Figure legends
Figure 1 Soil temperature (oC, 10 cm) (a) and
soil moisture (%, 10 cm) (a) under different plant diversity and N
addition level from April to October 2019. Mean (±se, n = 4 or 8)
soil temperature (c) and soil moisture (d) for the whole growing season
under different plant diversity and N addition level in 2019. We applied
the linear mixed effects models to test the effects of treatments (plant
diversity and N addition) on soil temperature and soil moisture. We set
treatments as fixed factors, time and block as random factors in each
model to account for variation among repeated measurements of soil
temperature and moisture. Points and lines with different shape
represent different nitrogen addition levels, points with different
colour represent different plant diversity levels. N represents nitrogen
addition, D represents plant diversity.
Figure 2 Average first flowering day (a), last flowering day
(b), flowering duration (c), and flower number (d) under different plant
diversity and N addition levels. All the analyses were performed using
the linear mixed effects models to test the effects of treatments (plant
diversity and N addition) on flower phenology. Treatments were treated
as fixed factors, block was treated as a random factor. Points and lines
with different shape represent different N addition levels, points with
different colour represent different plant diversity levels. N
represents nitrogen addition, D represents plant diversity.
Figure 3 Average leaf mass (a), leaf area (b), specific leaf
area (c), leaf carbon content (d), leaf nitrogen content (e), and leaf
C/N ratio (f) under different plant diversity and N addition levels. All
the analyses were performed using the linear mixed effects models to
test the effects of treatments (plant diversity and N addition) on leaf
traits. Treatments were treated as fixed factors, block was treated as a
random factor. Points and lines with different shape represent different
N addition levels, points with different colour represent different
plant diversity levels. N represents nitrogen addition, D represents
plant diversity.
Figure 4 Average M. Sativa biomass (a), relative biomass
(b), relative abundance (c), and relative height (d) under different
plant diversity and N addition levels. All the analyses were performed
using the linear mixed effects models to test the effects of treatments
(plant diversity and N addition) on plant traits of M. Sativa .
Treatments were treated as fixed factors, block was treated as a random
factor. Points and lines with different shape represent different N
addition levels, points with different colour represent different plant
diversity levels. N represents nitrogen addition, D represents plant
diversity.
Figure 5 Partial correlations between the flowering events and
the light acquisition traits, nutrient acquisition traits, and abiotic
factors after controlling N addition and plant diversity levels. The
x-axis shows the factors of which the correlations with the flowering
events are examined. The size and colour of the circles indicate the
strength and sign of the correlation. Differences in circle size and
colour indicate the level of dependency of the correlation between the
flowering events and the examined factor after controlling N addition
and plant diversity levels. FFD, first flowering day; LFD, last
flowering day; FD, flowering duration; FN, flowering numbers; LM, leaf
mass; LA, leaf area; LL, leaf length; LW, leaf width; SLA, specific leaf
area; LN, leaf nitrogen content; LC, leaf carbon content; LCN, leaf
carbon/ nitrogen ratio; AB, aboveground biomass; PA, plant abundance;
PH, plant height; RB, relative biomass; RA, relative abundance; RH,
relative height; AN, available soil nitrogen; SM, soil moisture; ST,
soil temperature. *P <0.05; **P <0.01;
***P <0.01.
Figure 6 Relative contributions of light acquisition traits,
nutrient acquisition traits, and abiotic factors to flowering events.
Variation partitioning analysis was to identify the variance in the
first flowering day (a), the last flowering day (b), flowering duration
(c), and flowering numbers (d) explained by these three groups of biotic
and abiotic factors.
Figure 7 A structural equation modelling of plant diversity
loss and N addition on the first flowering day (a), the last flowering
day (b), the flowering duration (c), and flower number (d). Red and
black arrows represent significant positive and negative pathways,
respectively. Solid and dashed arrows indicate significant and
non-significant pathways, respectively. Numbers near the arrow indicate
the standardized path coefficients indicating the effect size of the
relationship with * indicating P < 0.05, ** indicatingP < 0.01, and *** indicating P <
0.001. Arrow width is proportional to the strength of the relationship.R2 represent the proportion of variance
explained for each dependent variable. The goodness-of-fit statistics
for the structural equation modelling are shown below each model. N,
nitrogen.