Harmonising the invasiveness concept The EPPO prioritization scheme as a tool to identify the most invasive plant species in Europe Etienne Branquart, Mark Hill, Cathy Maguire, Uwe Starfinger, Johan van Valkenburg & Sarah Brunel Les abords des cours d'eau constituent des milieux très propices aux invasions biologiques (i) parce qu'il s'agit de milieux régulièrement perturbés par les crues, favorables à l'établissement d'espèces pionnières et (ii) parce que l'eau véhicule facilement les diaspores, facilitant ainsi la dispersion.

? Apparent dichotomy between scientific questions and societal and motivational issues (see e.g. Richardson et al. 2000, Davis & Thomson 2001, Larson 2007 & Colautti & Richardson 2009); Impact often perceived by scientists as not clearly associated to any specific ecological process and linked to subjective intepretation! Des mesures préventives contre les espèces invasives

Standardization of terminology The stage-based approach of Colautti & McIsaac (2004) SPREAD filter Stage III (localized + numerically rare) ENVI filter Stage IVa (widespread + numerically rare) EARLY WARNING Stage IVb (localized + dominant) Stage V (widespread + dominant) DISP = local dispersal ENVI = environment and community suitability ENVI filter DISP filter Des mesures préventives contre les espèces invasives

Standardization of the impact definition Loss in native species through competitive interactions at the stand scale at the landscape scale Data : Hejda et al. 2009, Journal of Ecology 97: 393-403 Des mesures préventives contre les espèces invasives

Standardization of the impact definition Species loss is density dependent Data : Hejda et al. 2009, Journal of Ecology 97: 393-403 Des mesures préventives contre les espèces invasives

Three main questions Harmonising the invasiveness concept To compare the invasiveness status of non-native plant species based on national definitions and a standardized terminology inspired by the stage-based approach of Colautti & McIsaac (local spread potential + plant capacity to dominate native vegetation); To see if the use of this standardized terminology allows to reduce subjective interpretation and to define plant invasiveness in an unambiguous way; To look how the use of standardized terminology may help in the development of early warning systems. Des mesures préventives contre les espèces invasives

1. The EPPO prioritization process 2. Testing the EPPO process 3. Early warning outcomes 4. Conclusion & perspectives Des mesures préventives contre les espèces invasives

The EPPO proritization process for IAP General principles The process is designed: to produce a reference list of Invasive Alien Plants (IAP) that are established or could potentially establish in the EPPO region, to determine which IAP have the highest priority for an EPPO pest risk analysis (= screening tool to identify quarantine organisms). Plant species invasiveness: (potential for establishment), local spread capacity, environmental impact Des mesures préventives contre les espèces invasives

Category Dispersion distances Dispersion agents Local spread capacity Natural dispersion + unintentional human assistance Assessed through a combination of plant life-history traits and field dispersion data. Category Dispersion distances Dispersion agents Low < a few meters/year - Medium < 100 meters/year ants High >> 100 meters/year wind, water vertebrates. Des mesures préventives contre les espèces invasives

Non-native species dominance Environmental impact Dominance & colonization of semi-natural habitats Proxy = plant species dominance. Ability to make large, dense and persistent populations. Cover > 80 %. Exclusion of native plant species. Species occurrence in semi-natural habitats is also taken into account. Non-native species dominance Low High Habitats Man-made habitats Natural habitats Low Medium Medium High Des mesures préventives contre les espèces invasives

Invasiveness categories Combination of spread and impact data High Medium Low Impact (dominance) Low Medium High Spread capacity Des mesures préventives contre les espèces invasives

Invasiveness categories Combination of spread and impact data High Medium Low Invasiveness Impact (dominance) High (V) Medium Low Low Medium High Spread capacity Des mesures préventives contre les espèces invasives

1. The EPPO prioritization process 2. Testing the EPPO process 3. Early warning outcomes 4. Conclusion & perspectives Des mesures préventives contre les espèces invasives

EPPO vs national definitions The European Atlantic region set of 27 non-native plant species established in Europe before 1950; independent assessments using the EPPO process by experts of 5 countries within the European Atlantic region: BE, DE, GB, IE and NL; comparison of plant invasiveness status based on national and EPPO definitions. Des mesures préventives contre les espèces invasives

