Responses of Grassland Invertebrates to Management by Cutting. V. Changes in Hemiptera Following Cessation of Management

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Abstract
From 1973 to 1975 the effects of cutting on the invertebrates of Arrhenatherum-dominated grassland [England, UK] were studied. Four treatments (cutting in May (M), July (J), both May and July (B) and no cutting (control, C)) were applied annually. The reversion of the plots was studied from 1976 to 1978 by taking 3 standard vacuum net samples at fortnightly intervals in Aug. Adult Hemiptera (Heteroptera and Auchenorrhyncha) were identified and counted. The hot, dry summer of 1976 had effects which were assessed on the C plots. In general, species of damp grasslands declined in abundance whereas those of dry, and of short swards increased. Some phenological effects may have been detected. The 1976 fauna of Heteroptera was least similar to that of any other year but the Auchenorrhyncha fauna in 1976 was similar to those of 1975 and 1977, with 1973 the least similar year. Heteroptera increased progressively in abundance from 1976 to 1978 on the previously managed plots. No differences between treatments were recorded in the abundance of individual species, or for N and S (total number of individuals and species, respectively), but the rates of increase from 1975 to 1978 were significantly different, with the treatments tending to segregate as the two pairs J + B and M + C. The rates of increase in Auchenorhyncha N and S were similarly grouped, but the rate of increase in diversity (D) was greater on every treatment than on the controls. In 1978, mean D was significantly greater on the J and B treatments than on C. Auchenorhyncha species displayed various responses to cessation management, with some differences between treatments persisting through 1976 and 1977, though not into 1978. Mean rates of increase were positive for most species, even on the C plots. On the J and B plots increases were generally significantly greater than on the M, and especially on the C, treatments. The relevance of the results to grassland management [primarily for sheep] for nature conservation is discussed. The importance of rotational management and of the rejuvenating effect of cessation of management are emphasized.