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Rothamsted

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.

Background

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:

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).

Soil pH :

Vegetation

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:

Related links

Key References

2008

2003

2002

2001

1999

1996

1971

1965

1895

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