SOIL RESPIRATION BEHAVIOUR IN A MEDITERRANEAN ALEPPO PINE FOREST IN NORTH TUNISIA

Little is known about the relationship between soil respiration and biophysical factors in the Tunisian Aleppo pine forest.We conducted our studies in two adjacent forests in Djebel Mansour region with the same micrometeorological conditions, but they differed in soil proprieties.The main goal of this research was to quantify soil respiration and its seasonal variations under two different soil characteristics.Soil respiration measurements were performed between Mai 2008 and July 2009.The magnitude of the soil respiration varied from 0.80 to 6.65 µmol m -2 s -1 in Sidi Ouedet forest (deep soil) and from 0.60 to 5.90 µmol m -2 s -1 in Oued El kbir forest (shallow soil).Results showed that soil respiration exhibited a same seasonal pattern in both sites, and it was controlled mainly by the soil moisture.The highest rates of soil respiration were observed in autumn and in spring and the lowest in summer, coinciding with the drought period.In autumn, high rates of soil respiration were observed immediately after rainfall events.Hence, annual soil respiration was higher in the deep soil than in the shallow soil (870.4 g C m -2 y -1 vs 492 g C m -2 y -1 ).As such, soil proprieties (depth, texture and structure) may indirectly drive soil respiration by controlling the soil moisture and site productivity through litter input.