Regional Patterns of Streamwater Acidity and Catchment Afforestation in Galloway,SW Scotland

This paper investigates the regional relationships between highflow water chemistry and conifer forest cover in 95 streamsspread over an area of approximately 2000 km² in Galloway,south-west Scotland, paying particular attention to the use ofdetailed catchment area data. Catchment forest data areextracted from a 30 m resolution tree height map derived fromsatellite imagery; geology data from a digital geology map; andaltitude and slope data from a 50 m resolution Digital TerrainModel (DTM). The results show that over the entire region pHlevels are lower with increasing catchment afforestation whilstaluminium concentrations are higher. Concentrations of sulphate arealso higher with increasing afforestation, which suggests thatconifers play a primary role in increasing the acidity levels ofstreams by exacerbating aerial acid deposition in the entireregion.