The hemiptera of two sown calcareous grasslands. II. Differences between treatments

Published source details Morris M.G. (1990) The hemiptera of two sown calcareous grasslands. II. Differences between treatments. Journal of Applied Ecology, 27, 379-393.
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Summary

In the UK, changes in agricultural policy due to over-production has led to the possibility that some arable land will be taken out of production. There therefore exist nature conservation opportunities, in particular, the re-establishment of grasslands of conservation interest is of importance, as so much semi-natural grassland has been lost to crop production in recent decades. Botanical aspects of grassland re-creation have received considerable attention. This study focused on Heteroptera (a group that has received little study) colonization of sown swards of two contrasting types, a fine-leaved grass mixture and a coarse one.

Study site: The field experiment established on level, ploughed chalk farmland which had previously grown cereals at Grange Farm (National Grid ref. TL363390), Royston, Hertfordshire, southeast England. The site was about 1.6 km from semi-natural chalk grassland at Therfield Heath.

Treatments and management: Two contrasting grass seed mixes were sown on 19 April 1973. Four replicates of two treatments (coarse and fine sown grasses) were arranged in a randomized block design. Each plot measured 30 x 30 m.

Coarse grass mixture – four coarse grass species: 16 lb (7.26 kg) cock's-foot Dactylis glomerata, 22 1b (9.98 kg) tall fescue Festuca arundinacea 12 1b (5.44 kg) timothy Phleum pratense and 30 1b (13.61 kg) perennial rye-grass Lolium perenne.

Fine grass mixture - five fine-leaved grass species: 40 1b (18.14 kg) red fescue Festuca rubra, 5 lb (2.27 kg) sheep's fescue Festuca ovina, 10 lb (4.54 kg) smooth meadow-grass Poa pratensis, 10 lb common bent Agrostis (capillaris) tenuis and 5 lb crested dog's-tail Cynosurus cristatus.

The plots were cut in mid-July 1973 and in subsequent years in early June. Cutting was necessary to control weeds.

Heteroptera densities: Only 810 Heteroptera were collected in the vacuum samples over the three years. On the first occasion (20 September 1973), a maximum of 34 Heteroptera/m² was recorded, but three non-grassland species (Anthocoris nemorum, Orius minutus and Lygus rugulipennis) comprised all but one individual. Subsequently density never rose above 11/m² in 1974 or 1975.

Species richness: Species richness of grassland Heteroptera was low and few differences between coarse grass- and fine grass-sown plots were observed. More plant bugs over-wintered in the coarse grassland (as it afforded better refugia) than in the fine, with consistent, significant differences between treatments for Notostira elongata and Nabis ferus.

Auchenorrhyncha (leafhoppers & froghoppers) were more abundant in the coarse grassland in 1974 but on the fine grassland in 1975. Species richness was higher on the coarse sward. The heteropteran fauna of the coarse grassland tended to be more diverse at any one time, but cumulatively on the fine sward was slightly more diverse.

Species predominant on the coarse grassland were: Neophilaenus lineatus, Conosanus obsoletus, Mocydia crocea, Cicadula persimilis, Stenocranus minutus, Zyginidia scutellaris and Javesella peiiucida (second generation only). The last four species were abundant.

Species predominant on the fine grassland were: Deltocephalus pulicaris, Turrutus socialis, Euscelis incisus, Paluda adumbrata, Mocydiopsis attenuata, Dikraneura variata and Criomorphus albomarginatus. None were abundant.

A few species showed a response which varied over time e.g. Arthaldeus pascuellus was significantly more numerous on the coarse sward in summer 1974 but much more so on the fine sward in summer 1975.

Conclusions: The author concluded that mixtures of many grass species should be used to establish patches of grassland of variable structure and composition to attract the greatest diversity of hemipterans.

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