Current projects 2012-2015

Impact of dew and atmospheric water vapor on heterotrophic respiration in arid and semi-arid ecosystems


The decay of dead plant material (litter) and soil organic matter releases CO2 from ecosystems back to the atmosphere, a process termed heterotrophic respiration (Rh). Heterotrophic respiration is a key process in storage of soil organic carbon and in modulating the fluxes of CO2 to and from ecosystems, and thus global atmospheric CO2 concentrations. The factors controlling Rh in the vast drylands of the globe are only partly known, especially during dry periods. Absorption of moisture from atmospheric water vapor was recently described to enhance plant-litter decay, but neither water vapor nor other non-rainfall water sources, such as dew were investigated regarding their effects on Rh. Moreover, solar radiation was shown to induce CO2 production in plant litter, but the contribution of this CO2 source to the carbon cycle of ecosystems was not investigated. The overarching goal of this project is to evaluate the impact of novel drivers of Rh and their significance for the ecosystem carbon balance in drylands of two continents. A series of parallel field and lab studies at a semi-arid and an arid site in each country will provide a mechanistic insight into CO2 fluxes from soil and litter as induced by non-rainfall moisture sources. Moreover, the contribution of CO2 production by solar radiation to ecosystem carbon balance will be determined. The role of water vapor, dew and solar radiation as drivers of CO2 production might become increasingly important, as many drylands are experiencing enhanced drought as a consequence of global climate change.

Gliksman D, Rey A, Seligmann R, Dumbur R, Sperling O, Navon Y, Haenel S, De Angelis P, Arnone JA, III, Grünzweig JM. 2016. Biotic degradation at night, abiotic degradation at day: positive feedbacks on litter decomposition in drylands. Global Change Biology (accepted for publication).

John A. Arnone III, Desert Research Institute, Reno NV, USA

Partner organizations:
United States – Israel Binational Science Foundation