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

Abstract

Invasive alien plant species impart considerable impacts that contribute to the decline of biodiversity worldwide. The ability of an invasive species to overcome barriers to establish and spread in new environments, and the long-term effects of plant invasions supporting their persistence are keys to invasion success. The capacity of introduced species to form soil seed banks can contribute to their invasiveness, yet few studies of invaders have addressed seed bank dynamics. Improved knowledge of this recruitment process can improve conservation management. We studied temporal and spatial changes in soil seed bank characteristics of the cordgrass Spartina densiflora from two continental invaded ranges. In the Odiel Marshes (Southwest Iberian Peninsula), S. densiflora formed transient seed banks (< 1 year). At Humboldt Bay Estuary (California), 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 with S. densiflora above-ground cover in both estuaries, pointing to the transient component of the seed bank as a critical component of vegetation dynamics during S. densiflora invasion. Even so, seed 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 fruiting S. densiflora plants. S. densiflora spikelet (dispersal unit) density was more than double close to the sediment surface than deeper within soil. Our study shows the importance of evaluating seed banks during the design of invasive species management since seed bank persistence may vary among invaded sites, and can affect the timing and duration required for desired management outcomes.

Seed Viability, Spikelet Dispersal, Seed Banks and Seed Storage Requirements for Native and Invasive Cordgrasses (Genus Spartina) in Southwest Iberian Peninsula

“…Due to its dormancy, S. densiflora was able to establish transient seed banks mainly at higher elevations along the intertidal gradient as recorded in this study. Abbas et al (2021) reported that S. densiflora formed short-term persistent seed banks at Humboldt Bay (North California) probably related to a cooler climate than in the Odiel Marshes. Nevertheless, S. densiflora was unable to establish permanent seed bank in the Odiel Marshes since only 1 spikelet with viable caryopsis remained in a HM soil sample after the germination period.…”

“…For this reason, to our knowledge, this is the first work that evaluates seed bank dynamics in S. maritima. Only one work has studied the seed bank of S. densiflora showing that this invasive species forms transient or persistent seed banks depending on environmental conditions (Abbas et al 2021). In this work, we tested the ability of S. maritima and S. densiflora spikelets to disperse in water, the spikelet longevity relative to different environmental conditions, and we quantified the pre-dispersal seed production and the seed banks of both cordgrasses along the intertidal gradient.…”

Invasive species in the soil seed bank of two limestone hills in Bogor, West Java, Indonesia

“…Results of this study are central to the development of effective conservation, management and control strategies of the invasive species in the sites. Abbas et al (2021) study highlights the importance of evaluating seed banks when making invasive species management decisions. Through this study, we are able to identify the invasive species present in the seed bank and analyze their composition and density.…”

Seed longevity and germination of the emerging invasive species wavyleaf basketgrass (Oplismenus undulatifolius) under varied light regimes

“…Seedbanks provide a degree of resilience to populations in highly variable or disturbed environments by temporally staggering emergence within a growing season or across multiple years (Evans and Dennehy 2005; Kalisz 1986; ten Brink et al 2020). Additionally, persistent seedbanks can facilitate population regeneration and help maintain genetic diversity within a population across generations, which may contribute to invasion success (Abbas et al 2021; Gioria et al 2012; Gremer and Venable 2014; Lennon et al 2021). Seedbanks can reduce vulnerability to local extinctions and potential negative consequences of founder effects, genetic bottlenecks, and small population sizes early in the invasion history (Houle and Phillips 1988; Meimberg et al 2006; Puillandre et al 2008; Williams and Fishman 2014).…”

“…This stabilizing effect of seedbanks results in part from the reserve of historical genetic diversity maintained in dormant seeds, which can supplement current populations experiencing low genetic diversity (McCue and Holtsford 1998; Rees 1993). Consequently, seedbank persistence can affect demographic persistence by promoting local patch reestablishment, as well as providing a source for propagules contributing to range expansion (Abbas et al 2021; Galatowitsch et al 2016; Leary et al 2018).…”