Grazing by non‐native ungulates negatively impacts vegetation important to a native species of concern

Abstract Non‐native grazers compete with native species across the globe. We present a novel approach to study the composition of the herbaceous understory across three study areas within the Great‐Basin with different historic and contemporary grazing regimes. We surveyed the landscape using distan...

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Main Authors: Phillip A. Street, Levi Jaster, Thomas E. Dilts, Tessa L. Behnke, James S. Sedinger
Format: Article
Language:English
Published: Wiley 2025-01-01
Series:Ecosphere
Subjects:
Online Access:https://doi.org/10.1002/ecs2.4974
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author Phillip A. Street
Levi Jaster
Thomas E. Dilts
Tessa L. Behnke
James S. Sedinger
author_facet Phillip A. Street
Levi Jaster
Thomas E. Dilts
Tessa L. Behnke
James S. Sedinger
author_sort Phillip A. Street
collection DOAJ
description Abstract Non‐native grazers compete with native species across the globe. We present a novel approach to study the composition of the herbaceous understory across three study areas within the Great‐Basin with different historic and contemporary grazing regimes. We surveyed the landscape using distance sampling for livestock and horse feces as an index of use. In addition, we surveyed the herbaceous understory of random sites as well as sites chosen by female Greater sage‐grouse to nest and brood their chicks. We used a novel Bayesian hierarchical modeling framework to link vegetation metrics with the spatial–temporal distribution of horses and livestock while accounting for observation error. When livestock and feral horses were not present, we found that Greater sage‐grouse use sites with higher percentages of perennial grasses and forbs to build their nests and brood their chicks compared with what was available to them. As livestock increased, we found evidence for decreases in the percentage of perennial grasses, forbs, cheatgrass (Bromus tectorum), and increases in the amount of bare ground. These effects were consistent at available sites and brood sites; however, we found less evidence for an impact of livestock at nest sites. As feral horses increased, we observed similar results at available sites, but at sites chosen by females to nest and brood their chicks, we observed increases in the amount of invasive cheatgrass as feral horses increased, which could reflect attempts by Greater sage‐grouse to compensate for reductions in protective cover. We present a noninvasive approach to assess space use that can be applied to other species. More importantly, we document that grazing by non‐native ungulates impacts components of the plant community important to Greater sage‐grouse reproduction. We provide spatial–temporal maps of livestock and feral horse use to aid managers attempting to balance the needs of livestock producers, feral horses, Greater sage‐grouse, and ecosystem function.
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spelling doaj-art-af463a93a71d48bea04aca99672f00c12025-01-30T01:44:38ZengWileyEcosphere2150-89252025-01-01161n/an/a10.1002/ecs2.4974Grazing by non‐native ungulates negatively impacts vegetation important to a native species of concernPhillip A. Street0Levi Jaster1Thomas E. Dilts2Tessa L. Behnke3James S. Sedinger4U.S. Fish and Wildlife Service Sacramento California USAKansas Department of Wildlife and Parks Emporia Kansas USADepartment of Natural Resources and Environmental Science University of Nevada‐Reno Reno Nevada USADepartment of Natural Resources and Environmental Science University of Nevada‐Reno Reno Nevada USADepartment of Natural Resources and Environmental Science University of Nevada‐Reno Reno Nevada USAAbstract Non‐native grazers compete with native species across the globe. We present a novel approach to study the composition of the herbaceous understory across three study areas within the Great‐Basin with different historic and contemporary grazing regimes. We surveyed the landscape using distance sampling for livestock and horse feces as an index of use. In addition, we surveyed the herbaceous understory of random sites as well as sites chosen by female Greater sage‐grouse to nest and brood their chicks. We used a novel Bayesian hierarchical modeling framework to link vegetation metrics with the spatial–temporal distribution of horses and livestock while accounting for observation error. When livestock and feral horses were not present, we found that Greater sage‐grouse use sites with higher percentages of perennial grasses and forbs to build their nests and brood their chicks compared with what was available to them. As livestock increased, we found evidence for decreases in the percentage of perennial grasses, forbs, cheatgrass (Bromus tectorum), and increases in the amount of bare ground. These effects were consistent at available sites and brood sites; however, we found less evidence for an impact of livestock at nest sites. As feral horses increased, we observed similar results at available sites, but at sites chosen by females to nest and brood their chicks, we observed increases in the amount of invasive cheatgrass as feral horses increased, which could reflect attempts by Greater sage‐grouse to compensate for reductions in protective cover. We present a noninvasive approach to assess space use that can be applied to other species. More importantly, we document that grazing by non‐native ungulates impacts components of the plant community important to Greater sage‐grouse reproduction. We provide spatial–temporal maps of livestock and feral horse use to aid managers attempting to balance the needs of livestock producers, feral horses, Greater sage‐grouse, and ecosystem function.https://doi.org/10.1002/ecs2.4974distance samplinggrazinghabitathierarchical modelhorselivestock
spellingShingle Phillip A. Street
Levi Jaster
Thomas E. Dilts
Tessa L. Behnke
James S. Sedinger
Grazing by non‐native ungulates negatively impacts vegetation important to a native species of concern
Ecosphere
distance sampling
grazing
habitat
hierarchical model
horse
livestock
title Grazing by non‐native ungulates negatively impacts vegetation important to a native species of concern
title_full Grazing by non‐native ungulates negatively impacts vegetation important to a native species of concern
title_fullStr Grazing by non‐native ungulates negatively impacts vegetation important to a native species of concern
title_full_unstemmed Grazing by non‐native ungulates negatively impacts vegetation important to a native species of concern
title_short Grazing by non‐native ungulates negatively impacts vegetation important to a native species of concern
title_sort grazing by non native ungulates negatively impacts vegetation important to a native species of concern
topic distance sampling
grazing
habitat
hierarchical model
horse
livestock
url https://doi.org/10.1002/ecs2.4974
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