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

`Grasshopper assemblages were sampled in 44 plots in each of three adjacent sites in a 40-year-old southern tall grassland experimental area in South Africa. Specific plots received particular mowing and/or burning treatments over the 40-year period. Grasshopper responses to vegetation type, and to different burning and mowing practices, were site-specific, despite the clo se proximity of sites. This suggests that grasshopper assemblage compositio n is not entirely deterministic and depends on the trajectory of plant succ ession. Grasshopper species richness and abundance decreased from annually to triennially burnt plots, and increased in plots mown once per year to pl ots mown three times per year. Burning in the first week of August (winter) was more favourable for grasshopper assemblages than burning in autumn or after the first spring rains. Mean grasshopper species richness was highest in plots mown after the first spring rains, and the mean number of individ uals was highest in plots mown early in summer. When annually burnt plots w ere compared with annually mown plots, grasshopper abundance and species ri chness were highest in the burnt plots. A rotational winter burning program me, which is practical under African conditions, is recommended for the con servation of grasshoppers and other invertebrates.