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HomeFarming NewsA bird’s eye view to calculate carbon storage
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A bird’s eye view to calculate carbon storage

Ruth Ruddell, Technologist, CAFRE- Greenmount Campus, outlines how a bird’s eye view can calculate carbon storage.

When it comes to carbon storage, farmers often ask how you can measure the carbon stored in farm hedgerows and trees.

Traditional survey methods to collect information on hedges, trees and woodlands would take a lot of time and be costly over large land areas.

Using technology to carry out remote surveys have been demonstrated to be cost-effective over large areas.

An accepted assessment method is through the use of a Light Detection and Ranging Survey (LiDAR).

This remote sensing survey measures variable distances by targeting an object with a laser and measuring the amount of time taken for the light to return to the receiver, a bit like a speed camera.

However, the LiDAR scanner is housed in an aeroplane, flying at 10,000 feet.

To calculate the above-ground biomass (the volume and density of hedges and tress), the survey needs to obtain high resolution (detailed) LiDAR data.

This high-resolution LiDAR scan takes between 25-30 measurements per square metre.

During the winter when the hedges and trees have no leaves, this time is also known as the Leaf Off phase.

Surveying at this time allows for better precision, with greater laser penetration, reducing the variability of the images produced.

CAFRE 

CAFRE recently commissioned a LiDAR survey of three CAFRE farms, the Lowland Dairy Centre, Lowland Beef & Sheep Centre and the Hill Farm Centre.

The Agri-Food and Biosciences Institute (AFBI) has used the survey data to identify and measure the above-ground biomass, categorised by height, into single trees, woodlands, and hedgerows for each farm.

They then used the information to calculate the potential carbon storage and carbon sequestration for each farm.

This initial LiDAR survey will provide a baseline measurement, allowing subsequent surveys to demonstrate the change in biomass over a set period and will assist with increased precision of carbon sequestration estimates.

Results: 

Table 1 shows the combined results for each of the three surveyed CAFRE farms

 

  Hedges Single Trees and Woodlands Total
Length/ area 51.8 km 37.47 ha mineral soils 14.85 ha organic soils*
Total carbon storage (t C) 718 2482 3200
Sequestration potential t CO2e/year 54.1 345 399.1

 

From the results in Table 1, they found a large portion of the hedge and woodland at the Lowland Dairy Centre.

This is due mainly to large blocks of mature woodland on this farm.

The Lowland Dairy Centre has 13% woodland cover, which is greater than the Northern Ireland average of 8%.

As expected, the hedges on both the Lowland Dairy Centre and the Lowland Beef & Sheep Centre are more prevalent when compared to the Hill Farm Centre, which has large areas of open moorland.

The Lowland Beef & Sheep Centre has areas of small woodlands with a large number of parkland trees and lines of trees.

Other technology 

Research has shown that areas of forestry on organic soils (peatland) found at the Hill Farm Centre, result in a net emission of GHGs.

These forested areas of the Hill Farm Centre are now in a CAFRE forest to bog restoration project.

This baseline measurement will also assist with planning opportunities to enhance and augment the carbon stores on each of the farms, by planning and managing for additional carbon storage.

Some technologies that will be used and demonstrated on the CAFRE farms include:

  • New hedgerow trees;
  • Incremental hedge cutting;
  • Establishing new hedges;
  • Agroforestry;
  • Woodland management;
  • Planting.
Potential routes of overland water flow

Another benefit of the LiDAR survey is identifying potential routes of overland water flow.

This helps CAFRE distinguish individual water catchment areas and produce nutrient run-off risk maps.

This also allows the introduction of techniques to reduce the overland flows and intercept nutrients at identified risk points.

DAERA Minister Edwin Poots, MLA, recently announced details of a LiDAR survey covering all of Northern Ireland.

This survey will form part of the Soil Nutrient Health Scheme (SNHS). The department will deliver this during the next five years.

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