COS 109-1
The role of dew in desert plants
Dew is often attributed as a major source of water in the desert. In arid environments, the importance of dew lies in its reliability and availability as a stable source of water throughout the year, compared with sporadic rainfall events. There is however, an ongoing debate about the importance of dew in ecosystems in general, and especially in plants as a water source.
The dew in plants is especially important in water limited environments, such as the Negev in Israel. The Negev is an arid ecosystem, which receives rain only during the winter (October to March), similar to the northern part of the Sahara Desert. However the contribution of dew in plants still remains a mystery.
We seeked to determine the fraction of dew absorbed directly by three different plant species in the desert, and the importance of this coverage to the development and survival of plants in the desert.
In this project we used a wide range of tools including innovative methods to study the role and contribution of dew in plant physiology and the environment. We examined three different species of desert plants that grow naturally in the Negev, in their natural habitat. Two perennials: desert sage - Artemisia sieberi Besser (Asteraceae) whose roots are relatively short (30 cm), and Haloxylon scoparium Pomel (Chenopodiaceae) which has a root system that is relatively deep (100 cm). The third species is an annual, - Salsola inermis Forssk (Chenopodiaceae) with 15-30 cm deep roots.
Understanding the mechanisms of plant water use and adaptation to stress are necessary to preserve the plant productivity and efficiency as well as sustainable use of water globally.
Results/Conclusions
Dew was isotopically enriched relative to rainfall and depleted relative to soil water. Using a simple isotope mixing model we found that S. inermis, A. sieberi and H. scoparium used on average 56%, 63% and 46% of their water from dewfall, respectively. These are the first results showing dew-water utilization by desert plant species. In light of future predicted climate change, there will be a premium on efficient use of water; for plants of the Negev desert the use of dew as a water resource may serve an important role in their being able to cope with such changes and in their life cycle ecology.