Tree species and genetic diversity increase productivity via functional diversity and trophic feedbacks
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, China
- College of Life Sciences, University of Chinese Academy of Sciences, China
- College of Forestry, Beijing Forestry University, China
- Ecological Networks, Technical University Darmstadt, Germany
- Forest Nature Conservation, Georg-August-University Göttingen, Germany
- Nature Conservation and Landscape Ecology, University of Freiburg, Germany
- Institute of Applied Ecology, School of Food Science, Nanjing Xiaozhuang University, China
- Department of Ecology, Evolution, and Behavior, University of Minnesota, United States
- The Morton Arboretum, United States
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, China
- Chair of Nature Conservation and Landscape Ecology, Faculty of Environment and Natural Resources, University of Freiburg, Germany
- Institute of Biology/Geobotany and Botanical Garden, Martin Luther University Halle-Wittenberg, Germany
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Germany
- Department of Community Ecology, Helmholtz Centre for Environmental Research–UFZ, Germany
- Department of Geography, University of Zurich, Switzerland
Figures
Figure 1
Conceptual illustration of the effects of functional diversity (a) and trophic feedbacks on tree productivity (b) and the species × genetic diversity experimental design (c).
(a) shows resources for plant growth or other trophic groups in complementary ways due to functional diversity: the four hypothetical species/genotypes (A, B, C, D) with different functional traits …
Figure 2 with 1 supplement
Tree community productivity, tree functional diversity, and trophic interactions in tree communities of low vs. high species and genetic richness.
The following effects were tested in linear mixed-effects models (LMMs) (n=92): species richness main effect (left vs. right pair of bars in each panel), genetic richness main effect (inset on upper …
Figure 2—figure supplement 1
Effects of tree species diversity and genetic diversity on tree functional diversity calculated from traits measured on individual trees.
The lower and upper hinges of the bars correspond to the first and third quartiles (the 25th and 75th percentiles); the lower and upper whisker extends from the hinge correspond to 1.5 * …
Figure 3 with 1 supplement
Bivariate relationships between tree community productivity and tree functional diversity (a), herbivory (b), and soil fungal diversity (c).
Green unfilled/dashed symbols represent genetic monocultures in species monocultures, green filled/solid symbols represent genetic monocultures in species mixture, orange unfilled/dashed symbols …
Figure 3—figure supplement 1
Effects of tree functional diversity calculated from traits measured on individual trees on community productivity.
Asterisks indicate statistical significance (*** p < 0.0001, ** p < 0.001, * p < 0.05, + p < 0.1, and ns p > 0.1). Details of the fitted models are shown in Appendix 2—table 1.
Figure 4 with 2 supplements
Effects of tree diversity on higher trophic levels and tree community productivity (global Fisher’s C = 1.677, DF = 4, p = 0.795).
Positive and negative paths are indicated in green and orange, respectively. The standardized path coefficients are indicated by the numbers, statistical significance is indicated by asterisks (*** …
Figure 4—figure supplement 1
Effects of tree diversity on higher trophic levels and tree community productivity with functional diversity calculated using trait values of individual trees (global Fisher’s C = 119.558 DF = 4, p=0.001).
Positive and negative paths are indicated in green and orange, respectively. The standardized path coefficients are indicated by the numbers, statistical significance is indicated by asterisks (*** …
Figure 4—figure supplement 2
Initial structural equation model (SEM) used in this study.
Tree species diversity represents the number of tree species, genetic diversity represents the number of seed families per tree species, and functional diversity (based on FDis) represents the mean …
Figure 5 with 2 supplements
Effects of tree genetic diversity on higher trophic levels and tree community productivity in tree species monocultures (a) and the mixture of the four tree species (b).
The results were obtained by a multigroup structural equation models (SEM) (global Fisher’s C = 3.416, DF = 4, p = 0.491). Positive and negative paths are indicated in green and orange, …
Figure 5—figure supplement 1
Effects of tree genetic diversity on higher trophic levels and tree community productivity in tree species monocultures (a) and mixtures of four tree species (b) with functional diversity calculated using trait values of individual trees.
The results were obtained by a multigroup structural equation models (SEM) (global Fisher’s C = 2.747, DF = 4, p = 0.601). Positive and negative paths are indicated in green and orange. The …
Figure 5—figure supplement 2
Initial structural equation models (SEM) structure of genetic diversity effects in both species monocultures and mixtures.
Genetic diversity represents the number of seed families per tree species. Functional diversity (based on FDis) represents the mean distance of seed-family means to the centroid of all seed …
Appendix 1—figure 1
Diagram of the seed families planted in the species × genetic diversity experiment.
