Estimation of cedar water requirements in Ras El Ma and Boutrouba forests (Central Middle Atlas, Morocco)

The forest trees water requirements are a growing concern in the forest sector due to the growing awareness on the impact of climate change on soil moisture regime. These requirements are still a concern in this area, especially as we search to quantify them over large scale areas and with probable climatic evolutions. The overall objective of this study is to estimate cedar water requirements in the Middle Atlas, in order to identify areas with high pedoclimatic potential for cedar and provide forest managers with new management tools. The specific objective is to search for a simple methodology to estimate cedar water requirements, through the monitoring of water regime, water storage and soil water balance, calculated from rainfall, runoff, evapotranspiration and drainage. Water requirement of different cedar age classes were evaluated in a wet year free from water and heat stress. The water requirements values of 320 mm for a young cedar forest and 460 mm for an adult cedar forest agree with estimates reported in the literature. These values ​​are in the same order of magnitude as the Thornthwaite evapotranspiration deduced from soil water balance, and correspond to the cumulative annual rainfall recorded during the two cedar growth periods described by M'hirit in the Middle Atlas.

Keywords: Water requirements, cedar, Middle Atlas, water balance, soil, evapotranspiration, Morocco.