Responses of grassland invertebrates to management by cutting: V. changes in Hemiptera following cessation of management

Published source details Morris M.G. & Plant R. (1983) Responses of grassland invertebrates to management by cutting: V. changes in Hemiptera following cessation of management. Journal of Applied Ecology, 20, 157-177.
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Summary

The type of semi-natural grassland management may greatly influence occurrence and abundance of invertebrates. In this study at Castor Hanglands National Nature Reserve (Cambridgeshire, southeast England), the effects of cutting of limestone grassland at different times of year on the abundance and diversity of heteroptera, and subsequently the effect of reversion following cessation of cutting from 1976 to 1978, was examined.

Treatments and experimental design: Four treatments were initiated on long-unmanaged limestone grassland (dominated by false oat-grass Arrhenatherum elatius) in 1973 to 1975: annual cutting in May or July, or both months, with an uncut control (four replicates of each in a randomized block design). The 16 plots (each 16 x 12 m) were separated by 2 m-wide unmown grassland strips. As much mown vegetation as possible was removed from cut plots by raking.

Sampling: In October 1972, and at 2- to 4-weekly intervals throughout April 1973 to December 1975, samples of invertebrates were taken from 1 m² quadrats in each plot using a D-Vac insect vacuum net. Similar samples were taken after experimental management ceased, from 1976 to 1978, each August. Adult Hemiptera (Heteroptera) and Auchenorrhyncha (Homoptera)) were identified and counted.

The summer of 1976 was exceptionally hot and dry. In general, species of damp grasslands declined whereas those of dry, and of short, swards increased. Average rates of increase were positive for most species. On the July-cut and May-and-July cut plots increases were generally significantly greater than on the May-cut plots, and especially on the controls. Heteroptera increased progressively in abundance from 1976 to 1978 on the previously-cut plots. No differences between treatments were recorded for abundance of individual species, or for total number of individuals and species. The rates of increase in Auchenorhyncha number of individuals and species were similar but the rate of diversity increase was greater on the cut treatments than on the controls. In 1978, average diversity was significantly greater on the July-cut and May-and-July-cut treatments than on controls. Auchenorhyncha species displayed various responses to cessation of management.

Conclusions: Semi-natural grasslands may be regularly mown but allowing periodic recovery (no management) over a period of years may be beneficial. A mix of rotational management and continual annual management to maintain habitat for e.g. thermophilous species, may be a good system to adopt.

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%28198304%2920%3A1%3C157%3AROGITM%3E2.0.CO%3B2-9