DOI: 10.5281/zenodo.12618490
title: Forest map of New Caledonia

description: Version 2.0 - July 2, 2024

This dataset contains the shapefile of the Caledonian forest produced by digitization at a scale of 1:3,000 from a mosaic of satellite images (Sentinel 2, Quickbird, Pléiades) and aerial photographs provided by the department of infrastructure, topography and land transport (DITTT) of the government of New Caledonia and available on the georep map server (georep.nc). Satellite images and aerial photographs were taken between 2009 and 2021 with a maximum spatial resolution of 0.5 m. We interpreted vegetation as forest when the trees (which should be taller than 5 m) formed a continuous canopy cover, obscuring the ground surface for a minimum of 0.5 ha (FAO 2020). The minimum distance between two polygons is 10 m, below polygons were merged.

In this version 2.0, any of the 12463 polygons was deeply verified through an overlap with the Tropical Moist Forests (TMF) cover change dataset using 41 years of Landsat time series (Vancutsem et al., 2021) and the ETH model providing a 10m resolution of world canopy height (Lang et al., 2023). The canopy height allows to accept or reject each polygon as belonging to the forest class. This analysis of consistency between photo-interpretation and radiometric detection was carried out on a 2 km² mesh with a verification of polygons beyond 15% divergence. Finally 1564 polygons, barely perceptible on images or having a homogeneous canopy grain were checked by helicopter. 

At least, forest classes were verified through databases of plant occurrences collected in the forest, in particular the Herbarium of New Caledonia database (NOU) and the Network of plant inventories and permanent plots of New Caledonia (NC-PIPPN). So this dataset is periodically updated with corrections made by field observations and the addition of new expert interpretations, especially on small islands that have not been digitized before. We plan to produce the whole map step by step

-------------------------------------Currently, only the North and South provinces are available, an area of 16,395 km² out of a total of 18,345 km². Digitization of the Loyaulties Islands will be available soon.

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The file contains the 6 files required for the GIS and can be uploaded to a spatial database such as PostgreSQL/PostGisThe attribute table displays information on features of forest polygons. Each row in the table represents a forest fragment (a polygon) with associated fields :



id (INTEGER) = unique identifier

pn (BOOLEAN) = True or False the polygon overlaps the Northern province

ps (BOOLEAN) = True or False the polygon overlaps the Southern province

pil (BOOLEAN) = True or False the polygon overlaps the Islands province (Loyaulties islands)

area_ha (NUMERIC) = area of the polygon in hectare

dry_ha = The area of the polygon that is in a dry environment according to the Holdridge classification

moist_ha = The area of the polygon that is in a moist environment according to the Holdridge classification

wet_ha= The area of the polygon that is in a wet environment according to the Holdridge classification

created_by (TEXT)= The creator of the data

date_created = Date when the polygon was firstly created

date_updated = The last date the polygon was modified

geom (geometry(polygon,4326)) = Polygon type geometry and datum EPSG: 4326 (= WGS 84– World Geodetic System 1984)