EPPO vs national definitions National invasiveness categories Protocol Assessor Spread Impact BE DE GB IE NL ISEIA E. Branquart * *** GABLIS U. Starfinger ns *** ISEIA M. Hill ns *** ISI C. Maguire ns *** - J. van Valkenburg *** * Des mesures préventives contre les espèces invasives

National definitions Mean stdev Invasiveness 0.58 High Medium Low Des mesures préventives contre les espèces invasives

EPPO definition Mean stdev Invasiveness 0.31 High Medium Low Des mesures préventives contre les espèces invasives

EPPO vs national definitions EPPO invasiveness categories / high Medium Low Crassula helmsii Fallopia japonica Heracleum mantegazzianum Impatiens glandulifera Ludwigia grandiflora Prunus serotina Rosa rugosa Impact (dominance) Low Medium High Spread capacity Des mesures préventives contre les espèces invasives

EPPO vs national definitions EPPO invasiveness categories / medium High Medium Low Impact (dominance) Cornus sericea Lysichiton americanus Robinia pseudacacia Spiraea spp. Low Medium High Spread capacity Des mesures préventives contre les espèces invasives

EPPO vs national definitions EPPO invasiveness categories / medium High Medium Low Impact (dominance) Buddleja davidii Mimulus guttatus Oenothera spp. Senecio inaequidens Low Medium High Spread capacity Des mesures préventives contre les espèces invasives

EPPO vs national definitions EPPO invasiveness categories / medium High Medium Low Impact (dominance) Duchesnea indica Quercus rubra Low Medium High Spread capacity Des mesures préventives contre les espèces invasives

1. The EPPO prioritization process 2. Testing the EPPO process 3. Early warning outcomes 4. Conclusion & perspectives Des mesures préventives contre les espèces invasives

Sounding the early warning bell Relevant EPPO invasiveness categories? High Medium Low Impact (dominance) Low Medium High Spread capacity Des mesures préventives contre les espèces invasives

Sounding the early warning bell 1 Sounding the early warning bell 1. Crossing of the environmental barrier (nat. habitats) Country Habitat Amelanchier lamarkii Cornus sericea Cotoneaster horizontalis Helianthus tuberosus Lupinus polyphyllus Lysichiton americanus Rhododendron ponticum Spiraea spp. NL Heathlands BE, IE Damp woodlands BE Chalk grasslands BE, DE River banks DE Acidic grasslands DE Damp woodlands GB, IE Heaths and woodlands BE Riparian areas Des mesures préventives contre les espèces invasives

Spread capacity: medium Cornus sericea Spread capacity: medium Dominance: high

Cotoneaster spp. Spread capacity: high Dominance: high

Rhododendron ponticum Spread capacity: medium to high Dominance: high

Sounding the early warning bell 2. New detrimental incomers Giant Rhubarb Purple Dewplant Redvein Maple Gunnera tinctoria Disphyma crassifolium Acer rufinerve Des mesures préventives contre les espèces invasives

Gunnera tinctoria Spread capacity: high Dominance: high

Disphyma crassifolium Spread capacity: high Dominance: high

Dominance: medium to high Acer rufinerve Spread capacity: high Dominance: medium to high

1. The EPPO prioritization process 2. Testing the EPPO process 3. Early warning outcomes 4. Conclusion & perspectives Des mesures préventives contre les espèces invasives

Three main questions Harmonising the invasiveness concept To compare the invasiveness status of non-native plant species based on national definitions and a standardized terminology inspired by the stage-based approach of Colautti & McIsaac >>> strong differences between national and standardized terminologies (national defintions are often impact-oriented) To see if the use of this standardized terminology allows to define plant invasiveness in an unambiguous way >>> strong reduction of data heterogeneity and improvement of the repeatability within a biogeographic region To look how the use of standardzed terminology may help in the development of early warning systems >>> provides an objective framework to document detrimental effects of newcomers and to detect behavioural shifts of established populations of non-native plant species. Des mesures préventives contre les espèces invasives

Data integration for early warning based on standardized definitions and protocols Data integration at a regional level (regional consensus under the umbrella of a European organization) Data integration at national level (national consensus) Independent assessments by national experts Country 1 Country 2 Country 3 Des mesures préventives contre les espèces invasives

Monitoring by Member States Field data needed to assess spread and impacts Des mesures préventives contre les espèces invasives