Next Article in Journal
Spatiotemporal Evaluation of Blue and Green Water in Xinjiang River Basin Based on SWAT Model
Previous Article in Journal
Evaluation of TIGGE Precipitation Forecast and Its Applicability in Streamflow Predictions over a Mountain River Basin, China
 
 
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Article

Dew Evaporation Amount and Its Influencing Factors in an Urban Ecosystem in Northeastern China

Key Laboratory of Songliao Aquatic Environment, Ministry of Education, Jilin Jianzhu University, 5088 XinCheng Road, Changchun 130118, China
*
Author to whom correspondence should be addressed.
Water 2022, 14(15), 2428; https://doi.org/10.3390/w14152428
Submission received: 6 July 2022 / Revised: 2 August 2022 / Accepted: 2 August 2022 / Published: 5 August 2022
(This article belongs to the Section Ecohydrology)

Abstract

:
Dew is an important water input and promotes plant growth. Dew condenses on plant leaves at night, and a portion of this dew returns to the atmosphere through evaporation. The amount of dew that evaporates is not equal to the amount of condensation; however, the dew evaporation process has not received enough attention. By monitoring the dew condensation and evaporation processes associated with four typical shrubs (Syringa, Hemiptelea, Buxus, and Cornus) in northeast China, we found that dew condensation started approximately 30 min after sunset, finished approximately 30 min before sunrise, and then turned to the evaporation phase. Dew had completely depleted approximately 4 h after sunrise. The dew evaporation period was negatively correlated with the wind speed (p < 0.01) and positively correlated with temperature, solar radiation, and relative humidity (RH) (p < 0.01). The average evaporation periods of Syringa, Buxus, Cornus, and Hemiptelea were 282 ± 21 min, 255 ± 26 min, 242 ± 22 min, and 229 ± 17 min, respectively. The daily evaporation amounts in May and September reached the minimum and maximum values, respectively, and the evaporation intensity of dew was positively correlated with RH (p < 0.01). There was no significant difference in the daily evaporation amounts of Syringa, Hemiptelea, Buxus, or Cornus (p > 0.05), and the annual evaporation amounts of these four plants were 17.05 mm/y, 16.38 mm/y, 21.94 mm/y, and 16.15 mm/y, respectively. The microstructure of leaves affected both the rate and amount of evaporation. Dew evaporated faster on hydrophilic leaves, and leaves with high trichome and stomatal densities had lower proportions of the dew evaporation amount to the condensation amount. The proportions of the dew evaporation amount to the condensation amount derived for Syringa, Hemiptelea, Buxus, and Cornus were 60.38%, 46.07%, 57.24%, and 52.81%, respectively. This study supplements our understanding of dew evaporation amounts, providing information that was missing in the near-surface hydrological cycle and aiding in the assessment of the ecological significance of dew to plants.

1. Introduction

Dew is a common weather phenomenon. Whether in arid deserts [1,2], semiarid grasslands [3], hilly regions [4,5], mountainous areas [6], urban areas [7,8], or island, coastal, or alpine areas [9], dew deposition provides a considerable amount of supplementary and steady water at a high frequency. The ecological and hydrological significance of dew cannot be ignored. In some arid and semiarid regions, dew not only helps initiate plant photosynthesis and enhance leaf hydration and growth [10] but also increases the relative water contents of shoots, the net accumulation of photosynthates, and the photosynthetic rate in leaves [11,12,13]. Foliar uptake of dew is an important water-acquisition mechanism for plants [14]. Plant functional traits (height, leaf area, leaf thickness, and chlorophyll content) and demographic traits (survival rate, total age, and mean life expectancy) both increase with increasing dew amounts [15,16,17,18]. Dew absorption affects leaf hydraulic functions during dehydration [19]. The ability of leaves to absorb dew also allows plants to restore their water status, and this is especially relevant in plants exposed to prolonged drought conditions [20,21,22]. The dew duration can significantly reduce transpiration rates [23,24], and dew can also be used as an evaporation source [25]. Cavallaro et al. estimated that the accumulated foliar water uptake represented 1.6% of the total annual transpiration associated with grasses and shrubs in arid ecosystems [20].
Dew condenses on plant leaves at night. Some of this dew is absorbed directly by the leaves, while some of it evaporates back into the atmosphere. In recent years, most dew observations have focused on the condensation process, while information on the dew evaporation process is scarce. However, the ecophysiological and hydrological importance of this process is suggested by the long surface-wetting duration with possible implications for gas exchange, leaf growth, leaf colonization by epiphylls, and water balance [26]. Water vapor near the ground surface provides heterogeneous transformation carriers for gaseous pollutants and promotes the formation of fine particles, such as sulfates and nitrates. Water vapor is a key factor affecting the transformation of polluted gases into secondary pollutants and is also a reactor for liquid-phase oxidation [27]. The abilities of plants to condensate and absorb dew vary greatly among different plant species [23]. This differentiation is also likely to cause variations in the dew evaporation process among different underlying surfaces. In view of the important ecological significance of dew and the effect of the evaporation process on the conversion and circulation of surface atmospheric matter, it is urgent to study the dew evaporation process. The aims of this study were to observe the time and amount of dew evaporated among different plants in a green urban ecosystem area and to reveal the influencing factors of the dew evaporation process from the perspective of meteorological factors and leaf microstructures. This study can reveal the utilization mechanisms of dew on different underlying surfaces.

2. Materials and Methods

2.1. Study Area

Our experiment was performed from early May to late October 2021. The green area of Changchun city in northeast China was selected as the research area (44°05′ N, 125°20′ E, 330 m asl). The research area belongs to the continental monsoon climate of the north temperate zone. The annual average temperature of Changchun is approximately 4.8 °C, and the annual average rainfall total is 522–615 mm. The frost-free period lasts approximately 145 days. Monsoon climate characteristics are obvious in this region, with rain and heat conditions occurring over the same period. Spring (March to May) is dry and windy. Summer (June to August) is humid, hot, and rainy. In autumn (September to November), the temperature difference between day and night is notable. Due to this climate feature, dew condensation is frequent and extensive in the study area, with 132–136 dew days [28]. The underlying surface types in the study area comprise four common plants in northern China. The plant species are dominated by shrubs, including Buxus sinica var. parvifolia M. Cheng (Buxus), Syringa oblata Lindl. (Syringa), Hemiptelea davidii (Hance) Planch. (Hemiptelea) and Cornus alba Linnaeus (Cornus).

