Differences between the invertebrate faunas of grazed and ungrazed chalk grassland. IV. Abundance and diversity of Homoptera - Auchenorhyncha

Published source details Morris M.G. (1971) Differences between the invertebrate faunas of grazed and ungrazed chalk grassland. IV. Abundance and diversity of Homoptera - Auchenorhyncha. Journal of Applied Ecology, 8, 37-52.
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Summary

Leafhoppers (Homoptera: Auchenorrhyncha) are very characteristic invertebrates of temperate grasslands. In Britain they occur on chalk grassland in large numbers, especially in late summer. Previous studies by the author have shown that in many groups of invertebrates more species and individuals occur in ungrazed chalk grassland than in grazed, but their diversity has not been measured. This study investigated the importance of the concept of management in relation to the abundance and diversity of Auchenorrhyncha in grazed and ungrazed chalk grassland plots.

Study site: Samples of the Auchenorrhyncha of ungrazed exclosures and grazed control plots at the Barton Hills, Bedfordshire, southeast England were taken in summer 1967 and April 1968 to March 1969.

Experimental design and sampling: Exclosures and control areas measured 40 x 25 m and one of each were established in March 1965 on two adjacent sites, on the upright brome Zerna (= Bromopsis/Bromus) erecta-dominated grassland covering the hills. The experimental area was intensively but not continuously grazed throughout the sampling period and before sampling began.

Vacuum net samples were taken from June to November 1967 and from April 1968 to March 1969 using a 'D-Vac' sampler. Two standard sample units were taken from 2 m² of vegetation in each of the grazed and ungrazed plots at intervals of about 2 weeks in summer and 4 weeks in winter. Sampling was interrupted from November 1967 to March 1968 due to a foot-and-mouth disease outbreak.

Forty-five species of leafhoppers in three families (Cercopidae, Cicadellidae and Delphacidae) were recorded, 15 in small numbers. Six showed no consistent pattern of occurrence related to management, two (Psammotettix cephalotes and Macrosteles laevis were consistently more abundant on the grazed grassland in all sampling years, whilst 22 were more numerous in the exclosures (ungrazed).

Larvae were taken in greater numbers in the ungrazed grassland. Marked increases in numbers in the exclosures from 1967 to 1968 were recorded for several species.

In both grazed and ungrazed plots, leafhopper diversity increased during the summer reaching a maximum in late summer or early autumn. Average diversity in the exclosures was greater than that on the grazed grassland at all times of the year.

Note: The compilation and addition of this summary was funded by the Journal of Applied Ecology (BES). If using or referring to this published study, please read and quote the original paper, this can be viewed at: http://links.jstor.org/sici?sici=0021-8901%28197104%298%3A1%3C37%3ADBTIFO%3E2.0.CO%3B2-A