River Management Techniques. Upper Wharfedale Best Practice Project (Information Series No 6)

6.2. Riverside fencing and tree planting

6.2

LOCATION:
Swarthgill, Oughtershaw, SD 845824

AREA: c.6.29ha

DATE UNDERTAKEN:
Autumn 2000

COST: c.£12,600

BACKGROUND INFORMATION

Upland landscapes connected with the Yorkshire Dales rivers have seen many changes during the passage of time and the presence of native deciduous trees was once a stronger feature on the fellsides, in gills, and along river banks.

In comparatively recent times (1940s) a considerable number of deciduous trees bordering the River Wharfe at Oughtershaw were destroyed by fire and have not since been replaced, leaving the landscape very open, reducing potential cover for wildlife and protection of the river bank from erosion.

DESCRIPTION

The area involved is generally described as grazed wet rushy pasture. It supports purple moor-grass mire Molinia caerulea, and mosses including Polytrichum alpestre, commune and a number of Sphagnum species. Relict birch wood was also present, together with the Molinia caerulea, and gave an opportunity to re-create wet birch woodland, a scarce commodity within this area of the Yorkshire Dales National Park.

DESIGN

The project mainly involved fencing and tree planting, but provision was also included for stock watering access to the stream.

From the landscape viewpoint it was considered appropriate to tie new tree planting in with the scattered trees remaining from the previous plantation. Open space was left in the planting to create a random scattered wet woodland, 40%-50% open space with planting densities ranging from 3-10m centres. A substantial amount of birch and willow was to be included in the mix to accommodate ground conditions and Biodiversity Action Plan priority woodland targets.

A total of 1,575 trees was planted in an area of about 6.29ha. The shrub species element was concentrated at the edges of the planting. Trees were protected with individual 0.75m tree shelters with the exception of holly, which was specified to have wider shrub guards. The fence was not rabbit proofed to minimise potential fence damage by debris accumulation during peak river flows. Consideration was given to landscape aesthetics and straight lines were avoided in the scheme. Approximately 1,875m of stockproof fence were used to secure the planted area, employing stock net and a barbed top wire. A water gate was specified to close the fence line where it crossed the stream to prevent stock access. Stockwatering points were incorporated within the fenced-off area.

SPECIFICATION

Tree planting stock was packaged and transplanted in accordance with BS3936. The plants were protected against mechanical damage, extremes of temperature and drying out. 45cm-60cm transplants, with a minimum root collar diameter of 5mm, were obtained from a local source of northern provenance and delivered on site in coextruded bags. All transplants were notch planted.

All planting distances were random to create a natural appearance to the woodland. The species mix used was 25% downy birch Betula pubescens, 15% ash Fraxinus excelsior, 10% alder Alnus glutinosa, 10% goat willow Salix caprea, 7% each of sessile oak Quercus petraea and hawthorn Crataegus monogyna, 6% rowan Sorbus aucuparia, 5% each of grey willow Salix cinerea, bog myrtle Myrica gale and eared willow Salix aurita, 3% hazel Corylus avellana, and 2% holly Ilex aquifolium.

Weeding was specified to be undertaken within a 1m diameter of the base of each tree. The area was to be maintained at least 80% weed free throughout the growing season. Application of the herbicides Kerb and Roundup was specified in winter and spring respectively.

Fencing

The fencing specification was as for section 1.2, with the exception that the straining posts were 3.03.6m long, depending  on the depth of peat, to accommodate soft ground. The intermediate posts were 2.1m long for the same reason.

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