2.2. Meteorological Factors and LAI

Daily meteorological factors, including relative humidity (RH) (%), air temperature (°C), solar radiation (W/m2), and wind speed (m·s−1), were measured at hourly intervals during the evaporation period with a Milos 520 automatic weather station (Vaisala, Vantaa, Finland). The leaf area index (LAI) of plants was measured daily using a LAI-2200C Plant Canopy Analyzer (LI-COR, Lincoln, NE, USA).

2.3. Dew Condensation–Evaporation Monitoring Process

In some past studies, researchers have chosen leaf-wetness sensors to measure the dew duration and amount. A calibration curve is required to convert the data (voltage) output obtained by the leaf-wetness sensor to the dew amount [1,5]. This process may lead to deviation between the amount of dew recorded and the actual situation due to the conversion process. Therefore, in this study, dielectric leaf-wetness sensors (LWSs, Decagon Devices Inc., Pullman, WA, USA) were installed at the canopy zone of each analyzed plant to monitor the dew condensation and evaporation time nodes. Signals from these sensors were automatically recorded. The times at which each sensor began to record a value (T1), reached the maximum value (T2), and became stable after sunrise (T3) were recorded. T1 was considered the time point when dew condensation began, T2 was considered the time point when dew condensation finished and evaporation began, and T3 was considered the time when evaporation was complete. The corresponding T2–T1 period was defined as the dew condensation period, and the corresponding T3–T2 period was defined as the dew evaporation period. Finally, T3–T1 was defined as the dew duration period.
A tray (with a 30 cm diameter) with turf covering both sides was placed on an electronic balance (range of 0.01 to 3000 g). This balance was then placed in a waterproof box (with small holes to discharge rainwater), and the box was placed on an observation shelf. The observation shelf was equipped with an arm that adjusted in height according to the growth of plants so that the tray and the plant canopy remained at constant heights. The weight change of the turf was continuously monitored and used as the objective dew condensation or evaporation indicator. The values were recorded at T1 (W0, g), T2 (W1, g), and T3 (W2, g). Dew is difficult to distinguish from rain; thus, the dewfall was recorded as zero if a rainfall event occurred during the measurement period.
The turf area was recorded (S, cm2). The difference between the initial value (W0, g) and maximum value (W1, g) of the balance was considered the dew condensation of turf, the difference between the maximum value (W1, g) and the constant value (W2, g) of the balance was considered the dew evaporation of turf, and 10 was used as the conversion factor. LAIi was derived as the LAI on each day (cm2/cm2). LAIi for each plant was measured three times, and the actual LAIi was computed as the average of the three measurements. Two was used as the coefficient of the leaf side, and n was set as the number of dew days. The daily dew condensation intensity (Ci, mm), daily dew evaporation intensity (Ei, mm), annual dew condensation amount (AC, mm), and annual dew evaporation amount (AE, mm) of each plant were determined based on the following formulas:
Ci = (W1W0) × 10/S,
A C = i = 1 n 2   ×   L A I i ×   C i ,
Ei = (W1W2) × 10/S,
A E = i = 1 n 2   ×   L A I i   ×   E i ,

2.4. Microstructural Analysis of Leaves

The microstructures of the leaves were examined using scanning electron microscopy (SEM). According to the method described by Muhammad et al., the drop contact angle (DCA) was determined using a Canon EOS550D camera attached to a macrolens (MP-E 65MM 1:2.8) [29]. A 6 µL droplet of distilled water was placed on each leaf sample.

2.5. Data Analysis

Statistical analyses were conducted using SPSS software version 16.0 (IBM Corp., Armonk, NY, USA). To test the daily evaporation amounts distributions of Syringa, Hemiptelea, Buxus, and Cornus, Q-Q Probability Plots were employed. The daily evaporation amount of each plant was subjected to a one-way analysis of variance (ANOVA) and the significance was set at p < 0.05. The LSD procedure or Tamhane’s T2 procedure was used to determine significant differences between the daily evaporation amounts of each plant. The data of daily evaporation and meteorological factors were subjected to Pearson correlation analysis.

3. Results and Discussion

3.1. Dew Evaporation Period

Dew condensation started approximately 30 min after sunset, finished approximately 30 min before sunrise, and then turned to the evaporation phase. The dew evaporation periods of the four plants ranged from 189 to 321 min (Figure 1). The average evaporation periods of Syringa, Buxus, Cornus, and Hemiptelea were 282 ± 21 min, 255 ± 26 min, 242 ± 22 min, and 229 ± 17 min, respectively. Relatively long daily dew evaporation periods were found in August, while these periods gradually shortened in September and October. For each plant, the dew evaporation period was negatively correlated with the wind speed during the dew evaporation process (p < 0.01) and positively correlated with air temperature, solar radiation, and RH during evaporation (p < 0.01). Extended evaporation periods were most influenced by wind speed decreases. Relatively low wind speeds slowed the flow of water vapor, resulting in slower evaporation rates [30,31]. Higher wind speeds removed more water vapor molecules from the air, increased the exchange of dry and wet air masses, and increased the water vapor pressure gradient on the evaporative surface to accelerate evaporation. Yu et al. also found that windy mornings do not facilitate longer dew durations [32]. The RH represents the degree of saturation of water molecules in the air. If the RH is high, the water molecules in the atmosphere prevent the dew present on a leaf surface from diffusing into the air and thus weaken the speed of evaporation. Temperature and radiation were found to be generally negatively correlated with the rate of evaporation because the wind speed in the study area was negatively correlated with temperature and radiation (p < 0.01), and wind speed was the dominant factor affecting the evaporation time. Therefore, dew took longer to evaporate in hot, humid weather at low wind speeds.
Dew was completely lost through evaporation 4 h after sunrise. Leaf surface wetness continuously existed for a period of 12.5–14.5 h and accounted for 55% to 60% of the day. Jia suggested that the temperature change following sunrise appeared to be the main factor influencing the dew duration [33]. Barradas and Glez-Medellin found that the upper strata of the sun rays and light winds during the early morning affected the dew duration [24]. As seen in Table 1, the dew duration has been found to be independent of the condensation amount. For example, Zhangye is located in an arid zone, while Luancheng has a subhumid climate. The dew amounts recorded in these two regions are significantly different, but the dew durations are basically the same [34]. The dew duration is also independent of the underlying surface type, elevation, climate type, and ecosystem type. Dew durations are not consistent among regions of the same climate or ecosystem type. Taking desert ecosystems as an example, dew in the Tengger Desert was found to last until 13:00–14:00 [2]. This dew duration is significantly longer than that of other deserts. Differences were also found in the dew durations in the Badain Jaran and Mu Us deserts with the same underlying surface types [35,36]. Most of these dew durations seemed to be related to the night length. Longer nights generally correlate with longer dew durations. This result is similar to findings reported in Llanos de Ojuelos, Jalisco, Mexico [3], Badain Jaran Desert, China [35], and the Middle Guanzhong Plain, China [1]. Dew forms after sunset as atmospheric temperatures gradually drop and evaporates after sunrise as temperatures increase in the second morning. The dew duration is mainly controlled by changes in meteorological factors (T, wind speed, RH, etc.) caused by the alternation of day and night.

