Individual study: The establishment of heather Calluna vulgaris plants in conjunction with soil acidification using sulphur, Sunnybrae Farm, Aberdeenshire, Scotland
Lawson C.S., Ford M.A., Mitchley J. & Warren J.M. (2004) The establishment of heathland vegetation on ex-arable land: the response of Calluna vulgaris to soil acidification. Biological Conservation, 116, 409-416
Lowland heaths are a semi-natural habitat with high biodiversity conservation value. Conversion to arable farmland, reduction of grazing on remaining heaths (leading to succession to woodland), afforestation, and urbanisation have resulted in large scale loss of lowland heaths throughout Western Europe. Consequently, the re-establishment of lowland heathland is a priority within the UK Biodiversity Action Plan, with a 2005 target of creating 6,000 ha of heathland. The conversion of agricultural land back to heathland may help achieve this target. However, simply abandoning arable land usually results in species-poor habitat dominated by common, competetive perennial grasses, which thrive in the nutrient-rich soil. Former arable land is often unsuitable for heathland regeneration because of such high levels of soil nutrients, and also because of a high pH (due to agricultural liming), and the presence already of agressive ruderals and weeds. In this study, the relationship between soil acidification using sulphur and the establishment of of heather Calluna vulgaris (a dominant and desirable heathland species) on arable soil is investigated.
Study site: The field site where heather Calluna vulgaris growth in relation to acidification through the application of sulphur was located on Sunnybrae Farm, 8 km northwest of Aberdeen, and had an imperfectly-drained sandy loam podzol, with a pH of 5.3. The site was cropped with oil seed rape in 1992 and was set-aside in 1993. In April 1994, the site was ploughed and harrowed. Growth of plants from cuttings and seeds was to be compared in the study.
Heather plants: Cuttings, 4 cm high of heather were taken from Brimmond Hill, Aberdeen (National Grid Reference NJ858091) during March 1995 and placed in a 1:1 peat:sand mixture under mist in a glasshouse. In May 1995, the rooted cuttings were transferred to peat-filled pots (78 mm across, 94 mm deep), and on 1st June 1995 they were moved outside.
Heather seeds: Heather litter was collected to a depth of 5 cm from beneath a stand of heather (thus seed-rich) at New Pitsligo (National Grid reference NJ895575).
Treatments: The experiment was arranged in a factorial design, with two methods of heather establishment and two levels of sulphur application. Treatments were replicated in each of three randomised block and each treatment plot was 2.6 x 2.6 m.
On 11 November 1994, sulphur (Thiovit: Pan Britannica Industries Ltd; 80% a.i.) was applied in water at 0 and 0.45 kg/m² (= 0 and 0.36 kg/m² sulphur). Glyphosate was applied to all plots on 2 May 1995 to kill regenerating weeds. Heather litter was applied at 0.30 kg/m² on 13 June 1995 to half the plots. On the 14 and 15 June, 100 heather cuttings were planted 25 cm apart, with 100 per plot. Supplementary water was applied.
Heather survival & soil pH: The survival of the cuttings was recorded after six, twelve, and 22 months after planting. Establishment of vegetation cover and soil pH were also recorded.
Soil pH: By August 1996, soil pH had fallen to 3.71 in sulphur treated plots compared to 5.13 in control plots.
Heather survival: Over the first six months, mortality of heather cuttings was very high, with less than 20% survival by December 1995. The addition of sulphur had a significant positive effect on survival: 77 of the 300 cuttings in sulphur treated plots survived compared to only 35 of 300 in control plots. However, by April 1997 only nine heather plants survived, all in the sulphur treated plots.
Establishment of cover: Establishment of heather was very slow, with only one seedling observed throughout the experiment. Vegetation cover and bare ground were significantly affected by application of sulphur, with much less vegetation (69.8% cover) in sulphur plots than control plots (105.2% cover).
Conclusions: Establishment of heather is more effective when cuttings are transplanted. Furthermore, sulphur addition (as long as not excessive) appears to aid growth of the cuttings, while reducing the growth of weeds and therefore competition. (See also Cases 356, 358 and 359).
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