Precipitation variability does not affect soil respiration and nitrogen dynamics in the understorey of a Mediterranean oak woodland
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- Jongen, M., Lecomte, X., Unger, S. et al. Plant Soil (2013) 372: 235. doi:10.1007/s11104-013-1728-7
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Background and aims
Future climate scenarios for the Mediterranean imply increasing precipitation variability. This study presents a large-scale water manipulation experiment simulating changes in precipitation variability, aiming at a better understanding of the effects of rainfall patterns on soil C and N cycling and understorey productivity in a Mediterranean oak woodland.
We used rain-out shelters to achieve (1) a normal dry period (7 days), and (2) a dry period increased three-fold (21 days), without altering total annual precipitation inputs.
The temporal patterns of soil respiration (Rs) and soil inorganic N were not affected by treatment. However, water infiltration and N leaching increased with large infrequent watering events. Rs and soil NH4+-N correlated with soil temperature, with soil NO3−-N being influenced by leaching.
The lack of significant treatment effects on either Rs or soil inorganic N can be explained by (1) minor differences in plant productivity between the treatments, suggesting equal plant N demand, and (2) the absence of moisture dependence of Rs and soil NH4+-N. Increased N leaching with large infrequent precipitation events may have longer-term consequences for ecosystem functioning. Our results contribute to an improved understanding of possible climate change effects on key ecosystem processes in Mediterranean ecosystems.