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Disturbance and the (surprising?) role of ecosystem engineering in explaining spatial patterns of non-native plant establishment
  • Meredith Root-Bernstein,
  • Cesar Muñoz,
  • Juan Armesto
Meredith Root-Bernstein
CNRS
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Cesar Muñoz
Pontificia Universidad Católica de Chile
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Juan Armesto
Universidad de Chile Instituto de Ecología y Biodiversidad
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Abstract

The Intermediate Disturbance Hypothesis is widely considered to be wrong but is rarely tested against alternative hypotheses. It predicts that soil disturbances and herbivory have identical impacts on species richness via identical mechanisms (reduction in biomass and in competition). An alternative hypothesis is that the specific traits of disturbance agents (small mammals) and plants differentially affects richness or abundance of different plant groups. We tested these hypotheses on a degu (Octodon degus) colony in central Chile. We ask whether native and non-native forbs respond differently to degu bioturbation on runways vs. herbivory on grazing lawns. We ask whether this can explain the increase in non-native plants on degu colonies. We found that biopedturbation did not explain the locations of non-native plants. We did not find direct evidence of grazing increasing non-native herbs either, but a grazing effect appears to be mediated by grass, which is the dominant cover. Further, we provide supplementary evidence to support our interpretation that a key mechanism of non-native spread is the formation of dry soil conditions on grazing lawns. Thus ecosystem engineering (alteration of soil qualities) may be an outcome of disturbances, which each interact with specific plant traits, to create the observed pattern of non-native spread in the colony. Based on these results we propose to extend Jentsch & White’s (2019) concept of combined pulse/ disturbance events to the long-term process duality of ecosystem engineering/ disturbance.

Peer review status:ACCEPTED

22 Jan 2021Submitted to Ecology and Evolution
25 Jan 2021Submission Checks Completed
25 Jan 2021Assigned to Editor
08 Feb 2021Reviewer(s) Assigned
30 Mar 2021Review(s) Completed, Editorial Evaluation Pending
08 Apr 2021Editorial Decision: Revise Minor
03 Jun 20211st Revision Received
14 Jun 2021Submission Checks Completed
14 Jun 2021Assigned to Editor
14 Jun 2021Review(s) Completed, Editorial Evaluation Pending
15 Jun 2021Editorial Decision: Accept