  * "Number of Pieces &gt;2mm" records the number of pieces of charcoal that are greater than 2 mm in size (i.e., were removed by a 2 mm sieve) within each sample. Pieces were collected from the screen of the 2 mm sieve, examined with a microscope to confirm their identity as charcoal, weighed, and counted.   * "Number of Pieces 0.5-2mm" records the number of pieces of charcoal that are between 0.5 mm and 2 mm in size (i.e., were removed by a 0.5 mm sieve, after &gt;2 mm material was removed with a 2 mm sieve) within each sample. Pieces were collected from the screen of the 0.5 mm sieve, examined with a microscope to confirm their identity as charcoal, weighed, and counted.  * "Mass &gt;2mm Fraction (mg charcoal/g soil)" records the total mass of pieces of charcoal &gt;2 mm within each sample, standardized to milligrams of charcoal per gram of soil using the bulk density. See description of number of pieces columns for details on collection.  * "Mass 0.5-2mm Fraction (mg charcoal/g soil)" records the total mass of pieces of charcoal 0.5-2mm within each sample, standardized to milligrams of charcoal per gram of soil using the bulk density. See description of number of pieces columns for details on collection.  * "Total Mass (mg charcoal/g soil)" records the mass of charcoal &gt;0.5 mm within each sample in milligrams of charcoal per gram of soil. It is the sum of the previous two columns.  *CPRS_radiocarbon.csv* – this file contains the uncalibrated radiocarbon results from accelerator mass spectrometer dating performed at the Woods Hole Oceanographic Institution National Ocean Sciences Accelerator Mass Spectrometry (NOSAMS) Facility. See [https://www2.whoi.edu/site/nosams/radiocarbon-data-and-calculations/](https://www2.whoi.edu/site/nosams/radiocarbon-data-and-calculations/) for more details.  * "Sample ID" is the identification code we assigned to each sample; see descriptions for *CPRS_macrocharcoal.csv*, above, for details.  * "Forest Type" records the forest type that the sample belongs to. See descriptions for *CPRS_site_info.csv*, above for details.  * "Forest Group" records the forest group that the sample belongs to. See descriptions for *CPRS_site_info.csv*, above for details.  * "Zone" records the spatial zone that the sample belongs to. See descriptions for *CPRS_site_info.csv*, above for details.  * "Type" indicates the type of sample submitted to NOSAMS. They accept a number of sample types in addition to charcoal, but all samples in this manuscript are charcoal.  * "Process" indicates the process used by NOSAMS to measure radiocarbon.  * "Accession Number" is a number used by the NOSAMS facility to track samples. Every sample submitted to NOSAMS has an unique accession number.  * "F Modern" represents the fraction modern; it is a measurement of how much a sample's radiocarbon deviates from the modern standard, with modern defined as 1950. This is used to calculate the radiocarbon age.  * "Fm Err" represents the error in the fraction modern calculation. See the NOSAMS website for more details: [https://www2.whoi.edu/site/nosams/calculations-and-reporting-of-results/](https://www2.whoi.edu/site/nosams/calculations-and-reporting-of-results/) * "d13C Corr" is used by NOSAMS to indicate whether or not the sample fraction modern value was corrected using the d13C value. The asterisks indicate that the radiocarbon result was corrected for isotopic fractionation using unreported d13C values measured on the accelerator. See "d13C" column description below for more details on d13C.  * "Age" represents the uncalibrated radiocarbon age reported by NOSAMS. The age reported here uses 5568 as the half-life of radiocarbon and does not include reservoir corrections. The age is relative to 1950, which is defined as "modern" in radiocarbon dating.  * "Age Err" the error in the age calculation. See the NOSAMS website for more details: [https://www2.whoi.edu/site/nosams/calculations-and-reporting-of-results/](https://www2.whoi.edu/site/nosams/calculations-and-reporting-of-results/) * "d13C" is the *δ*13C (delta c 13) of each sample. *δ*13C is the ratio of 13C and 12C (two isotopes of carbon) in parts per thousand. It is measured in order to correct the fraction modern used in calculating the sample radiocarbon age.  * "d13C Source" indicates how the d13C value was obtained by NOSAMS.  ## **References** Cannon, C. H., and M. Leighton. 2004. Tree species distributions across five habitats in a Bornean rain forest. Journal of Vegetation Science 15:257–266. Cannon, C. H., L. M. Curran, A. J. Marshall, and M. Leighton. 2007. Long-term reproductive behaviour of woody plants across seven Bornean forest types in the Gunung Palung National Park (Indonesia): suprannual synchrony, temporal productivity and fruiting diversity. Ecology Letters 10:956–969. Paoli, G. D., L. M. Curran, and D. R. Zak. 2006. Soil nutrients and beta diversity in the Bornean Dipterocarpaceae: evidence for niche partitioning by tropical rain forest trees. Journal of Ecology 94:157–170.