Litter from a tropical savanna woodland (Miombo) : chemical composition and C and N mineralization

摘要: The decomposability of 15 litter types from four miombo woodland species, two tree Brachystegia spiciformis and Julbernardia globiflora, a grass Dactylotaenium aegyptium, sedge, Bulbostylis megastachys, was determined on the assumption that different plant components could be used as predictors for C N mineralization. chemical composition litter, in terms lignin, polyphenol, cellulose total contents determined. mineralization patterns were also investigated during 75 days aerobic laboratory incubation with soil correlated initial composition. materials contained between 40–51% organic 13 low, ranging 0.47% D. aegyptium leaf to 1.29% lichens + bark fragments found associated B. stem. lignin ranged 0.03% 16.5% twig spiciformis. Polyphenol 0 6%, highest values being twigs pods. Cumulative data fitted first-order kinetics estimating decomposition parameters. Seed evolved more CO2, 68.8% C, than all other tested. It identical parts species showed similar rate mineralization, which follows: seed > leaflet rachis litter. Cellulose, has received less attention literature, influence both among natural biopolymers (P < 0.001) but content ash-free available calculated difference polyphenol an basis, had R2 value (0.910) (0.881) Net only apparent 6 samples, results 0.2% J. globiflora 46% seed. remaining samples immobilized days. mineralization-immobilization better C-to-N ratio (R2 = 0.695; P (lignin polyphenol) 0.688; lignin-to-N 0.656; or polyphenol-to-N 0.613; 0.001). Total concentrations, ratios cellulose-to-N appeared good rates N-poor major part may not source mineral first 2–3 months after addition fractionation into fractions gave indicator potential