Introduction The importance of Soil Respiration (SR) in the whole ecosystem functioning has

1. The role of soil respiration in the carbon balance of a semiarid ecosystem in the South East of SpainJoão Raimundo1, Ana Rey1, Cecilio Oyonarte21 Estación Experimental de Zonas Áridas, 2 Universidad de Almería Introduction The importance of Soil Respiration (SR) in the whole ecosystem functioning has been widely recognised. Semiarid ecosystems are poorly studied and thus not well understood. Other factors that so far have not been taken into account may play an important role in determining SR in semiarid ecosystems characterised by high temporal and spatial variability as well as high temperatures and low water availability. www.climatescience.gov Methodology SR is being measured with a portable CO2 EGM-4 Gas Analyser and RS SRC-1 Chamber (PP-System, UK) in two field study sites (Balsa Blanca – Pristine and Amoladeras – Land Degradation). Soil temperature and soil moisture are measured at the same points. Six plots of 10 x 10 m were set up (n=6) and in each plot three replicates of soil collars were placed in three different soil covers: E (Under plant) C (Biologic crust) S (Bare soil) Under Plant Biologic Crust Replicate Replicated in both BB and AM sites Bare Soil Experimental design Workshop, 5-9 September 2008, Technical University of Crete, Chania, Crete 3rd (BB) (AM)

2. Land Degradation Temporal and Spatial Variability • SR measured in two field sites every week (every fortnight in Summer): • Amoladeras (Land degradation) • Balsa Blanca (Pristine) SR measured on Plot 2 from BB during 14 h Inorganic Carbon • SR measured in BB and AM every week • (every fortnight in Summer): • -Diurnal Variation; Seasonal Variation; Interannual Variability. • SR variability between soil covers (E,C and S) Yan Li. 2008. Have Desert Researchers Discovered A Hidden Loop in the Carbon Cycle?. Science 320: 1409-1410. Rainfall Effect Expected results .Understanding of which factors control SR in semiarid ecosystems that have not been considered so far. .Quantification of the relative importance of rainfall events on the whole carbon balance. .Prediction of SR at ecosystem level by formulating a model that takes into account the temporal, spatial variability. .Impact of land degradation on SR in semiarid regions. .Quantification of the dynamics of inorganic C and its contribution to SR. SR measurements after every rainfall events.