Carbon sink hedgerows need urgent protection

Unmanaged areas could double CO2 sequestration

New research has confirmed Ireland’s estimated 700,000km of hedgerows could offer huge potential to sequester carbon on farms if properly managed.

However, the research confirms hedgerow biomass is in decline here in terms of area because of removals and intensive management, meaning hedgerow carbon stock is also in decline.

Up until now, an accurate picture of how much carbon is soaked up by Ireland’s hedgerows has been difficult to establish. However, the EPA last week published a report on a key research project to advance knowledge in this area.

The research, undertaken by Teagasc, found the highest increase in carbon stock change was found in emergent (recently planted) hedgerows, followed by unmanaged irregular hedgerows, while the largest biomass losses occurred when irregular hedge rows were permanently removed.

Notably, in the period 2015–2019, hedgerow management actually resulted in net emissions, even with significant net carbon sequestration in unmanaged hedge rows. Another major finding is that the long-term carbon sequestration of hedgerows may be overestimated.

To assess the impact of hedgerows at farm level, data from the National Farm Survey were applied to characterise the main farming systems in Ireland, including averages of greenhouse gas emissions, farm activity and hedgerow area.

The project found that the quantity of carbon accumulated by regular hedgerows would be equivalent to 7pc, 13pc and 43pc of dairy, beef and arable farm emissions respectively.

However, it also estimated that unmanaged hedgerows could almost double these values and, by doubling the area of unmanaged hedgerows, the CO2 sequestered would be equivalent to 26pc, 52pc and 172pc of dairy, beef and arable farm emissions respectively.

Enhance

The researchers highlighted that unlike most other EU member states, Ireland has a sizeable hedgerow stock and as the need to enhance carbon sinks to mitigate climate change is pressing, reversing the current declining trend in Irish hedgerows is urgently required.

They recommended policy incentives to allow less intensive management of existing hedges, establishment of new hedges and regeneration of older hedges, which would increase both their carbon sequestration and

biodiversity ecosystem service potential.

“Adapting management to increase the width and height of hedgerows, along with planting new hedgerows, offers the most potential for climate regulation in hedgerows,” the researchers confirmed.

The research also proposes a method to report hedgerow carbon stock changes for inclusion in the State’s greenhouse gas inventory estimates.

However, while the research indicates that the current management of hedgerows may result in net emissions from the biomass pool, it also highlights that alternative, less intensive hedgerow management can result in significant removals of CO2 within the LULUCF sector.