Humans strengthen bottom-up effects and weaken trophic cascades in a terrestrial food web.
Ongoing debate about whether food webs are primarily regulated by predators or by primary plant productivity, cast as top-down and bottom-up effects, respectively, may becoming superfluous. Given that most of the world's ecosystems are human dominated we broadened this dichotomy by considering...
Published in: | PLoS ONE |
---|---|
Main Authors: | , , , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Public Library of Science (PLoS)
2013
|
Subjects: | |
Online Access: | https://doi.org/10.1371/journal.pone.0064311 https://doaj.org/article/88661b80d7f84c959217feebf0610374 |
id |
ftdoajarticles:oai:doaj.org/article:88661b80d7f84c959217feebf0610374 |
---|---|
record_format |
openpolar |
spelling |
ftdoajarticles:oai:doaj.org/article:88661b80d7f84c959217feebf0610374 2023-05-15T15:51:13+02:00 Humans strengthen bottom-up effects and weaken trophic cascades in a terrestrial food web. Tyler B Muhly Mark Hebblewhite Dale Paton Justin A Pitt Mark S Boyce Marco Musiani 2013-01-01T00:00:00Z https://doi.org/10.1371/journal.pone.0064311 https://doaj.org/article/88661b80d7f84c959217feebf0610374 EN eng Public Library of Science (PLoS) http://europepmc.org/articles/PMC3648482?pdf=render https://doaj.org/toc/1932-6203 1932-6203 doi:10.1371/journal.pone.0064311 https://doaj.org/article/88661b80d7f84c959217feebf0610374 PLoS ONE, Vol 8, Iss 5, p e64311 (2013) Medicine R Science Q article 2013 ftdoajarticles https://doi.org/10.1371/journal.pone.0064311 2022-12-31T01:12:19Z Ongoing debate about whether food webs are primarily regulated by predators or by primary plant productivity, cast as top-down and bottom-up effects, respectively, may becoming superfluous. Given that most of the world's ecosystems are human dominated we broadened this dichotomy by considering human effects in a terrestrial food-web. We studied a multiple human-use landscape in southwest Alberta, Canada, as opposed to protected areas where previous terrestrial food-web studies have been conducted. We used structural equation models (SEMs) to assess the strength and direction of relationships between the density and distribution of: (1) humans, measured using a density index; (2) wolves (Canis lupus), elk (Cervus elapahus) and domestic cattle (Bos taurus), measured using resource selection functions, and; (3) forage quality, quantity and utilization (measured at vegetation sampling plots). Relationships were evaluated by taking advantage of temporal and spatial variation in human density, including day versus night, and two landscapes with the highest and lowest human density in the study area. Here we show that forage-mediated effects of humans had primacy over predator-mediated effects in the food web. In our parsimonious SEM, occurrence of humans was most correlated with occurrence of forage (β = 0.637, p<0.0001). Elk and cattle distribution were correlated with forage (elk day: β = 0.400, p<0.0001; elk night: β = 0.369, p<0.0001; cattle day: β = 0.403, p<0.0001; cattle, night: β = 0.436, p<0.0001), and the distribution of elk or cattle and wolves were positively correlated during daytime (elk: β = 0.293, p <0.0001, cattle: β = 0.303, p<0.0001) and nighttime (elk: β = 0.460, p<0.0001, cattle: β = 0.482, p<0.0001). Our results contrast with research conducted in protected areas that suggested human effects in the food web are primarily predator-mediated. Instead, human influence on vegetation may strengthen bottom-up predominance and weaken top-down trophic cascades in ecosystems. We ... Article in Journal/Newspaper Canis lupus Directory of Open Access Journals: DOAJ Articles Canada PLoS ONE 8 5 e64311 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Medicine R Science Q |
spellingShingle |
