Species interactions across trophic levels mediate rainfall effects on dryland vegetation dynamics

Ariel A. Farías, Cristina Armas, Aurora Gaxiola, Alex P. Cea, Jose Luis Cortés, Ramiro P. López, Fernando Casanoves, Milena Holmgren, Peter L. Meserve, Julio R. Gutiérrez, Douglas A. Kelt

Research output: Contribution to journalArticlepeer-review

Abstract

Arid ecosystems are strongly limited by water availability, and precipitation plays a major role in the dynamics of all species in arid regions, as well as the ecosystem processes that occur there. However, understanding how biotic interactions mediate long-term responses of dryland ecosystems to rainfall remains very fragmented. We report on a unique large-scale field experiment spanning 25 yr and three trophic levels (plants, small mammal herbivores, predators) in a dryland ecosystem in the northern Chilean Mediterranean Region where we assessed how biotic interactions influence the long-term plant community responses to precipitation. As the most persistent ecological changes in dryland systems may result from changes in the structure, cover, and composition of the perennial vegetation, we emphasized the interplay between bottom-up and top-down controls of perennial plants in our analyses. Rainfall was the primary factor affecting the dynamics of, and interactions among, plants and small mammals. Ephemeral plant cover dynamics closely tracked short-term annual rainfall, but seemed unaffected by top-down controls (herbivory). In contrast, the response of the perennial plant cover to precipitation was mediated by (1) a complex interplay between subtle top-down (herbivory) controls that become more apparent in the long-term, (2) competition with ephemeral plants during wet years, and (3) an indirect effect of predators on subdominant shrubs and perennial herbs. This long-term field experiment highlights how climate-induced responses of arid perennial vegetation are influenced by interactions across trophic levels and temporal scales. In the face of global change, understanding how multi-trophic controls mediate dryland vegetation responses to climate is essential to properly managing the conservation of biodiversity in arid systems.

Original languageEnglish
Article numbere01441
JournalEcological Monographs
Volume91
Issue number2
DOIs
StatePublished - May 2021
Externally publishedYes

Bibliographical note

Funding Information:
We thank Andrea Previtali and Bryan Milstead for their assistance in the field, lab, and for the management of the database. We are grateful to the Corporación Nacional Forestal (CONAF) from the IV Región for assistance at Bosque Fray Jorge National Park. This work was funded by grants from MIDEPLAN ICM P05-002, CONICYT/FPB-23, and AFB 170008 to A. Gaxiola and J. R. Gutiérrez. FONDECYT 1970576, 1000041, 1030225 and 1160026 to J. R. Gutiérrez and the U.S. National Science Foundation (most recently, NSF-LTREB DEB 1456729 to D. A. Kelt and P. L. Meserve). C. Armas received a postdoctoral fellowship from the Institute of Ecology and Biodiversity with additional support of contract ICM P05-002 and a Ramón y Cajal contract (RYC-2012-12277) from the Spanish Government. A. A. Farías was founded by project ANID PIA/BASAL FB0002. This is a contribution to the Chilean Long-Term Socio-Ecological Research Network (LTSER-Chile). Author contribution: Ariel A. Farías, Cristina Armas, and Aurora Gaxiola contributed equally to the paper.

Funding Information:
We thank Andrea Previtali and Bryan Milstead for their assistance in the field, lab, and for the management of the database. We are grateful to the Corporación Nacional Forestal (CONAF) from the IV Región for assistance at Bosque Fray Jorge National Park. This work was funded by grants from MIDEPLAN ICM P05‐002, CONICYT/FPB‐23, and AFB 170008 to A. Gaxiola and J. R. Gutiérrez. FONDECYT 1970576, 1000041, 1030225 and 1160026 to J. R. Gutiérrez and the U.S. National Science Foundation (most recently, NSF‐LTREB DEB 1456729 to D. A. Kelt and P. L. Meserve). C. Armas received a postdoctoral fellowship from the Institute of Ecology and Biodiversity with additional support of contract ICM P05‐002 and a Ramón y Cajal contract (RYC‐2012‐12277) from the Spanish Government. A. A. Farías was founded by project ANID PIA/BASAL FB0002. This is a contribution to the Chilean Long‐Term Socio‐Ecological Research Network (LTSER‐Chile). : Ariel A. Farías, Cristina Armas, and Aurora Gaxiola contributed equally to the paper. Author contribution

Publisher Copyright:
© 2020 by the Ecological Society of America

Keywords

  • El Niño Southern Oscillation (ENSO)
  • Long Term Research in Environmental Biology
  • Long Term Socio-economic and Ecosystem Research
  • abiotic vs. biotic control
  • herbivory
  • resource pulses
  • top-down and bottom-up controls
  • trophic cascades

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