Multiple scales of spatial heterogeneity control soil respiration responses to precipitation across a dryland rainfall gradient

Aims – Soil respiration (Rs) is a major pathway for releasing fixed carbon back to the atmosphere. However, controls over Rs are poorly understood in arid and hyper-arid systems where microbial activity is frequently constrained by moisture. We addressed key uncertainties in Rs: 1) How do short-term rainfall pulses affect Rs at sites that differ in long-term precipitation inputs?, 2) how do Rs responses to short and long-term rainfall differ across soil surfaces?, and 3) how are Rs responses affected by local-scale attributes?

Methods – We measured Rs responses to rainfall pulses over a 48 h period. Working across a climate gradient, we compared Rs responses on two contrasting soil surfaces which both had two vegetation/soil morphology patch types that differed in organic matter inputs and accumulation.

Results – Rates of Rs were low, but highly responsive to rainfall pulses. Stimulation of Rs by rainfall was generally greater in areas with higher annual rainfall. However, pattern...