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Small mammal herbivores mediate the effects of soil nitrogen and invertebrate herbivores on grassland diversity

1. Simultaneous reductions in herbivore abundance and increases in nitrogen deposition have led to radical shifts in plant communities worldwide. While the individual impacts of these human‐caused disturbances are apparent, few studies manipulate both herbivory and N, nor differentiate among herbivo...

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Autores principales: Poe, Nicole, Stuble, Katharine L., Souza, Lara
Formato: Online Artículo Texto
Lenguaje:English
Publicado: John Wiley and Sons Inc. 2019
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6434553/
https://www.ncbi.nlm.nih.gov/pubmed/30962912
http://dx.doi.org/10.1002/ece3.4991
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author Poe, Nicole
Stuble, Katharine L.
Souza, Lara
author_facet Poe, Nicole
Stuble, Katharine L.
Souza, Lara
author_sort Poe, Nicole
collection PubMed
description 1. Simultaneous reductions in herbivore abundance and increases in nitrogen deposition have led to radical shifts in plant communities worldwide. While the individual impacts of these human‐caused disturbances are apparent, few studies manipulate both herbivory and N, nor differentiate among herbivore guilds, to understand contingencies in the ability of these drivers to affect producer diversity and productivity. As such, understanding how the main and combined effects of increasing soil N with declining herbivores may influence plant community structure and function is critical to better understand the future of grassland ecosystems under multiple global change drivers. 2. In this study, we asked: (a) What are the main effects of small mammal herbivores, invertebrate herbivores, and soil N on plant community structure and function? and (b) Are the effects of invertebrate herbivores and soil N on plant community structure and function contingent on small mammal herbivory? We used a nested design, with invertebrate and soil N treatments nested within small mammal manipulations in an existing tallgrass prairie. We measured plant community structure by quantifying plant richness, evenness, diversity, and composition across two full growing seasons. We also recorded total aboveground biomass to quantify grassland productivity. 3. We found that small mammal herbivores strongly shaped plant diversity, species composition, and productivity. Small mammal herbivores also mediated the effects of soil N and invertebrate herbivores on grassland community structure, but not composition or productivity. Small mammal reduction lowered plant species richness while increasing aboveground biomass and altering compositional similarity. Invertebrate herbivores, in the presence of small mammals, promoted plant dominance by reducing evenness without altering compositional similarity. Additionally, soil nitrogen addition reduced plant richness, but only when small mammals were reduced, and no effects were detected on compositional similarity or productivity. 4. Our findings provide further evidence that temperate grasslands can be strongly influenced by consumers, and that consumers mediate the effects of resources as well as other consumer guilds on producer evenness and richness. Taken together, we provide evidence of strong contingencies in the drivers of grassland structure, with small mammals directly altering plant diversity as well as mediating the effects of soil nitrogen and invertebrate herbivory on plant richness and evenness. Therefore, we suggest it is imperative to consider how consumer guilds and resource types may interact to shape grassland plant communities.
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spelling pubmed-64345532019-04-08 Small mammal herbivores mediate the effects of soil nitrogen and invertebrate herbivores on grassland diversity Poe, Nicole Stuble, Katharine L. Souza, Lara Ecol Evol Original Research 1. Simultaneous reductions in herbivore abundance and increases in nitrogen deposition have led to radical shifts in plant communities worldwide. While the individual impacts of these human‐caused disturbances are apparent, few studies manipulate both herbivory and N, nor differentiate among herbivore guilds, to understand contingencies in the ability of these drivers to affect producer diversity and productivity. As such, understanding how the main and combined effects of increasing soil N with declining herbivores may influence plant community structure and function is critical to better understand the future of grassland ecosystems under multiple global change drivers. 2. In this study, we asked: (a) What are the main effects of small mammal herbivores, invertebrate herbivores, and soil N on plant community structure and function? and (b) Are the effects of invertebrate herbivores and soil N on plant community structure and function contingent on small mammal herbivory? We used a nested design, with invertebrate and soil N treatments nested within small mammal manipulations in an existing tallgrass prairie. We measured plant community structure by quantifying plant richness, evenness, diversity, and composition across two full growing seasons. We also recorded total aboveground biomass to quantify grassland productivity. 3. We found that small mammal herbivores strongly shaped plant diversity, species composition, and productivity. Small mammal herbivores also mediated the effects of soil N and invertebrate herbivores on grassland community structure, but not composition or productivity. Small mammal reduction lowered plant species richness while increasing aboveground biomass and altering compositional similarity. Invertebrate herbivores, in the presence of small mammals, promoted plant dominance by reducing evenness without altering compositional similarity. Additionally, soil nitrogen addition reduced plant richness, but only when small mammals were reduced, and no effects were detected on compositional similarity or productivity. 4. Our findings provide further evidence that temperate grasslands can be strongly influenced by consumers, and that consumers mediate the effects of resources as well as other consumer guilds on producer evenness and richness. Taken together, we provide evidence of strong contingencies in the drivers of grassland structure, with small mammals directly altering plant diversity as well as mediating the effects of soil nitrogen and invertebrate herbivory on plant richness and evenness. Therefore, we suggest it is imperative to consider how consumer guilds and resource types may interact to shape grassland plant communities. John Wiley and Sons Inc. 2019-02-21 /pmc/articles/PMC6434553/ /pubmed/30962912 http://dx.doi.org/10.1002/ece3.4991 Text en © 2019 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd. This is an open access article under the terms of the http://creativecommons.org/licenses/by/4.0/ License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
spellingShingle Original Research
Poe, Nicole
Stuble, Katharine L.
Souza, Lara
Small mammal herbivores mediate the effects of soil nitrogen and invertebrate herbivores on grassland diversity
title Small mammal herbivores mediate the effects of soil nitrogen and invertebrate herbivores on grassland diversity
title_full Small mammal herbivores mediate the effects of soil nitrogen and invertebrate herbivores on grassland diversity
title_fullStr Small mammal herbivores mediate the effects of soil nitrogen and invertebrate herbivores on grassland diversity
title_full_unstemmed Small mammal herbivores mediate the effects of soil nitrogen and invertebrate herbivores on grassland diversity
title_short Small mammal herbivores mediate the effects of soil nitrogen and invertebrate herbivores on grassland diversity
title_sort small mammal herbivores mediate the effects of soil nitrogen and invertebrate herbivores on grassland diversity
topic Original Research
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6434553/
https://www.ncbi.nlm.nih.gov/pubmed/30962912
http://dx.doi.org/10.1002/ece3.4991
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