RESULTS
Effects of warming on dew
formation
The multiple measurement methods showed decreased dew amounts under
warming conditions. Warming resulted in average decreases of 91.7%,
83.9% and 41.6% in dew amount by the artificial condensation surface
method, the in situ dew formation on plants and the leaf wetness
sensors, respectively (linear mixed-effects model: P <
0.001; Fig. 1). From 2015 to 2017, warming significantly decreased the
dew duration by an average of 10.3% (linear mixed-effects model:P < 0.001; Fig. 2a). Therefore, warming reduced the
total dew formation by not only reducing the daily dew amounts (mm/day)
but also the dew duration (days). The results also showed that warming
significantly increased the temperature differences
(Ta-Tdew) by 3.8% (P <
0.001; Fig. 2b), which made dew formation more difficult. Furthermore,
the differences in the dew amount between the control and warming
treatments (Dcontrol-Dwarming) showed
significant differences at the seasonal scale (Fig. 2c). The dew amounts
under the warming treatment decreased by an average of 0.05 mm (up to
64.5%) during the growing seasons and only decreased by an average of
0.006 mm (only 27.5%) in nongrowing seasons (Fig. 2c).
Effects of warming on dew amount among different functional
groups
The total aboveground biomass and dew amounts among each functional
group were measured as the in situ dew formation on plants in
this study. The results showed that different plant functional groups
significantly differed in dew formation, and warming significantly
decreased the dew amount among each functional group (a reduction of
83.5%, 71.6%, 97.6% and 87.0% for sedges, forbs, grasses and all
species combined, respectively, Fig. 3a), while it slightly changed the
aboveground biomass of different functional groups (Fig. 3b).
Effects of warming on the relationships between plant height
and dew
amount
Compared with the control treatment, the warming treatment significantly
affected the relationship between plant height and dew amount (P< 0.001, n=60; Fig. 4). In the control treatment, linear
regression revealed that the dew amount was significantly positively
correlated with plant height (R2 = 0.35, P< 0.001; Fig. 4a). However, dew amount was significantly
negatively correlated with plant height (R2 = 0.34,P < 0.001; Fig. 4b) in the warming treatment.