Introduction
Alien plant invasions still accelerating (Seebens et al. 2020), and it
has seriously threatened biodiversity and ecosystem function (Lewis et
al. 2015, Pyšek et al. 2020, Schaffner et al. 2020, Vilà et al. 2011).
Soil biota as a driver of successful alien plant invasions was supported
by many studies (Callaway et al. 2004, Keane et al. 2002, Reinhart et
al. 2006, Reinhart et al. 2003, Zhang et al. 2020). Mycorrhizal fungi
contribute to increased water and nutrient utilization to promote plant
growth (Batten et al. 2006, Keane et al. 2002), but pathogens decrease
plant growth (Maron et al. 2011). The enemy release hypothesis (ERH)
predicts that absence or reduced the numbers of enemies, such as
microbial pathogens, in their introduced range drives invasion success
of alien plants (Callaway et al. 2004, Keane et al. 2002). Prunus
serotina as a native species in United States but invasive in Europe, a
study showed that soil microbial from United States killed seedlings ofPrunus serotina , while soil microbes in European (i.e.,
non-native range) produced positive feedback on seedling
growth (Reinhart et al. 2003). On
the other hand, invasive plants may benefit from beneficial microbes.
The enhanced mutualist hypothesis (Callaway et al. 2004) predicts that
invasive plants may recruit more arbuscular mycorrhizal fungi in their
non-native ranges, which contributes to their successful invasion. For
example, Tian et al. (2021) found that arbuscular mycorrhizal fungi
colonization and biomass of invasive plants were higher than that in
their native range. Compared to native plants, invasive plants tend to
enhance their mutualistic relationship with arbuscular mycorrhizal fungi
(Davis 2018). However, this advantage may weak over time, as either
alien invasive species benefit from the presence of beneficial bacteria
or the escape of soil natural enemies in short-term, while enemies
accumulate in large numbers with the abundance of invasive species
(Dostál et al. 2013, Lau et al. 2016, Mitchell et al. 2010).
Several studies have shown that soil microbes are influenced by temporal
variation in alien plant invasions. In introduced range, pathogen
richness increased with the invasive plant residence time, while the
proportional release from pathogens decreased, and the increase in
pathogenic microbes may suppress the growth of invasive plants
themselves, thereby inhibited their invasion (Callaway et al. 2013,
McGinn et al. 2018, Mitchell et al. 2010, Stricker et al. 2016). But a
study showed that promotion of soil microbes on invasive plants
independent of invasion period (Day et al. 2015). There are also studies
have found that microbes richness tended to decrease with increasing
invasion history, but arbuscular mycorrhizal fungal communities showed
increasing recovery (Lankau 2011). The mixed results suggest that
whether invasive plants benefit from beneficial microbes, escape from
soil pathogens, or are more strongly suppressed by soil pathogens are
related to temporal variation, but how soil microbes affect invasive
plants over time remains uncertain.
Although it has been confirmed soil microbes affect invasive plants was
relative to temporal variation. But we usually focus on the effect of
soil microbes on a certain growth stage of invasive plants and native
plants (e.g., seedlings; Reinhart et al. 2003), rather than changes in
continuous growth processes. A meta-analysis found that soil microbes
had a greater effect on invasive plants than native plants, and this
effect by soil microbes tended to weak over time since introduction (Liu
et al. 2023). However, the above research results are all based on
comparing the historical time of invasion, and no research has focused
on that in the short term. Therefore, understanding the differences how
soil microbes affect invasive plants and native plants in short term may
help us better understand the mechanisms of invasive plant invasion.
To test the effects of soil biota and temporal variation in short-term,
as well as their interactions on invasive plant species and native
plants species, we grew four congeneric perennials pairs of invasive
plant species and native plant species under soil treatments (living vs
sterilized) and harvest time treatments (first vs second). We predicted
that soil microbes have different effects on invasive plant species and
native plant species over time in short-time, and for invasive plants,
will show a result of promoting first and then inhibiting.