Oikos OIK-06348

Benavides, R., Scherer-Lorenzen, M. and Valladares, F. 2019.

The functional trait space of tree species is influenced by the

species richness of the canopy and the type of forest. – Oikos

doi: 10.1111/oik.06348

Appendix

Trait data and sampling design

Table A1.1. Plot design and species composition in each study site, a boreal forest, a mountainous

beech forest (temperate), and a Mediterranean forest.

Boreal Temperate Mediterranean

Bp Pa Ps No. plots Aa Ap Fs Pa No. plots Pn Ps Qi Qf No. plots x 4 x 2 x 3

Monoculture x

4 x

2

x 3

x 4

x

2

x

3

- - - - x 2 x 3 x x 4 x x 2 x x 3

x x 4 x x

2 x x

3

2-sp mixture x

x 4

x x 2

x

x 3

- - - - x

x

3

x x 3

- - - - x

x 1 x

x

3 x x x 4 x x x 2 x x x 3

3-sp mixture - - - - x

x x 3 x x

x 3

- - - - x x x 2 - - - - -

4-sp mixture - - - - x x x x 3 x x x x 3

Total 28 28 36

Bp: Betula pendula; Pa: Picea abies; Ps: Pinus sylvestris; Aa: Abies alba; Ap: Acer pseudoplatanus; Fs: Fagus sylvativa; Pn: Pinus nigra; Qf: Quercus faginea; Qi: Quercus ilex.

Table A1.2. Sample size for each surveyed species in the three study sites (a boreal, a mountainous

beech forest (temperate), and a Mediterranean forest). The number of sampled trees is after

removing sampled individuals with missing data.

Type of forest Target species No. plots Sampled trees

Sampled leaves

Boreal Betula pendula 16 142 710 Picea abies 16 160 800 Pinus sylvestris 16 158 790

Temperate Abies alba 15 144 720 Acer pseudoplatanus 12 113 565 Fagus sylvatica 17 181 905 Picea abies 15 143 715

Mediterranean Pinus nigra 21 208 1040 Pinus sylvestris 15 133 665 Quercus faginea 21 190 950

Quercus ilex 15 143 715 TOTAL 92 1719 8575

Table A1.3. Coefficients of correlation (spearman) between traits in the three study forests -a boreal

forest, a mountainous beech forest (temperate), and a Mediterranean forest-. Study traits are H:

height; dbh: diameter at breast height; Hc: crown height; CP: crown projection area; SS: slenderness

(ratio between height and dbh); CPdbh: crown ratio (ratio between crown projection and dbh);

CLR: crown length ratio (ratio between crown height and total height); N and C leaf content; leaf

C:N; SLA: specific leaf area; LDMC: leaf dry matter content; LA: leaf area. In grey non-significant

coefficients (α=0.05).

dbh H Hc CA SS CPdbh CLR N C C:N SLA LDMC LA

bore

al

dbh 1.00 0.73 0.26 0.73 -0.66 0.25 0.03 0.07 -0.08 -0.07 -0.07 0.07 0.07 H 1.00 0.55 0.62 -0.05 0.27 -0.14 0.30 0.19 0.17 0.24 -0.08 0.32 Hc 1.00 0.24 0.21 0.10 -0.87 0.29 -0.15 -0.17 0.44 -0.17 0.53 CA 1.00 -0.44 0.82 0.03 0.32 0.15 0.17 0.21 -0.06 0.29 SS 1.00 -0.15 -0.22 0.21 0.28 0.25 0.35 -0.17 0.26 CPdbh 1.00 0.06 0.37 0.27 0.30 0.33 -0.13 0.33 CLR 1.00 -0.16 0.31 0.32 -0.38 0.13 -0.44 N 1.00 0.64 0.61 0.63 -0.45 0.82 C 1.00 0.97 0.45 -0.24 0.33 C:N 1.00 0.44 -0.21 0.31 SLA 1.00 -0.53 0.76 LDMC 1.00 -0.50 LA 1.00

tem

pera

te

dbh 1.00 0.80 0.44 0.65 -0.69 0.05 0.12 -0.24 -0.26 -0.28 -0.45 0.29 -0.23 H 1.00 0.61 0.47 -0.24 -0.05 0.04 -0.29 -0.27 -0.25 -0.43 0.32 -0.29 Hc 1.00 0.16 0.01 -0.18 -0.68 -0.04 -0.05 -0.15 -0.26 0.13 -0.04 CA 1.00 -0.46 0.75 0.25 0.13 0.13 0.17 0.01 0.09 0.14 SS 1.00 -0.10 -0.17 0.19 0.23 0.25 0.37 -0.20 0.19 CPdbh 1.00 0.24 0.35 0.36 0.44 0.38 -0.11 0.35 CLR 1.00 -0.16 -0.11 0.02 0.04 0.05 -0.15 N 1.00 0.89 0.69 0.72 -0.49 0.99 C 1.00 0.82 0.73 -0.40 0.84 C:N 1.00 0.77 -0.17 0.64 SLA 1.00 -0.53 0.73 LDMC 1.00 -0.50

