Mixed litter decomposition in a managed Missouri Ozark forest ecosystem

Abstract

We monitored the decomposition of mixed leaf litter ( Quercus spp., Carya spp., and Pinus echinata) in a Missouri Ozark forest eight years after experimental harvest. Leaf litter mass losses and changes in carbon chemistry (extractive, acid soluble, and acid insoluble fractions) were measured over 32 months in field incubations to determine the effects of litter composition and stand manipulation on decomposition and nitrogen (N) concentration in the remaining litter. The decay ( k) rate over this period ranged between 0.39 (±0.010) and 0.51 (±0.002) year −1 for oak, oak–hickory, and oak–pine litter. There were significant main effects of stand manipulation ( p = 0.03) and litter type ( p < 0.01) on decay. Mass losses of oak and oak–hickory litter were 7% ( p = 0.02) and 4% ( p = 0.04) higher on harvested stands than controls, respectively. Mass loss of oak–hickory litter was 3% faster than oak–pine ( p = 0.03) and 6% faster than oak ( p = 0.02) litter on control stands, whereas the oak–hickory litter mass loss was 5% higher than oak litter on harvested stands ( p = 0.01). The decay ( k) rate had a linear relationship with initial leaf litter nitrogen content and lignin-to-N ratio. The nitrogen concentration in remaining litter had a nonlinear relationship to cumulative mass loss suggesting an exogenous source of N. In summary, this study demonstrated significant effects of timber harvest and litter mixtures on decomposition and N dynamics in a managed Missouri Ozark forest.