Effects of rainfall pattern on the growth and fecundity of a dominant dune annual in a semi-arid ecosystem

Current and future changes in rainfall patterns - amount and frequency - may particularly impact annual plants in semi-arid ecosystems. The aim of this study was to investigate how changes in rainfall patterns affect the growth and fecundity of sand dune annuals. The effects of gradients in five rainfall amounts and five frequencies, based on historical and predicted values, on growth and fecundity of Agriophyllum squarrosum, a dominant annual in Mu Us Sandland, were examined in the near natural habitat. Rainfall amount and frequency significantly affected all vegetative and reproductive traits. With decreased amount of rainfall, height, biomass, seed number, seed mass and reproductive effort decreased, while root/shoot ratio increased. Except for the two extreme frequencies (1- and 120-day intervals), values of all vegetative and reproductive traits increased with the increase of rainfall frequencies. Germinability of offspring seeds tended to increase with increasing aridity, suggesting that a maternal effect may have been present. Our study shows that the plastic response in growth and fecundity of A. squarrosum to rainfall fluctuation allows the plant to survive and reproduce under current unpredictable environments as well as the increased variability predicted with climate change in semi-arid regions.