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Nutrient uptake by ephemerals is a key element of nutrient retention in some hardwood forests. However, little information is available regarding the role of ephemerals and soil microbes in deserts.

Seasonal patterns of nitrogen (N) and phosphorus (P) uptake by spring ephemerals and soil microbes were measured in 2011-2013 in a temperate desert. Seasonal dynamics of soil inorganic N and available P, nitrate leaching and soil microbial N and P were also monitored.

Ephemerals exhibited a large nutrient pool in their growing season, with net N and P uptakes of 0.49-0.94 g m(-2) and 0.05-0.09 g m(-2), respectively, in normal precipitation years (2011 and 2013). Within 6 months of death, spring ephemerals released 35 % of litter N and 60 % of litter P. N and P microbial immobilizations were 3.6 and 4.5 times greater, respectively, than spring ephemeral uptake during normal precipitation years, but soil microbes showed a net nutrient release during the dry year (2012).

This study demonstrated that the relative importance of soil microbes and spring ephemerals in soil nutrient retention is related to annual precipitation, with higher nutrient retention by soil microbes in normal precipitation years and by spring ephemerals in dry year.