Positive findings on forestry and water quality in Mayo and Wicklow

By Donal Magner

Study confirms effectiveness of Forest Service Water Quality Guidelines

The recent positive research report on forestry and water quality will be welcomed by forest owners, foresters and stakeholders who have long argued that forestry has been unfairly linked to poor water quality in some catchments. They claim that forestry activity should be regarded as the most environmentally friendly land use on the planet as it requires no fungicides and only an average of two herbicide and one fertilizer application over a 40 to 100 year rotation. Instead, forestry has been precluded from large areas of Ireland because of the perceived threat to water quality.

It is accepted that forestry needs to be monitored, especially in upland regions and some low nutrient sites in poorly buffered catchments. In some areas there was evidence to show that while forests and forestry activity might not lead directly to acidification of streams and rivers, the run off of pollutants that trees scavenge from the atmosphere could result in deterioration in water quality. Likewise, it has long been accepted that water quality guidelines need to be implemented to ensure that forest operations will not result in deterioration of water especially during intense forest operations. These include timber harvesting, especially clearfelling even though the latter operation is carried out on little more than one tenth of one percent of the land area of Ireland in any given year.

Ireland is no different from other developed countries where all land use activities from farming to forestry are now scrutinised especially in regards to their effect on water quality. Much of the scrutiny comes from outside the forest and the farm. In the US the irony of this was not lost on Virginia Scott Jenkins, author of The Lawn: A History of an American Obsession.

In relation to the 12 million hectares of lawns that blanket the USA, she wrote that "streams that flow through the gardened lawns of suburbia often carry more organic and pesticide runoff than the most intensively managed agricultural lands''.

Guidelines

Now, a new research study on forestry and water quality should bring a fresh objectivity into the forestry debate. The report, Forestry Operations and Eutrophication - PEnrich states that the Forest Service water quality guidelines if implemented are effective in ensuring that forestry activity does not cause deterioration in water quality.

The guidelines were introduced in 2000 to cover "all situations relating to forestry and water quality''. In particular the guidelines were designed to protect surface waters from over-enrichment due to phosphate loss from forest plantations.

Plantations on peatlands are the most susceptible to phosphate loss, particularly during the establishment phase, following fertilisation and during clearfelling. Implementation of the guidelines affords protection through the provision of buffer strips and other measures which reduce the likelihood of significant phosphate loss to surface waters.

A research team based at UCD, led by Professor Ted Farrell in conjunction with Coillte, tested the guidelines in studies in Wicklow and Mayo.

The research project, known as PEnrich, was funded jointly by COFORD and the EPA.

Wicklow

In Wicklow, the Ballinagee catchment was monitored for phosphate loss over a period of two years. The catchment is almost 100% blanket peat.

There was no evidence of any influence of the forest, or forest operations on either phosphate concentrations or acidity. Given the limited time span of the study, work over a longer duration will be announced shortly by COFORD and the EPA.

Mayo

Close to Crossmolina, in Mayo, a small study site, isolated on all sides by watercourses, was selected for study. The land had been heavily fertilised for many years before being designated for forestry. Sampling from a pipe drainage system prior to site selection indicated very high phosphorus concentrations in soil water. The site was monitored for almost a year before site preparation for afforestation. No fertilizer was applied at establishment and it is unlikely that any application will be required during the lifetime of the crop. Forest Service guidelines were fully complied with during crop establishment. Water monitoring was continued for 18 months after establishment. Water quality showed a small improvement during this period, which can possibly be attributed to a lowering of the water table giving rise to reduced surface runoff.

The results suggest that the Forest Service guidelines, correctly implemented, are effective in protecting water quality and commercial forest operations can be conducted without detrimental effects on water quality. However, given the conclusions of other studies referred to in the report, further research is needed.

Results

Results from the Crossmolina study are very encouraging. Significant areas of this type of relatively intensively managed farmland are likely to be converted to forestry in the future. It would be valuable to return to this site to investigate the longer-term effects of afforestation. The study should also be replicated on similar sites.

Water quality is just one of a range of issues that forest development has to satisfy but these research findings are extremely important and should at least now lead to a fresh look at reassessing many potential planting sites which have been precluded from the national afforestation programme in recent years. This applies especially to many western counties where afforestation has been written off. In these areas, afforestation could be increased substantially as a result of the latest research findings while in the more fertile well-buffered catchments, there is no reason why afforestation should not be allowed proceed without unnecessary referrals, especially in relation to water quality.

The report can be downloaded from the EPA website at http://www.epa.ie/downloads/pubs/research/land/. Copies are available from COFORD (phone 01-2130725 or email info@coford.ie).