a1 ORSTOM, BP. 11416, Niamey, Niger
a2 CNRS-CEFE, BP. 5051, 34 033 Montpellier, France et ORSTOM, BP. 1386 Dakar, Senegal
a3 ORSTOM, 1004 El Menzah, BP. 434, Tunis, Tunisia
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.
(Accepted April 17 1994)