A laissez-faire management approach in a grassland landscape results in a fine-scale, spatio-temporally heterogeneous fire pattern

Abstract

What are the spatio-temporal characteristics of a fire pattern that is allowed to develop over time across a species- rich, predominantly grassy landscape? More than 1 300 fires were documented over 13 years in the 48 000 ha Songimvelo Game Reserve in the Barberton Mountainland, South Africa. Most fires were set by pastoralists and were uncontrolled. Lightning fires and prescribed burns made up <2% and <8% respectively of the total area burnt. Median and mean burn areas in the 31 700 ha game-fenced section were 35 and 187 ha respectively with a fire return period of 2.9 years. In the less-grazed 14 000 ha section that receives a higher annual rainfall, median and mean fire sizes were 124 and 501 ha and the return period was 1.5 years. These fire return periods are in line with generally accepted management prescriptions for grasslands. The annual number of fires, individual patches and different fire histories occurring in a moving window across the landscape were consistently higher, compared with those resulting from a small-scale or large-scale fixed fire regime. This laissez-faire approach thus resulted in a fine-scale, dynamic fire pattern with high landscape indices that could be conducive to maintaining biodiversity.