Atmospheric deposition and interactions with Pinus pumila Regal canopy on Mount Tateyama in the Northern Japanese Alps

To estimate the impact of atmospheric deposition on alpine ecosystems, we evaluated the interactions between atmospheric deposition and the Pinus pumila canopy close to the summit of Mount Tateyama, central Japan. We analyzed the chemical characteristics of rain, fog, and throughfall under the canopy in the summertime for 5 years. The concentrations of inorganic nitrogen and sulfate in precipitation at the summit (2839 m a.s.l.) were lower than at the base (13 m a.s.l.), but the total amounts deposited tended to be larger, because the precipitation was greater at the summit and highly concentrated fog water was deposited on the pine canopy. Large fluctuations in the quality and quantity of deposition were due to interannual variations in the meteorological conditions. About 80% of NO₃ - -N and NH₄ ⁺-N (0.40 and 0.47 kg ha^-1 month^-1) from rain and fog were retained in the P. pumila canopy, and contributions from fog were twice those from rain. Considerable amounts of K⁺, Mg²⁺, and Ca²⁺ ions (0.97, 0.13, and 0.13 kg ha^-1 month^-1) were leached out from the canopy to the soil as throughfall. The leaching did not increase with rainfall, but increased as the duration of the fog and dew increase.