Impacts of alien grass invasion in coastal seed banks vary amongst native growth forms and dispersal strategies

Abstract

Impacts of alien grass invasion in coastal seed banks vary amongst native Impacts of alien grass invasion in coastal seed banks vary amongst native growth forms and dispersal strategies growth forms and dispersal strategies

Impacts of alien plant invasion on native plant communities are mediated by functional identity of resident species, not resource availability

“…In the case of S. secundatum , runner species (especially those with short‐distance dispersal capabilities) may require assisted reintroduction upon S. secundatum removal, through either the addition of propagules or seedlings, as this functional group is likely to exhibit more rapid species losses in response to invasion than either woody or tufted species. Furthermore, woody species, which are long lived and have a similar richness and density of soil‐stored propagules between S. secundatum ‐invaded and non‐invaded forest (Gooden and French ), may dominate regenerating vegetation following S. secundatum removal and suppress the recolonisation by herbaceous runners through pre‐empting available resources. Long term monitoring will be required to ensure that runner species gain sufficient representation in the regenerating standing vegetation following invader removal.…”

“…At this stage, most of the native species were well‐established (mean ± SE % total vegetation cover per plot = 45.32 ± 1.92) and had reached reproductive maturity. Stenotaphrum secundatum plants were introduced as seedlings rather than seeds because during monitoring of plots positioned at the edges of large infestations we found that S. secundatum spread via the lateral proliferation of stolons and there was no seed present within the seed bank (Gooden and French , ). Seedlings were propagated from the ends of adventitious stolons collected from the leading edges of large infestations at two locations (34°22′46.40″S, 150°54′51.80″E; Puckeys Estate: 34° 24′25.20″S, 150°53′46.60″E; Primbee: 34°30′15.10″S, 150°52′25.10″E), and were planted randomly across each of the 16 mesocosms at a rate of 10 stolons per plot.…”

“…It was introduced to eastern Australia in the mid‐1800s as an urban turf grass (Sauer , Loch et al ) and has since become naturalised in coastal forest. Stenotaphrum secundatum invasion is associated with significant declines in native plant fecundity as well as species richness and recruitment in both the standing vegetation and soil seed bank (Gooden and French , , Gooden et al ). It remains unknown, however, whether species losses are driven by S. secundatum invasion, or whether it simply proliferates within disturbance‐generated forest gaps that are no longer occupied by native plants.…”

Alien plant invasions and native plant extinctions: a six-threshold framework

“… Ohga 1923 ). Propagules (seeds) can persist in the soil without any seedlings or adult plants being visible (see Thompson and Grime 1979 ; Holmes and Cowling 1997 a ; Gooden and French 2014 ). Furthermore, determining the presence or size of soil-stored seed banks is difficult, partly because they are so spatially heterogeneous ( Jones 1998 ) and/or transient (see Thompson and Grime 1979 ).…”

Patterns of loss of biodiversity associated with invasion by Chrysanthemoides monilifera subsp. monilifera (boneseed) across a large geographic region

“…Low numbers of shrubs and trees were evident in seed banks from invaded and uninvaded sites, but as invaded sites may be the focus of restoration efforts in the near future, these areas are likely to be difficult to return to natural habitats. Large variation between seed bank and standing vegetation has been recorded in Australia (Mason et al ., ; Gooden & French, ) and overseas (Holmes & Cowling, ), although some uninvaded areas are more similar (Henderson et al ., ; Bekker et al ., ).…”