Grasshopper response to a 40-year experimental burning and mowing regime, with recommendations for invertebrate conservation management

  • Published source details Chambers B.Q. & Samways M.J. (1998) Grasshopper response to a 40-year experimental burning and mowing regime, with recommendations for invertebrate conservation management. Biodiversity and Conservation, 7, 985-1012.


In South Africa and elsewhere, the most common grassland management practices are mowing, grazing and burning. This study investigated how grasshoppers (Orthoptera) respond to a patchwork of variously burned and mowed long-term experimental plots in a South African grassland.

Study area: Sampling of grasshoppers was undertaken in a 40-year-old experimental area in a `southern tall grassland' on the Ukulinga Research Station, University of Natal, Pietermaritzburg (29°40'E, 30°24'S), South Africa.

Experimental design and treatments: Grasshopper assemblages were sampled in 44, 27.5m X 13.7 m randomized plots in each of three adjacent sites in the experimental area in. Specific plots received particular mowing and/or burning treatments over 40-years. Three summer hay cut treatments and a control were superimposed on 10 winter treatments (burning or mowing) and a control; a total of 44 treatments replicated three times (once at each site). The treatments were:

Summer treatments (i.e. four plot types)

A) Control (no summer management)
B) One hay cut early in summer (November to December)
C) One hay cut late in summer (February to March)
D) Two hay cuts (one with B and one with C)

Winter treatments (i.e. 11 plot types)

1) Control
2) Annual burn: first week in August
3) Annual burn: after first spring rains (>15mm in 24 hours)
4) Biennial burn: first week in August
5) Biennial burn: after first spring rains (>15 mm in 24 hours)
6) Biennial burn: in autumn
7) Triennial burn: first week in August
8) Triennial burn: after first spring rains (>15 mm in 24 hours)
9) Triennial burn: in autumn
10) Annual mow: first week in August
11) Annual mow: after first spring rains (>15 mm in 24 hours)

Grasshopper sampling: Sampling was undertaken from 20 February 1991 to 30 April 1991. One sample comprised 10 sample units (each 5 m x 1 m) within a plot. Each sample unit was walked with a two-pronged aluminium fork (prongs 1 m apart) carried in front of the surveyor and all adult grasshoppers between the prongs were recorded. This method has been shown to be effective for sampling grasshoppers in South African grassland.

A total of 3,027 individuals of 24 species was obtained. In all sites combined, 60% of the species had fewer than 50 individuals, 68% fewer than 100, and 88% fewer than 250. Three species had more than 300 individuals The five most abundant were: Parga xanthoptera, Dnopherula callosa, Coryphosima producta, Faureia milanjica and a Dnopherula sp.'1' These five species accounted for almost 74% of all individuals.

Grasshopper responses to vegetation type, and burning and mowing regime, were site-specific, despite the closeness of sites to one another. Grasshopper species richness and abundance decreased from annually to triennially burnt plots, and increased in plots mown once a year to plots mown three times a year. Winter burning in the first week of August was more favourable for grasshopper assemblages than burning in autumn or after the first spring rains. Average grasshopper species richness was highest in plots mown after the first spring rains, and the average number of individuals was highest in plots mown early in summer. Species richness and abundance was higher in annually burnt plots compared with annually mown plots.

The authors recommend a rotational winter burning programme (which is practical under the prevailing conditions) for the conservation of grasshoppers and other invertebrates.

Note: If using or referring to this published study, please read and quote the original paper, this can be viewed at:


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