Litter mass-loss rates in late stages of decomposition at some climatically and nutritionally different pine sites, a study on the effects of climate change

摘要

The patterns of some chemical changes and litter mass-loss rates were investigated for a variety of decomposing litters in pine forests under different climatic conditions and at sites with different nutrient status. A mixed deciduous forest was also compared. In initially chemically identical Scots pine needle litter incubated under different climatic conditions the lignin concentration increased faster, as a function of accumulated mass loss when the climatic conditions promoted a higher initial mass-loss rate. Also under artificially created conditions, e.g. after fertilization and irrigation, the same phenomenon occurred. Litter mass-loss rates decreased during decomposition as lignin concentrations increased. The relative decrease was significantly larger at sites with a climate that promoted an initially higher mass-loss rate. At the same lignin concentration, the mass-loss rate was significantly lower in drier and colder conditions, viz. climatic conditions that promote a lower initial mass-loss rate. Nevertheless, it was found that at very high lignin concentrations that lignin clearly dominated over climate as a rate-regulating factor. The authors speculate about that a consequence of this observation could be a higher rate of organic-matter accumulation at sites that initially promote a high initial mass-loss rate for litter than at sites with conditions that lower initial rates, at least for a given species of litter. 44 refs, 5 figs, 14 tabs