North America Holocene land cover: REVEALS-GMRF

Data files

Oct 02, 2025 version files 357.83 KB

Holocene_land_cover_trends_data.zip

354.98 KB
README.md

2.84 KB

Abstract

As a contribution to the Past Global Changes (PAGES) LandCover6k Working Group, we present a new suite of land cover reconstructions with uncertainty for North America, based on a network of 1445 sedimentary pollen records and the REVEALS pollen-vegetation model coupled with a Bayesian spatial model. These spatially comprehensive land cover maps are then used to determine the pattern and magnitude of North American land cover changes at continental to regional scales. These Holocene reconstructions for North America, along with similar LandCover6k products now available for other continents, serve the Earth system modeling community by providing better-constrained land cover scenarios and benchmarks for model evaluation, ultimately making it possible to better understand the regional- to global-scale processes driving Holocene land-cover, carbon-cycle, and climate dynamics.

Pollen-based land cover reconstructions were performed using the REVEALS pollen-vegetation model, and based on the standard protocol for PAGES LandCover6k.

We reconstructed land cover for 25 time intervals that cover the Holocene. These time intervals were defined according to the LandCover6k working group protocol. Time intervals are specified in kiloyears before present (ka), where present is defined as 1950 CE, but for time intervals <1ka we also note the Common Era (CE) timescale. Intervals in the period from 11.7 to 0.7 ka have a 500-year temporal grain (11.7 to 11.2 ka; 11.2 to 10.7 ka; etc.), while the three most recent intervals have a finer temporal grain (0.7-0.35 ka [1250-1600 CE]: 350 years; 0.35-0.1 ka [1600-1850 CE]: 250 years; 0.1-(-0.074) ka: 174 years [1850-2024 CE]) in order to better capture the changes associated with intensifying anthropogenic land use over the last five centuries.

We used a grid resolution of 1°x1°, also as specified by the LandCover6k protocol. Within a grid cell, REVEALS reconstructions for multiple sites were averaged, as is standard practice. Taxon-level reconstructions were aggregated to three land cover categories: summergreen trees and shrubs (STS), evergreen trees and shrubs (ETS), and open vegetation/land (OVL), which includes grasses, herbs, and low-stature shrubs.

We use the REVEALS-GMRF Bayesian hierarchical model to spatially interpolate the REVEALS-based land cover reconstructions.

First unzip the file

Holocene_land_cover_trends_data.zip

REVEALS Land Cover

land_grid.csv

Grid cell identifiers and corresponding midpoint latitude, longitude, and elevation (in meters) defined by the LandCover6k protocol.

cell_id	x	y	elev
cell identifier	longitude	latitude	elevation in meters

REVEALS_LCT_gridded.csv

cell_id	x	y	ages	ET	OL	ST
cell identifier	longitude	latitude	Years Before Present	Fraction Evergreen Trees and Shrubs	Fraction Open Vegetated Land	Fraction Summergreen Trees and Shrubs

REVEALS-GMRF Interpolated Land Cover

The compendium REVEALS-GMRF Interpolated Land Cover can be downloaded from https://github.com/BehnazP/SpatioCompo_entireHolocene_NA

These reconstructions are not contained in this Dryad submission due to a licensing conflict. Nevertheless, we describe them here, and direct users to github.

This github repository contains reconstructions of pollen-based land-cover (REVEALS) for entire Holocene (0-11700 BP). The reconstructions are based on the mathematical models developed in https://doi.org/10.1016/j.spasta.2018.03.005 and https://doi.org/10.1029/2018EA000547.

Reference:

Dawson, Andria, John W. Williams, Marie-José Gaillard, Simon J. Goring, Behnaz Pirzamanbein, Johan Lindstrom, R. Scott Anderson et al. "Holocene land cover change in North America: continental trends, regional drivers, and implications for vegetation-atmosphere feedbacks." Climate of the Past Discussions 2024 (2024): 1-52. (https://doi.org/10.5194/cp-2024-6)
Pirzamanbein, Behnaz, Johan Lindström, Anneli Poska, and Marie-José Gaillard. "Modelling Spatial Compositional Data: Reconstructions of past land cover and uncertainties." Spatial statistics 24 (2018): 14-31. (https://doi.org/10.1016/j.spasta.2018.03.005)
Pirzamanbein, Behnaz, Anneli Poska, and Johan Lindström. "Bayesian Reconstruction of Past Land Cover From Pollen Data: Model Robustness and Sensitivity to Auxiliary Variables." Earth and Space Science 7, no. 1 (2020): e2018EA00057. (https://doi.org/10.1029/2018EA000547)