Characteristics of dew on leaves of typical plants in Loess Hill and Gully Region of China

Abstract. Dew plays an important role as a non-precipitation input to the hydrological cycle and vegetation recovery in semi-arid ecosystems. To clarify the characteristics of dew on plant leaves, typical plants such as Tribulus, Hippophae and Elm were selected in the hilly and gully region of the Loess Plateau in China. The dew amount of typical plant leaves by manual weighing measurement was combined with automatic observation data from leaf wetness sensors (LWS) further to realize the automatic observation of dew on the leaf surface. The results showed that the cumulative dew amount on Tribulus, Hippophae and Elm from May to October in 2022 was in the order of Tribulus (17.46 mm) > Hippophae (11.14 mm) > Elm (5.88 mm), and the difference in the amount was mainly related to the leaf inclination angle and the microstructure of the leaf blade. Dew mainly occurred from 22:00 to 9:00 the next day on a daily scale, and was mainly concentrated in July–October during the year. The dew amount on the leaves of the three plants was less than the amount of rainfall, but the dew frequency was higher than that of rainfall. It was more favorable for the dew formation when the relative humidity is greater than 80.0 %, the difference between air temperature and dewpoint was less than 2 °C, and the wind speed was less than 1.0 m/s. In addition, there was more dew on the first day after a rainfall than on the day before due to sufficient moisture.