Ecosystem Functions across Trophic Levels Are Linked to Functional and Phylogenetic Diversity

<div><p>In experimental systems, it has been shown that biodiversity indices based on traits or phylogeny can outperform species richness as predictors of plant ecosystem function. However, it is unclear whether this pattern extends to the function of food webs in natural ecosystems. Here we tested whether zooplankton functional and phylogenetic diversity explains the functioning of 23 natural pond communities. We used two measures of ecosystem function: (1) zooplankton community biomass and (2) phytoplankton abundance (<i>Chl a</i>). We tested for diversity-ecosystem function relationships within and across trophic levels. We found a strong correlation between zooplankton diversity and ecosystem function, whereas local environmental conditions were less important. Further, the positive diversity-ecosystem function relationships were more pronounced for measures of functional and phylogenetic diversity than for species richness. Zooplankton and phytoplankton biomass were best predicted by different indices, suggesting that the two functions are dependent upon different aspects of diversity. Zooplankton community biomass was best predicted by zooplankton trait-based functional richness, while phytoplankton abundance was best predicted by zooplankton phylogenetic diversity. Our results suggest that the positive relationship between diversity and ecosystem function can extend across trophic levels in natural environments, and that greater insight into variation in ecosystem function can be gained by combining functional and phylogenetic diversity measures.</p></div

Zooplankton community biomass in the 23 ponds as predicted by the best diversity indices in each category: taxonomic diversity—species richness (a), functional diversity—abundance weighted functional divergence (b), phylogenetic diversity—abundance weighted standard effect size mean pairwise distance (c), and the variation partitioning for these three models with their adjusted R² (d).

<p>Significant model trends are shown as black lines. The grey bands indicate the 95% confidence intervals for the predicted values (a) and the slope of the regression lines (b,c).</p

Results of the linear models for predicting chlorophyll <i>a</i> (ln), ranked in increasing order of AIC.

<p>The highest ranked model of each diversity type is bolded. <i>P</i> values that are less than 0.05 are bolded.</p><p>* Environmental variable model includes % tree cover, DIC, ln area, ln depth, pH, and ln DOC</p><p>** Environmental PCA includes first 2 axes of PCA on all standardized environmental variables.</p><p>Results of the linear models for predicting chlorophyll <i>a</i> (ln), ranked in increasing order of AIC.</p

Supplementary figures S1-S4 from The strength of the biodiversity–ecosystem function relationship depends on spatial scale

Our understanding of the relationship between biodiversity and ecosystem functioning (BEF) applies mainly to fine spatial scales. New research is required if we are to extend this knowledge to broader spatial scales that are relevant for conservation decisions. Here, we use simulations to examine conditions that generate scale dependence of the BEF relationship. We study scale by assessing how the BEF relationship (slope and <i>R</i>²) changes when habitat patches are spatially aggregated. We find three ways for the BEF relationship to be scale-dependent: (i) variation among local patches in local (α) diversity, (ii) spatial variation in the local BEF relationship and (iii) incomplete compositional turnover in species composition among patches. The first two cause the slope of the BEF relationship to increase moderately with spatial scale, reflecting nonlinear averaging of spatial variation in diversity or the BEF relationship. The third mechanism results in much stronger scale dependence, with the BEF relationship increasing in the rising portion of the species area relationship, but then decreasing as it saturates. An analysis of data from the Cedar Creek grassland BEF experiment revealed a positive but saturating slope of the relationship with scale. Overall, our findings suggest that the BEF relationship is likely to be scale dependent

Appendix G. Linear mixed effects model summary statistics for the loge-transformed mean zooplankton community body size.

Linear mixed effects model summary statistics for the loge-transformed mean zooplankton community body size

Appendix E. Phytoplankton genus richness as a function of treatment combinations.

Phytoplankton genus richness as a function of treatment combinations

Appendix H. Summary statistics for the redundancy analysis (RDA) on Hellinger-transformed phytoplankton taxonomic composition data.

Summary statistics for the redundancy analysis (RDA) on Hellinger-transformed phytoplankton taxonomic composition data

Appendix C. The response of zooplankton community composition to different treatments.

The response of zooplankton community composition to different treatments

Appendix B. Interactive effect of warming and predation during winter.

Interactive effect of warming and predation during winter

Supplementary Materials from Signatures of the collapse and incipient recovery of an overexploited marine ecosystem

Two supplemental tables and six supplemental figures for the main tex