What’s the relationship of diversity and productivity?

David Tilman

Science Oct. 26, 2001, 294:843

168 plots, each 9 m x 9 m

Seeded plots with 1, 2, 4, 8, or 16 native grassland species

Each treatment replicated between 29 – 39 times

Annually measured for 7 years:

above-ground biomass

total biomass

number or remaining species

What’s the relationship of diversity and productivity?

What are they hypothesizing?

What’s the reasoning (or rationale) behind that hypothesis?

What do they expect to find if the hypothesis is supported?What do they expect to find if the hypothesis is refuted?

Any trends over the years?

What’s the relationship of diversity and productivity?

1, 2, 4, 8, or 16 native grassland speciesAnnually measured for 7 years:

above-ground biomasstotal biomassnumber or remaining species

What’s the relationship of diversity and productivity?

What’s the relationship of diversity and productivity?

What’s the relationship of diversity and productivity?

What’s the relationship of diversity and productivity?

What’s the relationship of diversity and productivity?

Conclusions?

Importance?

What’s the relationship of diversity and productivity?

… then again …

Peter Adler et al. studied 48 grassland plots around the world.

Sept. 23, 2011Science 333:1750

What’s the relationship of diversity and productivity?

Data for individual sites:

Above ground biomass (g/m2)

Spec

ies R

ichn

ess

What’s the relationship of diversity and productivity?

Pooled Data

What’s the relationship of diversity and productivity?

the real world is a complicated place