3.2. Evaporation Amount

The annual dew condensation amounts (AC) of Syringa, Hemiptelea, Buxus, and Cornus were 28.24, 35.55, 38.33, and 30.58 mm/y, respectively. These results are similar to the annual dew amounts recorded in farmland ecosystems in the middle of the Guanzhong Plain, China, and higher than those recorded in the Gurbantuggut Desert, Tengger Desert, or Taklimakan Desert, where the land surfaces are covered with shrubs or crusts (Table 1). This difference is due to the abundant water vapor and frequent dew days in the study area. During the 182-day study period, water vapor condensation occurred in 80 days when no precipitation occurred during the dew duration period. Dew occurred on 44% of the days of the growing season. In addition, the underlying surface of the study area comprises shrubs, and the LAI index can reach approximately 7 in August (Figure 2). These dense leaves provide abundant carriers for water vapor condensation.
The daily dew evaporation amounts (AE) of Syringa, Hemiptelea, Buxus, and Cornus were 0.002–0.69 mm/d (mean 0.23 ± 0.20 mm/d), 0.0006–1.02 mm/d (mean 0.22 ± 0.24 mm/d), 0.01–1.10 mm/d (mean 0.30 ± 0.26 mm/d), and 0.005–1.15 mm/d (mean 0.22 ± 0.27 mm/d), respectively. There was no significant difference in the daily evaporation amount among the four species (p > 0.05). The annual evaporation amounts of Syringa, Hemiptelea, Buxus, and Cornus were 17.05 mm/y, 16.38 mm/y, 21.94 mm/y, and 16.15 mm/y, respectively. The differences in the annual dew evaporation amounts of these different plants were caused by LAI differences among plants. A decrease in LAI reduces vegetation transpiration, canopy interception, and water evaporation [38]. Among the four plant species analyzed herein, Buxus had the highest LAI: the average LAI of Buxus in the plant growth season was 4.99 ± 1.80 cm2/cm2, higher than those of Syringa (4.31 ± 1.96 cm2/cm2), Hemiptelea (4.57 ± 2.06 cm2/cm2) and Cornus (4.13 ± 2.18 cm2/cm2) (Figure 2). A larger LAI means that plants can capture more radiation energy, resulting in increased evaporation.
The daily dew evaporation amount exhibited obvious seasonal regularity. The average daily dew evaporation amounts of Syringa (0.06 ± 0.05 mm/d), Hemiptelea (0.04 ± 0.03 mm/d), Buxus (0.09 ± 0.06 mm/d), and Cornus (0.04 ± 0.02 mm/d) were significantly lower in May (the spring season) than in other months (p < 0.05). The average daily dew evaporation amount of each plant was highest in September (autumn). The average daily dew evaporation amounts of Syringa, Hemiptelea, Buxus, and Cornus in September were 0.46 ± 0.16 mm/d, 0.64 ± 0.26 mm/d, 0.72 ± 0.32 mm/d, and 0.59 ± 0.44 mm/d, respectively.
The dew evaporation intensity (E) was positively correlated with RH (p < 0.01) but was not correlated with the wind speed, temperature, or solar radiation (p > 0.05). The dew condensation intensity (C) levels of the four plants were positively correlated with the evaporation intensity (p < 0.01), and the dew condensation intensity was higher at high RH values. However, neither the wind speed nor the temperature affected the dew evaporation intensity. In general, high temperatures and wind speeds were conducive to accelerating the evaporation process. The evaporation of dew is different from that of surface water. First, the dew evaporation period is short, last from only 30 min before sunrise to 3–5 h after sunrise. The range of variation in meteorological factors in this period is smaller than that over the whole day. Second, dew mostly condenses on plant leaves, and densely interlaced leaves also restrict the influence of the surface temperature and wind speed on dew evaporation. The dew condensation intensity recorded in the study area was positively correlated with the RH, air temperature, and solar radiation (p < 0.01) and negatively correlated with the nighttime wind speed (p < 0.01) [39]. The meteorological factors affecting the condensation stage and evaporation stage of dew differed. This was because during the condensation stage of dew, water vapor settles from the atmosphere onto plant leaves, and this process is obviously affected by both the wind and temperature conditions. In the evaporation stage, dew diffuses from leaves to the atmosphere. Thus, the adsorption of dew by the leaf accessory structures cannot be ignored.
The proportions of the annual evaporation amount to the condensation amount recorded for Syringa, Hemiptelea, Buxus, and Cornus were 60.38%, 46.07%, 57.24%, and 52.81%, respectively, indicating that most of the condensed dew returned to the atmosphere during the evaporation stage. However, different proportions were obtained for different plant species. Plants have different water requirements at different growing stages [40], and their ability to take up dew varies seasonally. Taking Buxus as an example, the RH in May (spring) was significantly lower than that in other months (p < 0.05). The average daily dew evaporation proportion was 45 ± 18%, and approximately 55% of this dew was intercepted by Buxus. RH increased in July and August (summer), when there was sufficient water vapor in the atmosphere, and the daily dew evaporation proportion increased to 56–63%. This may have been due to the abundant rainfall in summer, when plants can absorb more water sources. Plants can use rainwater first, thus reducing dew absorption. The wind speeds in September (autumn) were significantly higher than those in other months (p < 0.05), and the RH in this month was not significantly different from those in July and August (p > 0.05). Dew evaporation accounted for the highest proportion, reaching an average of 63 ± 21%. The leaf water uptake strategy is more important than the root water uptake strategy in this process [5]. We found that the dew evaporation proportion was larger in summer and autumn under humid conditions than in other seasons: dew was more absorbed and utilized by plants in spring when the conditions were drier. Zhang applied the isotope tracer method to discuss the dew absorption capacities of plants under different water stress conditions [41] and reached a similar conclusion: dew is more beneficial to plant growth in the dry season than in the wet season.

