EFFECTS OF TREE CLUMPS ON SOIL CHARACTERISTICS IN A HUMID SAVANNA OF WEST-AFRICA (LAMTO, COTE-DIVOIRE)

The effect of tree clumps on soil characteristics was investigated in a humid savanna (Lamto, Cote d'Ivoire). Soil texture and field capacit y were not significantly different under tree clumps compared to open grassland. On the other hand, bulk density was lower under tree clumps , likely due to a greater soil fauna activity under the trees. The pH, available phosphorus, cation exchange capacity, total carbon and tota l nitrogen contents were higher under tree clumps due to greater organ ic matter input beneath canopies. Potential soil respiration and miner al nitrogen accumulation were also enhanced, indicating a higher poten tial microbial activity under tree clumps. Soil water content was slig htly lower beneath canopies (from July to November only between 0 and 10 cm depth) when soil moisture was above field capacity. During the o ther months, no significant difference was measured.