Sphagnum -dominated peat bog: a naturally acid ecosystem

Abstract

Sphagnum -dominated peat bogs are naturally acid and cover perhaps 1 % of the Earth’s land surface. The tem poral and spatial variations of pH in a peat-bog in the northern Pennines are used to illustrate the relative im portance of different sources of acidity. At this site, where the pH of rain in summer was 4.0-4.2, rain and cation exchange of metal cations in the rain for H + in the newly grown Sphagnum were of about equal im portance, though cation exchange probably dom inated on hummocks in summer. Strongly acid ‘events’ are likely to follow heavy rain that follows a dry spell. The effects of interconversion of sulphur- and nitrogen-containing compounds on acidity is obscure.