Matter and nutrient dynamics of pine (Pinus tabulaeformis) and oak (Quercus variabilis) litter in North China

In the mountainous area of North China, a distinguishing feature of climate is the serious drought of spring and the humidity and high temperature of summer by which the litter production and decomposition of forest litter we re strongly characterized. We investigated the dynamic and nutrient charact eristics of litter in a 30-year-old mixed stand of Chinese pine (Pinus tabu laeformis Carr.) and deciduous orient oak (Quercus variabilis Bl.) and two comparable pure stands. Oak litterfall peaked in November and pine litterfa ll in December. The oak stand had the largest annual litterfall (347 g m(-2 )) and the forest floor mass (950 g m(-2)), the mixed stand the second (236 g m(-2) and 634 g m(-2)), and the pine stand the least (217 g m(-2) and 61 5 g m(-2)). The nutrient return through litterfall and the storage in fores t floor followed corresponding order between three stands. The weight loss of pine and oak Foliage litter in first year was 25% and 20%. For senesced pine and oak leaves, the translocation rates of N, P and K were 56-83%. Nut rient concentrations were higher in oak leaf litter than pine needle litter , and the concentration of N and Ca appeared to rise while K concentration decreased in both decomposing litter.