DOI: 10.5061/dryad.msbcc2g5p
title: Pollen and charcoal from Tolhuaca National Park, south-central Chile

description: Aim: Few paleoenvironmental studies have been performed in
 Araucaria-Nothofagus forests, which are highly vulnerable to ongoing
 threats from climate change and anthropogenic activities. The primary goal
 of this work is to reconstruct past environmental changes related to fire
 disturbances over the last 1800 years in Tolhuaca National Park, Chile.
 Location: Tolhuaca National Park, Araucanian region (38.2°S; 71.8°W),
 Northwestern Patagonia, Chile. Taxa: Araucaria araucana (Araucariaceae),
 Nothofagus spp. (Nothofagaceae). Methods: We completed charcoal and pollen
 analyses to create two new paleoecological records that span 1800 years.
 We compared the lake-based reconstruction with the available local
 tree-ring fire scar chronologies from the last 430 years. Using these
 data, we compute forest index changes, biomass burning trends, and compare
 with estimates of archaeological radiocarbon density. We place our
 inferences with context of published regional paleoclimatic proxies from
 the Patagonian-Andean region. Results: Our results showed that fire
 activity was higher than present between 200 and 1500 CE, with peaks
 around 200-400 CE and 1100-1500 CE. Periods with high fire activity are
 associated with reduced forest cover, as Araucaria declined when
 mixed-severity fire regime occurred for extended periods. Pollen
 assemblages suggested a shift from dry to wet climate conditions at 1500
 CE, and from 1750 CE onward, the arrival of exotic species reflected the
 land-use changes related to forest clearance and transhumance practices.
 Main conclusions: The paleoenvironmental reconstructions showed changes in
 vegetation, fire, and climate over the past 1800 years in TNP. Wildfires
 have been the main disturbance process modifying the vegetation structure
 in the Araucaria and Nothofagus forests. Since 1750 CE intensive
 post-Hispanic land-use changes (forest clearances by fire and logging)
 took place in the study area, reducing the native vegetation cover.
 Climate variability, modulated by SAM-like and ENSO-like conditions,
 influenced the fire activity (availability and flammability of fuels),
 concomitantly with high archaeological density. The recent (after 2000 CE)
 increase of catastrophic wildfires may negatively affect the conservation
 strategies of Araucaria-Nothofagus forests.
description: <strong>Chronology:</strong> Two sediment cores were
 collected in Verde (112 cm) and Malleco (120 cm) lakes using an UWITEC
 gravity corer. Radionuclide measurements using a gamma spectrometer were
 performed to estimate the <sup>210</sup>Pb,
 <sup>226</sup>Ra (to support <sup>210</sup>Pb
 activity), and <sup>137</sup>Cs activities on the first 20
 cm). In addition, AMS radiocarbon dating was performed in both lakes.
 Radiocarbon ages were calibrated using the SHCal20 curve (Hogg et al.,
 2020). The age-depth models were computed using an integrated chronology
 based on <sup>210</sup>Pb, <sup>137</sup>Cs, and
 <sup>14</sup>C dates through Bayesian analyses in “rPlum”
 package (Aquino-López et al., 2018; Blaauw et al., 2020) in R
 platform. <strong>Charcoal
 analyses:</strong> To infer fire regime, macroscopic (&gt;125
 µm) charcoal fractions were analyzed in Verde and Malleco cores. 2
 cm<sup>3</sup> of sediment were taken at 1 cm intervals for
 the length of the core, sieved through 125 μm and 250 μm screens,
 following the methodology outlined by Whitlock and Larsen
 (2001).  <strong>Pollen analyses:</strong>
 Verde and Malleco cores were subsampled for 1 cm<sup>3</sup>
 (Verde) and 2 cm<sup>3</sup> of sediment (Malleco) at discrete
 2 to 5 cm intervals. The samples were analyzed using conventional
 procedures (Faegri & Iversen, 1989). To calculate pollen
 concentration and accumulation rate, two tablets of <em>Lycopodium
 clavatum</em> were added to each sample (Stockmarr, 1971). Pollen
 identification was carried out using a modern reference collection
 (Palynology Lab-UACh) and palynological keys (Heusser, 1971; Markgraf
 & D'Antoni, 1978).
 <strong>References:</strong>
 Aquino-López, M. A., Blaauw, M., Christen, J. A., &
 Sanderson, N. K. (2018). Bayesian Analysis of 210Pb Dating. Journal of
 Agricultural, Biological and Environmental Statistics, 23(3), 317-333.
 doi:10.1007/s13253-018-0328-7 Blaauw, M., Christen, J.
 A., & Aquino-López, M. A. (2020). rplum: Bayesian Age-Depth
 Modelling of '210Pb'-Dated Cores. R package version 0.1.4.
  https://CRAN.R-project.org/package=rplum Faegri, K., & Iversen, J. (1989). Textbook of pollen analysis. Londres: John Wiley & Sons Ld. Heusser, C. J. (1971). Pollen and spores of Chile: Modern types of the Pteridophyta, Gymnospermae, and Angiospermae. Tucson: University of Arizona Press. Hogg, A. G., Heaton, T. J., Hua, Q., Palmer, J. G., Turney, C. S. M., Southon, J., . . . Wacker, L. (2020). SHCal20 Southern Hemisphere Calibration, 0–55,000 Years cal BP. Radiocarbon, 62(4), 759-778. doi:10.1017/RDC.2020.59 Markgraf, V., & D'Antoni, H. L. (1978). Pollen Flora of Argentina. Modern Spores and Pollen Types of Pteridophyta, Gymnospermae and Angiospermae. Tucson: The University of Arizona Press. Stockmarr, J. (1971). Tablets with spores used in absolute pollen analysis. Pollen spores, 13, 615-621.  Whitlock, C., & Larsen, C. (2001). Charcoal as a proxy fire. In J. P. Smol, H. J. B. Birks, & W. M. Last (Eds.), Tracking Environmental Change Using Lake Sediments: Terrestrial, Algal, and Siliceous Indicators (Vol. 3, pp. 75-97). Dordrecht, The Netherlands: Kluwer Academic Publishers.
