With trees featuring widely in new Welsh Government farm support schemes and pressure on the poultry industry to reduce emissions, egg and broiler producers are being urged to incorporate more planting on their ranges.

The role of trees in capturing carbon is well understood but what is less known is that they have the potential also to reduce nutrient loading, an important function on poultry units.

Concentrations of ammonia are at their highest levels close to the sheds and those emissions are often associated with smell and dust which can impact on the health of birds and workers.

Geraint Jones, Forestry Technical Officer at Farming Connect, says tree planting can be very beneficial in this situation.

“Creating tree belts downwind from emission sources such as poultry housing can capture emissions and particulates,’’ he says.

To mitigate losses, Mr Jones advises planting at a higher density near the shed, graduating to a lower density further away, to provide more open space to encourage the birds to range.

Aim for a mix of native species suitable for the unit’s soil and the local climate conditions.

“Utilise existing trees already growing on the site where possible by including these in the fenced areas,’’ says Mr Jones.

Provided trees are well maintained they should still achieve canopy closure within about five years, but local conditions will be variable.

Thinning is necessary once the canopies have started to close as ranging birds favour dappled light areas amongst tree cover.

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Species choice will be determined by the farm’s soil, elevation and topography.

For planting near the shed, Mr Jones recommends choosing fast growing species, such as white or grey poplar, fast growing willows or hybrid varieties; although these are not native they will meet the objective.

If poplars are planted remove these during subsequent thinning, when the wood becomes established, as this will allow room for the slower growing native species to dominate.

This situation is unlikely to be achieved for at least 15 years but could be sooner depending on the growth rate of the different species and the density of the planting.

If rapidly establishing canopy cover is a goal, aspen is a good choice while the fastest growing native species are birch, alder and willow.

To aid carbon capture and biodiversity, incorporate other native species, such as oak, silver birch, rowan, wild cherry and crab apple with lower storey shrub species such as hazel, hawthorn and elder, says Mr Jones.

“Providing a wider range of species will also provide resilience against potential losses,’’ he points out.

If there are particularly sensitive areas, such as at the base of ancient hedgerows, fence these off to protect them from scratching by the birds.

Spacing requirements will vary from species to species but a minimum requirement of 20% tree cover on the total area of land designated for birds to range on is needed to qualify for the premium paid for eggs marketed as ‘woodland’ produced.

For uniform and easy to manage lines, plant at regular 2m, 2.5m or 3m spacing, ideally with a gap of 2-3m between rows.

Planting at this density will require future thinning when the canopy closes but will become ‘woodland’ faster and could provide an early source of firewood.

Planting in rows makes management with tractor-mounted machinery possible, says Mr Jones.

“Avoid planting in grids and plant on a linear curve to create a wavy edge. This design will provide greater shelter from different wind directions and will also result in a more aesthetic landscape.’’

Alternatively, plant small groups of trees at irregular spacing of 2-3m, leaving larger spaces between the groups for the birds to roam through.

The planting design needs to accommodate mechanical weeding or for mowing the grass between rows.

To achieve this, consider the width of the tractor and topper or mower and allow sufficient space between rows with room at the end of the rows for tractors to turn.

“Planting at wider spacing, perhaps 4-5m, will allow for tractor mowing between the rows. Trees can then be spaced 2-3m apart in the rows,’’ says Mr Jones.