DOI: 10.5061/dryad.p8cz8w9rs
title: An ecoregion-based approach to restoring the world’s intact large mammal assemblages

description: Assemblages of large mammal species play a disproportionate role in the
 structure and composition of natural habitats. Loss of these assemblages
 destabilizes natural systems, while their recovery can restore ecological
 integrity. Here we take an ecoregion-based approach to identify landscapes
 that retain their historically present large mammal assemblages, and map
 ecoregions where reintroduction of 1–3 species could restore intact
 assemblages. Intact mammal assemblages occur across more than one-third of
 the 730 terrestrial ecoregions where large mammals were historically
 present, and 22% of these ecoregions retain complete assemblages across
 &gt;20% of the ecoregion area. Twenty species, if reintroduced or
 allowed to recolonize through improved connectivity, can trigger
 restoration of complete assemblages over 54% of the terrestrial realm
 (11,116,000 km2). Each of these species have at least two large, intact
 habitat areas (&gt;10,000 km2) in a given ecoregion. Timely
 integration of recovery efforts for large mammals strengthens area-based
 targets being considered under the Convention on Biological Diversity.
description: The IUCN Red List of Threatened Species, along with data on body
 mass, was used to generate a species list of 298 large extant terrestrial
 mammals (IUCN, 2019; Jones et al., 2009; Myers et al., 2020; Smith et al.,
 2003; Table S1). ‘Large mammals’ were defined as those exceeding 15 kg
 maximum recorded body mass, a threshold that allows the inclusion of key
 predators, their prey, and other large herbivores, and that is consistent
 with other studies (Ferreira et al. 2020; Ripple et al., 2014; Salom-Peréz
 et al. 2021; Wolf et al., 2018).  To identify intact
 and near-intact large mammal assemblages, data from the IUCN Red List
 (IUCN, 2019) were used for current species ranges and data from Faurby
 & Svenning (2015) for historical ranges. Faurby & Svenning
 (2015) modeled mammal species ranges as the ranges would have been today
 in the absence of human influence. AD 1500 was chosen as the cutoff for
 historical ranges, following the rationale provided by Morrison et al.
 (2007). Briefly, this marks a globally synchronous period after which
 there were the most profound anthropogenic changes to Earth’s terrestrial
 area; it is the same demarcation used by the IUCN Red List as the cutoff
 for examining ‘recent’ extinctions. Moreover, all except six of the large
 mammal species (&gt;15 kg) present in AD 1500 are still extant and
 have opportunities for in situ conservation. The six extinct species (EX)
 were removed from the analysis since there is no opportunity for their
 restoration; one species listed as extinct in the wild
 (EW; <i>Elapharus davidianus</i>) was retained.
 Intact and near-intact large mammal assemblages were identified
 by first converting current species range polygons into ~100 km² rasters
 to match the historical species range data. To ensure small ranges were
 not missed, any grid cells that overlapped the polygon were included.
 These raster layers of current and historical species ranges were then
 downscaled and refined to 10 km² using the Land Cover product published by
 the European Space Agency Climate Change Initiative (ESA CCI) (Bontemps et
 al. 2013). To perform this step, the ESA CCI landcover was first resampled
 to 10 km² and each landcover class was linked to habitat preferences from
 the IUCN Red List (IUCN, 2019). For example, the ESA CCI landcover class
 ‘Tree cover, broadleaved, evergreen, closed to open (&gt;15%)’ was
 linked to the IUCN habitat preference of ‘Forest’. The individual 100
 km² current and historical species range rasters were then downscaled by
 resampling them to 10 km² and removing grid cells that did not match the
 habitat preferences linked to the matching 10km² landcover data. This
 process removes unsuitable habitat form each species’ range, limiting
 errors of commission. Historical range maps were also downscaled using
 current landcover to ensure areas no longer suitable for a species were
 not included as potential restoration areas. Thus, the spatial scale at
 which decisions were made about presence or absence of a particular large
 mammal species was at a fine-grained scale of 10
 km<sup>2</sup>. Only later in the analysis was the ecoregion
 boundary coverage overlayed on the relevant grid cells.  
 To identify areas where a species is no longer present but might
 have occurred in the absence of human influence, each species'
 current refined range was then subtracted from its refined historical
 range. These areas of loss for each species were then combined, yielding a
 raster of the number of species missing per grid cell. Using this raster,
 places having all species present were identified as intact large mammal
 assemblage areas. Those with 1–3 missing species were identified
 as near-intact large mammal assemblages as. This range was chosen because
 the objective was to take a pragmatic approach to identify places for
 restoration to a complete assemblage. This decision serves as a reasonable
 starting place for operationally defining the term ‘near-intact’. The
 rationale wa if restoration of the assemblage will require targeted,
 species-based reintroductions, major effort required will be needed for
 each species. Conversely, areas with more than three species missing are
 more likely to be degraded, isolated, or have significant hunting
 pressures and make near-term restoration less feasible. Grid cell output
 was summarized within ecoregion boundaries (Dinerstein et al., 2017; Table
 S2).