description: # Pollen and charcoal from Tolhuaca National Park, south-central Chile ###
 Research article: ## Fire-climate-human dynamics over the last 1800 years
 in the mesic *Araucaria-Nothofagus* forests. **Authors:** Martel-Cea,
 Alejandra (1,2,3), Abarzúa, Ana M. (2,4), González, Mauro E. (5,6,7),
 Jarpa, Leonora (2), Hernández, Marjorie (2). **Journal:** Journal of
 Biogeography **Year:** 2024 **DOI:** 10.1111/jbi.14839 **Corresponding
 author:** [anaabarzua@uach.cl](mailto:anaabarzua@uach.cl)
 **Affiliations:** (1) Corporación Centro de Estudios Avanzados en Zonas
 Áridas, La Serena, Chile (2) Instituto Ciencias de la Tierra, Ciencias,
 Universidad Austral de Chile. Valdivia, Chile (3) Laboratorio Natural
 Andes del Sur, Universidad Austral de Chile. Valdivia, Chile (4) Núcleo de
 Estudios Transdisciplinarios del Cuaternario del Sur de Chile (TAQUACh),
 Universidad Austral de Chile. Valdivia, Chile (5) Instituto de
 Conservación Biodiversidad y Territorio, Facultad de Ciencias Forestales y
 Recursos Naturales, Universidad Austral de Chile. Valdivia, Chile (6)
 Centro de Ciencia del Clima y la Resiliencia (CR2). Santiago, Chile (7)
 Centro del Fuego y Resiliencia de Socioecosistemas (FireSES), Universidad
 Austral de Chile. Valdivia, Chile ## DATASET: Pollen and charcoal from
 Tolhuaca National Park, south-central Chile.
 [https://doi.org/10.5061/dryad.msbcc2g5p](https://doi.org/10.5061/dryad.msbcc2g5p) The dataset contains the palynological and charcoal sedimentary records from two lakes in the Tolhuaca National Park located in the western Andes Cordillera, northern Patagonia. Data cover the past 1800 years in Verde Lake and the 1100 years in Malleco Lake. **Location of the lakes:** Verde Lake: 38.213896°S; 71.734825°W, 1394 m a.s.l. Malleco Lake: 38.215660°S; 71.822219°W, 893 m a.s.l. ## Description of the data and file structure Two Excel files (xls) that contain the raw data pollen, including the taxa, depth, chronology, and *Lycopodium*-tracer information per sample, and the charcoal counts along with the volume of sediment, depths, and chronology per sample. Both pollen and charcoal records were analyzed in the core "VERD01" of Verde Lake, and the core "MALL09" of Malleco Lake. **"TolhuacaNP_Verde_Lake.xls" file contains two spreadsheets:** Sheet "Pollen Verde Lake": * Column A: name of variables * Column B to W: 22 sediment samples. * Row 1: "Depth (cm)" corresponds to the depths of the 22 samples in the sediment core. * Row 2: "Age (Common Era)" is the estimated age of each sediment sample. It is equivalent to the Anno Domini -AD- years. * Row 3 to 83: the raw counts of 81 pollen/spore morphotypes of the Verde Lake. * Row 84: counts of charcoal microparticles from pollen slides. * Row 85 to 88: contains the information of the tracer/spike *Lycopodium clavatum* to compute pollen, spore, and charcoal microparticle concentrations. Sheet "Charcoal Verde Lake": * Column A: "Depth (cm)" contains the depths of 112 analyzed samples of the core. * Column B: "Age (yr cal BP)" correspond to the estimated age of each sample in calendar years before present. 0 yr cal BP is the year 1950 CE. * Column C: "Volume (cm3)" is the wet sediment volume of each sample for charcoal analysis. * Column D: "Charcoal counts (&gt;125µm)" correspond to the raw counts of charcoal macroparticles larger than 125 µm. **"TolhuacaNP_Verde_Malleco.xls" file constains two spreadsheets:** Sheet "Pollen Malleco Lake": * Column A: name of variables * Column B to Y: 24 sediment samples. * Row 1: "Depth (cm)" corresponds to the depths of the 24 samples in the sediment core. * Row 2: "Age (Common Era)" is the estimated age of each sediment sample. It is equivalent to the Anno Domini -AD- years. * Row 3 to 105: the raw counts of 103 pollen/spore morphotypes of the Malleco Lake. * Row 106: counts of charcoal microparticles from pollen slides. * Row 107 to 110: contains the information of the tracer/spike *Lycopodium clavatum* to compute pollen, spore, and charcoal microparticle concentrations. Sheet "Charcoal Malleco Lake": * Column A: "Depth (cm)" contains the depths of 103 analyzed samples of the core. * Column B: "Age (yr cal BP)" correspond to the estimated age of each sample in calendar years before present. 0 yr cal BP is the year 1950 CE. * Column C: "Volume (cm3)" is the wet sediment volume of each sample for charcoal analysis. * Column D: "Charcoal counts (&gt;125µm)" correspond to the raw counts of charcoal macroparticles larger than 125 µm. #### Sharing/Access information For additional information, please contact to: Ana M. Abarzúa: [anaabarzua@uach.cl](mailto:anaabarzua@uach.c) Alejandra Martel-Cea: [jmartel.cea@gmail.com](mailto:jmartel.cea@gmail.c)