Browsing by Subject "dew"

Now showing 1 - 3 of 3
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    Convergent vegetation fog and dew water use in the Namib Desert
    (Wiley, 2019) Wang, Lixin; Kaseke, Kudzai Farai; Ravi, Sujith; Jiao, Wenzhe; Mushi, Roland; Shuuya, Titus; Maggs-Kölling, Gillian; Earth Sciences, School of Science
    Nonrainfall water inputs (e.g., fog and dew) are the least studied hydrological components in ecohydrology. The importance of nonrainfall waters on vegetation water status in arid ecosystems is receiving increasing attention. However, a clear understanding on how common plant water status benefits from nonrainfall waters, the impacts of different types of fog and dew events on vegetation water status, and the vegetation uptake mechanisms of nonrainfall waters is still lacking. In this study, we used concurrent leaf and soil water potential measurements from 3 years to investigate the species‐specific capacity to utilize moisture from fog and dew within the Namib Desert. Eight common plant species in the Namib Desert were selected. Our results showed that both fog and dew significantly increased soil water potential. Seven of the eight plant species studied responded to fog and dew events, although the magnitude of the response differed. Plants generally showed stronger responses to fog than to dew. Fog timing seemed to be an important factor determining vegetation response; for example, night fog did not affect plant water potential. We also found that Euclea pseudebenus and Faidherbia albida likely exploit fog moisture through foliar uptake. This study provides a first comprehensive assessment of the effects of nonrainfall waters on plant water status within the Namib Desert. Furthermore, this study highlights the importance of concurrent leaf and soil water potential measurements to identify the pathways of nonrainfall water use by desert vegetation. Our results fill a knowledge gap in dryland ecohydrology and have important implications for other drylands.
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    Investigating Dew Trends and Drivers Using Ground-Based Metreological Observations at the Namib Desert
    (2024-08) Javanmardi, Sara; Wang, Lixin; Li, Lin; Jacinthe, Pierre-André
    In arid environments such as the Namib Desert, sources of non-rainfall waters such as dew and fog are crucial for sustaining ecosystem functions such as vegetation dynamics and biogeochemical processes, yet they remain among the least studied features of the water cycle. There is a concern that dew may become increasingly scarce because of climate warming, a trend not yet documented in the Namib Desert. This study aims to examine how dew formation trends in this region are evolving, drawing on field observations and assessing the factors influencing these trends. Our analysis involved processing meteorological data gathered from SASSCAL (Southern African Science Service Center for Climate and Adaptive Land Management) between 2015 and 2022, supplemented by direct dew observations to estimate dew occurrence in Gobabeb, a research station in Namib Desert. We developed an empirical equation to calculate dew formation based on the meteorological data. We used field-based dew records to validate the empirical equation and applied this equation to calculate dew formation between 2015 and 2022. We found dew formation concentrated in December to May (wet season). We evaluated the trends of dew formation at both monthly and annual scales. The findings showed a decline in dew formation (13.74% in the annual dew days count), a trend that could significantly impact the ecosystems in the Namib Desert. We found that soil temperature, air temperature, and humidity are the major contributors of the observed dew trends. The inverse relationship observed between increasing temperatures and dew formation supports the notion that elevated temperatures accelerate evaporation rates and diminish the chances of dew formation. This association underscores the susceptibility of dew formation to the impacts of climate change, as rising temperatures and shifting precipitation patterns are anticipated outcomes.
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    Nonrainfall water origins and formation mechanisms
    (AAAS, 2017-03-01) Kaseke, Kudzai Farai; Wang, Lixin; Seely, Mary K.; Department of Earth Sciences, School of Science
    Dryland ecosystems cover 40% of the total land surface on Earth and are defined broadly as zones where precipitation is considerably less than the potential evapotranspiration. Nonrainfall waters (for example, fog and dew) are the least-studied and least-characterized components of the hydrological cycle, although they supply critical amounts of water for dryland ecosystems. The sources of nonrainfall waters are largely unknown for most systems. In addition, most field and modeling studies tend to consider all nonrainfall inputs as a single category because of technical constraints, which hinders prediction of dryland responses to future warming conditions. This study uses multiple stable isotopes (2H, 18O, and 17O) to show that fog and dew have multiple origins and that groundwater in drylands can be recycled via evapotranspiration and redistributed to the upper soil profile as nonrainfall water. Surprisingly, the non–ocean-derived (locally generated) fog accounts for more than half of the total fog events, suggesting a potential shift from advection-dominated fog to radiation-dominated fog in the fog zone of the Namib Desert. This shift will have implications on the flora and fauna distribution in this fog-dependent system. We also demonstrate that fog and dew can be differentiated on the basis of the dominant fractionation (equilibrium and kinetic) processes during their formation using the 17O-18O relationship. Our results are of great significance in an era of global climate change where the importance of nonrainfall water increases because rainfall is predicted to decline in many dryland ecosystems. Fog and dew in the Namib Desert have multiple origins and their formation can be differentiated using stable isotopes. Fog and dew in the Namib Desert have multiple origins and their formation can be differentiated using stable isotopes.