README — Predicted Prehuman Non-Wetland Forest, New Zealand (PEM v1.0)

Version: 1.0  
Publication date: June 2026  
Licence: Creative Commons Attribution 4.0 International (CC BY 4.0)  
https://creativecommons.org/licenses/by/4.0/

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Authors and Contact

James K. McCarthy
Sarah J. Richardson
Janet M. Wilmshurst

Bioeconomy Science Institute

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Citation

Please cite as:

McCarthy, J.K., Richardson, S.J., and Wilmshurst, J.M. (2026). *A Past Ecosystem Map of forested Ecosystem Functional Groups in New Zealand (PEM v1.0)*. Bioeconomy Science Institute Maiangi Taiao. [PLACEHOLDER REFERENCE]

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Overview

This dataset provides spatial predictions of prehuman non-wetland forest cover across mainland New Zealand, classified into two IUCN Global Ecosystem Typology Ecosystem Functional Groups. Predictions represent the likely distribution of forest prior to human arrival and associated land-use change. Modelling details are included in the report — see citation above.

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Files

PEM_v1.0_forest-efg.tif: Primary output. Classified raster of predicted forest EFGs, with masking applied (see Prediction Domain below).
 
PEM_v1.0_forest-efg_unmasked.tif: As above but without masking — predictions extend to all modelled cells including above-treeline, open water, and naturally uncommon ecosystems.
 
PEM_v1.0_stability.tif: Continuous stability layer indicating the consistency of forest predictions. Provided unmasked; users may apply PEM_v1.0_forest-efg.tif as a mask if required.
 
README_PEM_v1.0.txt: This file.

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Raster Values — Forest EFG Layers

Value: Meaning
 
1: T2.4 Warm temperate laurophyll forests
2: T2.3 Oceanic cool temperate rainforests
0: Absent or excluded (masked as non-forest; see below)
NA / NoData: Outside prediction domain (see below)
 
A Raster Attribute Table (RAT) is embedded in the GeoTIFF and will be recognised automatically by GIS software such as QGIS.

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Prediction Domain
 
The primary forest EFG raster (PEM_v1.0_forest-efg.tif) is masked to exclude areas where prehuman forest cover was unlikely. Further details are included in the report.
 
The following areas are set to NA/NoData (outside prediction domain entirely):
 
- Ocean and beyond-extent areas: outside the New Zealand mainland extent
- Open water: lakes, rivers, estuaries, and coastal water bodies as mapped in the Land Cover Database v6.0 (LCDB v6.0), including categories: Lake or Pond, River, Estuarine Open Water, Sand and Gravel, and Mangrove
 
The following areas are set to 0 (non-forest) rather than NA, as they fall within the terrestrial prediction domain but were unlikely to support prehuman forest:
 
- Above treeline: areas with mean annual temperature < 5.5 degrees C
- Naturally uncommon ecosystems: selected ecosystem types
 
Note that value 0 does not distinguish between predicted non-forest and these masked categories. Users requiring this distinction should apply the source layers directly (see report for details).
 
Predictions within prehuman wetland areas are beyond the model's primary training context and should be interpreted with caution. Currently, no spatial layers exist that can reliably distinguish open and forested wetlands from prehuman forest extent.

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Coordinate Reference System
 
All layers are projected in NZGD2000 / New Zealand Transverse Mercator 2000 (EPSG:2193).
 
Spatial resolution: 100 m x 100 m