Broadbalk and Geescroft Wilderness Experiments
The Broadbalk and Geescroft Wildernesses are two sites at Rothamsted that were fenced off in the 1880s and left to revert naturally to woodland. The sites had previously been arable for centuries. Although not experiments in the usual sense, they are of great value, especially for looking at long-term changes in soil and woodland vegetation.
For more details, refer to the Key References listed below or contact the e-RA Curators.
With thanks to Andy Macdonald, Paul Poulton, Tony Scott, Graham Shepherd and Derric Nimmo for data, background information and images.
Lawes set up the Broadbalk and Geescroft Wilderness experiments in the 1880s, as he was interested to see what plants would become established after abondoning arable cropping, and what changes might occur in the soil (Lawes, 1895).
Broadbalk Wilderness was originally part of the Broadbalk wheat experiment, and had grown unmanured winter wheat since 1843. The last wheat crop was sown in autumn 1881, but not harvested. The site was then fenced off and allowed to naturally revert to woodland. In around 1900 it was divided into two halves, one remained as regenerating woodland, in the other half all woody species were removed ('stubbed') each year, to allow open ground vegetation to develop. In 1957 the stubbed section was divided into two, one half remains 'stubbed', the other half was mown for three years, grazed by sheep each year from 1960-2000, and has been mown each year from 2001 (herbage not removed). Data is not shown for the stubbed and mown areas, but is available from the e-RA curators. The surface soil is calcareous (pH 7.7 in 1999).
See Broadbalk plan since 1968 (pdf) to see a plan of the Broadbalk Wilderness, in relation to the rest of the Broadbalk wheat experiment.
Geescroft Wilderness is a larger site about 1 km away from Broadbalk. It is also long-term arable land, and was originally part of an experimental field that grew field beans (Vicia faba) from 1847-1878, with frequent breaks due to crop failure. After bare fallowing for four years, clover was grown from 1883 to 1885, and the wilderness area was fenced off in January 1886. It has been uncultivated since spring 1883. The surface soil is now acidic (4.4 in 1999).
Site and soil details
Location: Both Wilderness sites are at Rothamsted Research:
- Location: Rothamsted Research, Harpenden, Herts, AL5 2JQ, UK
- Latitude: 51 degrees 48 mins 36 secs North
- Longitude: 0 degrees 22 mins 30 secs West
- GB Grid Reference: TL121134
- Gradient: A slope of 1 degree, West to East
- Irrigation: There is no irrigation
Size: Broadbalk Wilderness is a small site, approx 0.2ha in total (woodland, stubbed and mown areas). Geescroft Wilderness is much larger, approx 1.3ha.
History: Both the Broadbalk and Geescroft sites had been cultivated since at least 1623, and probably much earlier,
see Rothamsted map of 1623 .
Soil details: Batcombe soil series, silty clay loam surface overlying clay-with-flints, overlying chalk at a depth of several meters. The 0-23cm layer contains 20-25% clay, rising to 50-60% at depths of a meter or so (Poulton et al, 2003).
- FAO Classification: Chromic Luvisol
- U.S. Soil Taxonomy: Aquic (or Typic) Paleudalf
- Soil Survey of England & Wales Group: Paleo-argillic brown earth (Avery, 1980)
- Soil Survey of England & Wales Series: Predominately Batcombe Series (Avery & Catt, 1995 – see pop-out soil map at top right of this page).
Soil pH :
- Broadbalk Wilderness: large amounts of chalk were applied in the late 18th - early 19th centuries, and the surface soil pH is still calcareous (pH 7.7 in 1999).
- Geescroft Wilderness: small amounts of chalk were applied in the 1840s-1880s, and the soil is now acidic (pH fell from 7.1 in 1883 to 4.4 in 1999).
The calcareous site (Broadbalk Wilderness) is now dominated by ash (Fraxinus excelsior), with sycamore (Acer pseudoplatanus) and hawthorn (Craetagus monogyna). The acidic site (Geescroft Wilderness) is now a deciduous wood dominated by oak (Quercus robur), with an understory of holly (Ilex aquafolium). Because the soil is so acidic, there are few ground cover species, and there is a permanent litter layer, in contrast to the Broadbalk Wilderness, where each year's litter decomposes - see images to the right.
For more details of the site vegetation, see Key References, especially Harmer et al, 2001:
- Geescroft Wilderness is an ECN vegetation site, and is surveyed every three years.
- Geescroft Wilderness is also one of the Rothamsted Insect Survey sites, and has a range of traps, including a light-trap which has been running constantly since 1965. For more details, contact Insect Survey.
- Local Woodland Trust woodland site, Heartwood Forest.
- Guide to the Rothamsted Classical Experiments 2006, see pp 19-20.
- Jenkinson, D. S. , Poulton, P. R. and Bryant, C. (2008) "The turnover of organic carbon in subsoils. Part 1. Natural and bomb radiocarbon in soil profiles from the Rothamsted long-term field experiments", European Journal of Soil Science, 59, 391-399
- Poulton, P. R. , Pye, E. , Hargreaves, P. R. and Jenkinson, D. S. (2003) "Accumulation of carbon and nitrogen by old arable land reverting to woodland", Global Change Biology, 9, 942-955
- Pye, E. (2002) "Investigation of woodland regeneration within two Wilderness areas. PhD thesis", University of Hertfordshire.
- Blake, L. and Goulding, K. W. T. (2002) "Effects of atmospheric deposition, soil pH and acidification on heavy metal contents in soils and vegetation of semi-natural ecosystems at Rothamsted Experimental Station, UK", Plant and Soil, 240, 235-251
- Harmer, R. , Peterken, G. , Kerr, G. and Poulton, P. (2001) "Vegetation changes during 100 years of development of two secondary woodlands on abandoned arable land", Biological Conservation, 101, 291-304
- Blake, L. , Goulding, K. W. T. , Johnston, A. E. and Mott, C. J. B. (1999) "Changes in soil chemistry accompanying acidification over more than 100 years under woodland and grass at Rothamsted Experimental Station, UK", European Journal of Soil Science, 50, 401-412
- Poulton, P. R. (1996) "Geescroft Wilderness, 1883-1995", NATO Advanced Research Workshop, Evaluation of soil organic matter models using existing long-term datasets, NATO ASI Series I: Global Environmental Change, (Powlson D. S. , Smith P. and Smith J.U. (eds)), Vol 38, 385-389
- Kerr, G. , Harmer, R. and Moss, S. R. (1996) "Natural colonisation: a study of Broadbalk Wilderness", Aspects of Applied Biology, 25-32
- Jenkinson, D. S. (1971) "The accumulation of organic matter in soil left uncultivated", Rothamsted Experimental Station Report for 1970 , Part 2, 113-137
Get Paper from eRAdoc
- Garner, H. V. , Witts, K. J. , King, D. W. , Jenkinson, D. S. , Yuen, P. H. and Skinner, F. A. (1965) "Broadbalk Wilderness", Rothamsted Experimental Station Report for 1964, 218-223
Get Paper from eRAdoc
- Lawes, J. B. (1895) "Upon some properties of soils, which have grown a cereal crop and a leguminous crop for many years in succession. ", Agricultural Students' Gazette, New Series, 7, 65-72 (Series 1/91)