Correlations of the root–shoot ratio with soil water content in the patchy alpine grassland of the north‐eastern Qinghai–Tibetan Plateau using electrical resistivity tomography

Abstract

The root–shoot biomass ratio (R:S) changing the soil water redistribution is not well understood due to a lack of nondestructive technology to characterize the coexistence of plants and soil. This study aims to assess the correlations of the R:S ratios of Achnatherum splendens with soil water content by electrical resistivity tomography (ERT) on the north‐western Qinghai–Tibet Plateau (QTP). During the growing season, an experimental plot including bare patches (BK) and low‐ (LD) and high‐density (HD) A. splendens subplots was designed to quantify soil volumetric water content under different soil depths and antecedent total precipitation conditions for 7 days (AP7). The results showed that the R:S ratio was positive with soil water content in the surface soil layer of 0–10 cm. The synergistic effect of the R:S ratio on soil water in the surface soil layer promoted an increase in surface soil water. However, the nonsynergistic effect in the middle soil layer weakened the soil water increasing, and the effect of the R:S ratio on soil water in the deep soil layer of 40–80 cm was not obvious. In HD, soil water increased between 0.08% and 0.95% and was highest under AP7 > 20 mm conditions. In LD, soil water increased in the surface and deep soil layers but decreased in the middle soil layer, especially under AP7 = 10–20 mm conditions (−1.23%). These findings provide valuable insights that patchy alpine grass survival strategy under future climate change on the QTP, and the results are beneficial to the development of soil–plant–atmosphere continuum models.