Characteristics of Dew on Typical Plant Leaves in Loess Hill and Gully Region of China

Abstract

Dew plays an important role as a nonrainfall water input in semi-arid ecosystems. To analyse dew's variations and its influencing factors, Tribulus, Hippophae and Ulmus were selected as typical plant species because of these common plants having different leaf traits in loess hill and gully region of China. A dew monitoring method correlating manual measurements of plant leaf dew with automated sensor data was developed. During May–October 2022, the cumulative amount of dew on the foliage of the three plant species was in the following order: Tribulus (17.46 mm) > Hippophae (11.14 mm) > Ulmus (5.88 mm). Dew mainly occurred from 20:00 to 9:00 the next day and was mainly concentrated in July–October. Compared with rainfall, dew frequency is higher though the dew amount is less. Dew formation was more favourable when relative humidity at 0.2-m height was greater than 80.0%, the air temperature and dewpoint difference at 0.2-m height was less than 2°C, and the wind speed at 1.0-m height was less than 1.0 m/s. In addition, there was more dew on the first day after rainfall because of sufficient moisture. Under the same meteorological conditions, Tribulus is more prone to dew because of its dense, fine and vertical tomentum. Overall, meteorological factors significantly influenced the amount of dew condensation of the three plants. However, interspecific differences due to plant foliar characteristics were more prominent. Therefore, foliar characteristics of different plants cannot be ignored in dew studies.