3.3. Effect of Leaf Microstructure on Dew Evaporation

The dew evaporation amounts and rates varied among Syringa, Hemiptelea, Buxus, and Cornus. The distributions of these four plants in the study area are relatively concentrated, and meteorological factors have little influence on the spatial differences. The dew evaporation process was found to be largely dependent on the different microstructures of the plant leaves. As shown in Figure 3 and Table 2, regarding the decreasing DCA of the adaxial and abaxial surfaces, the plants could be ordered as follows: Syringa, Buxus, Cornus, and Hemiptelea. The DCAs of Hemiptelea and Cornus were less than 90°, and their surfaces can be called hydrophilic, meaning that a drop will increase the area of contact between the liquid and leaf surface and potentially favor the foliar absorption process (Figure 3f,i,k,n). For Syringa and Buxus, with DCAs greater than 90°, the surfaces were called hydrophobic, having less wettability and touching only a small area with a more spherical shape (Figure 3a,c,p,r). The affinity to water increased in the following order: Syringa < Buxus < Cornus < Hemiptelea. Hydrophilic droplets evaporated 34% faster than their hydrophobic counterparts due to the greater contact line length, liquid–gas interface temperature, and solid–liquid surface area present for the majority of the hydrophilic droplet evaporation process [42]. Hydrophilic surfaces have high affinities to water, and the dew evaporation duration order exhibited the opposite trend as the affinity to water.
The longer dew evaporates, the higher the proportion of the evaporation amount to the condensation amount is. The proportions of the annual evaporation amount to the condensation amount of Syringa, Hemiptelea, Buxus, and Cornus were 60.38%, 46.07%, 57.24%, and 52.81%, respectively. The morphoanatomical traits of these species may be related to these observed differences. As shown in Table 2, no trichomes were present on the adaxial or abaxial surfaces of Syringa or Buxus leaves. The trichome densities on both sides of Hemiptelea were higher than those of Cornus. Leaf trichomes are important epidermal dew-uptake structures that assist in partially sustaining the leaf hydraulic assimilation system and mitigate the adverse effects of drought stress. Hydrophilic trichomes may facilitate dew uptake [43,44,45]. Plants can absorb water when water diffuses into their leaf surfaces via their leaf trichomes or hydathodes [19]. Losada [10] and Jura-Morawiec and Marcinkiewicz [46] used a fluorescent dye tracer to evaluate the pathways by which water penetrates into leaves and identified that leaf hairs and idioblasts create microchannel networks that maintain leaf hydration and promote water uptake, inducing water penetration into leaves on both the adaxial and abaxial sides. In the first step, droplets nucleate at the tip of the trichomes. Then, small droplets move from the tip to the base of the trichomes and coalesce together to form larger droplets [47]. Hydrophilic surfaces are advantageous in obtaining moisture [16]. The leaf trichomes of Hemiptelea (Figure 3g,h,j) and Cornus (Figure 3l,m) promote the absorption and utilization of dew, so the proportion of dew that evaporated back to the atmosphere was low.
The leaves of the four analyzed plants all have stomatal structures, and stomata are an important gas exchange channel and are free of liquid water [48]. Eichert et al. found that stomatal uptake does not require the infiltration of solutions by dynamic mass flow, but is caused by the diffusion of solutes adsorbed to the walls of the stomatal pores [49]. The presence of dew caused an increase in stomatal conductance [11]. Guzmán-Delgado et al. also found that open stomata enabled up to 3–4 times higher fluxes and hydraulic conductance, and stomata are an important way for leaves to absorb water [48]. Burkhardt pointed out that pores can absorb liquid water through the “hydraulic activation of stomata (HAS).” HAS can make droplets form a continuous liquid water path along the pore wall to connect the leaf interior and with the exterior leaf surface [50]. Dew condenses on leaf surfaces to form a water film, which can extend to the pores to complete the pore water absorption process. The rate and amount of dew absorbed by leaves were strongly correlated with the stomatal density and aperture. As shown in Table 2, the average stomatal area accounted for 6.19% of the Hemiptelea leaves per unit area, higher than those of Syringa (5.43%), Buxus (3.81%) and Cornus (2.50%). Hemiptelea can absorb dew not only through trichomes but also through stomatal pathways. Furthermore, the margin of the Hemiptelea leaf is serrate, and the leaf margin splitting degree and leaf length to width ratio are also higher than those of the other analyzed plants. Such a leaf structure can increase the leaf boundary layer resistance and reduce water evaporation. Therefore, the dew evaporation amount of Hemiptelea leaves was the lowest. In general, species with trichomes on their leaves had smaller dew evaporation amounts than those without trichomes.

