In December 2021, the EPA warned that increasing demand on our waters, coupled with their deteriorating quality, poses a risk to the “health of a large portion of the population”. As the situation worsens, the consensus emerging is that, despite our best efforts, we can not protect our waters with current policy.
We present a nature-based solution to harness the synergies of an integrated catchment management plan. This innovative solution uses services provided by the natural environment to maximise return on investment. Whilst protecting our waterways, we can simultaneously achieve afforestation targets, store carbon and increase biodiversity.
Two-thirds of Ireland’s land is under agricultural management which is the most significant pressure on the Irish water environment. Fertiliser, slurry, silt, chemicals and pathogens ‘runoff’ fields into streams, rivers and lakes, especially after heavy rain. This is known as diffuse pollution and is responsible for a large proportion of water bodies failing to achieve good status as required by the Water Framework Directive (WFD).
A riparian buffer zone is a permanent, semi-natural strip of vegetation along a watercourse that intercepts pollution. These buffer zones incorporate trees, shrubs and grasses to attenuate and purify runoff, by order of magnitude, both above and below the ground (McIntyre, 2013). This is known as ‘breaking the pathway’.
Due to limitations of research at scale, the degree of water quality improvement through riparian vegetation remains to be clarified at a catchment level (Dosskey, 2010). However, when we consider the multi-factor benefits of application, large scale implementation should be considered for At-Risk rivers without delay.
A multi-species riparian buffer system can play an important role in connecting terrestrial and aquatic ecosystems, especially in the Irish context, where our woodlands are small and isolated. This strip facilitates migration and increases functional biodiversity (Schultz, 1995).
Over 70% of Irish agriculture is livestock which often drink from adjacent rivers: as can be seen in the image above. Their hooves break up the soil and accelerate erosion, which has the cumulative effect of carrying pollutants into watercourses, this is known as poaching, and causes nutrient enrichment (eutrophication).
Nutrients which were intended to support terrestrial plant life are now used by aquatic plants which require oxygen to grow. The nitrogen and phosphorus feed an unnatural and unsustainable population boom of algae which absorb all the dissolved oxygen and suffocate other aquatic life. This also creates the conditions for rooted plants to enter the habitat, further disturbing the riverbed.
Solar pumps can bring water from a watercourse to a trough which facilitates a setback while the roots of the vegetation provide additional bank stabilisation (Simon, 2002). This protects aquatic life, such as fish spawning beds, from being buried in sediment.
The buffer zone can be fenced from the main part of the field with a gate to allow occasional mob grazing, which has been proven to increase biodiversity and will allow farmers to continue to avail of their current grant schemes without penalty.
One example, amongst many nation-wide, is the Blackwater River in Meath, which flows from Ballyjamesduff, to Kells, and into the Boyne River. It is ‘at-risk’ of diffuse pollution yet there is currently no management plan to restore water quality. A riparian buffer is a viable solution that will protect this river and enhance the touristic chain value of the area.
Ballyjamesduff and the historic town of Kells would be enhanced by the natural beauty of a riparian buffer zone which would increase eco-tourism by offering anglers and walkers a spectacular, spiritually nourishing experience. A well designed riparian buffer zone will naturalise into the landscape and requires little maintenance.
An impediment to implementation, and probably the most daunting aspect, is landowner participation. However, this could be achieved with improved policy and engagement through environmental consultants and the Local Authorities Water Programme.
Soil health is crucial to improve resilience in Irish farming. Soil is 95% sand, silt, clay and air; the rest is Organic Matter. This is where the exchange of nutrients occurs, bringing bacteria and fungi. Fields adjacent to a riparian buffer zone will benefit from this organic matter, reducing reliance on fertiliser (Marquezi, 1999). The trees and shrubs also provide shelter for birds which offers natural pest management.
Flexibility of riparian design also means that farmers can diversify their income by producing marketable goods, such as apples. As we import 95% of our apples, this riparian crop would improve Ireland’s food security. Any land under tillage will also benefit from the wind-breaking over the trees which can protect crops from storms and can increase yields up to 16% (Smith, 2021).
Restoring adjacent wetlands, such as fen, creates an effective buffer and provides the opportunity for Paludiculture (wetland agriculture): facilitating the production of load-bearing insulation, typha boards, from cattails. As the price of insulation is currently skyrocketing, this indigenous material could reduce costs in construction; this requires rapid market chain development.
