Forest Litter Decomposition in Relation to Soil Nitrogen Dynamics and Litter Quality

Abstract

Decomposition and changes in nitrogen and organic—chemical content of six types of forest litter were studied for 2 yr in five adjacent Wisconsin forests. The five forests were floristically dissimilar, being dominated respectively by sugar maple (Acer saccharum), white oak (Quercus alba), bigtooth aspen (Populus grandidentata), white pine (Pinus strobus), and hemlock (Tsuga canadensis), Nitrogen mineralization rates in the five stands ranged from 29 to 125 kg°ha—1°yr—1. Decomposition rates of transplanted sugar maple leaves and red maple (Acer rubrum) wood were not correlated with nitrogen mineralization rates in all five stands, indicating that nitrogen mineralization rates do not affect initial decomposition rates. However, mineralization rates were correlated with decomposition rates of the native dominant foliage litter. Nitrogen first accumulated in all litters, but by the end of the 2—yr incubation period nitrogen release had begun in all foliage litters. Nitrogen concentrations increased approximately linearly with cumulative mass loss but eventually declined in some foliage litters. Neither maximum amount of nitrogen accumulated nor amount accumulated per gram of litter mass loss was related to the rate of soil nitrogen mineralization. Chemical composition of litter affected decomposition rates and patterns. Soluble substances and litters relatively rich in solubles disappeared rapidly during early stages of decomposition. Eventually, slowly disappearing acid—soluble and acid—insoluble substances dominated the pattern of mass loss in all litters.

Comparison of nutrient concentrations in organic layers between broad-leaved and coniferous forests

“…Although linear increases in Nand P concentrations were reported at the early stages of decomposition (McClaugherty et al 1985;Berg and McClaugherty 1989), there seemed to be a limit for the increase. N concentration had reached a plateau in the H layers, especially in the case of the broad-leaved forests and some sites even showed a decrease in N concentration in the H layers (APPENDIX).…”

“…In general, the concentrations of nutrients in the fresh litter of broad-leaved species are higher than those of coniferous species (Morita 1972), and broad-leayed litter usually decomposes more quickly than coniferous litter (Williams and Gray 1974). Chemical properties are one of the important factors controlling litter decomposition (Berg and Staaf 1980;McClaugherty et al 1985). This concept suggests that fertility and characteristics of soils may be affected if dominant species of vegetation and litter composition change due to changes in forest management or global climatic conditions.…”

Influence of nitrogen on cellulose and lignin mineralization in blackwater and redwater forested wetland soils

“…Numerous studies have shown that the lignin:N ratio can be used as a predictor of organic matter decomposition rates (Melillo et al 1982(Melillo et al , 1989McClaugherty et al 1985;Laishram and Yadara 1988;Aber et al 1990). Other studies have shown that the lignin:N ratio is only useful for the prediction of organic matter decomposition rates when comparing decomposition of litter types that have similar chemical compositions (Hendrickson 1985;Taylor et al 1989).…”

Temporal variation overshadows the response of leaf litter microbial communities to simulated global change

“…To complicate matters further, shifts in microbial composition are just one route by which environmental change impacts leaf litter decomposition. Decomposition rates are also influenced directly by abiotic conditions and changes in litter quality (for example, Mcclaugherty et al, 1985;Cotrufo et al, 1994;Cleveland et al, 2014).…”