Progress Report: Siberia
This past summer, French Ph.D. student Felix Brédoire from INRA Bordeaux worked on establishing a cryogenic extraction system at the ZALF isotope facilities. He had a short visit with Paul Koeniger to learn about his method using glass vials to expedite this normally laborious and time consuming first step to analysis.The method can be tricky and is specific for each sample type (soil vs. leaves vs. wood cores).
Because we are interested in the plant water access at our Siberian sites, we began with soil and found that after about an hour we could retrieve more than 97% of the water present in the sample using this method.
With further modification to avoid condensation in the transfer, we are achieving much better results. Next is to extract the water from samples collected from last year's sampling campaigns. The isotopic values of the extracted eater will establish a baseline to this current year's snow manipulation.
The question of different water pools available for plants is fundamental to understanding how forests, grasslands, and croplands might adapt to or be managed for climate change. So, we hope to learn which water pools are important to plants over the Siberian growing season. The dynamics of the refilling of soil water has become really interesting lately since Renée Brooks and colleagues discovered that plants play a bigger role than previously thought. Incidentally, the idea that soil water pools are very heterogeneous may complicate our use of isotopic mixing models to identify plant source water!
In this area of Siberia, snow levels are expected to increase. The higher level of snow may lead to soil that does not freeze (or not as much) over the winter. If the soil does not freeze then we might see an increase in the biogeochemical cycles of nutrients, and the soil water pools below ground may shift as well. In our experiment this year (2014) we will double the snow level on different plots. We are hoping for a good snow year for the manipulation (but not too much)!