1.1: species diversity = 1, genetic diversity = 1; 1.4: species diversity = 1, genetic diversity = 4; 4.1: species diversity = 4, genetic diversity = 1; 4.4: species diversity = 4, genetic diversity …
Appendix 2—figure 1
Trophic composition of soil fungi in this study.
All fungi from this study were pooled together to calculate the relative abundance of each trophic group.
Appendix 2—figure 2
Relationship between functional dispersion (FDis) and Rao’s Q (RaoQ).
Appendix 2—figure 3
Varimax rotation principal component analysis (PCA) biplot for the five functional traits.
Appendix 3—figure 1
Effects of tree diversity on higher trophic levels and tree community productivity without the path between genetic diversity and functional diversity (global Fisher’s C = 16.766, DF = 6, p = 0.01).
Positive and negative paths are indicated in green and orange, respectively. The standardized path coefficients are indicated by the numbers, statistical significance is indicated by asterisks (*** …
Appendix 3—figure 2
Effects of tree genetic diversity on higher trophic levels and tree community productivity in tree species monocultures (a) and mixtures of four tree species (b) without the paths between genetic diversity and functional diversity.
The results were obtained by a multigroup structural equation model (SEM) (global Fisher’s C = 3.485, DF = 4, p = 0.480). Positive and negative paths are indicated in green and orange, respectively. …
Tables
Appendix 1—table 1
The designed and planted occurrence times of each seed family per species in the four diversity treatment combinations.
1.1: species diversity = 1, genetic diversity = 1; 1.4: species diversity = 1, genetic diversity = 4; 4.1: species diversity = 4, genetic diversity = 1; 4.4: species diversity = 4, genetic diversity …
| Tree diversity | 1.1 (x = 100) | 1.4 (x = 25) | 4.1 (x = 100) | 4.4 (x = 25) | |
|---|---|---|---|---|---|
| SP | SF | Tree individuals | Tree individuals | Tree individuals | Tree individuals |
| AlFo | 1 | x | x | x | x + x + x |
| (A) | 2 | x | x | x | x + x + x |
| 3 | x | x(1) | x | x + x + x | |
| 4 | x | x | x | x + x + x | |
| 5 | x | x(2) | x | x + x + x | |
| 6 | x | x(4) | x | x + x + x(9) | |
| 7 | x | x | x | x + x + x | |
| 8 | x | x(7) | x | x + x + x | |
| CiCa | 1 | x | x | x | x + x + x |
| (B) | 2 | x | x | x | x + x + x |
| 3 | x | x | x(6) | x + x + x | |
| 4 | x | x | x(6/9) | x + x + x | |
| 5 | x | x | x | x + x + x(3) | |
| 6 | x | x | x | x + x + x | |
| 7 | x | x | x | x + x + x | |
| 8 | x | x | x | x + x + x | |
| DaOl | 1 | x | x | x | x + x + x |
| (C) | 2 | x | x | x(7) | x + x + x |
| 3 | x | x | x(7) | x(11) + x(11) + x(9) | |
| 4 | x | x | x | x + x(10) + x(12) | |
| 5 | x | x | x | x + x + x(13) | |
| 6 | x | x | x | x + x + x | |
| 7 | x | x | x | x + x + x(14) | |
| 8 | x | x | x(8/9) | x + x + x | |
| IdPo | 1 | x | x | x | x + x + x |
| (D) | 2 | x | x | x | x + x + x |
| 3 | x | x | x | x + x + x | |
| 4 | x | x | x | x + x + x | |
| 5 | x | x(4) | x | x + x + x | |
| 6 | x | x | x | x + x + x | |
| 7 | x(5) | x(8) | x | x + x + x | |
| 8 | x | x | x | x + x + x | |
Appendix 1—table 2
Data description of multi-trophic levels.
| Data type | Data description | Subplots | Year |
|---|---|---|---|
| Plant trait | LA, SLA, CHL, LN, LC | 77 | 2017 |
| Herbivore damage | Visually estimated | 77 | 2017 |
| Soil fungi | Mainly composed of saprophytes | 53 | 2017 |
| Community productivity | Sum of the biomass per subplot/area of subplot | 92 | 2018 |
-
LA, leaf area; SLA, specific leaf area; CHL, chlorophyll content; LN, leaf nitrogen content; LC, leaf carbon content.
Appendix 2—table 1
Summary of linear mixed-effects models (LMMs) of species diversity (SD), genetic diversity (GD), and their interactions on tree productivity, tree functional diversity, trophic interactions, and community-weighted mean (CWM) of functional traits.
