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Durham University

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Publication details for Professor Stephen G Willis

Wadsworth, RA, Collingham, YC, Willis, SG, Huntley, B & Hulme, PE (2000). Simulating the spread and management of alien riparian weeds: are they out of control? Journal Of Applied Ecology 37: 28-38.
  • Publication type: Journal Article
  • ISSN/ISBN: 0021-8901
  • Keywords: Heracleum mantegazzianum; Impatiens glandulifera; invasion dynamics;landscape ecology; seed dispersal; weed managementIMPATIENS

Author(s) from Durham


1. This paper examines the circumstances under which control programmes
may reduce the range of two widespread invasive weeds of riparian
habitats: Impatiens glandulifera (Himalayan balsam) and Heracleum
mantegazzianum (giant hogweed).
2. The spread of both species was modelled using MIGRATE, a spatially
explicit model that incorporates realistic demographic parameters and
multiple dispersal mechanisms. Simulations of a range of control
scenarios were run within a geographical information system (GIS) using
authentic landscapes based on topographic, hydrological and land cover
maps of County Durham, UK. Results were interpreted at both a catchment
and a regional scale.
3. Six representative strategies were explored that prioritized control
as follows: at random, in relation to human population density, or by
the size, age (new and old) or spatial distribution of weed
populations. These strategies were assessed at different intensities of
management (area treated per year) and for varying efficiencies
(proportion of plants destroyed) as well as the timeliness (how long
since the species became established) of implementations.
4. Strategies that prioritized control based on weed population and
spatial characteristics were most effective, with plant population size
and spatial distribution being the key parameters. The reduction in
geographical range within a catchment or region following control was
always greater for H. mantegazzianum than I. glandulifera due to its
slower rate of spread.
5. Successful control of both species at a regional scale is only
possible for strategies based on species distribution data, undertaken
at relatively high intensities and efficiencies. The importance of
understanding the spatial structure of the population and potential
habitat available, as well as being able to monitor the progress of the
eradication programme, is highlighted. Tentative conclusions an offered
as to the feasibility of eradicating these species at a regional scale.