Leaf Decomposition and Nutrient Release in Four Selected Species in Makurdi, Benue State, Nigeria

Leaf decomposition rates in Prosopis africana, Parkia biglobosa, Daniellia oliveriand Morinda lucida were investigated in Makurdi, Benue State, Nigeria.   Decomposition was determined as loss in mass of litter over a period of 8 weeks (January 15- March 15, 2016 and August 15 –October 15, 2016). The exponential decay model W_t / W₀ =e-^{kd t}. was used to evaluate the percentage mass of litter remaining over time while the time taken for half the initial material to decompose (t₅₀) was evaluated using t₅₀= ln 2/k and the nutrient accumulation index was determined by (NAI = ωtXt/ωoXo) Leaf decomposition rates (g d^-1) varied significantly (p<0.01) with species exposure time with % dry weight remaining ranging from 89.63% to 77.4% in both seasons.  P. africana (0.0033, 0.0039) had the fastest decomposition rates in both seasons, while P. biglobosa, M. lucidaand D. oliveri (0.0017) were slowest in the wet season. Mean projected residence time ranged between 363 and 476 days (wet and dry seasons) across species. Average C: N ratio increased generally across species in both seasons with a net mineralization of nitrogen except in M. lucida (0.99) and D. oliveri (0.16), while carbon was immobilized except in P. africana (0.93) with net mineralization in both seasons. The contributions of selected species in nutrient cycling are implicated in this study, hence their importance in ecosystem management.