Seed bank persistence of a South American cordgrass in invaded northern Atlantic and Pacific Coast estuaries

Authors: ABBAS, AHMED - South Valley University; PICKART, ANDREA - Us Fish And Wildlife Service; GOLDSMITH, LAUREL - Us Fish And Wildlife Service; DAVENPORT, DESIREE - Us Fish And Wildlife Service; NEWBY, BRITNEY - Us Fish And Wildlife Service; MUNOZ-RODRIGUEZ, ADOLFO - Universidad De Huelva; Grewell, Brenda; CASTILLO, JESUS - University Of Seville

Submitted to: AoB Plants
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/8/2021
Publication Date: 4/9/2021
Citation: Abbas, A.M., Pickart, A.J., Goldsmith, L.M., Davenport, D.N., Newby, B., Munoz-Rodriguez, A.F., Grewell, B.J., Castillo, J.M. 2021. Seed bank persistence of a South American cordgrass in invaded northern Atlantic and Pacific Coast estuaries. AoB Plants. 13:2. https://doi.org/10.1093/aobpla/plab014.
DOI: https://doi.org/10.1093/aobpla/plab014

Interpretive Summary: Invasive alien plants and climate change are major elements of current global change that have both increased rapidly, contributing to the worldwide decline of biodiversity. The ability of an invasive species to overcome barriers to establish and spread in new and changing climatic environments is key to invasion success. The question of how climate change will interact with invasive alien plants and their recruitment processes can provide a timely foundation for conservation management and ecological restoration to mitigate the undesirable impacts of plant invasions on biological diversity. In this context, the study of changing environmental factors influencing seed banks characteristics of invasive species is crucial for biodiversity conservation and ecosystem management. We studied temporal and spatial changes in soil seed bank characteristics of the cordgrass Spartina densiflora from two continental invaded ranges with contrasting climates. In the Odiel Marshes (southwest Iberian Peninsula) with hot summers, S. densiflora formed transient seed banks and short-term persistent seed banks. At Humboldt Bay (northern California) under cooler summer climate conditions, viable seeds persisted for at least four years though the germination percentage fell abruptly after the first year from 29% to less than 5% of remaining viable seeds. Total soil seed bank density increased together with S. densiflora above-ground cover at both studied estuaries. Even so, seeds densities as high as c. 750 seeds m-2 in Odiel Marshes and c. 12400 seeds m-2 in Humboldt Bay were recorded in some plots without emergent S. densiflora plants, reflecting a high capacity for hydrochorous dispersion. S. densiflora spikelet density was higher close to the sediment surface than deeper in the soil. In this scenario and from a seed bank perspective, global warming may facilitate improved management of S. densiflora invasions, since warmer temperatures are correlated with more transient seed banks. Our study shows the importance of evaluating seed banks during the design of invasive species management in a scenario of global environmental changes.

Technical Abstract: Invasive alien plants and climate change are both contributing to the worldwide decline of biodiversity. In this context, the study of changing environmental factors influencing seed banks characteristics of invasive species is crucial for biodiversity conservation and ecosystem management. We studied temporal and spatial changes in soil seed bank characteristics of the cordgrass Spartina densiflora from two continental invaded ranges with contrasting climates. In the Odiel Marshes (southwest Iberian Peninsula) with hot summers, S. densiflora formed transient seed banks and short-term persistent seed banks. At Humboldt Bay (northern California) under cooler summer climate conditions, viable seeds persisted for at least four years though the germination percentage fell abruptly after the first year from 29% to less than 5% of remaining viable seeds. Total soil seed bank density increased together with S. densiflora above-ground cover at both studied estuaries. Even so, seeds densities as high as c. 750 seeds m-2 in Odiel Marshes and c. 12400 seeds m-2 in Humboldt Bay were recorded in some plots without emergent S. densiflora plants, reflecting a high capacity for hydrochorous dispersion. S. densiflora spikelet density was higher close to the sediment surface than deeper in the soil. In this scenario and from a seed bank perspective, global warming may facilitate improved management of S. densiflora invasions, since warmer temperatures are correlated with more transient seed banks. Our study shows the importance of evaluating seed banks during the design of invasive species management in a scenario of global environmental changes.