RESPONSES OF GRASSLAND INVERTEBRATES TO
MANAGEMENT BY CUTTING
V. CHANGES IN HEMIPTERA FOLLOWING CESSATION OF
BY M. G. MORRIS
Institute Terrestrial of ResearchCouncil),
BH20 SAS and
Cambridgeshire, 7 2LS
(1) From 1973 to 1975 the effectsof cuttingon the invertebrates Arrhenatherumof dominated were studied.Four treatments grassland (cuttingin May (M), July (J), both
May andJuly(B) andno cutting(control, wereapplied annually. (2) Thereversion the plotswas studied of from 1976to 1978by takingthreestandard at in vacuumnet samples fortnightly intervals August.AdultHemiptera and (Heteroptera were Auchenorhyncha) identified counted. and (3) The hot, dry summer 1976 had effectswhichwereassessedon the C plots.In of declined abundance in general,speciesof dampgrasslands whereas thoseof dry, andof increased. Somephonological effectsmayhavebeendetected. short,swards
(4) The 1976 faunaof Heteroptera least similar that of any otheryearbut the was to
faunain 1976 was similar those of 1975 and 1977, with 1973 the to leastsimilar year. increasedprogressively abundance in (5) Heteroptera from 1976 to 1978 on the previously-managed plots. No differencesbetween treatmentswere recordedin the abundance individual of of species,or for N andS (totalnumber individuals and-species, respectively), the ratesof increase but from 1975to 1978weresignificantly with different, thetreatments to as tending segregate thetwo pairsJ + B andM + C.
(6) The ratesof increase Auchenorhyncha andS weresimilarly but grouped, the rate of increasein diversity(D) was greater everytreatment on thanon the controls.
1978meanD was significantly greater theJ andB treatments on C. on than
(7) Auchenorhyncha speciesdisplayed variousresponses cessation management, to of with somedifferences between treatments persisting through1976 and 1977,thoughnot into 1978. werepositive mostspecies,evenon the C plots.OntheJ for (8) Meanratesof increase andB plotsincreases weregenerally thanon theM, andespecially on significantly greater the C, treatments.
(9) The relevance the resultsto grassland of for is management natureconservation discussed.The importance rotational of and effect of management of the rejuvenating cessation management emphasized. of are
At least part of the invertebratefauna of intensively-managedgrassland is impoverished, as measured by the abundance of individuals, representation of species, and species diversity, compared with the fauna of otherwise similar,but less intensively-managed,land.
Cessation of heavy, almost continuous, grazing by sheep allowed many species of a chalk grassland fauna to increase in numbers and diversity (Morris 1971a). Management by
0021-8901/83/0400-0157$02.00 ? 1983British
Cessation grasslandmanagement:faunal of changes
cutting adversely affected species of Heteroptera (Morris 1979a) and Auchenorhyncha
(Morris 198 la) on oolitic limestone grassland, although a few species respondedpositively to cutting (Morris 198 ib). However, the effects were strongly influencedby the timing and frequency of management. Species diversity of both Heteroptera and Auchenorhyncha was also reduced, at least on some occasions (Morris & Lakhani 1979). Although there is less information,burningof carboniferouslimestone grassland had some effects similarto those caused by cutting (Morris 1975). The general principle that grassland
Auchenorhyncha are greatly influenced by the vertical structure of the vegetation they inhabit, first detailed by Andrzejewska (1965), has since been confirmedfor a wide range of differentgrasslandtypes…