Stable Isotope Analysis of Rainfall and “Non-Rainfall” Inputs in the Namib Desert

Abstract:

Water is a limiting factor to dryland productivity, therefore any additional source may have a positive impact on the ecosystems. Fog and dew resources are important links of the micro-hydrology of arid and semi-arid ecosystems and can exceed annual rainfall. The Central Namib Desert is characterized by erratic rainfall, advective fog and dew events which complement each other to provide water resources. This study aims to better understand the contributions from each of these vectors to ecosystem functions using a stable isotope approach. A first attempt is to evaluate the isotopic compositions of the different components. Fog has been found to be isotopically enriched compared to rain but our preliminary results show the opposite of this trend whilst our dew sample is the most depleted. The distinctness of the isotope signatures indicates that these can potentially be used to calculate the contribution of each of these water sources to the overall water balance of plants in this area.