181 Land Contamination & Reclamation, 16 (3), 2008 © 2008 EPP Publications Ltd DOI 10.2462/09670513.898 Experimental woodland establishment on brick clays in southern England A.J. Moffat, T.R. Hutchings, I. Tubby, K.R. Butt and C.N. Lowe Abstract A series of long-term field experiments examining a range of reclamation options for the establish- ment of woodland on Oxford Clay soil-forming materials restored after landfilling is described. Hostile soil physical and nutritional characteristics prevent normal tree survival and growth, but the experi- ments show that there are limited options to alleviate these conditions. The combined results show that tree species of alder, poplar and willow planted on loose-tipped mounds are most suited to the soil conditions, although growth is slow. Application of organic fertilizers has mixed effects. Key words: community woodland; field experimentation; land reclamation; Oxford Clay; tree establishment INTRODUCTION The quarrying of clay for brick making has been one of the largest causes of land disturbance by an extractive industry in England, and remains an important one today (Bloodworth et al. 2001). The principal clayey sedimentary lithologies have all been exploited, partic- ularly from Carboniferous, Triassic, Jurassic and Creta- ceous formations. In southern Britain, the Jurassic Oxford Clay has been especially important in the 20th century, partly because of the proximity to the Home Counties’ markets and partly because the organic car- bon content in the clay helps significantly to reduce energy costs associated with brick firing. It has been estimated that there are nearly 5000 km 2 of Oxford Clay outcropping in Great Britain, of which approxi- mately 180 km 2 are workable for brick clay. 1 Bedford- shire is the county most associated with brick making on this geology, but brickworks have also been located in Buckinghamshire and Cambridgeshire. Excepting the Chiltern woodlands in southern Buckinghamshire, these counties have sparse tree cover. It has been recog- nized for several decades that establishing woodland on land restored after clay extraction could be a good opportunity to increase woodland cover, and an appro- priate land type on which to do so. In the majority of brick-clay sites, reclamation has taken place in con- junction with the infilling of clay pits with domestic and industrial wastes, though weathered Oxford Clays are invariably used to generate ‘soil-forming materials’ on which to establish the vegetation cover. Forest Research (the research agency of the Forestry Commission) has been studying tree establishment techniques on land affected by brick clay extraction for several decades. Experimental work began at Elstow, south Bedfordshire in the early 1980s, and was fol- lowed by a series of experiments at Calvert, in Buck- inghamshire and at Brogborough in Bedfordshire. Existing experiments have been recently reviewed on site, and this paper reports on the collective results and 1. http://www.mmc.gov.uk/rep_pub/reports/1976_1979/full- text/088c05.pdf Received February 2008; accepted May 2008 Authors A.J. Moffat, 1 * T.R. Hutchings, 1 I. Tubby, 2 K.R. Butt 3 and C.N. Lowe 3 1. Environmental and Human Sciences Division, Forest Research, Alice Holt Lodge, Farnham, Surrey, GU10 4LH, UK 2. Biometrics, Surveys and Statistics Division, Forest Research, Alice Holt Lodge, Farnham, Surrey, GU10 4LH, UK 3. School of Built and Natural Environment, University of Central Lancashire, Preston PR1 2HE, UK * Corresponding author (Tel. +44 1420 526202; email andy.moffat@forestry.gsi.gov.uk)