4. Conclusions

By monitoring the dew condensation and evaporation processes of Syringa, Hemiptelea, Buxus, and Cornus during the plant growth season in 2021, we found that the dew condensed on the leaf surfaces did not deplete quickly following sunrise. Dew formation continued until 30 min before sunrise and ultimately evaporated approximately 4 h after sunrise in the analyzed green urban ecosystem area in northeast China. The evaporation period was negatively correlated with the wind speed (p < 0.01), but positively correlated with the temperature, solar radiation, and RH (p < 0.01). The evaporation periods varied among the analyzed plant species, and leaves with hydrophilic surfaces (Syringa) experienced faster evaporation. No significant difference was found in the daily evaporation amounts among Syringa, Hemiptelea, Buxus, and Cornus (p > 0.05). The daily average dew evaporation amount recorded during the study period peaked in September, reaching 1.15 mm (Cornus). The factors that influence the dew evaporation process differ from those that affect the dew condensation stage. The dew evaporation intensity was found to be positively correlated with RH (p < 0.01), but not with wind speed, temperature, or solar radiation (p > 0.05). The annual evaporation amounts of Syringa, Hemiptelea, Buxus, and Cornus were 17.05, 16.38, 21.94, and 16.15 mm/y, respectively. These differences were caused by the LAI. The proportions of the annual dew evaporation amount to the condensation amount of Syringa, Hemiptelea, Buxus, and Cornus were 60.38%, 46.07%, 57.24%, and 52.81%, respectively, indicating that most of the condensed dew returned to the atmosphere in the evaporation stage. Dew provides significant amounts of water and is thus especially relevant in the dry season. The leaf microstructure was the main factor affecting the dew evaporation processes observed on different plants, and the proportion of the dew evaporation amount to the dew condensation amount was lower for plants with high trichomes and stomata densities on their leaves. However, the present study did not examine the pathway or ratio of dew absorption on leaves. In future studies, these processes can be confirmed by isotope or fluorescent tracer methods. Evaporation from the underlying surface varies greatly among different functional areas, and systematic observations should also be carried out in this regard in the future.

Author Contributions

Conceptualization, Y.X.; methodology, Y.X.; validation, Y.X., C.J. and H.L.; formal analysis, C.J.; data curation, H.L.; writing—original draft preparation, Y.X.; writing—review and editing, Y.X.; visualization, C.J.; supervision, Y.X.; project administration, Y.X.; funding acquisition, Y.X. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by the National Nature Science Foundation of China (grant 42175140).

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

Data available on request due to restrictions, e.g., privacy. The data presented in this study are available from the corresponding author by request.

Conflicts of Interest

The authors declare no conflict of interest.

