Non-linear responses of plants enhance their resistance to drought in drylands

Drylands are areas where rain is below 65% of potential evapotranspiration and collectively cover 41% of earth’s land surface. These regions support more than 38% of the global human population and harbor a unique biodiversity. Increased aridity, due to atmospheric warming and changes in rainfall patterns, is a major effect of climate change on global drylands and will have large consequences on plant growth and vegetation dynamics. Understanding how plants respond to increasing aridity is of paramount importance to anticipate ecosystem responses to climate change and to ensure sustainable development. Based on a standardized field survey in chemical and morphological traits of perennial plant species across global drylands, Gross et al. found that phenotypic trait diversity increased by 88% when aridity [calculated as 1– (precipitation/potential evapotranspiration)] surpassed ~0.7 (i.e., the transition between semi-arid and arid ecosystems).1 Their data emphasized that plants in the most arid regions tend to exhibit richer phenotypic trait diversity than in less extreme regions, challenging the conventional view that harsh environmental conditions reduce plant trait diversity.