Litter breakdown and mineralization in a central African rain forest dominated by ectomycorrhizal trees

Abstract

Based on litter mass and litterfall data, decomposition rates for leaveswere found to be fast (k = 3.3) and the turnover times short (3.6mo) on the low-nutrient sandy soils of Korup. Leaf litteroffour ectomycorrhizal tree species (Berlinia bracteosa, Didelotiaafricana, Microberlinia bisulcata and Tetraberliniabifoliolata) and of three non-ectomycorrhizal species(Cola verticillata, Oubanguia alata andStrephonema pseudocola) from Korup were left to decomposein 2-mm mesh bags on the forest floor in three plots ofeachof two forest types forest of low (LEM) and high (HEM) abundance ofectomycorrhizal (caesalp) trees. The litter of the ectomycorrhizal speciesdecayed at a significantly slower rate than that of thenon-ectomycorrhizal species, although the former were richer in P and Nconcentrations of the start. Disappearance rates of the litter layer showed asimilar trend. Ectomycorrhizal species immobilized less N, but mineralized moreP, than non-ectomycorrhizal species. Differences between species groupsin K, Mg and Ca mineralization were negligible. Effect of forest type was clearonly for Mg: mineralization of Mg was faster in the HEM than LEM plots, apattern repeated across all species. This difference was attributed to a muchmore prolific fine root mat in the HEM than LEM forest. The relatively fastrelease of P from the litter of the ectomycorrhizal species suggests that thematmust allow an efficient uptake to maintain P in the forest ecosystem.