JFA have always prided ourselves in being in the forefront of habitat creation and innovation in environmental planning. A lot of the work we have undertaken takes a long time to show results, so we thought we would look at one of our earliest projects: the re-planting of Nutwood in Darley Abbey, Derbyshire.
In 1990, after development in the vicinity, a landslip occurred on a slope adjacent to new housing, insured by the National House Building Council. The landslip was undermining houses and the insurer had a duty to investigate and rectify matters. Geotechnical investigations were undertaken, with the advice that if a drainage blanket was constructed within the slope soil profile, the instability would be solved.
Ancient Woodland Replanted
Before construction of the drainage blanket, which is a layer of crushed rock which creates a channel for subsurface water to move down-slope, a portion of the ancient woodland was felled. The soils were removed in lifts and stored adjacent to the site in a stockpile not exceeding 1m in depth. This was to maximise the viability of the soil biota, so that when it was replaced on site, it still retained its biodiversity.
The woodland was replanted using species from local sources, to replicate the woodland on site (an NVC W10 ash-oak woodland). Only shrub and tree species were re-planted. The work was done under a JCLI small works contract, and the insurer was responsible for maintenance over a three year period, after which the responsibility for woodland maintenance was passed back to the local planning authority.
Our Principal visited Nutwood in May 2016, approximately 24 years after it was planted. She found an abundance of bluebells, which are ancient woodland indicator species, and a good tree cover of ash, silver birch and very occasional oak. There was little evidence of invasive of undesireable species, such as sycamore, which often happens on disturbed sites. On the negative side, there was poor survival of oak. Oak and ash was planted simultaneously, but ash grows more quickly than oak. As the woodland has been little managed, there is actually too much tree cover: the ash are crowded and the dense canopy prevents oak from surviving. The abundant ash trees are eteliolated meaning they are spindly with sparse, high canopies with little leaf growth. This also shows in the relative paucity of leaf litter. If there were more of this, the ground level biota would be richer.
Notwithstanding the outcome, Nutwood was designated a statutory Local Nature Reserve in 2008. It would benefit from thinning out the overly dominant ash, to allow the oaks room to grow, to improve the forest canopy and to increase light and leaf litter at ground level. Nontheless Nutwood replanting should be counted as a success, in terms of planning and execution, with the pointer that better management would improve the overall outcome.
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