Native dominants in British woodland – a potential cause of reduced species-richness?

Abstract

Contact CEH NORA team at noraceh@ceh.ac.ukThe NERC and CEH trademarks and logos ('the Trademarks') are registered trademarks of NERC in the UK and other countries, and may not be used without the prior written consent of the Trademark owner. The invasion of native habitats by alien species has received considerable attention. 1 However, in Britain high levels of dominance by a small number of aggressive native 2 plant species may have an equal, or greater, impact on the richness of native 3 woodlands. Here, we examine this hypothesis by modelling the realized niche of 4 native-dominant species along the principal coenocline of British woodlands, and 5 examined niche overlaps with 78 woodland specialist species and two alien species. 6Four native species had a much greater cover than all other field-layer species, and 7 between them they entirely covered the response range of all other field-layer species, 8 replacing one another along the coenocline. These findings, combined with 9 autecological information suggest that Hedera helix, Mercurialis perennis, Pteridium 10 aquilinum and Rubus fruticosus have the potential to become 'over-dominant ' and 11 perhaps may impinge on other field-layer species. Our results also identified which 12 field-layer species are likely to be impacted by a change in abundance of each of these 13 dominant-species, and as such, provide a novel quantitative method of risk assessment 14 to aid conservation policy. Understanding how woodland communities remain 15 diverse, even in the presence of aggressive native species, may provide insights into 16 how the impact of exotic invasive species can be managed. 17 18

Increasing status of non-native vascular plants in the Sefton Coast sand-dune system, north Merseyside, UK

“…The impact of invasive native species is widely acknowledged. Marrs et al (2013) argued that a few aggressive native plants may have an equal or greater impact on some habitats than alien species, while Pearman (2004) contended that a small number of native plants was a greater threat to the UK's native flora than invasive non-natives.…”

Woodland survey of Great Britain 1971–2001

“…A subsequent survey based on these methods (Bunce and Shaw, 1973b), the Classification of the Native Pinewoods of Scotland, set the conservation agenda for that scarce resource (Bunce and Jeffers, 1977). In later work, the concept of a woodland site, and subsequently a 1 km square sampled at random, with random plots sampled within, be- came a standard sampling strategy used as the basis of surveys such as the Cumbria Survey (Bunce and Smith, 1978) and the Terrestrial Survey of Shetland (Milner, 1975). Variations of this method are currently used very successfully in several other large ecological surveys in Britain, such as the Countryside Survey (Carey et al, 2008) and the Glastir Monitoring and Evaluation Programme (Emmett and GMEP team, 2014).…”

Drivers of vascular plant species area relationships in British broadleaved woodlands and their effects on the species area curve

“…constructed. Similarly, SOM can have a homogenizing effect on the plots due to loss of species richness, either directly (Kooijmann & Cammeraat, 2010) or because increased SOM indicates increased nitrogen deposition and eutrophication that favours the abundance of competitive species potentially suppressing species diversity in the understorey, (Maskell et al, 2010, Pallet et al 2016. Both HI and SOM can be seen therefore, as influencing community structure either positively or negatively and so effecting nest z.…”