Medicine R Science Q Tyler B Muhly Mark Hebblewhite Dale Paton Justin A Pitt Mark S Boyce Marco Musiani Humans strengthen bottom-up effects and weaken trophic cascades in a terrestrial food web. |
topic_facet |
Medicine R Science Q |
description |
Ongoing debate about whether food webs are primarily regulated by predators or by primary plant productivity, cast as top-down and bottom-up effects, respectively, may becoming superfluous. Given that most of the world's ecosystems are human dominated we broadened this dichotomy by considering human effects in a terrestrial food-web. We studied a multiple human-use landscape in southwest Alberta, Canada, as opposed to protected areas where previous terrestrial food-web studies have been conducted. We used structural equation models (SEMs) to assess the strength and direction of relationships between the density and distribution of: (1) humans, measured using a density index; (2) wolves (Canis lupus), elk (Cervus elapahus) and domestic cattle (Bos taurus), measured using resource selection functions, and; (3) forage quality, quantity and utilization (measured at vegetation sampling plots). Relationships were evaluated by taking advantage of temporal and spatial variation in human density, including day versus night, and two landscapes with the highest and lowest human density in the study area. Here we show that forage-mediated effects of humans had primacy over predator-mediated effects in the food web. In our parsimonious SEM, occurrence of humans was most correlated with occurrence of forage (β = 0.637, p<0.0001). Elk and cattle distribution were correlated with forage (elk day: β = 0.400, p<0.0001; elk night: β = 0.369, p<0.0001; cattle day: β = 0.403, p<0.0001; cattle, night: β = 0.436, p<0.0001), and the distribution of elk or cattle and wolves were positively correlated during daytime (elk: β = 0.293, p <0.0001, cattle: β = 0.303, p<0.0001) and nighttime (elk: β = 0.460, p<0.0001, cattle: β = 0.482, p<0.0001). Our results contrast with research conducted in protected areas that suggested human effects in the food web are primarily predator-mediated. Instead, human influence on vegetation may strengthen bottom-up predominance and weaken top-down trophic cascades in ecosystems. We ... |
format |
Article in Journal/Newspaper |
author |
Tyler B Muhly Mark Hebblewhite Dale Paton Justin A Pitt Mark S Boyce Marco Musiani |
author_facet |
Tyler B Muhly Mark Hebblewhite Dale Paton Justin A Pitt Mark S Boyce Marco Musiani |
author_sort |
Tyler B Muhly |
title |
Humans strengthen bottom-up effects and weaken trophic cascades in a terrestrial food web. |
title_short |
Humans strengthen bottom-up effects and weaken trophic cascades in a terrestrial food web. |
title_full |
Humans strengthen bottom-up effects and weaken trophic cascades in a terrestrial food web. |
title_fullStr |
Humans strengthen bottom-up effects and weaken trophic cascades in a terrestrial food web. |
title_full_unstemmed |
Humans strengthen bottom-up effects and weaken trophic cascades in a terrestrial food web. |
title_sort |
humans strengthen bottom-up effects and weaken trophic cascades in a terrestrial food web. |
publisher |
Public Library of Science (PLoS) |
publishDate |
2013 |
url |
https://doi.org/10.1371/journal.pone.0064311 https://doaj.org/article/88661b80d7f84c959217feebf0610374 |
geographic |
Canada |
geographic_facet |
Canada |
genre |
Canis lupus |
genre_facet |
Canis lupus |
op_source |
PLoS ONE, Vol 8, Iss 5, p e64311 (2013) |
op_relation |
http://europepmc.org/articles/PMC3648482?pdf=render https://doaj.org/toc/1932-6203 1932-6203 doi:10.1371/journal.pone.0064311 https://doaj.org/article/88661b80d7f84c959217feebf0610374 |
op_doi |
https://doi.org/10.1371/journal.pone.0064311 |
container_title |
PLoS ONE |
container_volume |
8 |
container_issue |
5 |
container_start_page |
e64311 |
_version_ |
1766386324096417792 |