The Loch Dee Project - Galloway
Ernie Michie (Inverness) has kindly allowed his paper on the Loch Dee Project to be placed on this website. At the time he was District Forest Manager in Galloway Forest District and submitted the paper as Voluntary Paper No 8 to the 10th World Forestry Congress.
The paper highlights the situation at this period when the topic of a ‘acid rain’ was very much to the forefront and the discovery that whole tracts of forests in the upper mountain elevations in central Europe were dying from the effects of industrial and domestic pollutants - a major one being sulphur dioxide. These chemicals, drifting in the air stream often at high levels, could and did mix with rain water causing a very significant change in the chemical composition of the rain fall to the detriment of many types of ecosystems.
Conifer trees and in particular spruce and firs by their needle configuration proved to be very efficient pollutant collectors when the rainfall solution dried on their needles. When this happened on several occasions following light showers there was a strong likelihood in the event of a period of heavy rainfall that the concentrated dried solution mixed with the water creating a very acidic water mix which dropped off the trees. Sometimes this fell directly into the water courses. In low pH base rock geology or other naturally slightly acidic conditions this direct acidic top up to the stream could have severe repercussions on water based wildlife.
The paper describes the 10 year partnership and the range of measurements and measures taken to ameliorate the conditions which were leading to the fall in trout number catches in this calcium poor Loch Dee catchment area. The success is alluded to in the paper’s subtitle ‘A successful reversal of trout decline in acid waters’ with a rider stating that it was not known if this reversal was long term or only a brief respite.
The Forestry Water Guidelines partially addressed this situation by stating that conifer trees should be kept back from watercourses so that there was a vegetation filtration buffer zone between the dripping edges of the canopies and the steam.
The sulphur dioxide issues are not in the headlines today (possibly giving way to the CO2 debate) but pollutant levels have changed radically following several decades of pan European clean air legislation. Perhaps the mantra to remove all trees next to and over water courses will be modified to consider the very obvious beneficial effects of partial shade and direct insect drop.
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