Root-induced alterations in soil hydrothermal properties in alpine meadows of the Qinghai-Tibet Plateau

Abstract

By altering the physical properties of soil through root activity, plants can act as important agents in affecting soil hydrothermal properties. However, we still know little about how plant roots regulate these properties in certain ecosystems, such as alpine meadows. Thus, we studied the influence of roots on soil hydrothermal properties in the Qinghai-Tibet Plateau (QTP). Root biomass as well as soil physicochemical and hydrothermal properties were examined at a depth of 0–30 cm at three study sites in the QTP. The relationship between root biomass and saturated soil hydraulic conductivity (Ks) was examined, as was the applicability of common soil hydrothermal properties models to the alpine meadow system. Results revealed that approximately 91.10%, 72.52%, and 76.84% of root biomass was located in the top 0–10 cm of soil at Maqu, Arou, and Naqu, respectively. Compared with the bulk soil, the water-holding capacity of rhizosphere soil was enhanced by 20 %–50%, while Ks was decreased by at least 2- to 3-fold. The thermal conductivity (λ) of rhizosphere soils was lower than that of the bulk soil by 0.23–0.82 W m−1∙K−1 on average. Lastly, soil hydrothermal properties models that do not explicitly consider root effects overestimated the Ks and λ in the rhizosphere soil of these systems. Overall, our results revealed distinctive differences in soil hydrothermal properties between the rhizosphere soil and the bulk soil in the QTP. This research has important implications for future modeling of soil hydrothermal processes of alpine meadow soils.