Carbon fluxes under simulated climate change and nitrogen deposition in Mediterranean and desert ecosystems

Alterations in land-use and atmospheric composition brought by human activity have been associated with recent changes in the climate system and in nitrogen deposition to the Earth surface. Such changes might affect natural ecosystems and their ability to sequester carbon and to regulate water fluxes. The impact of a long-term precipitation change, the main concerns for the dry regions of the world, and of nitrogen additions on ecosystem carbon cycling and water relations is practically unknown. The objectives of two studies on these topics were to quantify CO2 and water fluxes in Mediterranean and desert shrubland under different realistic scenarios of changes in precipitation and nitrogen deposition, to assess effects of climate variables and nitrogen on these fluxes and to evaluate possible interactions between ecosystem processes linked to carbon dynamics and water. A study on climate-change impacts was conducted at 4 study sites along a precipitation gradient from mesic (800 mm mean annual rain fall) to arid (90 mm) climatic zones. Field manipulations to simulate scenarios of increasing and decreasing of 30% of the average annual rain fall, was situated at the dry Mediterranean (540 mm) and the semiarid (300 mm) climatic zones, the two central stations along the gradient. Another study quantified net ecosystem CO2 exchange and evapotranspiration at patch-scale in a desert ecosystem under precipitation and nitrogen manipulations. These projects contribute to a better understanding of global-change effects on carbon cycling, water relations and the interaction between carbon and water in Mediterranean and arid ecosystems. Results from this research might improve predictions of future changes in the carbon cycle and in water relations under changed climate and nitrogen deposition. In addition, the project might contribute to the development of scientific tools to management of carbon and water in drought-affected ecosystems.

Talmon Y, Sternberg M, Grünzweig JM. 2011. Impact of rainfall manipulations and biotic controls on soil respiration in Mediterranean and desert ecosystems along an aridity gradient. Global Change Biology 17, 1108-1118.

John A. Arnone III, Desert Research Institute, Reno NV, USA
Marcelo Sternberg, Tel Aviv University, Tel Aviv, Israel

Ophir Tal (postdoc)
Yiftach Talmon (MSc student)

Partner organizations:
International Arid Land Consortium