Riparian Buffer

By MIKE O’CONNOR Ecologist at IRD Duhallow

Tackling declining water quality and maintaining good water quality is becoming increasingly important in agri-environmental policy. In this article we will explore riparian buffers, one of the most effective measures to protect water quality. Riparian zones are the transition zone between land and river.

Riparian buffers are strips of vegetation that grow along watercourses. These zones offer many significant ecosystem services. Tap roots from trees, for example, act as a filter to maintain water quality, protecting the watercourse from pollutants such as nitrates. Roots of riparian zone plants also stabilise the riverbank, minimising the impact of bank erosion. They also create a habitat for many terrestrial (land) species and their leaf matter feeds many aquatic insects which play an important role in the food chain. Other benefits include natural flood management, carbon sequestration and natural beauty.

A healthy riparian buffer zone will have a diversity of plant species. At the river margin you will find plants capable of waterlogging but also periods of dry conditions, such as Hemlock Water Dropwort and Reed Canary Grass. Trees, brambles, and wildflowers may dominate the riparian area as it transitions from the river margin to dry land. Establishing Riparian Buffers on Farmland.

Establishing a riparian buffer can be done by fencing (ideally at least 2m) back from the watercourse. From then onwards, maintenance is minimal and, provided no invasive species are present, you can then let nature do its own thing. It is likely that brambles will be the first plant to colonise, but it is important to remember that although they may be prickly and unattractive, they offer important benefits to High quality riparian buffers support wildlife and protect biodiversity rivers and water quality and trees will eventually succeed them. It is crucial for biodiversity and water quality that fence lines are not sprayed.

Where bank erosion is occurring, buffers can be established by planting trees. Trees should be planted about five feet back from the edge of the bank, especially if erosion is severe, to give them a chance to put down roots and function as natural bank stabilisers. These trees should always be native and of Irish provenance; Willow (Sallys), Alder and Birch are native trees that thrive on wet soil. Willows can be grown by simply cutting a branch off another willow and staking it into the ground!

Riparian buffers are a popular measure implemented by farmers participating in the Duhallow Blue Dot project and the Owentaraglin River EIP project, both coordinated by IRD Duhallow. They will also form an action in the new agrienvironment climate measure ‘ACRES’ and tree planting will count as a measure in the upcoming eco-scheme that will be rolled out in 2023.

High levels of bank erosion in the absence of a buffer