Almost half of Ireland’s “surface waters are in an unsatisfactory condition due to the damage being caused by activities that release pollutants into our environment and physical alterations that damage habitats and ecosystems, “ states the EPA.

Worryingly, the agency also reports that water quality at a national level is “getting worse”.

Over half (54%) of Ireland’s surface waters are classed as “good or better ecological” status, while the remainder is “moderate to bad”.

The main contributors are agriculture (63%), hydromorphology, or activities that impact on the physical shape, flow and form of waterbodies (28%), urban wastewater and urban runoff (25%); and forestry (14%).

Some waterbodies are affected by more than one activity, so the summed total for all activities will be greater than 100%.

Categorised nationally, forestry is down the list of offenders and can be less or more impactful depending on activity, scale and location. For example, in the Mal Bay catchment in west Clare, forestry impacts negatively “on 58% of the 19 ‘at risk’ waterbodies, followed by agriculture (47%) and hydromorphological pressures (32%),” according to the HA 28 Mal Bay Catchment Report, issued last May by the EPA.

This is an area which has had a high degree of forestry development, especially since the early 1990s, when private afforestation began to overtake Coillte.

The county now has 18% forest cover (57,450ha) compared with the national average of 11.5%. Many of these forests are now at the final harvest phase when major issues such as water and nutrient runoff, erosion and siltation can occur.

Last week’s water quality field day in the Upper Inagh River Catchment examined forestry practices, including ways to address and improve water quality.

Titled ‘Forestry and water quality – the physical and cultural connections’, it was organised by Ruairí Ó Conchúir of the Local Authority Waters Programme (LAWPRO) and Dermot Houlihan, chair of the Association of Irish Forestry Consultants (AIFC).

We need to think at a catchment scale for water quality, and forestry needs to be part of the solution and not part of the problem

The objective of the field day, as outlined by Ó Conchúir, included reviewing “how forestry can play a positive role in restoring, protecting and enhancing local water quality in stream habitat and the riparian biodiversity”.

The aim of Houlihan and Ó Conchúir is to reverse quality decline. Ó Conchúir maintained that water quality can be restored, often by simple and cost-effective measures.

“We need to think at a catchment scale for water quality, and forestry needs to be part of the solution and not part of the problem,” he said.

Changing forestry practices

The group visited forest sites to explore ways to enhance waterbodies by changing existing practices. Measures included introducing a more diverse tree species mix in second and subsequent rotations, creating buffer zones and managing watercourses to provide the right balance of shade and light to protect fish from thermal stress.

The emerging theme of the field day centred on how forestry can optimise its environmental impact while retaining profitability for the owner.

These issues were outlined during a visit to Cloontabonniv, where Martin O’Shea, IForUT, discussed the importance of safeguarding watercourses during log extraction by constructing silt traps and planning extraction routes. As the area contained 100% Sitka spruce there was an opportunity to introduce native broadleaves into the species mix after clearfelling.

Ragna Gruendler, whose property is beside IForUT’s, is not opposed to Sitka spruce, but she wished to see a more diverse reforested site and to minimise water runoff.

IForUT responded by planting 40% of the site with native species including oak, birch and mountain ash. While this will reduce the profitability of the forest considerably, IFoUT took the long view and factored in environmental and water quality gains.

The ensuing debate raised questions about the viability of a 60:40 conifer-native tree mix, especially for small-scale forest owners.

Gruendler is a forest owner herself but opted for native species, even though, she was advised to plant Sitka spruce at the time. She has no plans to commercially manage the crop although some of the alder and birch are emerging that will, in time, provide excellent timber. Instead, she points to the diverse tree and plant understory, and the nearby pristine stream, which she maintains are the main objectives of her management approach.

The final visit was to Mount Callan forest, which was established by Robert Tottenham in the 1970s. His son, George, outlined the approach to managing the Sitka spruce on staggered rotations to ensure continuity of income. This also results in an uneven-aged forest with some properties managed on rotations beyond 45 years.

Management regime

The management regime is close to continuous cover forestry (CCF) as larger trees were removed in early thinnings, which suits the concept of extended rotations.

While he is practising CCF on some of the forest, he is yet to be convinced of its suitability, especially in areas that may be prone to windthrow, while there are challenges in the early years due to competition from willow, which can be as aggressive as rhododendron.

The field day in the Upper Inagh Catchment highlighted the need for a change in practices in forest management to protect water quality, especially in coniferous plantations.

If handled properly, well-managed production coniferous forests can offer similar and, in some cases, greater benefits to the water environment than non-productive broadleaf woodlands, as outlined by Tom Nisbet in The Role of Productive Woodlands in Water Management for Forest Research and Confor in the UK.

The benefits identified by Nisbet in reducing waterflow include: greater ‘water use’ of trees in reducing the volume of water at source; high infiltration rates of woodland soils to reduce rapid surface runoff and flood generation; and “greater hydraulic roughness exerted by trees, shrubs and large woody debris, [which] slows down flood flows and enhances flood storage”.

Nisbet says that coniferous trees can reduce the volume of rainfall landing on the ground by 25% to 45% on an annual basis, compared to 10% to 25% for broadleaves.

In addition, all afforestation requires minimal chemicals throughout a 30- to 40-year rotation.

Fertiliser should rarely be applied – nitrogen is never needed and, at most, one spot application of rock phosphate may be required. Likewise, one herbicide application may only be needed at establishment. Afforestation sites don’t need insecticides or fungicides while one application of Cypermethrin should be sufficient on a reforested site to control pine weevil damage.

It is clear that most of the benefits of coniferous forests are lost at clearfell and can last until ground vegetation and the subsequent crop re-establishes.

Virtually all forests – established up until the early 2000s in this part of Clare – are single-age and single-species Sitka spruce. These differ from forests currently being established which must contain 35% native species and open biodiverse areas, so sufficient species diversity and accompanying buffer zones are achievable.

The challenge facing forest owners in Co Clare and elsewhere is restructuring commercial forests to create uneven-aged and mixed-species crops that are economically and ecologically sustainable.

The LAWPRO and AIFC field day was an excellent start in addressing these challenges.