Unraveling the wheel of recruitment for salt-marsh seedlings: Resistance to and recovery after dislodgement

Zhiyuan Zhao; Liquan Zhang; Lin Yuan; Tjeerd J Bouma

doi:10.1016/j.scitotenv.2022.157595

Unraveling the wheel of recruitment for salt-marsh seedlings: Resistance to and recovery after dislodgement

Sci Total Environ. 2022 Nov 15:847:157595. doi: 10.1016/j.scitotenv.2022.157595. Epub 2022 Jul 27.

Authors

Zhiyuan Zhao¹, Liquan Zhang², Lin Yuan³, Tjeerd J Bouma⁴

Affiliations

¹ State Key Laboratory of Estuarine and Coastal Research, Institute of Eco-Chongming, Center for Blue Carbon Science and Technology, East China Normal University, 200241 Shanghai, China; Department of Estuarine and Delta Systems, Royal Netherlands Institute for Sea Research, 4401 NT Yerseke, the Netherlands; Faculty of Geosciences, Department of Physical Geography, Utrecht University, 3584 CB Utrecht, the Netherlands.
² State Key Laboratory of Estuarine and Coastal Research, Institute of Eco-Chongming, Center for Blue Carbon Science and Technology, East China Normal University, 200241 Shanghai, China.
³ State Key Laboratory of Estuarine and Coastal Research, Institute of Eco-Chongming, Center for Blue Carbon Science and Technology, East China Normal University, 200241 Shanghai, China; Yangtze Delta Estuarine Wetland Ecosystem Observation and Research Station, 202162 Shanghai, China. Electronic address: lyuan@sklec.ecnu.edu.cn.
⁴ Department of Estuarine and Delta Systems, Royal Netherlands Institute for Sea Research, 4401 NT Yerseke, the Netherlands; Faculty of Geosciences, Department of Physical Geography, Utrecht University, 3584 CB Utrecht, the Netherlands; HZ University of Applied Sciences, Building with Nature group, 4382 NW Vlissingen, the Netherlands. Electronic address: Tjeerd.Bouma@nioz.nl.

PMID: 35905966
DOI: 10.1016/j.scitotenv.2022.157595

Abstract

Elucidating bottlenecks at critical life stages and quantifying associated resilience (including resistance and recovery) to physical processes are central in inform restoration and attain sustainable development of coastal biogeomorphic ecosystems. Seedling establishment is a key life stage determines saltmarsh restoration potentials. However, the resilience of these recruits, especially through recovery, remains poorly understood. Here, two contrasting globally occurring saltmarsh species, namely Salicornia europaea and Spartina anglica, were employed to generate insights in i) seedling resistance against dislodgement, and ii) seedling recovery potential after dislodgement. Regarding resistance, we found that 1) root-shoot antagonism characterizes the growth rate of seedling resistance to dislodgement through hydraulic disturbance, 2) the root length determines seedling resistance to dislodgement through sheet erosion; 3) a 5 mm sedimentary setting amplifies seedling resistance without inhibiting their morphological evolution. Regarding recovery, we found that 4) dislodged seedlings have a high probability for achieving long-distance dispersal; 5) seedling age and the inundation-free period regulate the re-establishment potential of dislodged seedlings. Overall, S. anglica showed stronger resilience than S. europaea, characterized by stronger seedling resistance against dislodgement and higher re-establishment potential. Our results on seedling resilience suggest that seedling dislodgement is not an end-of-life cycle but a new spin on the "Wheel of Recruitment", a proposed short-term cyclic behavior with alternating phases of seedling dislodgement, dispersal, and (re-)establishment. The Wheel of Recruitment concept is important for forecasting resilience and persistence of biogeomorphic systems such as salt marshes under global change and for guiding life cycle informed restoration.

Keywords: Recovery; Resistance; Saltmarsh; Seedling establishment; Wheel of recruitment; Windows of opportunity.

MeSH terms

Chenopodiaceae*
Ecosystem
Poaceae
Seedlings*
Seeds
Wetlands