The United Kingdom has a problem in the disposal of municipal green waste (MGW). This is unsuitable for landfill, but when properly composted may be beneficial to tree growth. A formal controlled trial of the 11-year growth (height, diameter at breast height [DBH]) and survival of 3 tree species was evaluated on degraded former opencast coal land on the margins of UNESCO’s Blaenavon Industrial Landscape World Heritage site in South East Wales. Forest reclamation is considered a viable cost-effective approach to reclamation but success may be compromised by infertile and seriously compacted substrates, the depleted bio-geoecological system, and a lack of funding. In this trial, trees were (or were not) supplied, on planting, with 0.75 kg per stem of composted MGW – here a mixture of 40% domestic food waste and 60% garden waste. Results show that the application of MGW made no significant difference to either tree height or DBH. Survival rates were highest for Common Alder ( Alnus glutinosa (L.) Gaertn.) followed by Silver Birch ( Betula pendula, Roth) and European Larch ( Larix decidua Mill.). However, Silver Birch and Larch treated with MGW compost had significantly greater survival rates, whereas Alder had significantly lower survival rates, compared with trees planted without MGW treatment.

Forest phytoremediation through forestry may be an effective means for reducing the metal loading in lands reclaimed after surface-coal-mining in the UK. Planted with mixed woodland, soil loadings of 5 key metals (Zn, Cd, Mn, Pb and Cu) decreased, significantly and progressively, compared to soils left as grassland, through a 14 year forestation chronosequence on land reclaimed from the former Varteg opencast coalmine, South Wales, UK. Fourteen years after initial tree planting, soil metal loadings decreased by 52% for Cd (4.3 mg.kg-1 per year), 48% for Cu (2.1 mg.kg-1 per year), 47% for Zn (7.3 mg.kg-1 per year), 44% for Pb. (7.1 mg.kg-1 per year) and 35% for Mn (45 mg.kg-1 per year). Analysis of metal loadings in the leaves of Alnus glutinosa (L. Gaertn) (Common Alder) and Betula pendula (Roth) (Silver Birch) found both species involved in metal uptake with birch taking up more Cd, Cu, Zn and Mn and Alder taking up more Pb. Concentrations of Zn, Mn and Cd (Birch only) increased significantly in leaves from, but not soils under, older plantings. Since different tree species take up metals at different rates, mixed plantings may be more effective in forest phytoremediation.