Cradle for Nature

Varteg Hill research site and its purpose

The project is situated on ca. 40-years old opencast coal-mine spoils on the Varteg Hill Reclamation, near Garndiffaith and Pontypool, South Wales (03W46, 51N45). This reclamation dates from 1963 and was completed under the direction of the National Coal Board's Opencast Executive, who sought to restore the area to open grazing, managed as common land, rather than the woodland that existed before industrialisation. Problems, including poor grass growth and gully incision, developed early, so, in 1970 large tracts of land between Varteg and Blaenavon were laid out for grass seeding trials of varying success. The effect of the different seeding mixtures remains visible today, although the project's results have never been assessed. In any case, these measures did not cure the site's problems, partly because its common-land status meant it was impossible to prevent overgrazing and because of autocompaction of the mine spoils. However, today, British Coal is privatised and the land, still counted as 'reclaimed' in official statistics, is effectively orphaned. Local Government occasionally acknowledges the problem but, because of the costs involved, countenances three main types of solution. First is further restoration linked to development, such as the extraction of any remaining coal. Second is land reclassification, which often involves declaring the wasteland to be an ecological reserve for the few, but occasionally unusual, species that survive in these stressed conditions. For example, these degraded spoils often support a rich growth of lichens and cryptogamic soil crusts, more usually encountered in desert environments. Third is land reclamation by community volunteers, occasionally assisted by small grants.

Meanwhile, it is well appreciated that degraded lands have a negative impact on economic and social regeneration. Inward investment is deterred by the poor quality of the local environment, which impacts on an enterprises' external image and its abilities to recruit staff. The poor economic and environmental conditions also contribute to a culture of 'hopelessness', 'alienation' and emigration in local communities. Self-help through environmental projects is considered one way to combat these issues and part of the function of the larger project is to demonstrate how a community could help themselves, their habitat and its prospects. Another part is to explore and develop reliable, low investment, low maintenance and low technology techniques that may be useful to voluntary community groups aiming to restore degraded lands.

Consequently, the chief aim of the larger project is to overcome the problem of the degradation of 'reclaimed' lands by undertaking research and development towards inexpensive strategies that will restore these lands to a condition where their quality becomes self-sustaining. To achieve this trees are planted as bioaccumulators; to act as a 'cradle' for the regeneration of natural ecosystem control. The work includes determining which species of trees to use, how best to persuade them to grow in sterile and compacted mine spoil and how quickly they can transform the environmental system to a self-sustaining condition.

The project was launched in 1990 and, until 2005, engaged volunteers recruited by the international NGO Earthwatch, after which the project became independent. Volunteers planted trees in test plots and monitored tree growth and changing soil conditions across a 5 hectare area. About 10,000 of the trees planted between 1991 and 1997 survive in test plots that examine the effects of different tree species, planting strategies, and fertilisation regimes on tree growth and soil development. Each replicated test plot is a ca. 400m2 block of 4300 trees in which each tree has been numbered, tagged and measured in its 1st, 2nd, 3rd, 5th and 10th year after planting. All three plantings involved trees planted at 51.0m spacing in 0.5 by 0.5m contour trenches. On planting, each tree was provided with 0.5 kg of spent mushroom compost. Since Nitrogen (N), Phosphorus (P) and Potassium (K) levels in these spoils are very low, nutrient levels were boosted for one test plot by the addition of one 'Osmacot' 2-year slow release 15g NPK fertiliser (15:9:9 plus 3MgO) tablet per stem, another by the addition of two tablets, while a third, the Control, received no additional fertilisation.

Thus far, the work has demonstrated the value of a new planting strategy and the relative merits of different species, whilst also highlighting the physical problems such sites pose for reclamation. The project has found a way of reliably transforming degraded, poorly vegetated wasteland, with massively compacted soil, into dense woodland using its system of contour trench plantings. This has been achieved with mixed plantings that use Common Alder (Alnus glutinosa L.) as a matrix, and an interplanted 'succession' to be dominated by Welsh Oak (Quercus petraea (Mattuschka) Liebl.). These species are supplemented with Scots Pine (Pinus sylvestris L.), Mountain Ash (Sorbus aucuparia L.), Silver Birch (Betula pendula Roth.) and Goat Willow (Salix capraea L.). Currently, the mixture is being transformed by the growth of self-set Hawthorn (Crateagus monogyna) and Mountain Ash and dominated by the success of the Silver Birch.

Collection of 10-year data from the full suite of experimental test plots was completed in 2007 and publication will follow. However, due to the harsh conditions on the site, both growth rates and canopy development are slow and, locally, tree die-back occurs.

Taken from:
Plamping, K., Haigh, M. Cullis M, and Jenkins, R.E., 2008, Evaluation of Cambial Electrical Resistance (CER) for the appraisal of tree vitality on reclaimed coal lands, International Journal of Mining, Reclamation and Environment, 22, 3 (x+13pp).