Moderate water supply and partial sand burial increase relative growth rate of two Artemisia species in an inland sandy land

Artemisia ordosica and Artemisia sphaerocephala seedlings were buried in sand to depths of 0, 0.25, 0.5, 0.75, 1 and 1.25 times the seedling height (H) and supplied with 2.5, 5.0, 7.5 and 10.0 mm of water every three days. For A. ordosica, the highest relative growth rate (RGR) and seedling height were achieved with 75 mm/month water supply and 0.5 H burial at 50 days, and the RGR decreased with 100 mm/month water supply. For A. sphaerocephala, the highest RGR was reached with 50 mm/month water supply and 0.5 H burial, but plants from this species had the greatest seedling height with 25 mm/month water supply and 0.75 H burial. A. ordosica and A. sphaerocephala have different proportions of their biomass in roots and shoots and thus are adapted to sandy environments in different ways. Partial sand burial significantly increased the RGR and growth height of the two Artemisia species, but complete burial lead to seedling death. Differences in the growth response to burial and moisture levels help explain why A. sphaerocephala is primarily found on drifting dunes and A. ordosica on semi-fixed and fixed dunes.