Acidic deposition on Japanese cedar (Cryptomeria japonica) in mountain and on suburban hill

Abstract

Chemical species in bulk precipitation, through fall and stemflow of Japanese cedar (Cryptomeria japonica) were determined during the period from September 2000 until August 2001 at the Oku-Chichibu (CCB) in the mountainous site, and at the Tama Hills (TAM) and Kamakura (KMK) in the suburban forest hills sites. The pH values of throughfall was the highest of all sites at CCB, presumably due to neutralization by base cations such as K⁺ The pH values of the stemflow was low at TAM and KMK, presumably because the contribution of input acidity “Ai (N0₃^- + nss-SO₄^2-)” was large. Dry deposition and canopy leaching fluxes were estimated for forest canopies. utilizing a model based on the material balance method. Dry deposition fluxes of anions were estimated to be much larger at TAM and KMK in comparison with those of CCB. Therefore, it was supposed that dry deposition in forest canopies is more important to acidic deposition in suburban hills than in remote mountains. Leaching flux of N0₃^- was estimated to be as large as dry deposition flux in suburban hills, whereas adsorption flux of N0₃^- was estimated in the mountainous site. Concentrations of K⁺ and Ca²⁺ in leachate collected at all sites were higher than concentratins of other cations. The concentration of Mg²⁺ in the leachate collected at TAM and KMK was much higher than that at CCB, though the ratio of this ion in total cations was low.