Journal list menu

Volume 32, Issue 8 e2706
ARTICLE

Tipping the balance: The role of seed density, abiotic filters, and priority effects in seed-based wetland restoration

Emily E. Tarsa

Emily E. Tarsa

Ecology Center and Department of Watershed Sciences, Utah State University, Logan, Utah, USA

Search for more papers by this author
Bailey M. Holdaway

Bailey M. Holdaway

Ecology Center and Department of Watershed Sciences, Utah State University, Logan, Utah, USA

Search for more papers by this author
Karin M. Kettenring

Corresponding Author

Karin M. Kettenring

Ecology Center and Department of Watershed Sciences, Utah State University, Logan, Utah, USA

Correspondence

Karin M. Kettenring

Email: [email protected]

Search for more papers by this author
First published: 09 July 2022
Citations: 2
Handling Editor: Miaojun Ma

Funding information: Garden Club of America; Institute for Wetland and Waterfowl Research, Ducks Unlimited Canada; U.S. Fish and Wildlife Service; Utah Division of Forestry, Fire, and State Lands; Utah Division of Wildlife Resources; Utah State University Ecology Center; Utah Department of Agriculture and Food; USU Extension; Community Foundation of Utah

Abstract

Sowing native seeds is a common approach to reintroduce native plants to degraded systems. However, this method is often overlooked in wetland restoration despite the immense global loss of diverse native wetland vegetation. Developing guiding principles for seed-based wetland restoration is critical to maximize native plant recovery, particularly in previously invaded wetlands. Doing so requires a comprehensive understanding of how restoration manipulations, and their interactions, influence wetland plant community assembly. With a focus on the invader Phragmites australis, we established a series of mesocosm experiments to assess how native sowing density, invader propagule pressure, abiotic filters (water and nutrients), and native sowing timing (i.e., priority effects) interact to influence plant community cover and biomass in wetland habitats. Increasing the density of native seeds yielded higher native cover and biomass, but P. australis suppression with increasing sowing densities was minimal. Rather, community outcomes were largely driven by invader propagule pressure: P. australis densities of ≤500 seeds/m2 maintained high native cover and biomass. Low-water conditions increased the susceptibility of P. australis to dominance by native competitors. Early sowing of native seeds showed a large and significant benefit to native cover and biomass, regardless of native sowing density, suggesting that priority effects can be an effective restoration manipulation to enhance native plant establishment. Given the urgent wetland restoration need combined with the limited studies on seed-based wetland restoration, these findings provide guidance on restoration manipulations that are grounded in ecological theory to improve seed-based wetland restoration outcomes.

CONFLICT OF INTEREST

The authors declare no conflict of interest.

DATA AVAILABILITY STATEMENT

Data (Tarsa, Holdaway, et al., 2022) are available in the Dryad Digital Repository at https://doi.org/10.5061/dryad.m63xsj43f.