The AMMA-CATCH Gourma observatory site in Mali: 7The experimental strategy includes deployment of a variety of instruments, from local to 8 meso-scale, dedicated to monitoring and documentation of the major variables characterizing 9 the climate forcing, and the spatio-temporal variability of surface processes and state 10 variables such as vegetation mass, leaf area index (LAI), soil moisture and surface fluxes. 11This paper describes the Gourma site, its associated instrumental network and the research 12 activities that have been carried out since 1984. In the AMMA project, emphasis is put on the 13 relations between climate, vegetation and surface fluxes. However, the Gourma site is also 14 important for development and validation of satellite products, mainly due to the existence of 15 large and relatively homogeneous surfaces. The social dimension of the water resource uses 16 and governance is also briefly analyzed, relying on field enquiry and interviews. 18The climate of the Gourma region is semi-arid, daytime air temperatures are always high and 29Land surface in the Gourma is characterized by rapid response to climate variability, strong

Phenological patterns of herbaceous and woody plants well represented in the Sudano-Sahelian savannas of northern Cameroon were studied in relation to water availability in three contrasted soil types. Mean annual precipitation in this region is 800 mm, entirely restricted to the period May-June to September-October, but redistribution of rainwater by varying soil substrates leads to considerable heterogeneity in available water resources for plants. Results are discussed in terms of probable competition for water resources among co-occurring plants and the adaptations shown by observed patterns to prevailing environmental conditions. Water stress is seen to be a limiting factor to plant growth but does not constitute the sole trigger for the phenological phases observed, nor is it the principal factor responsible for the preponderance of annual species in the herbaceous stratum.