The potential role of seed banks in the recovery of dune ecosystems after removal of invasive plant species

Abstract

Question: How resilient is the seed bank of an invaded dune system? Is that resilience dependent on duration of invasion? How does the accumulated litter layer contribute to the soil seed bank? Location: Coastal sand dunes invaded by Acacia longifolia, Portugal. Methods: Seedling emergence was used to quantify and compare soil seed banks in long‐invaded, recently invaded and non‐invaded areas. Changes in seed banks were also compared with areas where A. longifolia and the litter layer were removed. Results: Species richness, seedling density and diversity were higher in non‐invaded and recently‐invaded areas than in long‐invaded areas. Although there was an apparent similarity between non‐invaded and recently‐invaded areas, analyses of species traits revealed differences. Non‐invaded areas had a wider array of traits. Exotic/invasive species dominated invaded seed banks while native species dominated non‐invaded seed banks. Life forms, growth forms, longevity and dispersal mode showed differences between areas, with cleared plots of long‐invaded areas being apparently the most similar to non‐invaded plots. Acacia longifolia seeds were most abundant in long‐invaded areas, particularly where the litter layer remained. Removal of A. longifolia plus the litter had little effect on the seed bank composition of recently‐invaded areas but resulted in noticeable changes in seed banks of long‐invaded areas. Conclusions: Long‐invaded areas are less resilient and show a higher reinvasion potential, despite severe alteration of the seed banks of both areas. Seed bank studies can be a useful tool to guide management, but can give misleading results when invasion periods are protracted.

Impacts of invasive Australian acacias: implications for management and restoration

“…As A. longifolia reaches maturity, it rapidly reaches > 80% cover, out-competes native species and accumulates a thick litter layer. The native seed bank (E), which persists when A. longifolia is present for short periods and/or at low densities (Marchante et al, 2011b), decreases after fire owing to seed germination or destruction. As the invasion becomes protracted, native species cover decreases even more although native species richness (F) is sustained for much longer because some species persist at low densities (Marchante et al, 2003;Marchante, 2011).…”

“…As the invasion becomes protracted, the autogenic recovery potential of invaded areas decreases: native seed banks (E) become more impoverished (Marchante et al, 2011b), reinvasion potential (acacia seed bank, C) increases (Marchante et al, 2010) and soil carbon and nutrients, especially nitrogen (B), become and remain high for long periods (Marchante et al, 2009). Autogenic recovery after removal of A. longifolia is slow with only partial recovery after 6 years (Marchante et al, 2009(Marchante et al, , 2011a suggesting that full autogenic recovery may not be possible.…”

Invasion of alien Acacia dealbata on Spanish Quercus robur forests: Impact on soils and vegetation

“…These changes in the composition of the soil seed bank can have serious consequences for the regeneration of the native community and must be taken into account in prospective plans of ecosystem conservation and restoration. Previous studies show that the presence of invasive species generally diminishes species richness in the soil seed bank (Holmes and Cowling, 1997;Mason et al, 2007;Giantomasi et al, 2008;Marchante et al, 2011). For instance, Gioria and Osborne (2010) compared the effect of three invasive grass species (Fallopia japonica, Gunnera tinctoria and Heracleum mantegazzianum) on soil seed bank and established vegetation sampled in different habitats of Ireland, and found a common tendency to the depletion and homogenization of the soil seed bank through species with long-lived and persistent seeds.…”

The role of Pteridium arachnoideum(Kaulf) on the seed bank of the endangered Brazilian Cerrado

“…These invasive species can outcompete established native species, reducing both their number and abundance, and altering the structure and function of the invaded communities (Marchante et al, 2011). As a consequence, the restoration potential of the ecosystem is affected, especially in areas where dispersal from nearby seed sources is limited (Funk et al, 2008).…”