From tropical shelters to temperate defaunation: The relationship between agricultural transition stage and the distribution of threatened mammals

Abstract

Aim: Agriculture is a key threat to biodiversity; however, its relationship with biodiversity patterns is understudied. Here, we evaluate how the extent, intensity and history of croplands relate to the global distribution of threatened mammals. We propose two hypotheses to explain these relationships: shelter, which predicts that threatened species concentrate in areas with low human land use; and threat, according to which threatened species should concentrate in areas of high human land use.Location: Global. Time period: c. 6000 BC -AD 2014. Major taxa studied: Terrestrial mammals. Methods: We used boosted regression trees (BRT) that include spatial autocorrelation to investigate the relationship between the proportion of threatened terrestrial mammals [as defined by the International Union for Conservation of Nature (IUCN) Red List] and multiple metrics describing agricultural extent, intensity and history derived from remote sensing data and statistical projections. Data were analysed with a grain size of c. 110 km 3 110 km at both global and biogeographical-realm scales.Results: Agricultural extent and intensity were the most relevant indicator types, with specific metrics important for each realm. Forest cover (extent) was identified as important in several regions. Tropical regions in early agricultural transition stages (e.g. frontier landscapes) were consistent with the shelter hypothesis, whereas patterns found for regions in later stages (e.g. intensified agricultural landscapes) were mostly found in temperate regions and agreed with the threat hypothesis. Main conclusions: These results highlight the need to consider multiple land-use indicators when addressing threats to biodiversity and to separately assess areas with divergent human and ecological histories in global-scale studies. Different relationships associated with different agricultural transition stages suggest that high concentrations of threatened species may have contrasting meanings in different regions worldwide. We propose a new unifying hypothesis following a cyclic relationship along agricultural transition stages resulting in alternating negative and positive relationships between agriculture and threatened species richness. K E Y W O R D S agricultural transition, agriculture, conservation, IUCN Red List, land-use extent, land-use intensity, shelter, terrestrial mammals, threat Global Ecol Biogeogr. 2018;27:647-657.wileyonlinelibrary.com/journal/geb

The legacy of past human land use in current patterns of mammal distribution

“…On the other hand, areas modified at a more constant pace throughout history (e.g. Europe or India) may have more resilient species, as these areas are more likely to have suffered more severe extinction filters in the past (Newbold et al 2018, Polaina et al 2018.…”

“…These studies have often used broad study units such as ecoregions or countries, and have linked the occurrence of threatened species with human pressures, measured in terms of land use or human population density (Lenzen et al 2009, Pekin and Pijanowski 2012, Brum et al 2013) and with different socioeconomic profiles (Polaina et al 2015). Polaina et al (2018) analyzed threatened species richness at a finer resolution (1 × 1° grid cells) and showed that the relationship between this biodiversity metric and land-usechange derived impacts varied across regions, likely reflecting different stages of human development and appropriation of land. In some areas, threatened species were more abundant in more impacted areas, whereas in others threatened species remained in less impacted zones.…”

Insights on the role of forest cover and on the changes in forest cover on thirty-five endangered mammal species distributions

“…Overall, I argue that there is a need for a standardized monitoring of endangered mammals species data, for gathering of intensive data and evidences on the changes in forested landscape, and of detailed data on negative impacts of any forest activity on forests like clear-cutting, selective logging (selective tree cutting), mechanization use (for tree removal), of forest activity noise, and on the stage of agriculture development. Ester et al (2018) found that different stages of agriculture landscape (high intensified, low intensified agriculture) determined the distribution of terrestrial mammal species. Strindberg et al (2018) measured the canopy height (Gorilla beringei species preferred high trees between 25 m to 35 m), to distinguish between selective logging (high trees) and swap forests (shorter trees) and found that tropical forests were degraded, when selective logging was applied.…”

“…Threatened terrestrial mammal species can possibly occupy frontier landscape for refuge (shelter). (Estavillo et al, 2013;Fernández et al, 2003;Kanagaraj et al, 2011;Rogers & Gorman, 1995;Fernandez et al, 2006;Nüchel et al, 2018;Ester et al, 2018) packages of 'bbmle', 'biodiversityR', 'biomod2', 'brglm', 'DAAG', 'foreign', 'glmmboot', 'verification'. There were thirty-five candidate models fitted (one GLM model for each species).…”

“…Forested landscape modification caused by the expansion of cropland (and or pastureland) to forested land was one of the key drivers of global species loss (Fischer & Lindenmayer, 2007). Ester et al (2018) found that intensified agricultural landscapes threaten worldwide terrestrial mammal species, while the expansion of low intensity agriculture can be considered as a threat (to the Wildness Areas including mammals), if the agricultural expansion occurs in the future (Veach et al, 2017).…”