Forestry and the ecology of streams and rivers: Lessons from abroad?

  • John O'Halloran Department of Zoology, University College, Cork.
  • Paul S. Giller Department of Zoology, University College, Cork.
Keywords: Dry deposition, wet deposition, foliar absorption, geology, soil, aquatic ecology, afforestation, water quality, water yields, soil chemistry, atmospheric pollution, fresh-water habitats, forest soils afforestation, environment, river ecology.


Forests are a natural part of our environment. However, with afforestation representing a major land-use of the upland regions, the possible interactions with waters flowing or draining from these areas merits examination. Several studies from various northern temperate regions have shown that afforestation on poorly buffered soils and in areas of high atmospheric pollution and marine salt influence, can result in profound changes to surface water quality and to the ecology of aquatic systems. The preparation of land for planting and subsequent development of a large canopy of trees can also result in significant changes in water budgets, stream hydro-graphs and water yields, in comparison to unafforested moorland. Attention has always been focused on the geologically sensitive areas that are negatively affected, but on well buffered soils less significant changes in stream chemistry, due to afforestation, may be expected. However, information from such areas is scarce. In Ireland little research has been carried out on the interactions between afforestation and aquatic systems, and forestry guidelines for protection of fisheries have been drawn up based on information mainly from the United Kingdom and elsewhere. This extrapolation from abroad may not be universally appropriate, as in many parts of Ireland, the soils and geology are generally well buffered, atmospheric pollution (by European standards) is low and the ecology of the systems is somewhat different from that in other countries. This review outlines the nature of changes to freshwater systems that have been found in geologically sensitive areas, but also stresses that extrapolation of results from such afforested areas to all areas under afforestation in general must be undertaken with care. Considerable further work is needed in Ireland and it is hoped this will lead to a better understanding of the interaction between forestry and water resources.
How to Cite
O’Halloran, J. and Giller, P. S. (1993) “Forestry and the ecology of streams and rivers: Lessons from abroad?”, Irish Forestry. Available at: (Accessed: 5March2024).