Sedgwick Reserve

05 Apr, 07 AM - 05 Apr, 10 AM

In ecosystems which experience extended wet and dry seasons such as Mediterranean annual grasslands, the pulse of CO2 and nutrients released with wet up after the summer drought is a key temporal marker in the annual dynamics. A primary source for these pulses is easily-mineralized compounds that are accumulated by soil microorganisms as part of drought-resistance strategies over the preceding dry period. The accumulated substrates are then mineralized by heterotrophic soil microorganisms that are primed for rapid activation with wetting. The drought tolerance strategies that result in the accumulation of substrate pools and the occurrence of rapid-responding microbes, set the stage for semiarid ecosystem response to wet-up, shaping both the immediate CO2 pulse and the burst of nutrients available for plant germination and growth or leaching loss. The proposed project will: i) identify which soil bacteria are primed for immediate activation upon wet up, ii) use the expression of selected genes as an index of major drought-survival strategies in soil bacterial communities, and iii) assess how predicted global change scenarios for precipitation in California may impact both the accumulated substrate pools and the responding microbes to frame the characteristics of the wet-up pulse. We will then compare and contrast the information gained from a California grassland (Hopland) to two other California grasslands (Sierra Foothills and Sedgwick Reserve) with contrasting climate conditions. This project addresses microbial drought-tolerance strategies at the molecular level that shape wet-up CO2 fluxes at the regional level. Changing patterns of precipitation in California will likely affect the composition and activity of indigenous soil microbial communities, potentially changing the character of fall wet-up pulses. We are looking at changes in the soil microbial community composition over the summer, so we will be taking soil cores (10 cm depth) and taking them back to the lab to extract the microbial DNA for our analysis. We will be coming out with Josh Schimel from UC Santa Barbara on Monday, because we'd like to sample near his plots, to be close to his soil sensors. We will mark a small 1 x 1 m plot with flags that we can return to later in the summer, to take cores from the same area, but it is a small experiment, with very little impact on the site, except for some small coring holes.

Visit #21099 @Sedgwick Reserve

Approved

Under Project # 21551 | Research

The combined drought strategies of soil microbial communities shape wet-up CO2 pulses in Mediterranean annual grasslands

research_scientist - University of California, Berkeley

Reservation Members(s)

Catherine Osborne Apr 5, 2010 (1 days)
Group of 2 Research Scientist/Post Doc Apr 5, 2010 (1 days)

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