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Willow

In 2010 Teagasc released the Short Rotation Coppice Willow Best Practice Guidelines

Willow is not a demanding species in terms of its site requirements and will flourish on a wide range of soil types and environmental conditions and in common with other crops productivity will be determined by site fertility availability of water, light and temperature.

• Soils; most agricultural soils with pH in the range 5.0-7.0 will produce satisfactory coppice growth.  However light sandy soils particularly in drier areas will have a problem with moisture availability and highly organic or peaty soils should be avoided as initial weed control, which is vital, will be extremely difficult.  Medium to heavy clay- loams with good aeration and moisture retention are ideal although they must have a capability of allowing a minimum cultivation depth of 200-250mm to facilitate mechanical planting.

• Water availability; Willow coppice requires more water for its growth than any other conventional agricultural crop and hence requires a good moisture retentive soil.  Areas with an annual rainfall of 9-1,100 mm are best or areas where the crop has access to ground water.  The crop can tolerate occasional inundation but this may have implications for harvesting.

• Temperature; Willow in its native environment is a northern temperate zone plant consequently temperatures in Ireland are unlikely to be an issue.  However elevated sites can result in exposure problems and a reduction in the number of growing days pert year.  Therefore production sites should generally be below 100M above sea level.

• Access; Harvesting is carried out in winter in the period December to April and whilst the root system of the growing coppice will support the harvesting and extraction equipment on the coppice site, hard access is required to the site.  Slopes in excess of 13% will provide difficulty for harvesting machinery particularly in wet conditions and should be avoided.

• Area; for logistical reasons there is a minimum sustainable planted area.  In most situations a commitment of at least 5.0ha is minimal and further more with the harvesting machinery involved this area should be in at least 2.0ha blocks. Smaller and irregular shaped fields are more difficult to manage and if rabbit fencing is necessary will be more costly to fence on an area basis.

• Location in the Landscape; Short rotation coppice has more similarities with arable cropping than conventional forestry – it has a regular harvest pattern, its deciduous nature gives a seasonal diversity of texture and colour.

• S.R. Coppice at the end of a three year growing cycle will be up to 8 m tall and therefore creates a three dimensional mass in the landscape which arable crops do not.  Poorly planted SRC plantations have the potential to adversely affect the rural landscape. However, well-designed and carefully sited plantations could bring small but important landscape improvement.  In most cases with some thought, the establishment of short rotation coppice is likely to bring at best a significant improvement or at worst no detrimental effect to most mixed agricultural landscapes.

• Siting in the landscape may well be constrained by existing enclosure patterns.  Where these are well developed with hedgerows and trees the problem is limited because sight lines are short.  Diversity can be created with clonal mixtures and harvesting patterns in addition to its deciduous nature.

• Because of the likely small-scale production and use patterns of SRC in Northern Ireland they are unlikely to be a dominant landscape feature in any particular area.  A 1% uptake in a catchment area with a 20 km radius (acceptable delivery distance for coppice chip to a conversion plant) would provide 1200 ha or 15,000 tonnes of dry matter, sufficient for 2 MW continuous generation.

• If enclosure patterns are weak, site lines long, or topography flat plantings should provide interlocking blocks with organic rather than geometric shapes.  Additionally in a large landscape SRC plantings should be in scale and link up if possible with existing woodland to give visual and environmental benefits.

• If the extent of planting in any particular landscape is greater than the field pattern it should conform to the overlying landform rather than larger rectangular blocks.

• SRC development is likely to be sited in landscapes, which are already in agricultural use, and it is unlikely that they would impinge on landscapes of species interest or scarcity.  It could be argued that SRC would improve and enhance landscape by providing diversity of shape and colour though varietal differences its deciduous nature and harvesting patterns.

Short rotation coppice should not be planted on or adjacent to sites of historical importance or where they would obscure natural landscape features.  Power lines will require consultation with the Utility company involved remembering that mature coppice can reach to 8 m before harvest.

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