Results
Averaged across the harvest time
and soil treatments, invasive plant species tended to produce higher
total biomass (+102.5%) than native plants species (marginally
significant effect of invasion status; Table 1; Figure 2A). Total
biomass production was significantly increased over time (+88.0%)
(significant effect of harvest time; Table 1 & Fig. 2A), and the
increase in total biomass was significantly stronger for invasive plant
species (+112.1%) than for native plant species (+49.0%) (significant
effect of invasion status × harvest time; Table 1 & Figs. 2A & S1)
over time. But root mass fraction was significantly decreased over time
(-3.3%) of the plants (significant effect of harvest time; Table 1 &
Fig. 2B), and this effect were stronger on native plant species than on
invasive plant species, the decrease in root mass fraction of native
plant species (-17.0%) over time, but increased of invasive plant
species (+11.8%) (significant effect of invasion status × harvest time;
Table 1 & Figs. 2B & S1) over time. The presence of soil microbes
significantly decreased the root mass fraction (-13.6%) of the plants
(significant effect of soil; Table 1 & Figs. 2B & S2).
For total biomass of the plants, we found a marginally significant
three-way interaction of the
invasion status, harvest time and soil microbes treatments (marginally
significant effect of plant invasion status × harvest time × soil; Table
1 & Fig. 2A). Specifically, the presence of soil microbes decreased the
total biomass of invasive plant species when at second harvest
(-14.5%), however, under the other three combinations of harvest time
and invasion status treatments, it tended to increase total biomass
(first & invasive: +4.1 %; first & native: +7.3%; second & native:
+2.7%).
Separate analyses of the main and interactive effects of plant invasion
status, soil, harvest time treatments on total biomass found that
significant differences in invasion status on Sphagneticola ,Paspalum , and Solidago (Table S3; Figs. 2a-1 to a-3), and
significant differences in harvest time on Sphagneticola andPaspalum (Table S3; Figs. 2a-1 & a-2). Significant interactions
between invasion status and soil treatments, and significant
interactions between invasion status and harvest time treatments were
found in Paspalum (Table S3; Fig. 2a-2). Significant interactions
between invasion status and harvest time treatments were found inSolidago and Alternanthera , respectively (Table S3; Figs.
2a-3 & a-4). In addition, significant three-way interaction was found
in Paspalum (Table S3; Fig. 2a-2).
Separate analyses of the main and interactive effects of plant invasion
status, soil, harvest time treatments on root mass fraction found that
significant differences in invasion status on Sphagneticola ,Paspalum , and Alternanthera (Figs. 2b-1, b-2 & b-4), and
marginally significant differences in invasion status on Solidago(Table S4; Fig. 2b-3). Significant differences in harvest time onPaspalum (Fig. 2b-2), and marginally significant differences in
harvest time on Sphagneticola , Solidago andAlternanthera , respectively (Table S4; Figs. 2b-1, b-3 & b-4).
Soil treatment had a significant effect on three congeneric pairs of
invasive and native plant species (Table S4; Figs. 2b-1 to b-3).
Significant interactions between invasion status and harvest time were
found in Paspalum and Alternanthera (Table S4; Fig. 2b-3
& b-4). Significant interactions and marginally significant
interactions between invasion status and soil treatments was found inPaspalum and Solidago , respectively (Table S4; Fig. 2b-2
& b-3). But only significant interactions between soil and harvest time
treatments was found in Solidago (Table S4; Fig. 2b-3). In
addition, two significant three-way interaction were found inPaspalum , and Solidago (Table S4; Fig. 2b-2 & b-3).