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Symposium

Session: Advances in our understanding of the central role of environmental variability in ecological dynamics

SYMP 15-2 - CANCELLED - Persistence and coexistence in variable environments: Leveraging abiotic and biotic variation for ecological restoration and maintaining diversity

Thursday, August 18, 2022

8:20 AM – 8:40 AM EDT

Location: 520F

Presenting Author(s)

LS

Lauren G. Shoemaker

University of Wyoming
Laramie, Wyoming, United States

Co-author(s)

CB

Catherine Bowler

University of Queensland
AF

Akasha M. Faist

Assistant Professor of Rangeland Ecology
New Mexico State University
Las Cruces, NM, United States
CW

Christopher Weiss-Lehman

Professor
University of Wyoming, Wyoming, United States
MM

Margie M. Mayfield

University of Melbourne, Australia
CW

Chhaya M. Werner

University of Wyoming
Laramie, WY, United States
LA

Lina Aoyama

PhD Student
University of Oregon
Eugene, Oregon, United States
GB

György Barabás

Linköping University
JC

Jonathan Chase

German Centre for Integrative Biodiversity Research (iDiv), Germany
CC

Chengjin Chu

Sun Yat-sen University, China (People's Republic)
SC

Sharon K. Collinge, Collinge

President-Elect
Ecological Society of America
Boulder, Colorado, United States
BG

Benjamin Gilbert

University of Toronto, Department of Ecology & Evolutionary Biology
Toronto, Ontario, Canada
OG

Oscar Godoy

UCA
WH

W Stanley Harpole

German Centre for Integrative Biodiversity Research (iDiv) Leipzig-Halle-Jena
EL

Emma Ladouceur

German Centre for Integrative Biodiversity Research, Germany
LL

Loralee Larios

Faculty advisor
University of California, Riverside
Riverside, California, United States
JL

Jacob Lucero

New Mexico State University
NS

Nancy Shackelford, PhD

Professor
University of Victoria, Canada
VT

Vicky Temperton

Leuphana University Lüneburg
LH

Lauren Hallett

Institute of Ecology and Evolution, University of Oregon, Eugene, OR, United States

Background/Question/Methods
Environmental variability and species interactions are two cornerstones in our longstanding effort to understand species coexistence and the mechanisms that maintain biodiversity. Recently, it has become increasingly evident that these two factors are not independent, but rather that environmental variability mediates species interactions. As such, here we ask: how do direct effects of environmental variability versus indirect effects mediated by species interactions (i.e., competition) alter species persistence and coexistence? We first present a conceptual framework unifying advances in modern coexistence theory and restoration ecology, allowing us to leverage variability to manage single species populations of native or exotic species as well as community diversity. We couple this conceptual framework with species fecundity data from a highly diverse annual understory community in SW Western Australia that spans environmental gradients in canopy cover and soil phosphorus. We apply a recent method for modeling species interactions in diverse ecosystems and across environmental variability (Weiss-Lehman et al. 2022) to compare how abiotic variability, biotic variability, and their joint interaction can modify species persistence using low-density growth rate calculations.

Results/Conclusions
Observed environmental variability in canopy cover and soil phosphorous had direct effects on all focal species’ demography, altering density independent growth rates. In the most extreme case (for the native, Trachymene cyanopetala), density independent growth doubled across the gradient in canopy cover. In parallel, after accounting for underlying environmental variability, we found strong variation in species’ interactions ranging from facilitative to strongly competitive. Incorporating neighborhood stochasticity (i.e., variability in neighboring species’ identities and abundances), however, yielded similar overall net effects across our focal species: a moderately weak competitive neighborhood. Native species tended to experience more variation in the strength of species interactions compared to exotic species. Critically, we found strong evidence of indirect effects of environmental variation; the strength of species’ interactions was mediated by underlying environmental variability in both canopy cover and soil phosphorous. Variability in the environment and species interactions can alter focal species’ low-density growth rates from positive (predicted persistence) to negative (predicted local extinction), informing when—and under what environmental conditions—restoration efforts could result in successful removal of exotics or improved growth rates of natives. Our results highlight the joint impact of abiotic and biotic variation as drivers of species’ demography, species interactions, and coexistence.