Global Ecosystem Analysis: The relationship between species richness and the functional properties of their ecosystems has often been studied at small scales in experimental plots.Maestreet al.(p.214; see the Perspective byMidgley) performed field measurements at 224 dryland sites from six continents and assessed 14 ecosystem functions related to carbon, nitrogen, and phosphorus cycling. Positive relationships were observed between perennial plant species richness and ecosystem functionality. The relative importance of biodiversity was found to be as large as, or larger than, many key abiotic variables. Thus, preservation of plant biodiversity is important to buffer negative effects of climate change and desertification in drylands, which collectively cover 41% of Earth's land surface and support over 38% of the human population.