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A Comparison of Grazed and Ungrazed Grassland A in East Anglian Breckland
A. S. Watt
Journal of Ecology
Vol. 69, No. 2 (Jul., 1981), pp. 499-508
Published by: British Ecological Society
Stable URL: http://www.jstor.org/stable/2259680
Page Count: 10
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(1) The vegetation of intensively grazed Grassland A in the East Anglian Breckland was first recorded in 1933. The ungrazed vegetation in a rabbit-proof enclosure (6 × 6 m: established 1936) was recorded annually near early July from 1942 to 1975, supplemented by casual records of new arrivals in the intermittently but lightly grazed surround. Twenty-one species not previously recorded in Grassland A appeared in the enclosure and seven in the surround. (2) Most of these twenty-eight species are well known to be palatable and sensitive to grazing, but the list includes Euphrasia confusa and Gentianella amarella which are just nibbled, and Centaurium minus, Thymus drucei, T. pulegioides and T. serpyllum which show no evidence that their former absence was due to grazing. (3) Four species were deliberately introduced to the enclosure as seed: Artemisia campestris, Linum perenne ssp. anglicum and Silene otites are established in the enclosure and have spread outside but are in various degrees sensitive to grazing, Artemisia campestris particularly so. One plant only of Veronica spicata ssp. spicata (sown in 1961) was first noted as late as 1975. (4) The absence of fresh urine and the progressive decay of rabbits' dung may affect the numbers and even survival of Catapodium rigidum, Galium parisiense and Minuartia hybrida. (5) Inside and outside the enclosure the vegetation shows a sequence of physiognomic dominants, Festuca ovina, Hieracium pilosella and Thymus spp., and is developing to an open pine-wood (Pinus silvestris). (6) Most species in Grassland A belong to the Sedo-Scleranthetea and the Festuco-Brometea, but nearly all the new entrants belong to the latter, except notably Artemisia campestris and Thymus serpyllum. Grassland A is a complex reflecting the spatial variation in the proportion of sand to chalk in the surface soil. (7) In being the meeting place of the three species of Thymus, in containing several species at their geographical boundaries (Carex ericetorum, Galium parisiense, Silene otites, Rhytidium rugosum), and in its characteristic lichen flora (Fulgensia fulgens, Lecidea decipiens, Squamarina lentigera and Toninia coeruleonigricans) Grassland A is a community sui generis and is not an overgrazed Grassland B.
Journal of Ecology © 1981 British Ecological Society