SMARTER_BufferZ- Right measure:Right Place
Riparian Buffer Zones (RBZ) are patches of land adjacent to rivers, streams and drains, removed from intensive production and containing permanent vegetation. Daire Ó hUallacháin explains how RBZ can provide a variety of environmental and ecological services
Riparian Buffer Zones (RBZ) are patches of land adjacent to rivers, streams and drains, removed from intensive production and containing permanent vegetation. RBZ can provide a variety of environmental and ecological services, including a habitat for biodiversity, enhancing connectivity, alleviating flood threat, enhancing carbon storage and improving water quality.
Riparian buffer measures have been included in most European Agri-Environment Schemes, including Ireland’s (e.g. Rural Environment Protection Scheme (REPS); the Agri-Environment Option Scheme (AEOS), GLAS (Green Low carbon Agri-environment Scheme). However, there are gaps of knowledge regarding the effectiveness of riparian measures, or how to develop tools for improving the effectiveness of RBZs in delivering multiple ecosystem services.
The SMARTER_BufferZ project aims to ensure optimal targeting and management of riparian buffers for the effective management of Irish rivers, and ensure the right measure is in the right place.
Riparian buffer zones are typically designed such that vegetation in the RBZ increases roughness and infiltration, thus slowing flows and reducing sediment, nutrients and pesticides loads. Numerous factors influence runoff dynamics and the efficacy of RBZ, including soil-type, land management/vegetation and topography/slope. Topography of the surrounding landscape can channel flow into areas of converging or diverging flow. This can result in large areas of a traditional linear buffer strips rarely experiencing significant overland flow, rendering them obsolete in their buffering effectiveness, whereas smaller areas can be subjected to significant overland flow and become overwhelmed (Image 1). Targeting RBZ to key locations may be more cost-effective than a one size fits all approach. SMARTER_BufferZ is working closely with the EPA funded DIFFUSE_Tools to improve the targeting of riparian buffer zones to Hydrologically Sensitive Areas (i.e. delivery routes and stream interception points). Lessons learned from appropriate targeting can also help inform the optimal design and management of RBZs.
Although riparian buffer zones have been established in Ireland for over 25 years, variables such optimal establishment and management of buffer zone have often been overlooked. Riparian vegetation type plays a key role in how RBZ function. Trees favour uptake of nitrogen and phosphorus, whereas the dense grass cover favour sediment trapping, whilst combining grass and trees may reduce sediment trapping. Management can also influence effectiveness, close cut/grazed vegetation increases vegetation density and increase runoff trapping. Management of vegetation also facilitates removal of phosphorus from the riparian zone. Nitrogen and most pesticides undergo biogeochemical transformations that reduce the quantities present over time, this does not occur for P. There is a danger that phosphorus accumulation in the buffer may occur, such that over time the buffer becomes a source of P. Thus establishment and management of riparian vegetation is critical.
Key messages for SMARTER_BufferZ
- Targeting riparian buffer zones to key locations (right place) may be more cost-effective than a one size fits all approach.
- The design and management of riparian buffers (right measure) are linked to factors that inform the identification of ‘right place’.
- Whilst it is important to develop new approaches in relation to the right measure in the right place, it is also important to recognise the value of existing landscape features and the role these features play in maintaining and enhancing water quality and delivering multiple ecosystems benefits (Image 2)
Image 1: Poorly designed riparian buffer strips can become overwhelmed, thus reducing their buffering capacity.
Image 2: A targeted riparian buffer incorporating trees and grasses can have benefits for water quality, whilst also providing benefits for biodiversity and carbon storage.
Smarter_BufferZ is a collaborative project involving Teagasc and the James Hutton Institute and is funded by the Environmental Protection Agency. See the Teagasc SignPost Seminar series for further information.