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Table 4 Models of shrub layer alpha diversity, estimated using Gaussian distribution GLMMs (for species richness – Poisson distribution and z statistic instead of t). Significant variables were bolded. AICc – Akaike Information Criterion, AICc0 – AIC of null model (intercept-only), AICcfull – AIC of full model (including all hypothesized variables), R2m – marginal coefficient of determination, R2C – conditional coefficient of determination; *for Shannon’s index model block random effect SD = 0.43, AICc = 198.4, AICcfull = 275.0, AICc0 = 199.5, R2m = 0.005, R2c = 0.577

From: How do invasive trees impact shrub layer diversity and productivity in temperate forests?

Response

Variable

Estimate

SE

t value

Pr( >|t|)

Species richness

(Intercept)

0.2992

0.2806

1.0660

0.2863

Block SD = 0.464

type = Pinus poor

1.1945

0.3506

3.4070

0.0007

R2m = 0.185

type = Pinus poor—Ps

1.0788

0.2885

3.7390

0.0002

R2c = 0.611

type = Pinus rich

1.1043

0.2562

4.3110

 < 0.0001

AICc = 735.0

type = Pinus rich—Ps

1.3298

0.2789

4.7690

 < 0.0001

AICcfull = 749.7

type = Q. petraea

0.8720

0.3016

2.8910

0.0038

AICc0 = 757.4

type = Q. rubra

0.5930

0.3084

1.9230

0.0545

 

type = Quercus-Acer-Tilia

1.2184

0.2769

4.3990

 < 0.0001

 

type = Robinia

1.0889

0.2878

3.7830

0.0002

 

plot area

2.2364

1.1208

1.9950

0.0460

Shannon’s index*

(Intercept)

0.6744

0.1174

5.7430

 < 0.0001

 

plot area

1.1690

0.9572

1.2210

0.2240

Faith’s phylogenetic diversity

(Intercept)

-110.5760

314.8080

-0.3510

0.7259

Block SD = 161.4

type = Pinus poor

469.2930

146.7530

3.1980

0.0017

R2m = 0.200

type = Pinus poor—Ps

338.9640

108.1080

3.1350

0.0021

R2c = 0.458

type = Pinus rich

352.0510

92.8780

3.7900

0.0002

AICc = 2134.2

type = Pinus rich—Ps

423.9690

110.8620

3.8240

0.0002

AICcfull = 2135.1

type = Q. petraea

278.2840

104.7440

2.6570

0.0088

AICc0 = 2317.8

type = Q. rubra

153.7750

113.7170

1.3520

0.1786

 

type = Quercus-Acer-Tilia

471.3920

121.1010

3.8930

0.0002

 

type = Robinia

400.9820

133.4240

3.0050

0.0031

 

plot area

1317.3750

653.2330

2.0170

0.0456

 

soil = Cambic Brunic Arenosols

-57.7010

99.0880

-0.5820

0.5615

 

soil = Cambisols

311.7780

153.8550

2.0260

0.0513

 

soil = Fluvic cambisols

17.1870

121.5210

0.1410

0.8877

 

soil = Haplic_luvisols

16.2190

77.1860

0.2100

0.8339

 

soil = Luvisols

-9.9400

156.6710

-0.0630

0.9495

 

soil = Phaeozems

7.1050

174.6060

0.0410

0.9676

 

soil pH

16.5210

51.5050

0.3210

0.7489

 

soil C:N ratio

1.1630

6.2510

0.1860

0.8526

 

slope

5.0060

4.0180

1.2460

0.2149

Mean pairwise distance

(Intercept)

72.4005

90.1711

0.8030

0.4236

Block SD = 173.8

type = Pinus poor

141.5714

44.7482

3.1640

0.0019

R2m = 0.156

type = Pinus poor—Ps

87.0001

33.2801

2.6140

0.0099

R2c = 0.163

type = Pinus rich

90.0641

28.8302

3.1240

0.0022

AICc = 1786.9

type = Pinus rich—Ps

96.5288

33.6354

2.8700

0.0047

AICcfull = 1791.2

type = Q. petraea

66.5041

31.7062

2.0980

0.0378

AICc0 = 1913.2

type = Q. rubra

62.8079

35.9769

1.7460

0.0830

 

type = Quercus-Acer-Tilia

122.4130

37.1091

3.2990

0.0012

 

type = Robinia

120.1737

40.9860

2.9320

0.0039

 

plot area

87.6556

196.8772

0.4450

0.6569

 

soil = Cambic Brunic Arenosols

-21.9510

25.6269

-0.8570

0.3953

 

soil = Cambisols

4.3161

30.5268

0.1410

0.8890

 

soil = Fluvic cambisols

-20.8138

34.5952

-0.6020

0.5487

 

soil = Haplic_luvisols

-18.3451

20.1093

-0.9120

0.3653

 

soil = Luvisols

37.9113

42.9147

0.8830

0.3802

 

soil = Phaeozems

-12.8832

44.5796

-0.2890

0.7735

 

soil pH

-0.1346

14.1209

-0.0100

0.9924

 

soil C:N ratio

1.5462

1.8371

0.8420

0.4016

 

slope

1.0309

1.2053

0.8550

0.3939

Functional richness

(Intercept)

-3.0597

2.5481

-1.2010

0.2327

Block SD = 1.654

type = Pinus poor

5.7151

2.8663

1.9940

0.0490

R2m = 0.306

type = Pinus poor—Ps

4.0715

2.5775

1.5800

0.1175

R2c = 0.471

type = Pinus rich

4.4319

2.2961

1.9300

0.0566

AICc = 592.2

type = Pinus rich—Ps

3.8239

2.4957

1.5320

0.1288

AICcfull = 625.8

type = Q. petraea

3.9039

2.4783

1.5750

0.1186

AICc0 = 633.7

type = Q. rubra

0.7129

2.5616

0.2780

0.7814

 

type = Quercus-Acer-Tilia

3.5561

2.4585

1.4460

0.1512

 

type = Robinia

3.5517

2.5750

1.3790

0.1709

 

plot area

29.7410

9.9720

2.9820

0.0036

 

soil = Cambic Brunic Arenosols

1.3442

1.4428

0.9320

0.3545

 

soil = Cambisols

4.8713

1.8885

2.5790

0.0181

 

soil = Fluvic cambisols

4.7057

1.5907

2.9580

0.0040

 

soil = Haplic_luvisols

3.1945

1.2380

2.5800

0.0126

 

soil = Luvisols

1.1916

2.1302

0.5590

0.5772

 

soil = Phaeozems

2.7698

1.8606

1.4890

0.1422

 

soil pH

-0.1346

14.1209

-0.0100

0.9924

Functional dispersion

(Intercept)

0.4997

0.2537

1.9700

0.0509

Block SD = 0.504

type = Pinus poor

0.9499

0.3459

2.7460

0.0068

R2m = 0.122

type = Pinus poor—Ps

0.2492

0.2577

0.9670

0.3350

R2c = 0.513

type = Pinus rich

0.7353

0.2215

3.3190

0.0011

AICc = 347.8

type = Pinus rich—Ps

0.5377

0.2616

2.0550

0.0416

AICcfull = 408.9

type = Q. petraea

0.8143

0.2533

3.2150

0.0016

AICc0 = 349.7

type = Q. rubra

0.3549

0.2721

1.3040

0.1944

 

type = Quercus-Acer-Tilia

1.0440

0.2654

3.9330

0.0001

 

type = Robinia

0.6024

0.2921

2.0630

0.0409

 

plot area

-0.3263

1.5009

-0.2170

0.8282

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Annals of Forest Science

ISSN: 1297-966X