Effects of initial fertilizer treatment on the 10‐year growth of mixed woodland on compacted surface‐coal‐mine spoils, S. Wales

Abstract

The degradation of land formerly reclaimed after surface‐coal‐mining (opencast) is a widespread problem in upland Wales (UK). This community‐based project aims to support the voluntary sector in land reclamation by investigating the means of reversing land degradation. It explores ways of encouraging trees to ameliorate the severely compacted, infertile, mine‐soils typical of former opencast sites. This study evaluates the benefits of a single initial application of 2‐year slow release fertilizer (SRF), both with and without additional supplements, through a 10‐year controlled experiment in a mixed planting of common Alder (Alnus glutinosa (L.) Gaertn), Oak (Quercus petraea (Matt.) Liebl., Quercus robur L. and hybrids) supplemented with Scots Pine (Pinus sylvestris, L.); Silver Birch (Betula pendula, Roth); Goat Willow (Salix caprea, L.) and Rowan (Sorbus aucuparia, L.). After 10 years, SRF treatment resulted in a small, marginally significant, decrease in survival (85% vs. 83%) across all species, except Oak, but SRF‐treated trees were significantly larger than those given no‐SRF at planting (421 cm vs. 368 cm). By contrast, in Year 5 data, only SRF‐treated Alders are marginally significantly larger, whereas in Years 1–3 across all six species, significantly more records show greater mean growth in trees with no‐SRF than those given SRF at planting. Probably, this delayed response to SRF treatment resulted from the slow development of the larger soil ecosystem. Treatment with additional supplements (double SRF, remineralization agent and superphosphate) tended to have negative impacts on growth but double SRF and to a lesser degree remineralization had a positive effect on survival.

Composted Municipal Green Waste Enhances Tree Success in Opencast Coal Land Reclamation in Wales

“…Liebl., Quercus robur L., and hybrids), Scots Pine (Pinus sylvestris, L.), Goat Willow (Salix caprea, L.), and Rowan (Sorbus aucuparia, L.). 33 This produced very different results. After 10 years, SRF-treated trees had a survival rate that was slightly, albeit marginally significantly, smaller (85% vs 83%) across all species, except Oak.…”

“…Being assessed 'unsuitable for forestry', it was then reseeded as grassland. 33 The 30 m × 30 m 'MD07' test plot for this forest planting is located on a terrace bench on the southern edge of this former opencast coal mine at about 384 m above mean sea level ( Figure 2). The site has a monthly mean air temperature of between 2.5°C and 15°C.…”

“…The site has a monthly mean air temperature of between 2.5°C and 15°C. 33 Average rainfall (1971-2000) is 1543 mm per year at Cwmavon Reservoir, 800 m northeast on the Afon Lwyd Valley floor (51°45′26 ′N 03°3′35 ′W). 33 Evaporation is estimated as 472 mm per year on rough grazing land, whereas natural soils are at field capacity for 285 to 325 days per year.…”

“…Since 1990, this has involved mixed plantings of native broad-leaved species, mainly Common Alder, Oak, and Scots Pine, with some Silver Birch, Rowan, and Goat Willow, using a variety of fertilisers, planting regimes, and subsequent records of tree growth. 33,37 The 2007 (MD07) planting differs from the earlier plantings on the Varteg site in using mono-specific blocks of trees, which reduces potential problems from allelopathy. It also introduces European Larch (Larix decidua Mill.)…”

“…The MD07 test plot was planted out at a high planting density of 10 000 stems per hectare 23 in an attempt to achieve early canopy closure and in anticipation of slow growth in the poor and compacted soils. 33 The trees were notch-planted, as in normal forestry practice, as 2-year whips in root trainer plugs. 37 During planting out, half of the trees were treated with a supplement of ~750 g of MGW compost, which was used to backfill the planting-notch void ahead of soil closure.…”