3.3 Plant community composition
Inter-annual precipitation fluctuation strongly shaped plant community
composition through altering the relative aboveground biomass of main
plant species (Table S2; Y: all p < 0.01). In
particular, the relative plot biomass of C. aristatum was
drastically decreased in the dry year (Fig. 4a–d). Mycorrhizal
suppression had no significant impact on plant community composition
across the two experimental years (Table S3; all p >
0.05). P input alone greatly enhanced the relative aboveground biomass
of C. aristatum and A. mongolicum (Table S2, Fig. 3).
Inter-annual precipitation fluctuation strongly changed species richness
and plant Shannon index (Table S3; Y: all p < 0.01),
which was higher in 2019 than in 2020 (Fig. S2). P input alone
significantly increased plant species richness from 2019 to 2020 (Fig.
S2a and b; F 1, 28 = 21.06, p <
0.01; F 1, 28 = 22.50, p < 0.01,
respectively), but N addition alone and fungicide application did not
change it (Table S3, all p > 0.05).