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CO 2 fluxes following simulated monsoon rain events

CO 2 fluxes following simulated monsoon rain events. Rene Aguilera Mentor: Shirley Kurc, University of Arizona August 16 th , 2007 Sevilleta LTER - REU Symposium. Photo Credit: Doug Moore. How do ecosystems respond to changes in precipitation patterns?. Photo Credit: Greg Greene.

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CO 2 fluxes following simulated monsoon rain events

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  1. CO2fluxes following simulated monsoon rain events Rene Aguilera Mentor: Shirley Kurc, University of Arizona August 16th, 2007 Sevilleta LTER - REU Symposium Photo Credit: Doug Moore

  2. How do ecosystems respond to changes in precipitation patterns? Photo Credit: Greg Greene

  3. Monsoon Rainfall Manipulation Experiment (MRME): Water addition alters size and frequency of rainstorms during the summer monsoon (July – Sept) at the black grama grassland. Treatment 1: Ambient rainfall only Control Treatment 2: One 5 mm storm each week Small Treatment 3: One 20 mm storm each month Large Same amount of water addition, different timing!

  4. Hypothesis 1: In the first day or two following all rainfall events, CO2 will be released, followed by a period of lagged CO2 uptake (Potts et al. 2006, Huxman et al. 2004) Hypothesis 2: Over the course of the monsoon season, there will be less CO2 response following the treatment of more frequent small storms than infrequent large storms. (Spoonseller 2007).

  5. How do I measure CO2 flux? Whole plant chamber Licor-7500 ~ 380 ppm Either soil is releasing carbon (respiration) or plants are taking up carbon (sequestration), so that concentration in chamber will become higher or lower than ambient.

  6. Flags outline measured area Licor-7500 sensor head Fan Tripod to mount sensor head

  7. Example of How Water Bends Apply chamber Remove Chamber Water increases as plants transpire

  8. Example of How Water Bends Water flux is the slope of this line! Water increases as plants transpire

  9. Example of How Carbon Dioxide Bends

  10. 7 hours following 1st stimulated rainstorm on July 12 Large has largest response! Rainfall applied: 0 mm control 5 mm small 10 mm large Control has smallest response!

  11. 7 hours following 1st stimulated rainstorm on July 12 Net Ecosystem Exchange of CO2 Rainfall applied: 0 mm control 5 mm small 10 mm large Lagged ‘respiration’ after small storm? (+) Respiration NEE (umol/m2/s) ( - ) Uptake Uptake in all 3 cases Continued uptake after large storm?

  12. One week after July 12 Natural Rain Event

  13. One week after July 12

  14. More measurements to come, including a diurnal measurement in September. • Results thus far: • Large less frequent storms trigger grasses to sequester more C, which alters carbon storage. • H2O availability drives carbon storage

  15. Acknowledgments • Jennifer Johnson • Shirley Kurc • Scott Collins • Chris Chen • Ben Gutzler • Tori, Ash, Jarrod, Enrico, Kate, Alexandra & Judd • Kathy McQueen • Mom & Dad Photo Credit: Doug Moore

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