These incentives will not be sufficient for most farmers who haven’t the equipment for tillage, so a stipend for this public service must be provided. At the Gaelic Woodland Project, we believe that we must support our rural communities as their well-being and stewardship is a necessity.
Riparian buffer zones as Natural Flood Management features aren’t being seriously considered for our Integrated Catchment Management Plans due to a lack of large-scale empirical evidence. However, conceptual models suggest that this could be a complimentary alternative to hard infrastructure, which often has disastrous ecological consequences.
Rain falls on a catchment and flows from headwaters, into streams, rivers, lakes and into the flood plain before entering transitional waters. The volume increases incrementally as sub-catchments merge which collectively contribute to large scale flooding events in the lower-catchment.
The riparian buffer strips increase channel complexity and hydraulic resistance to slow the flow into waterways, reducing Peak Flow (Dixon, 2018). Research suggests that as these trees age, they become important areas for water storage and sinks for storm rainfall, with their root networks facilitating lateral infiltration toward groundwater (Archer, 2015).
Each riparian buffer zone requires a site-specific design but may include holly, willow, hazel, guelder rose, alder & downy birch with hawthorn scattered throughout and pedunculate oak as the climax tree species. As this oak grows, cracks appear in the bark which allows for ferns and mosses to create a rising ecosystem, which can support over 900 species.
If we do not remedy our deteriorating water quality we create greater problems in the years to come. As farming is a family business, those working the land have seen rivers change throughout their lifetime. Perhaps there is even a sadness to see their parents’ farm lost to the Common Agricultural Policy.
We eagerly await a new forestry policy in June 2022, where we hope that riparian forestry will replace peatland plantations. Research published in Kerry last year showed that the carbon emitted from degrading peat can emit more carbon than the trees sequester (Sancho, 2021). This requires a drastic change in policy as 40% of Irish forestry is on peatland.
Mistakes have been made but now we know our approach to land management isn’t adequate. We must harness the synergies and work with nature. This requires courage from the Department and pressure from an informed public. Failing to make this necessary shift is a disservice to posterity.
The Gaelic Woodland submitted this suggestion during consultations for the CAP in November 2021. Please share this article.
References:
- The role of riparian vegetation in protecting and improving chemical water quality in streams Dosskey, M.G., Vidon, P., Gurwick, N.P., Allan, C.J., Duval, T.P. & Lowrance, R. 2010. Journal of the American Water Resources Association 46(2):261-277.
2. Land use management effects on flood flows and sediments – guidance on prediction McIntyre, N. & Thorne, C. (Eds.). 2013. CIRIA Report C719. CIRIA, London.
3. Design and placement of a multi-species riparian buffer strip system Schultz, R.C., Collettil, J.P., Isenhart, T.M., Simpkins, W.W., Mize, C.W. & Thompson, M.L. 1995. Agroforestry Systems 29(3):201-226.
4. Quantifying the mechanical and hydrologic effects of riparian vegetation on streambank stability Simon, A. & Collison, A.J.C. 2002. Earth Surface Processes & Landforms 27:527-546.
5. Windbreaks in the United States: A systematic review of producer-reported benefits, challenges, management activities and drivers of adoption. Agricultural Systems. Volume 187. February 2021. Matthew M.Smith, Gary Bentrup, Todd Kellerman, Katherine MacFarland, Richard Straight, Lord Ameyaw.
6. Assessing soil quality in a riparian buffer by testing organic matter fractions in central Iowa, USA (1999) C. O. Marquezi, *, C. A. CAMBARDELLA2 , T. M. ISENHART1 and R. C. SCHULTZ1 1 Department of Forestry, 251 Bessey Hall, Iowa State University, Ames, IA 50011, USA.
7. A conceptual model of riparian forest restoration for natural flood management (October 2018). Water and Environment Journal Vol:33(1-2). Anthropocene Landscapes and Processes Group. Simon J. Dixon, David A Sear, Keith H Nislow
8. Rainfall infiltration and soil hydrological characteristics below ancient forest, planted forest and grassland in a temperate northern climate (2015)Nicole A. L. Archer, Wilfred Otten, Sonja Schmidt,A. Glyn Bengough, Nadeem Shah, Mike Bonell. Ecohydrology.
9. Soil carbon balance of afforested peatlands in the maritime temperate climatic zone (May 2021) Global Change Biology: vol: 27(1) Antonio Jonay Jovani Sancho, Thomas Cummins, Kenneth A Byrne