Biological Invasions

, Volume 15, Issue 3, pp 529–545 | Cite as

Challenges in predicting invasive reservoir hosts of emerging pathogens: mapping Rhododendron ponticum as a foliar host for Phytophthora ramorum and Phytophthora kernoviae in the UK

  • Bethan V. Purse
  • Philipp Graeser
  • Kate Searle
  • Colin Edwards
  • Catriona Harris
Original Paper


Invasive species can increase the susceptibility of ecosystems to disease by acting as reservoir hosts for pathogens. Invasive hosts are often sparsely recorded and not in equilibrium, so predicting their spatial distributions and overlap with other hosts is problematic. We applied newly developed methods for modelling the distribution of invasive species to the invasive shrub Rhododendron ponticum—a foliar reservoir host for the Phytophthora oomycete plant pathogens, P. ramorum and P. kernoviae, that threaten woodland and heathland habitat in Scotland. We compiled eleven datasets of biological records for R. ponticum (1,691 points, 8,455 polygons) and developed Maximum Entropy (MaxEnt) models incorporating landscape, soil and climate predictors. Our models produced accurate predictions of current suitable R. ponticum habitat (training AUC = 0.838; test AUC = 0.838) that corresponded well with population performance (areal cover). Continuous broad-leaved woodland cover, low elevation (<400 m a.s.l.) and intermediate levels of soil moisture (or Enhanced Vegetation Index) favoured presence of R. ponticum. The high coincidence of suitable habitat with both core native woodlands (54 % of woodlands) and plantations of another sporulation host, Larix kaempferi (64 % of plantations) suggests a high potential for spread of Phytophthora infection to woodland mediated by R. ponticum. Incorporating non-equilibrium modelling methods did not improve habitat suitability predictions of this invasive host, possibly because, as a long-standing invader, R. ponticum has filled more of its available habitat at this national scale than previously suspected.


Invasive species management Sudden Oak death Woodland management Species distribution model Maximum entropy modelling, Rhododendron ponticum Phytophthora ramorum Phytophthora kernoviae 



The authors would like to thank Alexandra Schlenzig, SASA for advice on premise types, Jim McCleod and Steve Albon from MLURI for soil data, Prof. David Rogers and the Spatial Ecology and Epidemiology Group, Oxford University for MODIS data, Adam Butler for statistical advice and the Local Record Centres and contributing biological recorders for providing data. The authors gratefully acknowledge sponsorship from the UK Population Biology Network (UKPopNet) funded by Natural England, and the Natural Environment Research Council (with additional support from the Centre for Ecology and Hydrology) and funding from the Scottish Government under research contract CR/2008/55.

Supplementary material

10530_2012_305_MOESM1_ESM.docx (1.5 mb)
Supplementary material 1 (DOCX 1510 kb)


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Copyright information

© Springer Science+Business Media B.V. 2012

Authors and Affiliations

  • Bethan V. Purse
    • 1
  • Philipp Graeser
    • 1
  • Kate Searle
    • 1
  • Colin Edwards
    • 2
  • Catriona Harris
    • 3
  1. 1.NERC Centre for Ecology and HydrologyMidlothianUK
  2. 2.Forest Management DivisionForest ResearchMidlothianUK
  3. 3.Centre for Research into Ecological and Environmental Modelling, The Observatory, Buchanan GardensUniversity of St AndrewsSt AndrewsUK

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