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Individual study: Effect of removal of the accumulated litter layer on adder's-tongue spearwort Ranunculus ophioglossifolius germination at Badgeworth Nature Reserve and Hawkesbury, Gloucestershire, England

Published source details

Dring M.J. & Frost L.C. (1972) Studies of Ranunculus ophioglossifolius in relation to its conservation at the Badgeworth Nature Reserve, Gloucestershire, England. Biological Conservation, 4, 48-56

Summary

In the UK, adder’s-tongue spearwort Ranunculus ophioglossifolius survives only at two sites in Gloucestershire. In 1933 one of these, Badgeworth, became a nature reserve and was fenced. This excluded cattle, and float-grass Glyceria fluitans (previously trampled and grazed by cattle) spread, forming extensive mats with litter up to 5 cm in depth covering the soil. By 1962 (when leased to the Gloucestershire Trust for Nature Conservation), much of the reserve was covered with Glyceria-mat and plant litter. The Management Committee decided to investigate the effects of the removal of this material.

Vegetation and litter removal: Two small plots (1 and 2; dimensions not given in original paper) in the centre of the reserve were cleared of the vegetation mat and accumulated litter in June 1962 and1963, respectfully. In the summer of 1965, similar measures were carried out at the other R. ophioglossifolius site near Hawkesbury. Here, drainage and a reduction in cattle-grazing resulted in the site becoming overgrown; spearwort, recorded intermittently until 1953, was presumed extinct.

Effects of flooding: To assess the effects of flooding on R.ophioglossifolius growth, some seedlings from Plot 2 were transplanted in November 1963 to an adjacent area where flooding is rare. Two other species commonly growing with the spearwort, water forget-me-not Myosotis caespitosa and clustered dock Rumex conglomeratus were transplanted amongst them.

Vegetation and litter removal: At Badgeworth, in the Septembers following management hundreds of spearwort seedlings germinated in the plots. The previous flowering of any size (about 150 plants in 1960 along the reserve edge) is unlikely to have provided seed for the plot seedlings (the plant lacks an efficient seed dispersal mechanism); the last extensive flowerings in the central area were in 1938 and 1939.
 
Thus, these seedlings probably germinated from seed lying dormant in the soil for 25-30 years, with germination induced by the Glyceria mat and litter removal.  The seedlings in Plot 1 were killed during the severe winter of 1962-63, and only five weak, spring-germinated plants in 1963 produced seed in 1963. The plots rapidly became dominated again by G.fluitans. At Hawkesbury, similar management likewise caused germination of long-dormant seed in the following autumn; about 100 plants flowered in a cleared plot in the subsequent summer (June 1966).
 
The removal of litter and humus in small plots has been continued successfully.
 
Effects of flooding: Three months after transplanting (February 1964), all the spearworthad been eaten or uprooted and appeared to have been selected from forget-me-not and dock. Birds were considered probably responsible, although slugs may also feed on the leaves. Thus early flooding of R.ophioglossifolius seedlings appears necessary to protect them from uprooting/herbivory.
 
 
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