Early seed dynamics and tidal marsh revegetation of a salt pond following tidal reconnection. Issue 2 (12th May 2022)

• Record Type: Journal Article
• Authors: Beaumont, Kieren P.; Dittmann, Sabine
• Editors: Hölzel, Norbert
• Is Part Of: Applied vegetation science. Volume 25:Issue 2(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-05-12
• Subjects: hydrochory -- managed realignment -- restoration -- Salicornia -- salt marsh -- seed bank -- seed dispersal; Plant ecology -- Periodicals; Plant communities -- Periodicals; Plant populations -- Periodicals; Nature -- Effect of human beings on -- Periodicals; 581.705
• DOI: 10.1111/avsc.12661
• Languages: English
• ISSNs: 1402-2001

Abstract

Abstract: Question: (1) Following reconnection, does ground cover in the pond become similar to mature salt marsh sites over time? (2) Do seed densities and species composition of seed banks and seed rain differ between the pond and mature salt marsh, and between elevations? (3) Do seed densities vary over time? (4) Within the pond, can seed densities be explained by the abundance of reproductive plants, elevation, or distance from the pond inlet. Location: Dry Creek salt field, South Australia. Methods: We sampled seed rain (monthly) and seed banks (every three months) 6 to 18 months after tidal reconnection and surveyed ground cover (plant species, logs, seagrass wrack and bare ground) up to 34 months after reconnection. Samples were collected from the pond and from mature marsh vegetation at a reference site, and a site immediately adjacent to the pond inlet. Results: Vegetation cover in the pond increased more quickly at mid elevations compared with low elevations. Regarding the composition of ground cover, seed rain and seed banks, the site became more similar to the adjacent site than to the reference site. Seed densities increased from late autumn to early winter. The pattern of seed densities across sites and elevations differed between seed rain and seed banks. Seeds of Salicornia quinqueflora and Suaeda australis dominated in the pond, reflecting their high seed densities adjacent to the pond inlet. Variation in seed densities of both species in the pond was explained by the abundance of nearby, reproductive conspecifics but not by the distance from the inlet. Conclusions: Early stages of salt marsh revegetation were driven by tidal import of seeds and by the rapid seed production of early colonising species; however, low seed densities may reduce rates of revegetation at low elevations. Seed dispersal and revegetation may be maximised by undertaking tidal reconnection when seed densities are highest. Abstract : Key processes of salt marsh revegetation were investigated within a tidally reconnected salt pond. Seed rain, seed banks and vegetation colonising the pond reflected species that predominated at a nearby site. Plant recruitment and in‐situ seed production occurred within 12 months of reconnection. We recommend that tidal reconnection is timed to coincide with the seasonal peak in seed abundance to maximise revegetation.