Decay and nitrogen dynamics of litter from disjunct, congeneric tree species in old-growth stands in northeastern China and Wisconsin

Abstract

Decay and nitrogen dynamics of leaf litter from four tree species in an old-growth forest in northeastern China was measured in a litter-bag experiment and compared with decomposition of congeneric species in a Wisconsin old-growth forest with similar climatic regimes and soil. Leaf litter decay in both China and Wisconsin decreased in the order Acer > Populus > Quercus > Pinus and was negatively correlated with initial lignin content (r = 0.961, P < 0.001). Decay was also correlated with other chemical properties depending on locale. In contrast with decay rates, N-immobilization kinetics were not correlated with litter chemistry or comparable between congeners. Principal component analysis showed that almost half the total variation in litter decay is explained by grouping congeneric species according to litter quality. In northern mixed hardwood–conifer forests, generic similarity implies functional similarity in decomposition and nutrient cycling. Key words: decomposition, China, litter, nitrogen, Wisconsin.