A global map of terrestrial habitat types

Abstract

We provide a global, spatially explicit characterization of 47 terrestrial habitat types, as defined in the International Union for Conservation of Nature (IUCN) habitat classification scheme, which is widely used in ecological analyses, including for quantifying species' Area of Habitat. We produced this novel habitat map for the year 2015 by creating a global decision tree that intersects the best currently available global data on land cover, climate and land use. We independently validated the map using occurrence data for 828 species of vertebrates (35152 point plus 8181 polygonal occurrences) and 6026 sampling sites. Across datasets and mapped classes we found on average a balanced accuracy of 0.77 ([Formula: see text]0.14 SD) at Level 1 and 0.71 ([Formula: see text]0.15 SD) at Level 2, while noting potential issues of using occurrence records for validation. The maps broaden our understanding of habitats globally, assist in constructing area of habitat refinements and are relevant for broad-scale ecological studies and future IUCN Red List assessments. Periodic updates are planned as better or more recent data becomes available.

Fig. 1

Sequential order in which habitat classes were identified using our decision tree approach. For instance, if the conditions do not match for IUCN habitat class 1.9, then the conditions for class 1.7 are tested afterwards. Black boxes indicate default classes (Level 1 code) in case no conditions could be met at level 2. Artificial habitat classes (blue border) are masked out from all other habitat classes. Codes and rulesets for each habitat class are further explained in Supplementary Table 1.

Fig. 2

Distribution of IUCN habitat classes globally (a) Showing the Level 1 classification (coarsened to ~5 km for this visualization). (b) Proportion of global land area occupied by each Level 1 IUCN habitat class. (c) Tree map showing the most dominant IUCN habitat class at Level 2 nested within the Level 1 classes. Colours as in (a) with classes scaled proportional to the land area. Level 2 classes with very long names were converted to their id number, while small proportions might not be mapped.

Fig. 3

Validation results for the habitat map. Estimates of the balanced accuracy are shown for all habitats for which suitable validation data existed. Symbols indicate the validation data source, while point size shows the number of contributing records. The id corresponding to the specific IUCN habitat classes is indicated at the bottom and top of the figure. Colours match those of the online interactive interface (https://uploads.users.earthengine.app/view/habitat-types-map).