Productivity correlates positively with mammalian diversity independently of the species' feeding guild, body mass, or the vertical strata explored by the species

Mammals can influence ecosystem functioning through essential ecological processes. In patchy landscapes, mammalian diversity can be correlated with ecosystem productivity through its effect on resource availability. However, mammals comprise species with contrasting habitat use and requirements, and it is unknown whether the diversity-productivity relationship changes as a function of the mammal species' traits. We use meta-analytical techniques to quantify the effect and assess whether mammal species richness and abundance correlates positively with productivity. Further, we assess whether the diversity-productivity relationship is influenced by the species' body mass (<1 kg: small, and >1 kg: large, and mixed small and large), the vertical strata explored by the species (terrestrial, arboreal, and mixed terrestrial and arboreal species), and the species' feeding guild (herbivore, omnivore, insectivore, and mixed feeding guilds). In total, 53 studies fitted the eligibility criteria worldwide, comprising 285 different effect sizes representing the magnitude of the mammal diversity-productivity relationship in six biogeographical realms. Ecosystem productivity was quantified with various surrogate variables, such as soil nutrients, annual rainfall, above-ground production, evapotranspiration, net primary production, plant cover, and elevation. The relationships between productivity measures and both mammal species richness and abundance were significant and positive. Mammal diversity correlated positively with ecosystem productivity, for mammal species differing in body mass, the vertical strata explored by species (except arboreal mammals), and feeding guilds (except insectivorous mammals). Overall, this result supports the view that diversity in the entire mammal community is positively related to increasing productivity. Sites with greater ecosystem productivity are usually associated with more resources and higher ecosystem carrying capacity, which provide greater resilience to human disturbance than less productive sites. Thus, quantifying productivity can help researchers to identify critical areas for restoration and to propose effective guidelines for mammal conservation.