Reduced plant–soil feedback of plant species expanding their range as compared to natives

Abstract

Summary 1.As a result of global warming, species may spread into previously cool regions. Species that disperse faster than their natural enemies may become released from top-down control. We investigated whether plants originating from southern Europe and recently established in north-western Europe experience less soil pathogen effects than native species. 2. We selected three plant species originating from southern Europe that have immigrated into the Netherlands and three similar native Dutch species. All six plant species were grown in sterilized soils with a soil inoculum collected from the rhizospheres of field populations. As a control we grew a series of all six plant species with a sterilized rhizosphere inoculum. 3. We harvested the plants, added the conditioned soil to sterilized soil and grew a second generation of all six plant species in order to test for each plant pair feedback effects from the conditioned soil communities to conspecifics and heterospecifics. 4. The effect of the soil community is dependent on plant species, and is dependent on soil fertility in only one of the three pairs. 5. Soil conditioning caused less biomass reduction to exotic plant species than to native species, suggesting that exotic immigrants are less exposed to soil pathogens than similar native plant species. 6. Our results suggest that plant species that expand their range as a result of climate change may become released from soil pathogenic activity. Whether the exotics are released from soil pathogens, or whether they experience enhanced benefit from mutualistic symbionts remains to be studied. We conclude that range expansion may result in enemy release patterns that are similar to artificially introduced invasive exotic plant species. 7. The escape from enemies through range shifts changes key biotic interactions and complicates predictions of future distribution and dominance.

In their native range, invasive plants are held in check by negative soil-feedbacks

“…Kulmatiski et al (2008) and Callaway et al (2011) suggested that missing plant-soil feedbacks may explain why some non-native plants become invasive and dominant in a new biogeographical range whereas others do not. The advantage of invasive species over native species in new ranges may, in addition, be due to negative soilfeedbacks affecting the native, but not the invasive plants (Klironomos 2002, van Grunsven et al 2007, although this effect may weaken over time in the new ranges as new enemies adjust to invasive species (Diez et al 2010).…”

Disease in Natural Plant Populations, Communities, and Ecosystems: Insights into Ecological and Evolutionary Processes

“…Another approach focuses on whether plant-microbe interactions change as plants from warmer climates invade more northern habitats. Recent work, for example, suggested reduced soil pathogen effects (or, alternatively, increased soil mutualist activity) for plant species that moved into northwest Europe compared to plant species native to this region (133).…”

Range-expanding plant species and their belowground neighbours : digging into novel interactions

“…Moreover, these range-expanders may experience less negative effects of soil organisms in their new range than congeneric natives (van Grunsven et al 2007;Engelkes et al 2008). This suggests that range shifts result in a release from natural enemies, which has been proposed as an important cause of invasiveness of introduced exotic species (Keane & Crawley 2002;Mitchell & Power 2003).…”

“…Nevertheless, within their new range, the few studies published thus far have shown that rangeexpanding plant species on average accumulate fewer pathogens and root-feeding nematodes, and are less negatively affected by soil communities than related native plant species (van Grunsven et al 2007;Engelkes et al 2008;Morriën, Duyts & Van der Putten 2012;Morriën & van der Putten 2013).…”

“…In their new range, successful range-expanding plant species on average are less negatively affected by soil communities than congeneric natives (van Grunsven et al 2007;Engelkes et al 2008). This effect has been explained by the on average lower accumulation of soil-borne fungal pathogens (Morriën & van Therefore, the aim of the present study was to examine how differences in plant-nematode interactions between range-expanding and native plant species relate to differences in root chemistries.…”