LA 1.00

Med

iterr

anea

n

dbh 1.00 0.77 0.56 0.89 -0.47 0.66 -0.07 -0.34 0.50 0.38 -0.53 0.13 -0.34 H 1.00 0.81 0.70 0.14 0.53 -0.20 -0.20 0.45 0.27 -0.46 -0.11 -0.35 Hc 1.00 0.46 0.22 0.31 -0.70 -0.17 0.37 0.22 -0.37 -0.07 -0.27 CA 1.00 -0.41 0.92 0.02 -0.24 0.40 0.28 -0.43 0.06 -0.24 SS 1.00 -0.29 -0.16 0.29 -0.21 -0.27 0.26 -0.41 0.10 CPdbh 1.00 0.09 -0.13 0.25 0.16 -0.27 0.00 -0.13 CLR 1.00 0.10 -0.16 -0.11 0.16 -0.07 0.13 N 1.00 -0.68 -0.99 0.76 -0.51 0.66 C 1.00 0.75 -0.88 0.30 -0.78 C:N 1.00 -0.81 0.47 -0.70 SLA 1.00 -0.43 0.76 LDMC 1.00 -0.35 LA 1.00

Table A1.4. Mean and coefficient of variation (CV) of traits used to assess the functional space per species in the three study sites (a boreal forest, a mountainous beech forest (temperate), and a Mediterranean forest). Data are figures with pooled data, and distinguishing individuals growing in pure and mixed stands.

H (m) CPdbh (unitless) C:N (unitless) LDMC (mg g–1) mean CV(%) mean CV(%) mean CV(%) mean CV(%)

bore

al

Betula pendula pooled 20.04 14.78 1.23 33.09 21.9 11.72 398.25 6.41 pure 20.56 12.85 1.01 23.47 20.40 8.79 379.51 5.40

mixed 19.85 15.42 1.31 32.62 22.44 11.57 405.10 5.87 Pinus sylvestris pooled 18.42 14.64 0.9 33.37 35.5 17.39 421.52 7.29

pure 18.83 9.65 0.81 32.52 37.47 16.57 417.01 7.39 mixed 18.29 16.02 0.93 32.98 34.83 17.35 423.05 7.26 Picea abies pooled 16.95 25.29 0.87 29 45.88 11.62 440.86 8.75

pure 17.98 22.85 0.80 27.10 44.81 11.34 444.36 9.87 mixed 16.61 25.93 0.90 29.10 46.24 11.65 439.69 8.36

Tem

pera

te

Abies alba pooled 27.28 38.37 0.51 41.91 39.64 10.51 490.91 9.7 pure 34.47 10.15 0.49 32.33 40.28 10.37 511.10 8.67

mixed 26.12 41.00 0.51 42.93 39.54 10.47 487.66 9.66 Acer pseudoplatanus pooled 27.52 16.62 0.79 73.09 21.11 15.35 366.2 14.12

pure 26.00 19.14 0.90 50.90 20.59 14.22 374.68 14.06 mixed 27.85 15.76 0.77 77.54 21.23 15.43 364.38 14.01 Fagus sylvatica pooled 26.93 31.09 1 59.28 22.65 13.14 452.24 9.28

pure 34.03 19.07 1.14 34.09 25.25 13.00 467.78 9.12 mixed 26.15 31.21 0.98 61.70 22.36 12.45 450.53 9.19 Picea abies pooled 31.8 26.65 0.49 42.54 38.54 13.35 465.63 14.31

pure 31.32 13.98 0.47 34.00 36.92 11.75 463.79 11.95 mixed 31.88 28.02 0.50 43.43 38.81 13.39 465.92 14.60

