Biological Invasions

, Volume 16, Issue 3, pp 535–551

A standardized set of metrics to assess and monitor tree invasions

  • John R. U. Wilson
  • Paul Caplat
  • Ian A. Dickie
  • Cang Hui
  • Bruce D. Maxwell
  • Martin A. Nuñez
  • Aníbal Pauchard
  • Marcel Rejmánek
  • David M. Richardson
  • Mark P. Robertson
  • Dian Spear
  • Bruce L. Webber
  • Brian W. van Wilgen
  • Rafael D. Zenni
Original Paper

Abstract

Scientists, managers, and policy-makers need functional and effective metrics to improve our understanding and management of biological invasions. Such metrics would help to assess progress towards management goals, increase compatibility across administrative borders, and facilitate comparisons between invasions. Here we outline key characteristics of tree invasions (status, abundance, spatial extent, and impact), discuss how each of these characteristics changes with time, and examine potential metrics to describe and monitor them. We recommend quantifying tree invasions using six metrics: (a) current status in the region; (b) potential status; (c) the number of foci requiring management; (d) area of occupancy (AOO) (i.e. compressed canopy area or net infestation); (e) extent of occurrence (EOO) (i.e. range size or gross infestation); and (f) observations of current and potential impact. We discuss how each metric can be parameterised (e.g. we include a practical method for classifying the current stage of invasion for trees following Blackburn’s unified framework for biological invasions); their potential management value (e.g. EOO provides an indication of the area over which management is needed); and how they can be used in concert (e.g. combining AOO and EOO can provide insights into invasion dynamics; and we use potential status and threat together to develop a simple risk analysis tool). Based on these metrics, we propose a standardized template for reporting tree invasions that we hope will facilitate cross-species and inter-regional comparisons. While we feel this represents a valuable step towards standardized reporting, there is an urgent need to develop more consistent metrics for impact and threat, and for many specific purposes additional metrics are still needed (e.g. detectability is required to assess the feasibility of eradication).

Keywords

Biodiversity assessments Biological invasions Invasive alien species Management Impact Distribution Non-native 

Supplementary material

10530_2013_605_MOESM1_ESM.doc (44 kb)
Supplementary material 1 (DOC 51 kb)
10530_2013_605_MOESM2_ESM.doc (85 kb)
Supplementary material 2 (DOC 85 kb)

Copyright information

© Springer Science+Business Media Dordrecht 2013

Authors and Affiliations

  • John R. U. Wilson
    • 1
    • 2
  • Paul Caplat
    • 3
  • Ian A. Dickie
    • 4
    • 5
  • Cang Hui
    • 2
  • Bruce D. Maxwell
    • 6
  • Martin A. Nuñez
    • 7
  • Aníbal Pauchard
    • 8
  • Marcel Rejmánek
    • 9
  • David M. Richardson
    • 2
  • Mark P. Robertson
    • 10
  • Dian Spear
    • 1
    • 2
  • Bruce L. Webber
    • 11
    • 12
  • Brian W. van Wilgen
    • 2
    • 13
  • Rafael D. Zenni
    • 14
  1. 1.Invasive Species Programme, South African National Biodiversity InstituteKirstenbosch National Research CentreClaremontSouth Africa
  2. 2.Department of Botany and Zoology, Centre for Invasion BiologyStellenbosch UniversityMatielandSouth Africa
  3. 3.Department of Physical Geography and Ecosystem SciencesUniversity of LundLundSweden
  4. 4.Landcare ResearchLincolnNew Zealand
  5. 5.Bio-Protection Research CentreLincoln UniversityLincolnNew Zealand
  6. 6.Department of Land Resources and Environmental SciencesMontana State UniversityBozemanUSA
  7. 7.Laboratorio Ecotono, INIBIOMA, CONICETUniv. Nacional del ComahueSan Carlos de BarilocheArgentina
  8. 8.Facultad de Ciencias Forestales, Institute of Ecology and Biodiversity (IEB)Universidad de ConcepciónConcepciónChile
  9. 9.Department of Evolution and EcologyUniversity of California, DavisDavisUSA
  10. 10.Department of Zoology and Entomology, Centre for Invasion BiologyUniversity of PretoriaPretoriaSouth Africa
  11. 11.CSIRO Ecosystem SciencesP.O. WembleyAustralia
  12. 12.School of Plant BiologyThe University of Western AustraliaCrawleyAustralia
  13. 13.CSIR, Natural Resources and the EnvironmentStellenboschSouth Africa
  14. 14.Department of Ecology and Evolutionary BiologyThe University of TennesseeKnoxvilleUSA

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