References

  1. Jia, Z.F.; Zhao, Z.Q.; Zhang, Q.Y.; Wu, W.C. Dew yield and its influencing factors at the western edge of Gurbantunggut Desert, China. Water 2019, 11, 733. [Google Scholar] [CrossRef] [Green Version]
  2. Pan, Y.X.; Wang, X.P.; Zhang, Y.F.; Hu, R. Dew formation characteristics at annual and daily scale in xerophyte shrub plantations at Southeast margin of Tengger Desert, Northern China. Ecohydrology 2018, 11, e1968. [Google Scholar] [CrossRef]
  3. Aguirre-Gutiérrez, C.A.; Holwerda, F.; Goldsmith, G.R.; Delgado, J.; Yepez, E.; Carbajal, N.; Escoto-Rodríguez, M.; Arredondo, J.T. The importance of dew in the water balance of a continental semiarid grassland. J. Arid Environ. 2019, 168, 26–35. [Google Scholar] [CrossRef]
  4. Gao, Z.Y.; Shi, W.J.; Wang, X.; Wang, Y.K. Non-rainfall water contribution to dryland jujube plantation evapotranspiration in the Hilly Loess Region of China. J. Hydrol. 2020, 583, 124604. [Google Scholar] [CrossRef]
  5. Wang, X.; Gao, Z.Y.; Wang, Y.K.; Wang, Z.; Jin, S.S. Dew measurement and estimation of rain-fed jujube (Zizyphys jujube Mill) in a semi-arid loess hilly region of China. J. Arid Land 2017, 9, 547–557. [Google Scholar] [CrossRef]
  6. Tomaszkiewicz, M.; Najm, M.A.; Zurayk, R.; El-Fadel, M. Dew as an adaptation measure to meet water demand in agriculture and reforestation. Agric. Forest Meteorol. 2017, 232, 411–421. [Google Scholar] [CrossRef]
  7. Beysens, D.; Mongruel, A.; Acker, K. Urban dew and rain in Paris, France: Occurrence and physico-chemical characteristic. Atmos. Res. 2017, 189, 152–161. [Google Scholar] [CrossRef] [Green Version]
  8. Richards, K. Urban and rural dewfall, furface moisture, and associated canopy-level air temperature and humidity measurements for Vancouver, Canada. Bound. Lay. Meteorol. 2005, 114, 143–163. [Google Scholar] [CrossRef]
  9. Beysens, D.; Muselli, M.; Nikolayev, V.; Narhe, R.; Milimouk, I. Measurement and modelling of dew in island, coastal and alpine areas. Atmos. Res. 2005, 73, 1–22. [Google Scholar] [CrossRef] [Green Version]
  10. Losada, J.M.; Miriam, D.; Holbrook, N.M. Idioblasts and peltate hairs as distribution networks for water absorbed by xerophilous leaves. Plant Cell Environ. 2021, 44, 1346–1360. [Google Scholar] [CrossRef]
  11. Zhuang, Y.L.; Ratcliffe, S. Relationship between dew presence and Bassia dasyphylla plant growth. J. Arid Land 2012, 4, 11–18. [Google Scholar] [CrossRef] [Green Version]
  12. Prado, R.D.; Sancho, L.G. Dew as a key factor for the distribution pattern of the lichen species Teloschistes lacunosus in the Tabernas Desert (Spain). Flora 2007, 202, 417–428. [Google Scholar] [CrossRef]
  13. Csintalan, Z.; Takács, Z.; Proctor, M.; Nagy, Z.; Tuba, Z. Early morning photosynthesis of the moss Tortula ruralis following summer dew fall in a Hungarian temperate dry sandy grassland. Plant Ecol. 2000, 151, 51–54. [Google Scholar] [CrossRef]
  14. Wang, L.X.; Kaseke, K.F.; Ravi, S.; Jiao, W.Z.; Mushi, R.; Shuuya, T.; Maggs-Kölling, G. Convergent vegetation fog and dew water use in the Namib Desert. Ecohydrology 2019, 12, e2130. [Google Scholar] [CrossRef]
  15. Schreel, J.D.M.; Vandewal, B.A.E.; Herve-Fernandez, P.; Boeckx, P.; Steppe, K. Hydraulic redistribution of foliar absorbed water causes turgordriven growth in mangrove seedings. Plant Cell Environ. 2019, 42, 2437–2447. [Google Scholar] [CrossRef]
  16. Yang, X.D.; Lv, G.H.; Ali, A.; Ran, Q.Y.; Gong, X.W.; Liu, Z.D.; Qin, L.; Liu, W.G. Experimental variations in functional and demographic traits of Lappula semiglabra among dew amount treatments in an arid region. Ecohydrology 2017, 10, 1858. [Google Scholar] [CrossRef]
  17. Adamu, I.; Adamu, U.A.; Danjuma, M.N.; Aminu, I.U.; Bello, Y.I.; Asiya, A.B.; Maigatari, A.A. Effects of humidity and dew on the early growth of jatropha (Jatropha curcas (Linn) seedlings in Kano, Nigeria. Bayero, J. Pure Appl. Sci. 2017, 10, 56–62. [Google Scholar] [CrossRef]
  18. Zhuang, Y.L.; Zhao, W.Z. The ecological role of dew in assisting seed germination of the annual desert plant species in desert environment, northwestern China. J. Arid Land 2016, 8, 264–271. [Google Scholar] [CrossRef] [Green Version]
  19. Waseem, M.; Nie, Z.F.; Yao, G.Q.; Hasan, M.M.; Xiang, Y.; Fang, X.W. Dew absorption by leaf trichomes in Caragana korshinskii: An alternative water acquisition strategy for withstanding drought in arid environments. Physiol. Plant. 2021, 172, 528–539. [Google Scholar] [CrossRef]
  20. Agustin, C.; Silleta, L.C.; Pereyra, D.A.; Goldstein, G.; Scholz, F.G.; Bucci, S.J. Foliar water uptake in arid ecosystems: Seasonal variability and ecophysiological consequences. Oecologia 2020, 193, 337–348. [Google Scholar] [CrossRef]
  21. Chávez-Sahagún, E.; Andrade, J.L.; Zotz, G.; Reyes-Garcia, C. Dew can prolong photosynthesis and water status during drought in some epiphytic bromeliads from a seasonally dry tropical forest. Trop. Conserv. Sci. 2019, 12, 479–488. [Google Scholar] [CrossRef]
  22. Sergi, M.; Salvador, N.; Leonor, A. Diurnal variations of photosynthesis and dew absorption by leaves in two evergreen shrubs growing in Mediterranean field condition. New Phytol. 1999, 144, 109–119. [Google Scholar]
  23. Holanda, A.E.R.; Souza, B.C.; Carvalho, E.C.D.; Oliveira, R.S.; Soares, A.A. How do leaf wetting events affect gas exchange and leaf lifespan of plants from seasonally dry tropical vegetation? Plant Biol. 2019, 21, 1097–1109. [Google Scholar] [CrossRef] [PubMed]
  24. Barradas, V.L.; Glez-Medellin, M.G. Dew and its effect on two heliophile understorey species of a tropical dry deciduous forest in Mexico. Int. J. Biometeorol. 1999, 43, 1–7. [Google Scholar] [CrossRef]
  25. Eller, C.B.; Burgess, S.S.; Oliveira, R.S. Environmental controls in the water use patterns of a tropical cloud forest tree species, Drimys brasiliensis (Winteraceae). Tree Physiol. 2015, 35, 387–399. [Google Scholar] [CrossRef] [Green Version]
  26. Dietz, J.; Leuschner, C.; Holscher, D.; Kreilein, H. Vertical patterns and duration of surface wetness in an old-growth tropical montane forest, Indonesia. Flora 2007, 202, 111–117. [Google Scholar] [CrossRef]
