Competition mode and soil nutrient status shape the role of soil
microbes in the diversity--invasibility relationship
Abstract
Understanding the relationship between plant diversity and invasibility
is essential in invasion ecology. Elton proposed that species-rich
communities are more resistant to invasions than species-poor
communities. While soil microorganisms play a crucial role in regulating
this diversity–invasibility relationship, the effects of plant
competition mode and soil nutrient status on their role remain unclear.
To address this, we conducted a two-stage greenhouse experiment. Soils
were first conditioned by growing nine native species separately in them
for one year, then mixed in various configurations with soils
conditioned using one, three, or six species, respectively. Next, we
inoculated the mixed soil into sterilized substrate soil and planted the
alien species Rhus typhina and native species Ailanthus altissima as
test plants. We set up two competition modes (intraspecific and
interspecific) and two nutrient levels (fertilization using slow-release
fertilizer and non-fertilization). Under intraspecific competition,
regardless of fertilization, the biomass of the alien species was higher
in soil conditioned by six native species. In contrast, under
interspecific competition, the biomass increased without fertilization
but remained stable with fertilization in soil conditioned by six native
species. Analysis of the soil microbial community suggests that the
greater diversity of arbuscular mycorrhizal fungi (AMF) in the soil
conditioned by six native species might reflect the primary influence on
R. typhina growth, but the interaction between AMF and R. typhina varies
depending on competition mode and nutrient status. Our findings suggest
that the soil microbiome is pivotal in mediating the
diversity–invasibility relationship, and this influence varies with
competition mode and nutrient status.