Effects of gravel on soil and vegetation properties of alpine grassland on the Qinghai-Tibetan plateau

•Gravel decreases soil C and N sequestration.•Increasing of gravel content in soil is not beneficial to vegetation growth.•Findings suggest ecosystem modeling studies should consider gravel.

Gravel is common in soil profiles of alpine grassland on the Qinghai-Tibetan plateau (QTP). However, little is known about the effect of gravel on soil and vegetation properties. In this study, we investigated the gravel content in the topsoil (0–40 cm) at three sites with different surface gravel mulch and analyzed the influence of gravel on soil organic carbon (SOC), soil total nitrogen (TN), fractional vegetation cover (FVC), and aboveground biomass (AGB). Results showed that (1) gravel content was the highest in sites with high surface gravel mulch, and the lowest in sites with light surface gravel mulch; (2) gravel was significantly negatively correlated with SOC, TN, FVC and AGB, and (3) gravel of 2–20 mm in size was the most important factor determining soil and vegetation properties. Our results suggested that the presence of gravel in the soil profile is not beneficial to soil nutrition sequestration and vegetation growth of alpine grassland on the QTP and should be considered in ecosystem modeling studies.