Reintroducing bison results in long-running and resilient increases in grassland diversity

Abstract

The widespread extirpation of megafauna may have destabilized ecosystems and altered biodiversity globally. Most megafauna extinctions occurred before the modern record, leaving it unclear how their loss impacts current biodiversity. We report the long-term effects of reintroducing plains bison ( Bison bison ) in a tallgrass prairie versus two land uses that commonly occur in many North American grasslands: 1) no grazing and 2) intensive growing-season grazing by domesticated cattle ( Bos taurus ). Compared to ungrazed areas, reintroducing bison increased native plant species richness by 103% at local scales (10 m 2 ) and 86% at the catchment scale. Gains in richness continued for 29 y and were resilient to the most extreme drought in four decades. These gains are now among the largest recorded increases in species richness due to grazing in grasslands globally. Grazing by domestic cattle also increased native plant species richness, but by less than half as much as bison. This study indicates that some ecosystems maintain a latent potential for increased native plant species richness following the reintroduction of native herbivores, which was unmatched by domesticated grazers. Native-grazer gains in richness were resilient to an extreme drought, a pressure likely to become more common under future global environmental change.

Functional substitutability of native herbivores by livestock for soil carbon depends on microbial decomposers

“…1), one expects the two assemblages to be functionally similar. Yet, consistent with other parts of the world, the livestock and native herbivores differ in their impacts on vegetation composition (Bagchi et al, 2012;Bagchi & Ritchie, 2010b;Price et al, 2022;Ratajczak et al, 2022;Wells et al, 2022). Specifically, native herbivores lead to forb-and-grass dominated vegetation whereas sedges dominate under livestock (Fig.…”

“…1). Such differences in vegetation composition can be attributed to diet selectivity of the two herbivore types (Augustine & McNaughton, 1998; Bagchi et al, 2012; Bagchi & Ritchie, 2010b; Ratajczak et al, 2022). However, peak-season live biomass, both above and below-ground, are comparable (Fig.…”

“…Analyses of key traits, such as body size, diet-choice, and fermentation type, hypothesize that livestock can be approximate surrogates for native herbivores, i.e., nearest neighbors in trait-space have similar ecological roles (Lundgren et al, 2020; Malhi et al, 2016; Schowanek et al, 2021). On the other hand, in many ecosystems, livestock differ from native herbivores in how they impact vegetation composition (Bagchi et al, 2012; Bagchi & Ritchie, 2010b; Price et al, 2022; Ratajczak et al, 2022; Wells et al, 2022). This alters the quantity and quality of C-input to soil from plants by changing the underlying distribution of plant traits (e.g., root:shoot ratio, C:N stoichiometry of leaf and litter, etc.)…”

After the mammoths: The ecological legacy of late Pleistocene megafauna extinctions

“…Numerous studies have documented the important influence of large-bodied herbivores on plant structure and composition, and on maintaining habitat heterogeneity (e.g., Owen- Smith 1987Smith , 1988Smith , 1989Cummings et al 1997;Whyte et al 2003;Western and Maitumo 2004;Waldram, Bond and Stock 2008;Johnson 2009;Haynes 2012;Rule et al 2012;Keesing and Young 2014;Asner et al 2016;Bakker et al 2016a, b;Ratajczak et al 2022). Browsers, such as deer or antelope, tend to have an inhibiting effect on woody vegetation, while the effects of grazers, such as zebra, bison and horses, appear to be mixed (Bakker et al 2016a, b).…”

Bison come back to boost grassland biodiversity

“…Recently, a study led by scientists at the Kansas State University published in the Proceedings of the National Academy of Sciences suggests that reintroducing bison can help increase grassland biodiversity [2].…”