Are native bluebells(Hyacinthoides non-scripta) at risk from alien congenerics? Evidence from distributions and co-occurrence in Scotland

Abstract
The UK has the highest density of the worldwide distribution of its native bluebell, Hyacinthoides non-scripta (Liliaceae). The prevalence of non-native (hybrids or "Spanish") bluebells has been interpreted as an urgent threat. To assess the potential for competitive and hybridising interactions between natives and non-native taxa in the UK, we quantified occurrence and co-occurrence of bluebells in south-central Scotland in relation to physical variables, land cover, and habitat types. To do this we estimated abundance near random points within 17 selected 10-km squares, and tested the influence of explanatory variables acting at 3 spatial scales (10 km, 1 km, and records) on densities, encounter rates, and group sizes. We found that 1) natives were nearly 99% of all bluebells recorded, 2) non-natives were encountered as often as natives, 3) increasing rainfall was associated with increasing native and decreasing non-natives densities, and 4) the presence of non-natives related to variables correlated with human density, and 5) there was little evidence for habitat exclusivity. Mixed groups accounted for 10 % of natives recorded, and 40 % of natives grew within about one kilometre of non-natives. These distributions suggest that a high proportion of natives may be within potential range of gene flow via insect pollinators.
Year
2009
Category
Refereed journal
Output Tags
SG 2006-2011 WP 3.7 Management of Biodiversity Change