Expressed values are Df representing degree of freedom and F-values with related significances, *** p < 0.001; * *p < 0.01; * p < 0.05, + p < 0.1. Note that the very small F-values for CWMs are due …
| Tree productivity | FD(Mean) | FD (Individual) | Herbivory | Soil fungal diversity | CWM (RC1) | CWM (RC2) | |||
|---|---|---|---|---|---|---|---|---|---|
| Factors | Df | Random | F-value | F-value | F-value | F-value | F-value | F-value | F-value |
| SD | 1 | Plot | 6.16* | 44.80*** | 20.60*** | 0.08 | 1.06 | 0.004 | 0.002 |
| GD | 1 | Plot | 0.51 | 3.66+ | 0.11 | 5.86* | 1.57 | 0.000 | 0.033 |
| SD × GD | 1 | Plot | 0.23 | 7.44* | 0.05 | 1.44 | 5.29* | 0.003 | 0.011 |
| SD | 1 | Plot | 6.16* | 44.80*** | 20.60*** | 0.08 | 1.06 | 0.004 | 0.002 |
| GD (Sp-mono) | 1 | Plot | 0.00 | 11.09** | 0.15 | 0.17 | 1.35 | 0.002 | 0.000 |
| GD (Sp-mix) | 1 | Plot | 0.74 | 0.00 | 0.02 | 7.13* | 5.51* | 0.001 | 0.044 |
Appendix 2—table 2
Dimension reduction of community-weighted mean trait values (CWMs) by varimax rotation principal component analysis (PCA).
Loadings and eigenvalues of rotation principal components (RC) selected from a varimax rotation PCA on the CWM of leaf traits (most influential variables in bold).
| RC1 | RC2 | |
|---|---|---|
| LA | 0.49 | 0.11 |
| SLA | 0.17 | –0.34 |
| CHL | 0.05 | 0.86 |
| LN | –0.20 | 0.16 |
| LC | –0.55 | –0.01 |
| Explained | 41% | 23% |
| Cumulative explained | 41% | 64% |
-
LA, leaf area; SLA, specific leaf area; CHL, chlorophyll content; LN, leaf nitrogen content; LC, leaf carbon content.
Appendix 2—table 3
Results of linear models of leaf damage excluding undamaged leaves (this study) – leaf damage including undamaged leaves (from other plots of the BEF-China experiment) for the four species used in this study.
These models were used to correct the potential bias of herbivory estimates as a result of only collecting damaged leaves.
| Species | Slope | Intercept | R2 | Pearson’s correlation |
|---|---|---|---|---|
| Alniphyllum fortunei | 0.89970 | 2.83483 | 0.86 | 0.93 |
| Cinnamomum camphora | 0.94465 | 2.07484 | 0.73 | 0.86 |
| Daphniphyllum oldhamii | 0.88387 | 2.54032 | 0.92 | 0.96 |
| Idesia polycarpa | 0.92406 | 1.77523 | 0.86 | 0.93 |
Appendix 2—table 4
Contrast coding of genetic diversity in species monocultures and species mixtures separately.
Sp-mono presents species monocultures, and Sp-mix presents species mixtures.
| Species diversity | Genetic diversity | Genetic diversity in Sp-mono | Genetic diversity in Sp-mix |
|---|---|---|---|
| 1 | 1 | -1 | 0 |
| 4 | 1 | 0 | -1 |
| 1 | 4 | 1 | 0 |
| 4 | 4 | 0 | 1 |
Appendix 2—table 5
The interaction of significant results and the explained variance of the whole model of the multigroup structural equation models (SEM) shown in Figure 5.
*** p < 0.001; ** p < 0.01; * p < 0.05.
| Response | Predictor | DF | Test.Stat | Explained variance % |
|---|---|---|---|---|
| Tree functional diversity | GD:SD | 1 | 0.5* | 11 |
| Herbivory | GD:SD | 1 | 0.0 | 11 |
| Herbivory | Tree functional diversity:SD | 1 | 0.0* | |
| Soil fungal diversity | GD:SD | 1 | 52982.7*** | 6 |
| Tree community productivity | GD:SD | 1 | 327.6*** | 24 |
| Tree community productivity | Herbivory:SD | 1 | 327.6 | |
| Tree community productivity | Soil fungal diversity:SD | 1 | 327.6 | |
| Tree community productivity | Tree functional diversity:SD | 1 | 327.6* |
-
SD, species diversity; GD, genetic diversity.
