Nutrient Elements in the Litterfall of Deciduous Broad-leaved Forests and Evergreen Coniferous Forests in Northern Hokkaido, Japan ·

Contents of such nutrient elements as nitrogen (N), phosphorus (p), potassium (K), magnesium (Mg) and calcium (Ca) in the litterfall of deciduous broad-leaved forests (DBF) and evergreen coniferous forests (ECF) were studied.Fractions of the litterfall showed differences in their nutrient concentrations; for example, the concentrations of N, P and K were high in the seed litter, while they were low in the branch litter.The concentrations of nutrient elements in the leaf litter of coniferous tree species were generally lower than those of deciduous broad-leaved tree species.Seasonal changes of N, P and K concentrations in the leaf litter of the dominant tree species were similar each other, with high rates occurring in summer, and low rates in autumn.The concentrations of N, P and K in the leaf litter were obviously lower than those in the growing leaves.Since the amounts of nutrients returned to the forest floor fluctuated seasonally in similar trends with the fluctuation of the litterfall rates in all investigated forests, it is suggested that the seasonal changes of nutrient input were largely controlled by the rates of litterfall.The total amounts of nutrients returned to the floor of the forests were probably more affected by the concentrations of nutrient elements in the litterfall.Ranges of nutrient amounts in the litterfall of the DBF obtained in this study were 27.3-30.9kg/ha•yr for N, O.8-1.8Kg/ha•yr for P, 5.60-5.63Kg/ha•yrfor K, 23.7-35.1kg/ha•yrfor Ca and 2.4 -4.3kg/ha•yr for Mg; while those of the ECF were 28.3-28.4kg/ha'yr for N, l.4-1.6kg/ha•yr for P, 4.0-4.3kg/ha•yrfor K, 29.76-29.81kg/ha•yrfor Ca and 2.1-2.6kg/ha•yr for Mg.