The Hemiptera of two sown calcareous grasslands. III. Comparisons with the Auchenorrhyncha faunas of other grasslands.
Abstract
The Auchenorrhyncha faunas of 2 contrasting types of grasslands seeded on chalk at Royston, Herts, UK, were compared with those from a range of semi-natural and agricultural grasslands. Among intensively studied sites, the Royston fauna was most similar to that of Castor Hanglands, an oolitic limestone grassland, and less closely related to those of 3 established chalk grassland sites. The similarity of the Royston and Castor Hanglands faunas lay mainly in the predominance of Arthaldeus pascuellus [Sorhoanus pascuellus] at both sites. On the established chalk grassland sites, other species predominated. The species richness of the Royston fauna was not markedly lower than the richness of established sites, but resident species were fewer. All sites had similar numbers of multi- and bivoltine breeding species, but significantly fewer univoltine species bred at Royston. Comparisons of annual totals of Auchenorrhyncha recorded showed grouping strictly by site. The Royston fauna was significantly richer than that of ryegrass leys on neutral soil, but not richer than the fauna of the classic Park Grass Plots established at Rothamsted in 1856, though more individuals were recorded at Royston. The Royston fauna was similar to the faunas of flood meadow grassland and 8-year-old seeded grassland on calcareous boulder clay in Cambridgeshire, particularly in the predominance of S. pascuellus. An extensive survey of calcareous grassland sites revealed few sites with faunas similar to that of Royston, mainly because S. pascuellus was not abundant on these sites. Later surveys at sites in Yorkshire and the East Midlands were similar to Royston, with S. pascuellus abundant on many of them. The results are discussed in relation to the establishment of grasslands for wildlife conservation. Interactions with plant species composition, soil type, availability of nitrogen, and management are considered.