  27. Zhang, Q.; Quan, J.N.; Tie, X.X.; Li, X.; Liu, Q.; Gao, Y.; Zhao, D.L. Effects of meteorology and secondary particle formation on visibility during heavy haze events in Beijing, China. Sci. Total Environ. 2015, 502, 578–584. [Google Scholar] [CrossRef]
  28. Xu, Y.Y.; Zhu, H.; Pan, Y.P.; Xie, J. Influence of fog-haze on dew condensation in urban areas. Teh. Vjesn. 2018, 25, 876–883. [Google Scholar] [CrossRef]
  29. Muhammad, S.; Wuys, K.; Nuyts, G.; Wael, K.D.; Samson, R. Characterization of epicuticular wax structures on leaves of urban plant species and its association with leaf wettability. Urban For. Urban Gree. 2020, 47, 126557. [Google Scholar] [CrossRef]
  30. Stephens, C.M.; Mcvicar, T.R.; Johnson, F.M.; Marshall, L.A. Revisiting pan evaporation trends in Australia a decade on. Geophys. Res. Lett. 2018, 45, 11164–11172. [Google Scholar] [CrossRef]
  31. You, G.Y.; Zhang, Y.P.; Liu, Y.H.; Song, Q.H.; Lu, Z.Y.; Tan, Z.H.; Wu, C.S.; Xie, Y.N. On the attribution of changing pan evaporation in a nature reserve in SW China. Hydrol. Process. 2012, 27, 2676–2682. [Google Scholar] [CrossRef]
  32. Yu, R.H.; Zhang, Z.Z.; Lu, X.X.; Chang, I.-S.; Liu, T.X. Variations in dew moisture regimes in desert ecosystems and their influencing factor. Wires. Water 2020, 7, e1482. [Google Scholar] [CrossRef]
  33. Jia, Z.F.; Wang, Z.; Wang, H. Characteristics of dew formation in the semi-arid loess plateau of central Shaanxi Province, China. Water 2019, 11, 126. [Google Scholar] [CrossRef] [Green Version]
  34. Meng, Y.; Wen, X.F. Characteristics of dew events in an arid artificial oasis cropland and a sub-humid cropland in China. J. Arid Land 2016, 8, 399–408. [Google Scholar] [CrossRef] [Green Version]
  35. Zhuang, Y.L.; Zhao, W.Z. Dew formation and its variation in Haloxylon ammodendron plantations at the edge of a desert oasis, northwestern China. Agric. For. Meteorol. 2017, 247, 541–550. [Google Scholar] [CrossRef]
  36. Guo, X.N.; Zha, T.S.; Jia, X.; Wu, B.; Feng, W.; Xie, J.; Gong, J.N.; Zhang, Y.Q.; Peltola, H. Dynamics of dew in a cold desert-shrub ecosystem and its abiotic controls. Atmosphere 2016, 7, 32. [Google Scholar] [CrossRef] [Green Version]
  37. Hao, X.m.; Li, C.; Guo, B.; Ma, J.X.; Ayup, M.; Chen, Z.S. Dew formation and its long-term trend in a desert riparian forest ecosystem on the eastern edge of the Taklimakan Desert in China. J. Hydrol. 2012, 472–473, 90–98. [Google Scholar] [CrossRef]
  38. Chen, F.; Zhang, G.; Barlage, M.; Zhang, Y.; Hicke, J.A.; Meddens, A.; Zhou, G.; Massman, W.J.; Frank, J. An observational and modeling study of impacts of bark beetle-caused tree mortality on surface energy and hydrological cycles. J. Hydrometeorol. 2015, 16, 744–761. [Google Scholar] [CrossRef]
  39. Xu, Y.Y.; Tang, J.; Zhu, H.; Lin, Y.Z.; Jin, M.L.; Zhu, X.Y. Monitoring dew condensation and its response to conventional meteorological factors in an urban ecosystem of northeastern China. Acta Ecol. Sin. 2017, 37, 2382–2391, (In Chinese with English Abstract). [Google Scholar] [CrossRef] [Green Version]
  40. Wagg, C.; Hann, S.; Kupriyanovich, Y.; Li, S. Timing of short period water stress determines potato plant growth, yield and tuber quality. Agric. Water Manag. 2021, 247, 106731. [Google Scholar] [CrossRef]
  41. Zhang, Y.; Hao, X.M.; Sun, H.T.; Hua, D.; Qin, J.X. How Populus euphratica utilizes dew in an extremely arid region. Plant Soil 2019, 443, 493–508. [Google Scholar] [CrossRef]
  42. Gibbons, M.J.; Marco, P.D.; Robinson, A.J. Heat flux distribution beneath evaporating hydrophilic and superhydrophobic droplets. Int. J. Heat Mass Trans. 2020, 148, 119093. [Google Scholar] [CrossRef]
  43. Kiwoong, K.; Hyejeong, K.; Sung, H.P.; Sang, J.L. Hydraulic strategy of Cactus trichome for absorption and storage of water under arid environment. Front. Plant Sci. 2017, 8, 1777. [Google Scholar] [CrossRef] [Green Version]
  44. Pina, A.L.C.B.; Zandavalli, R.B.; Oliveira, R.S.; Martins, R.F.; Soares, A.A. Dew absorption by the leaf trichomes of Combretum leprosum in the Brazilian semiarid region. Funct. Plant Biol. 2016, 43, 851–861. [Google Scholar] [CrossRef]
  45. Malik, F.T.; Clement, R.M.; Gethin, D.T.; Beysens, D.; Cohen, R.E.; Krawszik, W.; Parker, A.R. Dew harvesting efficiency of four species of cacti. Bioinspir. Biomim. 2015, 10, 036005. [Google Scholar] [CrossRef]
  46. Jura-Morawiec, J.; Marcinkiewicz, J. Wettability, water absorption and water storage in rosette leaves of the dragon tree (Dracaena draco L.). Planta 2020, 252, 30. [Google Scholar] [CrossRef]
  47. Masrahi, Y.S. Glochids microstructure and dew harvesting ability in Opuntia stricta (Cactacerae). J. King Saud Univ. Sci. 2020, 32, 3307–3312. [Google Scholar] [CrossRef]
  48. Guzmán-Delgado, P.; Laca, E.; Zwieniecki, M.A. Unraveling foliar water uptake pathways: The contribution of stomata and the cuticle. Plant Cell Environ. 2020, 44, 1728–1740. [Google Scholar] [CrossRef]
  49. Eichert, T.; Kurtz, A.; Steiner, U.; Goldbach, H.E. Size exclusion limits and lateral heterogeneity of the stomatal foliar uptake pathway for aqueous solutes and water-suspended nanoparticles. Physiol. Plant. 2008, 134, 151–160. [Google Scholar] [CrossRef]
  50. Burkhardt, J. Hygroscopic particles on leaves: Nutrients or desiccants? Ecol. Monogr. 2010, 80, 369–399. [Google Scholar] [CrossRef]
Figure 1. Meteorological factors in the study area and evaporation periods of different plants.
Figure 1. Meteorological factors in the study area and evaporation periods of different plants.
Water 14 02428 g001
Figure 2. LAIs, daily dew evaporation intensities, and amount changes derived for different plants in the experimental period.
Figure 2. LAIs, daily dew evaporation intensities, and amount changes derived for different plants in the experimental period.
Water 14 02428 g002
