Biological soil crusts influence carbon release responses following rainfall in a temperate desert, northern China

How soil cover types and rainfall patterns influence carbon (C) release in temperate desert ecosystems has largely been unexplored. We removed intact crusts down to 10 cm from the Shapotou region, China, and measured them in PVC mesocosms, immediately after rainfall. C release rates were measured in soils with four cover types (moss-crusted soil, algae-crusted soil, mixed (composed of moss, algae, and lichen)-crusted soil, and mobile dune sand). We investigated seven different rainfall magnitudes (0-1, 1-2, 2-5, 5-10, 10-15, 15-20, and > 20 mm) under natural conditions. C release from all four BSCs increased with increasing rainfall amount. With a rainfall increase from 0 to 45 mm, carbon release amounts increased from 0.13 +/- A 0.09 to 15.2 +/- A 1.35 gC m(-2) in moss-crusted soil, 0.08 +/- A 0.06 to 6.43 +/- A 1.23 gC m(-2) in algae-crusted soil, 0.11 +/- A 0.08 to 8.01 +/- A 0.51 gC m(-2) in mixed-crusted soil, and 0.06 +/- A 0.04 to 8.47 +/- A 0.51 gC m(-2) in mobile dune sand, respectively. Immediately following heavy rainfall events (44.9 mm), moss-crusted soils showed significantly higher carbon release rates than algae- and mixed-crusted soils and mobile dune sands, which were 0.95 +/- A 0.02, 0.30 +/- A 0.03, 0.13 +/- A 0.04, and 0.51 +/- A 0.02 mu mol CO2 m(-2) s(-1), respectively. Changes in rainfall patterns, especially large rain pulses (> 10 mm) affect the contributions of different soil cover types to carbon release amounts; moss-crusted soils sustain higher respiration rates than other biological crusts after short-term extreme rainfall events.