Med

iterr

anea

n

Pinus nigra pooled 11.41 33.55 0.89 49.86 49.68 16.34 464.5 10.03 pure 12.53 26.05 0.92 42.77 57.01 10.68 447.65 8.55

mixed 11.24 34.60 0.89 51.04 48.54 16.08 467.12 10.12 Pinus sylvestris pooled 12.36 30.73 0.93 56.52 45.47 16.91 498.27 11.61

pure 15.50 13.19 0.67 57.37 44.86 15.05 486.06 10.67 mixed 11.49 33.64 1.00 54.32 45.64 19.89 501.68 15.27 Quercus faginea pooled 8.28 30.97 0.73 65.74 18.69 20.83 365.56 20.76

pure 7.71 22.90 0.51 43.07 19.10 20.83 328.50 19.28 mixed 8.40 32.41 0.78 64.76 18.73 21.76 372.58 20.43 Quercus ilex pooled 5.57 33.62 0.62 50.52 39.9 15.18 562.76 7.89

pure 4.48 25.49 0.55 47.10 40.57 18.67 515.39 5.80 mixed 5.84 32.90 0.64 50.74 39.72 14.17 574.91 6.81

Figure A1.1. Boxplots of total basal area (BA) assessed in plots with different species

richness pooled by species in the three study sites, a boreal forest, a mountainous beech

forest (temperate), and a Mediterranean forest (Bp: Betula pendula; Pa: Picea abies;

Ps: Pinus sylvestris; Aa: Abies alba; Ap: Acer pseudoplatanus; Fs: Fagus sylvatica;

Pn: Pinus nigra; Qf: Quercus faginea; Qi: Quercus ilex). Kruskal–Wallis tests showed

no significant differences along the species richness gradient for most of the species,

and only Betula pendula and Pinus sylvestris in Finland showed certain trend of

increasing basal area in more diverse communities (• p < 0.1).

Appendix 2 Hypervolumes and metrics Table A2.5. Hypervolumes (HV) calculated for every study species. The HV is a set of points achieved by a multidimensional kernel density

estimation (KDE) procedure, expressed in SD4 units (standard deviation units) (Blonder et al. 2014), pooling data from all surveyed plots, and

stratifying per species richness level in the canopy. It is included the sample size (number of surveyed individuals) of each hypervolume

calculation. The three study sites are a boreal forest, a mountainous beech forest (temperate), and a Mediterranean forest.

all plots monocultures 2-species mixture 3-species mixture 4-species mixture all mixed n HV n HV n HV n HV n HV n HV

Bore

al Betula pendula 142 84.09 38 34.82 75 76.17 29 44.18 104 78.46

Pinus sylvestris 158 117.17 40 61.12 80 105.84 38 56.92 118 109.25

Picea abies 160 138.64 40 83.86 80 105.62 40 73.53 120 124.48

Tem

pera

te Abies alba 144 102.66 20 38.80 49 72.47 47 75.75 28 71.00 124 99.91

Acer pseudoplatanus 113 101.74 20 59.38 29 40.96 36 85.53 28 58.83 93 94.66

Fagus sylvatica 181 131.48 18 52.07 69 101.72 68 93.37 26 78.73 163 126.98

Picea abies 143 127.44 20 45.58 49 75.43 44 92.25 30 78.24 123 128.16

Med

iterra

nean

Pinus nigra 208 95.28 28 40.75 89 72.31 60 69.13 31 53.96 180 92.16

Pinus sylvestris 133 109.43 29 37.07 50 76.90 30 54.70 24 44.52 104 101.12

Quercus faginea 190 77.98 29 22.61 77 72.31 55 45.34 29 31.89 161 80.65

Quercus ilex 147 45.46 30 24.66 58 37.23 30 27.52 29 26.10 117 42.35

Table A2.6. Pairwise overlaps and distance between centroids of species hypervolumes within

the three study sites (a boreal, a mountainous mixed forest (temperate), and a Mediterranean

forest). Overlaps are assessed as Sørensen overlap index = [2 × volume (intersection A,B)]/

(volume A + volume B) ( Lamanna et al., 2014 ), and can varied between 0 and 1, which means

no overlap and full overlap respectively. Distance among centroids are expressed in forth power

of standard deviations units (SD4, the product of the 4 axes’ units).

overlap dist centroid

Bore

al B. pendula vs P. sylvestris 0.258 1.782

B. pendula vs P. abies 0.028 2.805

P. sylvestris vs P. abies 0.420 1.152

Tem

pera

te

A. alba vs A. pseudoplatanus 0.101 2.795

A. alba vs F. sylvatica 0.161 2.278

A. alba vs P. abies 0.673 0.741

A. pseudoplatanus vs F. sylvatica 0.462 1.310

A. pseudoplatanus vs P. abies 0.157 2.480

F. sylvatica vs P. abies 0.184 2.210

Med

iterra

nean

P. nigra vs P. sylvestris 0.675 0.502

P. nigra vs Q. faginea 0.055 2.545

P. nigra vs Q. ilex 0.231 1.946

P. sylvestris vs Q. faginea 0.083 2.500

P. sylvestris vs Q. ilex 0.266 1.819

Q. faginea vs Q. ilex 0.071 2.692

Table A2.7. Coordinates of hypervolumes’ centroids assessed per species and species richness

(SR) level in the three study forest types (a boreal, a mountainous mixed forest (temperate), and

a Mediterranean forest). H: tree height, CPdbh: ratio between crown area projection and dbh,

CN: ratio between C and N content in leaves, LDMC: leaf dry matter content.

