A Comparison of Element Fluxes in Throughfall beneath Larch and Sitka Spruce at Two Contrasting Sites in the United Kingdom

Abstract

Annual chemical fluxes for ten elements beneath larch and Sitka spruce are presented for contrasting sites in N.E. Scotland and mid-Wales. The Scottish site is relatively low altitude with moderate rainfall and the Welsh site is relatively high altitude with high rainfall; both sites have low air concentrations of SO 2 and NO 2 The data show clear differences in throughfall element fluxes between larch and Sitka spruce of similar age and, for the same species, between the two sites. For sea-derived ions and Ca, the trees appear to respond differently to the contrasting climatic and depositional environments at the two sites; this overrides any consistent differences between species for these elements. Species related differences, consistent at both sites, are apparent for H ion, SO 4 and the major nutrients. Larch releases more K and P but retains more inorganic N than Sitka spruce. Beneath larch, the H ion flux is approximately three times and the SO 4 flux 1.5 times that beneath Sitka spruce, indicating that larch is more acidifying than spruce.