Differences in life history and trait plasticities of short- and long-lived summer annuals in a Chinese desert

Background and Aims: Water and nutrients are the main environmental factors affecting plant growth in desert ecosystems, and there is significant spatiotemporal heterogeneity in their availability. In response to such resource heterogeneity, plants have evolved different life history strategies. We hypothesized that short-lived summer annuals and a long-lived summer annual, found in the desert of NW China, differ in plasticity in response to water and nutrient availability. Methods: The effects of soil moisture and nutrients on the life history of the two short-lived summer annuals Alyssum linifolium and Tetracme quadricornis and the long-lived summer annual Agriophyllum squarrosum were tested in pot experiments. They were grown in soil with different moisture and nutrient contents, and their life history, fitness and architectural traits, as well as germination of offspring were determined. Results: Compared with the long-lived annual, short-lived annuals exhibited a shorter and more stable vegetative period, along with greater survival under drought and nutrient stress. In contrast, most traits of the long-lived annual had greater plasticity than the two short-lived annuals, for instance by shortening the vegetative period with increased soil moisture. All three species produced larger and non-dormant seeds in response to environmental stress. Conclusions: Short- and long-lived summer annuals differed in life history and trait plasticities in response to environmental stress, where the short-lived annuals adopted a drought escape strategy. In contrast, the long-lived annual tolerated drought aided by its higher plasticity to environmental changes, which may set it up to respond to future climate change.