SR level centroid H CPdbh CN LDMC

bore

al

Betula pendula 1 0.446 0.033 -1.339 -1.078 2 0.423 0.885 -1.153 -0.356 3 0.136 0.902 -1.085 -0.526

mixed 0.361 0.914 -1.134 -0.402 Pinus sylvestris 1 0.107 -0.502 0.307 -0.009

2 0.022 -0.100 0.051 0.173 3 -0.227 -0.279 -0.037 -0.048

mixed -0.040 -0.170 0.025 0.105 Picea abies 1 -0.198 -0.495 0.895 0.665

2 -0.406 -0.189 1.083 0.635 3 -0.843 -0.307 0.922 0.478

mixed -0.592 -0.211 1.027 0.596

Tem

pera

te

Abies alba 1 0.756 -0.484 1.049 0.977 2 -0.575 -0.463 1.135 0.719 3 -0.312 -0.376 0.801 0.645 4 -0.642 -0.275 0.852 0.227

mixed -0.556 -0.367 0.938 0.581 Acer pseudoplatanus 1 -0.220 0.444 -1.010 -0.994

2 0.274 -0.012 -0.937 -0.990 3 -0.195 0.638 -0.943 -1.112 4 -0.279 0.246 -1.048 -1.589

mixed -0.123 0.534 -0.971 -1.231 Fagus sylvatica 1 0.586 0.961 -0.581 0.236

2 -0.208 0.926 -0.811 0.131 3 -0.599 0.508 -0.864 0.036 4 -0.481 1.354 -0.897 -0.061

mixed -0.448 0.927 -0.842 0.060 Picea abies 1 0.325 -0.513 0.697 0.129

2 0.647 -0.444 0.997 0.389 3 0.253 -0.340 0.858 0.517 4 -0.296 -0.472 0.705 -0.348

mixed 0.123 -0.392 0.869 0.200

Med

iterra

nean

Pinus nigra 1 0.757 0.305 1.320 -0.185 2 0.504 0.355 0.880 0.036 3 0.296 0.189 0.722 -0.072 4 0.688 0.035 0.732 0.505

mixed 0.453 0.237 0.803 0.100 Pinus sylvestris 1 1.444 -0.179 0.492 0.255

2 0.633 0.619 0.475 0.236 3 0.052 0.474 0.599 0.520 4 0.803 0.421 0.769 0.745

mixed 0.476 0.545 0.574 0.433 Quercus faginea 1 -0.351 -0.656 -1.378 -1.534

2 0.103 0.592 -1.408 -0.999 3 -0.662 -0.282 -1.347 -1.004

4 -0.086 -0.355 -1.322 -0.614 mixed -0.121 0.248 -1.376 -0.908 Quercus ilex 1 -1.212 -0.483 0.207 0.558

2 -1.007 -0.299 0.224 1.266 3 -0.823 -0.195 0.055 0.934 4 -0.575 -0.026 0.042 1.348

mixed -0.835 -0.187 0.145 1.198

Table A2.8. Importance of each trait shaping species hypervolumes in the study forest types

along the species richness gradient (SR) in the canopy. It is calculated following Blonder and

Harris (2017) by comparing the n-dimensional input hypervolume’s volume to all possible n-1

dimensional hypervolumes where each trait of interest has been deleted. H: plant height, CPdbh:

crown ratio (ratio between crown area projection and diameter at breast height), C:N: ratio

between C and N content in leaves, LDMC: leaf dry matter content. Significance of observed

data in comparison to relative importance assessed with null models: •10%, *5 %, **1 %,

***0.1%.

Target species SR H CPdbh CN LDMC

Bore

al

Betula pendula 1 2.58 2.41 (-)*** 1.65 2.27 2 2.79 (+)* 3.74 (+)** 1.69 2.41 3 2.24 2.97 1.70 (+)* 2.28

