Spatial distribution of sea salt deposition in a coastal pinus thunbergii forest

Abstract

We investigated the sea salt deposition process on the soil in a coastal black pine (Pinus thunbergii Parlatore) forest in Japan with reference to sea salt scavenging by the forest canopy and the following washout by precipitation. We collected throughfall and soil-infiltration water along transects crossing the coastal forest and measured the water chemistry—electric conductivity, pH, major cations (NH4+, Na+, K+, Mg2+, and Ca2+), major anions (Cl−, SO42−, NO2−, NO3−, and PO43−), and total organic carbon—at 10-m intervals on the survey transects. Leaching of base cations from surface soil kept lower acidity of soil water in the evergreen broadleaf forest, whereas soil infiltration water was acidified in the soil surface in the P. thunbergii forest. Hot spots of sea salt deposition on the soil surface were observed at hollows of the ground surface, slope-facing coastal line, or sites with an abrupt increase in height where the canopy faces the coast. However, the edge effect in sea salt scavenging was not evident in the juvenile stand at the forest edge, which had a height of <5 m. The sea salt deposition was only evident in the coastal black pine forest with canopy height >10 m.