Variations in soil nutrient availabilities and foliar nutrient concentrations of trees between temperate monsoon karst and non‐karst forest ecosystems on Mount Ibuki in Japan

Abstract

AbstractPlants growing on karst soils, which are characterized by high pH (>7.5–8.0) and low phosphorus availability, often exhibit phosphorus deficiency. However, little is known about the soil nutrient availabilities and foliar nutrient concentrations of trees in karst ecosystems with lower soil pH (<7.0). In this study, we analyzed soil properties and nutrient concentrations of leaf litter from two secondary forests in the Asian monsoon temperate region of Japan, one on karst (limestone) soil and the other on non‐karst (sandstone) soil. We also compared the live leaf nutrient concentrations of four dominant tree species (Carpinus tschonoskii, Cornus macrophylla, Neolitsea sericea, and Quercus variabilis) found in both sites. The karst soil had a higher pH (6.5) than the non‐karst soil (5.6), as well as higher phosphorus concentrations and calcium availability, but lower potassium availability. The phosphorus concentrations measured using Truog ([NH4]2SO4) and Olsen (NaHCO3) extraction methods were both higher in the karst soil. The availabilities of ammonium and nitrate in the soil did not differ significantly between the sites. The concentrations of calcium, potassium, and phosphorus in the live leaves and leaf litter reflected their availability in the soil, and the litter nitrogen concentration was higher in the karst forest. Overall, this karst soil with a relatively low pH (6.5) was rich in phosphorus but poor in potassium. Karst soil may provide a large quantity of phosphorus for trees at low pH. Future research should investigate the change in phosphorus availability of karst soils at different degrees of weathering.