Picea abies 1 2.88 2.07 1.78 3.17 (+)** 2 3.00 (+)• 2.31 (+)• 2.08 (+)*** 3.09 (+)*** 3 2.63 2.37 (+)* 1.69 (-)* 2.38 (-)**

Pinus sylvestris 1 2.04 (-)** 2.55 2.13 (+)** 2.76 (+)*** 2 2.78 (+)** 2.70 2.11 2.81 (+)*

3 2.05 (-)* 2.68 2.20 (+)• 2.35

Tem

pera

te

Abies alba 1 2.17 (-)* 2.07 (+)* 2.29 (+)** 2.89 (+)*** 2 3.72 (+)*** 2.21 (+)*** 2.09 (+)* 3.03 (+)*** 3 3.35 (+)* 2.31 (+)** 2.35 (+)** 2.43 4 3.44 (+)* 2.02 2.03 2.69 (+)**

Acer pseudoplatanus 1 2.32 (+)** 2.89 1.84 (+)** 2.56 (+)* 2 2.10 2.81 2.06 (+)** 2.78 (+)** 3 2.14 (+)• 3.58 (+)** 2.02 (+)** 2.64 (+)* 4 2.21 (+)* 3.35 (+)* 1.82 (+)* 2.69 (+)*

Fagus sylvatica 1 2.50 2.53 1.91 (+)*** 2.32 (+)** 2 3.21 (+)** 3.50 (+)** 1.97 (+)** 2.54 (+)** 3 3.31 (+)*** 3.88 (+)** 1.93 (+)** 2.44 (+)** 4 2.28 3.83 (+)** 1.78 (+)** 2.02

Picea abies 1 2.22 2.02 (+)*** 2.25 (+)** 2.96 (+)** 2 2.83 (+)* 2.15 (+)** 2.41 (+)*** 3.11 (+)** 3 2.72 (+)• 2.35 (+)** 2.35 (+)** 3.03 (+)**

4 3.19 (+)** 1.93 (+)** 1.98 3.31 (+)***

Med

iterra

nean

Pinus nigra 1 2.42 2.35 1.94 1.85 2 2.72 (+)** 2.89 (+)** 2.35 (+)** 2.17 (+)* 3 2.92 (+)** 2.67 (+)* 2.24 (+)• 2.09 4 2.25 2.33 2.11 1.93

Pinus sylvestris 1 1.90 (-)*** 2.54 1.87 2.00 2 2.45 2.94 (+)• 2.04 (+)* 1.98 3 2.33 2.67 1.76 2.03 4 1.93 (-)** 2.57 1.86 2.23 (+)*

Quercus faginea 1 2.17 2.03 (-)** 1.60 2.45 2 2.45 (+)** 3.39 (+)*** 1.71 (-)* 2.72 3 1.86 (-)* 2.74 1.79 2.91 (+)** 4 2.12 2.12 (-)* 1.55 3.01 (+)*

Quercus ilex 1 1.71 (-)** 1.92 1.73 (+)*** 1.79 2 2.04 2.71 (+)* 2.22 (+)• 2.29 3 1.91 2.56 1.95 2.03

4 2.27 (+)** 2.58 1.86 (-)• 1.60 (-)***

Figure A2.2. Standardised effect size (SES) of the hypervolumes of each tree species assessed in communities with two-species mixture,

pooling all combinations versus combinations with only those species belonging to different and same functional groups (FG), i.e. conifers

and broadleaved species. The line showing SES=0 represents the null expectation, and the lines SES >|0.95| represent the significant levels

beyond which it is assumed that species richness affects the functional space of each species (filled symbols). Empty symbols mean no

significant different from the null expectation. The three study forest types are a boreal, a mountainous beech forest (temperate), and a

Mediterranean forest. (Bp: Betula pendula; Pa: Picea abies; Ps: Pinus sylvestris; Aa: Abies alba; Ap: Acer pseudoplatanus; Fs: Fagus

sylvatica; Pn: Pinus nigra; Qf: Quercus faginea; Qi: Quercus ilex).

11

Figure S2.3. Hypervolumes assessed for monocultures (red) vs mixed stands (green) of each study

species shown as pair plots, in the three study forest types, namely a boreal a), a mountainous beech

forest b), and a Mediterranean forest c). The hypervolumes are based on 4 functional traits selected

for their low correlation representing 4 dimensions, i.e. tree height, the ratio between crown area

projection and dbh (CPdbh), ratio between C and N content in leaves (C:N), and leaf dry matter

content (LDMC). Units in each axis are standard deviation (SD). Larger, coloured dots are species

centroids and coloured lines are the envelopes around the hypervolumes.