Facultative mycorrhizal associations promote plant naturalization worldwide

Petr Pyšek,Jan Pergl,Martin Zobel,C Guillermo Bueno,Mark Van Kleunen,Maret Gerz,Wen‐Yong Guo,Franz Essl,Holger Kreft,Patrick Weigelt,Kateřina Štajerová,Marten Winter,Mari Moora,Wayne Dawson

doi:10.1002/ecs2.2937

Abstract

AbstractMycorrhizal symbiosis has received relatively little attention as a mechanism explaining plant naturalizations at a global scale. Here, we combined data on vascular plant species occurrences in over 840 mainland and island regions from the Global Naturalized Alien Flora (GloNAF) database with up‐to‐date databases of mycorrhizal associations. We tested whether the mycorrhizal type (arbuscular, AM; ectomycorrhizal, ECM; and non‐mycorrhizal, NM) and status (facultative and obligate) were associated with two measures of naturalization success, (1) naturalization incidence (reflecting the ability to naturalize, and expressed as whether or not a plant species is recorded as naturalized anywhere in the world) and (2) naturalization extent (expressed as the number of GloNAF regions where the species occurs). In total, we found information on mycorrhizal type and status for 3211 naturalized plant species and 4200 non‐naturalized plant species. Mycorrhizal plant species, both AM and ECM, were more likely to be naturalized and naturalized to a greater extent than NM plants. The effect of being an AM species was always stronger, with AM species having a greater naturalization extent than ECM species. Being the same mycorrhizal type or status, annual species were generally more likely to be naturalized than perennials. Species with facultative mycorrhizal associations were more successful than those with obligate mycorrhizal associations, but both groups tended to have a greater chance of being naturalized than NM species. These results indicate that being NM is generally less favorable for naturalization. Overall, our results confirm, at the global scale, those of regional studies that facultative association with AM provides plant species with a naturalization advantage. For the first time, we have shown that being mycorrhizal contributes not only to the size of the naturalized range, reflecting the ability to spread, but also to the ability to become naturalized in the first instance.

Highlights

A key stage in the process of plant invasion is the naturalization phase (Richardson and Pysek 2012), which involves the establishment of selfsustaining populations in resident plant communities after anthropogenic introduction into a new region (Divısek et al 2018)
Mycorrhizal associations in naturalized vs. global flora. For both the empirical and taxonomic datasets, the G tests of goodness of fit revealed significant differences between observed numbers, which reflect the frequencies of mycorrhizal types among naturalized plant species, and expected numbers, derived from the global flora based on Brundrett (2017; empirical—G = 955.99, df = 4, P < 0.001; taxonomic—G = 3285.9, df = 4, P < 0.001; Fig. 2 and Appendix S1: Fig. S4)
Naturalization extent Generally, analyses of the effect of mycorrhizal symbiosis on naturalization extent (Table 1) yielded similar results when we considered all regions, mainland regions, or islands separately

Summary

Introduction

A key stage in the process of plant invasion is the naturalization phase (Richardson and Pysek 2012), which involves the establishment of selfsustaining populations in resident plant communities after anthropogenic introduction into a new region (Divısek et al 2018). Success or failure in naturalization is driven by complex interactions of multiple factors including climatic matching between the native and introduced region, habitat legacy, propagule pressure (Lonsdale 1999), and species’ biological and ecological traits (van Kleunen et al 2015b, Pysek et al 2015). The role these factors play depends on the stage of invasion process and may differ for naturalized and invasive plants (Williamson 2006, Ku€ster et al 2008, Pysek et al 2009), that is, a subset of naturalized species that spread over large distances (Richardson et al 2000b). The role of mycorrhizal symbioses in plant invasions is becoming better understood (Delavaux et al 2019, Steidinger et al 2019)

Methods

Results

Conclusion