Seasonal variations and sources of the dew from stable isotopes in alpine meadows

Abstract The dew is closely related to the micro‐use water of plants and the large‐scale hydrological processes, its formation on grassland plays a vital role especially in maintaining the eco‐hydrological cycle. We used structural equation modelling to investigate how environmental factors would affect dew formation on alpine graminoid‐Kobresia meadow in northern Qinghai‐Tibet Plateau. The stable isotope information of dew, ambient vapour, soil water, plant water, creek water and precipitation were tracked to explore the source of dew, the dew transport route of the six dominant species by Mix SIAR model. Our results showed that the frequency of dew on the graminoid‐Kobresia meadow in 2020 and 2021 was 42.86% and 45.83%, respectively. Both atmospheric pressure ( r = 0.4) and temperature ( r = 0.382) showed significant positive effects dew formation while wind speed ( r = −0.309) had a negative effect. The contribution rates of soil water, plant water and ambient water vapour to dew were 48.20 ± 5.46%, 38.30 ± 5.07%, and 13.50 ± 1.82%, respectively. The proportion of dew utilization in the dominant species had no significant species differences. Our results provided an improved understanding of dew formation based on isotope technology on alpine meadow in northern Qinghai‐Tibet Plateau.