Nitrogen cycling and water pulses in semiarid grasslands: are microbial and plant processes temporally asynchronous?
- 4 May 2012
- journal article
- Published by Springer Science and Business Media LLC in Oecologia
- Vol. 170 (3), 799-808
- https://doi.org/10.1007/s00442-012-2336-6
Abstract
Precipitation pulses in arid ecosystems can lead to temporal asynchrony in microbial and plant processing of nitrogen (N) during drying/wetting cycles causing increased N loss. In contrast, more consistent availability of soil moisture in mesic ecosystems can synchronize microbial and plant processes during the growing season, thus minimizing N loss. We tested whether microbial N cycling is asynchronous with plant N uptake in a semiarid grassland. Using 15N tracers, we compared rates of N cycling by microbes and N uptake by plants after water pulses of 1 and 2 cm to rates in control plots without a water pulse. Microbial N immobilization, gross N mineralization, and nitrification dramatically increased 1–3 days after the water pulses, with greatest responses after the 2-cm pulse. In contrast, plant N uptake increased more after the 1-cm than after the 2-cm pulse. Both microbial and plant responses reverted to control levels within 10 days, indicating that both microbial and plant responses were short lived. Thus, microbial and plant processes were temporally synchronous following a water pulse in this semiarid grassland, but the magnitude of the pulse substantially influenced whether plants or microbes were more effective in acquiring N. Furthermore, N loss increased after both small and large water pulses (as shown by a decrease in total 15N recovery), indicating that changes in precipitation event sizes with future climate change could exacerbate N losses from semiarid ecosystems.Keywords
This publication has 48 references indexed in Scilit:
- Has water limited our imagination for aridland biogeochemistry?Trends in Ecology & Evolution, 2011
- Rhizosphere interactions, carbon allocation, and nitrogen acquisition of two perennial North American grasses in response to defoliation and elevated atmospheric CO2Oecologia, 2010
- Increasing precipitation event size increases aboveground net primary productivity in a semi-arid grasslandOecologia, 2008
- Ecohydrology and the Partitioning AET Between Transpiration and Evaporation in a Semiarid SteppeEcosystems, 2006
- Microbial dynamics and carbon and nitrogen cycling following re-wetting of soils beneath two semi-arid plant speciesOecologia, 2004
- Temporal Asynchrony in Soil Nutrient Dynamics and Plant Production in a Semiarid EcosystemEcosystems, 2004
- Precipitation pulses and carbon fluxes in semiarid and arid ecosystemsOecologia, 2004
- Hierarchy of responses to resource pulses in arid and semi-arid ecosystemsOecologia, 2004
- Water pulses and biogeochemical cycles in arid and semiarid ecosystemsOecologia, 2004
- Soil microbial activity and N availability with elevated CO2 in Mojave Desert soilsGlobal Biogeochemical Cycles, 2004