Leaching of base and metal cations from litter and soils vary in two forest stands with different tree species

Abstract

Understanding the distribution of cations in forest soils is important for forest management. Here, we evaluated the leaching of cations, potassium (K+), sodium (Na+), calcium (Ca2+), magnesium (Mg2+), iron (Fe3+), aluminium (Al3+), and manganese (Mn2+), from litter through soils in two forest stands with different tree species. We incubated Castanopsis carlesii leaf litter in a Castanopsis carlesii stand and Cunninghamia lanceolata needle litter in a Cunninghamia lanceolata stand using a microcosm method with monthly collections of litter and soil leachates, and the concentrations of cations and fluxes of these cations were assessed separately. We found more Ca2+ but less Na+, Mg2+, and Fe3+ fluxes in litter leaching solutions in Cunninghamia lanceolata than in Castanopsis carlesii stand because of their different initial concentrations in fresh litter. Although cations leached from leaf litter differed among tree species, the leaching fluxes did not vary between stands. Moreover, annual fluxes of cations leached from soils were significantly higher than those from leaf litter, leading to a net loss of soil nutrients to downstream environment. Therefore, the results suggest that reforestation with mixed stands by introducing broadleaved trees in Chinese fir monoculture plantations might reduce soil nutrient loss through the leaching pathway.