We collected soil samples from three alpine meadow sites on the Tibetan Plateau, China, where substantial quantities of soil organic C (15.3 Pg) were stored in the top 3 m (44). In the past decades, mean annual temperature on the plateau increased at a rate about twice that of global warming (45). The high rate of climate warming, together with the high Q10 on the plateau (46), could induce potential positive C-climate feedback in this unique geographic region. Moreover, because of the detected differences in substrate quality, environmental constraints, and microbial properties among soil depths (17), there might be considerable differences in Q10 through soil profile. To test this possibility, we selected three sampling sites (Halejing, Xihetai, and Zhagamu) on the northeastern Tibetan Plateau (fig. S1A) and examined Q10 in different soil depths and various soil C components, as well as the associated mechanisms.

The sites are situated at latitudes of 37.02°N to 37.61°N and longitudes of 100.11°E to 101.24°E, with an elevation of 3200 to 3400 m. The mean annual temperature varies from 0.12° to 2.20°C, and the mean annual precipitation ranges from 340 to 378 mm. The vegetation type belongs to alpine meadow, characterized by the dominant species of Kobresia pygmaea in Halejing and Zhagamu, and Kobresia humilis in Xihetai. The soil type at the three study sites is Cambisol according to the World Reference Base for Soil Resources (46). Cambisols are widespread not only on the Tibetan Plateau but also worldwide (47), accounting for ~38% of the Tibetan Plateau and ~11% of the global land surface. Soil physicochemical properties at these sites are given in table S3.

We conducted soil sampling in July and August 2014 (44). At each sampling site, we set up a 10 m × 10 m square plot and excavated three replicate soil pits at two corners and the center along a diagonal line (fig. S1B). We then collected topsoil at depths of 0 to 10 cm and subsoil at depths of 30 to 50 cm (fig. S1C). Soils from each depth were divided into two subsamples: one of which was passed through a 2-mm sieve and stored at −20°C to determine SOM composition and microbial communities; the other set was air-dried and processed for measurements of other physicochemical properties.

Note: The content above has been extracted from a research article, so it may not display correctly.

Please log in to submit your questions online.
Your question will be posted on the Bio-101 website. We will send your questions to the authors of this protocol and Bio-protocol community members who are experienced with this method. you will be informed using the email address associated with your Bio-protocol account.

We use cookies on this site to enhance your user experience. By using our website, you are agreeing to allow the storage of cookies on your computer.