Effects of distance from the sea and bedrock on foliar mineral contents in Japanese forests: Implications for mineral acquisition by folivores

Minerals are among the important nutritional components that are indispensable for animals. In particular, the acquisition of sodium is important for plant-feeding animals because sodium may be deficient for these animals as plants do not need sodium. This study compiled data on the mineral contents of leaves in 28 forests in Japan, with special emphasis on the effect of distance from the sea and bedrock type. The aim of this study was to provide basic data on mineral availability for forest-dwelling folivores, which provide important baseline data for understanding the mineral acquisition strategy of plant-feeding animals. Sodium and phosphorus contents of live leaves were lower than the levels required for folivores (captive non-human primates and ungulates). The effect of the distance from the sea was evident only for magnesium and sodium. The sodium content of live leaves was high enough to satisfy folivores' requirements at only a few hundred meters from the sea. The live leaves in forests growing on sedimentary bedrocks contained more minerals than those on granite/rhyolite. Seasonality was also evident based on repeated sampling at three study sites. The mineral contents of dead leaves at the three study sites showed similar inter-site and inter-season variations to those of live leaves. Phosphorus and potassium contents in dead leaves were consistently lower and iron content was consistently higher than in live leaves.