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The Legacy of Winter Climate Change on Summer Soil Biogeochemical Fluxes

SSCZO 2012 Annual Meeting – 21 August 2012. The Legacy of Winter Climate Change on Summer Soil Biogeochemical Fluxes. Joey Blankinship, Emma McCorkle, Matt Meadows, Ryan Lucas, and Steve Hart University of California, Merced.

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The Legacy of Winter Climate Change on Summer Soil Biogeochemical Fluxes

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  1. SSCZO 2012 Annual Meeting – 21 August 2012 The Legacy of Winter Climate Change on Summer Soil Biogeochemical Fluxes Joey Blankinship, Emma McCorkle, Matt Meadows, Ryan Lucas, and Steve Hart University of California, Merced

  2. To simulate climate change, we moved forest soils within the rain-snow transition zone (field incubation experiment) High Elevation Site 2365 m; MAT = ~6.8 °C; MAP = 1517 mm (2005-2007); 75-90% Snow Meteorological data are from Hunsaker et al. (2012) J. American Water Resources Assoc. Downward Transfer Low Elevation Site 1816 m; MAT = ~8.2 °C; MAP = 1512 mm (2005-2007); 40-65% Rain n = 12 for both soils (n = 8 for gas flux measurements) Upward Transfer

  3. Another goal was to isolate effects of snowmelt timing at the high-elevation site

  4. Early Snowmelt

  5. n = 12

  6. Late Snowmelt 3.1 m 3.1 m n = 12

  7. Soil Temperature

  8. Our snowmelt treatments worked! • Good luck to simulate climate change in contrasting Water Years

  9. Providence soil warmer than Bull, except during summer and when snow covered • Response of soil temperature to winter drought varied with elevation * indicates significant elevation difference (P < 0.05 in one-way ANOVA); # indicates significant effect of snowmelt timing

  10. Soil Volumetric Water Content 0-12 cm deep inside soil cores 0-15, 15-30, and 30-60 cm deep outside cores

  11. Snowmelt timing influenced shallow (0-30 cm) but not “deep” soil moisture (30-60 cm) during the subsequent summer Blankinship et al., Water Resources Research, in review

  12. Soil Greenhouse Gas Fluxes Carbon Dioxide (CO2) Methane (CH4) Nitrous Oxide (N2O)

  13. Soil CO2 flux tracks moisture during spring and summer, but temperature during fall and winter • Low Elevation: Warmer winter = Less spring CO2emission

  14. Warming increased high-elevation soil CO2 emission by 32%

  15. 2- to 3-week advancement of snowmelt reduced summer CO2emission by 10-35%

  16. Warming increased high-elevation soil CH4 uptake by 48%

  17. And for N2O too, the high elevation soil responded more strongly to warming than low elevation soil

  18. Conclusions • Our results suggest that climatic warming in snow-dominated ecosystems of the Sierra will increase net greenhouse gas emission from the soil to the atmosphere in the short-term. • However, continued advancement of the snowmelt date, without a simultaneous increase in precipitation, will likely constrain the extent of the temperature-induced increase in greenhouse gas fluxes. Other Directions: • Rates and ‘leakiness’ of nitrogen cycling • Microbial population sizes (e.g., total biomass, methane oxidizers, nitrifiers, denitrifiers) • Mechanisms for C release with warming and C sequestration with drying • Scale up snowmelt treatments to larger areas to include plant responses and plant-soil interactions • What exactly is going on during winter?

  19. The End

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