Compensation of plant functional groups as a key

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Supporting Information

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Table S1 Selected treatments from the full IMGRE experiment. “×” indicates the removal of a plant

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functional group (PFG). PFGs: PB, perennial bunchgrasses; PR, perennial rhizomes; PF, perennial forbs;

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AB, annuals/biennials. Treatment number

Number of PFGs removed

1

0

2

1

3

1

4

1

5

1

6

2

×

7

2

×

8

2

×

9

2

×

10

2

×

11

2

12

3

×

×

13

3

×

×

14

3

×

15

3

16

4

Total number of plots

5

AB

PF

PR

PB

Replicates 5

×

5 ×

5 ×

5 ×

×

5 ×

5 ×

× ×

×

5

5 5

×

5

×

5

×

5 ×

5

×

×

5

×

×

×

5

×

×

×

5 80

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Table S2 Treatments for detecting the effects of plant functional group (PFG) identity on

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above-ground plant biomass, soil properties, and the characteristics of soil microbial and nematode

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communities. PFGs: PB, perennial bunchgrasses; PR, perennial rhizomes; PF, perennial forbs; AB,

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annuals/biennials.

PB identity

PF identity

AB identity

Absence

Presence

Absence

Presence

Absence

Presence

Absence

Presence

PR

PR+PB

PB

PR+PB

AB

PF+AB

PF

PF+AB

PF

PR+PF

PF

PB+PF

PR

PR+PF

PR

PR+AB

AB

PR+AB

AB

PB+AB

PB

PB+PF

PB

PB+AB

PB+PF

PR+PB+PF

PR+PF

PR+PB+PF

PR+AB

PR+PF+AB

PR+PF

PR+PF+AB

PB+AB

PR+PB+AB

PR+AB

PR+PB+AB

PB+AB

PB+PF+AB

PB+PF

PB+PF+AB

PF+AB

PR+PF+AB

PF+AB

PB+PF+AB

PR+PB

PR+PB+PF

PR+PB

PR+PB+AB

PB+PF+AB PR+PB+PF+AB

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PR identity

PR+PF+AB PR+PB+PF+AB

PR+PB+AB PR+PB+PF+AB

PR+PB+PF PR+PB+PF+AB

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Table S3 Soil nematode food resources for nematode trophic groups and variables of below-ground

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communities used to explain variation in net ecosystem exchange (NEE). BF, bacterial-feeding

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nematodes; FF, fungal-feeding nematode; PF, plant-feeding nematodes; OC, omnivorous +

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carnivorous nematodes; FF:BF ratio, ratio of FF to BF nematodes; Ba PLFAs, bacterial PLFAs; Fu PLFAs,

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fungal PLFAs; F:B ratio, ratio of Fu to Ba PLFAs. Variables

Nematode food resources

Total nematode abundance (ind. g-1) Total PLFA abundance (nmol g-1) BF abundance (ind. g-1)

Ba PLFA abundance (nmol g-1)

FF abundance (ind. g-1)

Fu PLFA abundance (nmol g-1)

PF abundance (ind. g-1)

Above-ground plant biomass (g m-2)

OC abundance (ind. g-1)

Ba PLFA abundance (nmol g-1), Fu PLFA abundance (nmol g-1), BF abundance (ind. g-1), FF abundance (ind. g-1), PF abundance (ind. g-1)

FF:BF ratio

F:B ratio

BF relative abundance (%)

Ba PLFA relative abundance (mol%)

FF relative abundance (%)

Fu PLFA relative abundance (mol%)

PF relative abundance (%)

Above-ground plant biomass (g m-2)

OC relative abundance (%) NEE (μmol m-2 s-1)

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Ba PLFA relative abundance (mol%), Fu PLFA relative abundance (mol%), BF relative abundance (%), FF relative abundance (%), PF abundance (ind. g-1) Total PLFA abundance (nmol g-1), F:B ratio, Total nematode abundance (ind. g-1), FF:BF ratio

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Table S4 Simplified results of the effect of PFG identity or PFGs removal on below-ground

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communities, above-ground plant biomass, soil factors, and NEE using mixed linear models with loss

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of a specific number of PFGs or individual PFGs (absent or present) as fixed factors and block as a

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random factor. PFGs: PB, perennial bunchgrasses; PR, perennial rhizomes; PF, perennial forbs; AB,

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annuals/biennials. Microbes: Ba PLFAs, bacterial PLFAs; Fu PLFAs, fungal PLFAs; F:B ratio, ratio of Fu to

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Ba PLFAs; Nematodes: BF, bacterial-feeding nematodes; FF, fungal-feeding nematode; PF,

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plant-feeding nematodes; OC, omnivorous + carnivorous nematodes; FF:BF ratio, ratio of FF to BF

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nematodes;. NEE, net ecosystem exchange; Soil factors: SOC, soil organic C; TSN, total soil N; PC,

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principal components. Differences between loss of a specific number of PFGs or the absence and

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presence of individual PFGs are indicated (*, P