Figure 3. DCAs and microstructures of different species derived using SEM: (a): DCA of the Syringa adaxial surface; (b): adaxial leaf surface of Syringa (1600×); (c): DCA of the Syringa abaxial surface; (d): abaxial leaf surface of Syringa (1000×); (e): one stomata of the abaxial leaf surface of Syringa (5000×); (f): DCA of the Hemiptelea adaxial surface; (g): adaxial leaf surface of Hemiptelea (1600×); (h): the base of one of a dense mat of glochid trichomes of Hemiptelea (8000×); (i): DCA of the Hemiptelea abaxial surface; (j): abaxial leaf surface of Hemiptelea (700×); (k): DCA of the Cornus adaxial surface; (l): adaxial leaf surface of Cornus (1200×); (m): one glochid trichome of the adaxial leaf surface of Cornus (4000×); (n): DCA of the Cornus adaxial surface; (o): abaxial leaf surface of Cornus (5000×); (p): DCA of the Buxus adaxial surface; (q): adaxial leaf surface of Buxus (500×); (r): DCA of the Buxus abaxial surface; (s): abaxial leaf surface of Buxus (2000×); (t): one stomata of the abaxial leaf surface of Buxus (12,000×).
Figure 3. DCAs and microstructures of different species derived using SEM: (a): DCA of the Syringa adaxial surface; (b): adaxial leaf surface of Syringa (1600×); (c): DCA of the Syringa abaxial surface; (d): abaxial leaf surface of Syringa (1000×); (e): one stomata of the abaxial leaf surface of Syringa (5000×); (f): DCA of the Hemiptelea adaxial surface; (g): adaxial leaf surface of Hemiptelea (1600×); (h): the base of one of a dense mat of glochid trichomes of Hemiptelea (8000×); (i): DCA of the Hemiptelea abaxial surface; (j): abaxial leaf surface of Hemiptelea (700×); (k): DCA of the Cornus adaxial surface; (l): adaxial leaf surface of Cornus (1200×); (m): one glochid trichome of the adaxial leaf surface of Cornus (4000×); (n): DCA of the Cornus adaxial surface; (o): abaxial leaf surface of Cornus (5000×); (p): DCA of the Buxus adaxial surface; (q): adaxial leaf surface of Buxus (500×); (r): DCA of the Buxus abaxial surface; (s): abaxial leaf surface of Buxus (2000×); (t): one stomata of the abaxial leaf surface of Buxus (12,000×).
Water 14 02428 g003
Table 1. Dew amounts and durations recorded in different ecosystems.
Table 1. Dew amounts and durations recorded in different ecosystems.
ReferenceRegionEcosystem TypeUnderlying SurfaceClimate
Conditions
Dew AmountDew Duration
[3]Llanos de Ojuelos, Jalisco, Mexico (21.78° N, 101.60° E, 2240 m asl)GrasslandBouteloua gracilis
(grass)
Semiarid16.5–69.0 mm/yDew formed around sunset (20:00 p.m.), completely evaporated before late morning (10:00 a.m.)
[33]Middle of Guanzhong Plain, China (34°33′ N, 108°54′ E, 41.72 m asl)FarmlandWheat/cornSemiarid temperate32.8 mm/y18:00 p.m.–8:00 a.m.
[34]Zhangye, Gansu Province, China (38°51′ N, E100°22′, 1550 m asl)FarmlandMaizearid9.9 mm/y21:00 p.m.–9:00 a.m.
Luancheng, Hebei Province, China (37°49′ N, 114°40′ E, 50 m asl)Wheat/maizeSubhumid20.2 mm/y20:00 p.m.–10:00 a.m.
[5]Chinese Loess Plateau (38°11′ N, 109°28′ E, 1049 m asl)FarmlandZizyphus jujube (shrub)Semiarid temperate0.11–2.30 mm/day
Mean 0.75 mm/day
0–16 h
[4]Chinese Loess Plateau (38°11′ N, 109°28′ E, 1049 m asl)FarmlandZizyphus jujube (shrub)Semiarid temperate75.3 mm/y19:00 p.m.–9:00 a.m.
[1]Western edge of the Gurbantuggut desert, China (44°48′ N, 85°33′ E)DesertH. persicum, H. ammodendron and moss crust (shrub and crust)Temperate continental12.1 mm/y21:00 p.m.–10:00 a.m.
[2]Tengger Desert, China (37°27′ N, 104°57′ E, 1339 m asl)Desert-oasisMoss crustTemperate continental15.3 mm/yDew formed during the night, completely evaporated by 13:00–14:00 p.m. next day
[35]Southern edge of the Badain Jaran Desert, China (39°21′ N, 100°07′ E, 1374 m asl)Desert-ShrubH. ammodendron (shrub)Temperate continental16.1 mm/yDew formed after sunset, completely evaporated before 10:30 a.m.
[36]Southern edge of the Mu Us desert, China (37°42′31″ N, 107°13′45″ E, 1530 m asl)Desert-Shrubmixture of deciduous shrubMid-temperate semiarid continental monsoon0.09–0.16 mm/day10:00 p.m.–6:30 a.m. (Summer)
8:30 p.m.–7:30 a.m. (Spring and Autumn)
[37]Eastern edge of the Taklimakan Desert, China (40°28′2.3″ N, 87°51′27.1″ E, 842 m asl)ForestPopulus Euphratica Oliv. (arbor)Extremely arid0.12 mm/day
12.87 mm/y
1–2.5 h in nighttime
[24]Pacific coast of Mexico (19°30′ N, 105°03′ E)ForestDeciduous forestTropical0.013–0.203 mm/d60–129 min after sunrise (11 m)
259–290 min after sunrise (2 m)
This studyChangchun, Jilin Province, China (44°05′ N, 125°20′ E, 330 m asl)UrbanMixture of deciduous shrubsSemihumid monsoon28.24–38.33 mm/yDew formed 30 min after sunset, completely evaporated 4 h after sunrise
Table 2. Leaf microstructural traits of different plants.
Table 2. Leaf microstructural traits of different plants.
Density of TrichomeDensity of StomataLong-Axis Diameter of StomataDrop Contact Angle
Adaxial (Pieces/mm2)Abaxial (Pieces/mm2)Adaxial (no./mm2)Abaxial (no./mm2)Adaxial (μm)Abaxial (μm)Adaxial (°)Abaxial (°)
RangeAverageRangeAverageRangeAverageRangeAverageRangeAverageRangeAverageRangeAverageRangeAverage
Syringa13–9237.1 ± 30.982–235121.3 ± 54.215–2520.0 ± 3.215.2–32.521.3 ± 4.565.7–175.5102.7 ± 42.3116.9–146.1131.8 ± 10.9
Hemiptelea10–13456.7 ± 50.914–21091.9 ± 85.9121–367311.7 ± 82.512.5–20.915.9 ± 4.944.4–66.455.0 ± 8.025.0–58.037.4 ± 13.5
Buxus163–268210.3 ± 44.412.1–18.415.2 ± 5.953.7–129.583.2 ± 26.658.0–144.992.5 ± 32.1
Cornus12–8017.7 ± 13.02–409.7 ± 6.662–158120.1 ± 55.810.8–15.216.3 ± 3.649.7–100.771.4 ± 21.521.5–130.662.8 ± 39.1
Note: “—” indicates that the structure is not present.
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Share and Cite

MDPI and ACS Style

Xu, Y.; Jia, C.; Liu, H. Dew Evaporation Amount and Its Influencing Factors in an Urban Ecosystem in Northeastern China. Water 2022, 14, 2428. https://doi.org/10.3390/w14152428

AMA Style

Xu Y, Jia C, Liu H. Dew Evaporation Amount and Its Influencing Factors in an Urban Ecosystem in Northeastern China. Water. 2022; 14(15):2428. https://doi.org/10.3390/w14152428

Chicago/Turabian Style

Xu, Yingying, Chenzhuo Jia, and Hongzhao Liu. 2022. "Dew Evaporation Amount and Its Influencing Factors in an Urban Ecosystem in Northeastern China" Water 14, no. 15: 2428. https://doi.org/10.3390/w14152428

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop