Table 1.
Factor | Effects on species richness |
Effects on evenness |
||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
Herbivory | Fertilization | Interaction | Herbivory | Fertilization | Interaction | |||||||
Model | MA | GLM | MA | GLM | MA | GLM | MA | GLM | MA | GLM | MA | GLM |
System† | T > F** | T > M > F** | F > T*** | / | NS | / | T > F*** | / | NS | F = M > T+ | NS | / |
Productivity (rel. units) | 0.062* | 0.043+ | −0.038* | / | NS | 0.081+ | NS | / | NS | 0.086** | NS | / |
Herbivore effect biomass | 0.080** | / | — | — | NS | / | NS | / | — | — | NS | −0.081* |
Fertilization effect biomass | — | — | NS | / | −0.119** | −0.217* | — | — | NS | / | NS | 0.182*** |
Pielou's evenness (J) | −0.471** | −0.445** | 0.267** | 0.334** | 0.414* | 0.435* | — | — | — | — | — | — |
Species richness (ln S) | — | — | — | — | — | — | −0.061* | −0.148*** | NS | / | −0.144* | / |
Experiment duration (ln d) | 0.028** | −0.126*** | −0.059** | −0.051*** | NS | / | NS | / | NS | / | NS | / |
Experiment size (ln m2) | NS | / | −0.036** | / | NS | / | NS | / | −0.034* | / | 0.036* | 0.027* |
Latitude,° N or S | NS | / | NS | / | / | −0.004* | / | NS | / | NS | / | |
F ratio (d.f.) | — | 7.46 (5;45) | — | 16.68 (2;63) | — | 3.53 (3;22) | — | 11.92 (1;92) | — | 2.30 (3;81) | — | 9.23 (3;22) |
P | — | <0.0001 | — | 0.0024 | — | 0.0316 | — | 0.0008 | — | 0.0838 | — | 0.0004 |
R2 | — | 0.453 | — | 0.346 | — | 0.325 | — | 0.115 | — | NS | — | 0.557 |
For each response variable, the significant parameter estimates (NS, not significant; /, not included in the final model, –, not applicable) and their significance levels (∗∗∗, P < 0.001; ∗∗, P < 0.01; ∗, P < 0.5; +, P < 0.1; NS, P > 0.1) are given as well as overall model statistics (F ratio with degrees of freedom, significance level, and R2). rel., relative; ln, natural log.
†Significant differences between terrestrial (T), freshwater (F), and marine (M) ecosystems are shown.