Fire is a major driver in many ecosystems. Yet, little is known about how different ground-living arthropods survive fire. Using three sampling methods, and time-since-fire (last fire event: 3 months, 1 year, and 7 years), we investigate how ground-living arthropod diversity responds to fire, and how species richness, diversity, abundance, and composition of the four dominant taxa: ants, beetles, cockroaches and mites, respond. We did this in the naturally fire-prone Mediterranean-type scrubland vegetation (fynbos) of the Cape Floristic Region. Surprisingly, overall species richness and diversity was the same for all time-since-fire categories. However, when each dominant taxon was analysed separately, effect of fire on species richness and abundance varied among taxa. This emphasizes that many taxa must be investigated to really understand fire-driven events. We also highlight the importance of using different diversity measures, as fire did not influence species richness and abundance of particular taxa, while it affected others, overall greatly affecting assemblages of all taxa. Rockiness affected species richness, abundance and composition of a few taxa. We found that all time-since-fire categories supported distinctive assemblages. Some indicator species occurred across all time-since-fire categories, while others were restricted to a single time-since-fire category, showing that there is a wide range of responses to fire between taxa. Details of local landscape structure, abiotic and biotic, and frequency and intensity of fire add complexity to the fire-arthropod interaction. Overall, we show that the relationship between fire and arthropods is phylogenetically constrained, having been honed by many millennia of fire events, and highly complex. Present-day species manifest a variety of adaptations for surviving the great natural selective force of fire.

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Natural forests are important for terrestrial biodiversity conservation. In South Africa, many forest patches are naturally small and surrounded by either natural grassland or exotic plantations. Here we compared arthropod diversity and composition among natural forest patches, pine plantations and grassland. We also assess how arthropod assemblages respond to the environmental changes at the boundaries between natural forest patches and the two different surrounding vegetation types. Twenty transects were selected, ten natural forests surrounded by pines, and ten natural forests surrounded by natural grassland. Transects ran from natural forest interiors, across the boundary into the interior of the surrounding vegetation. Arthropods were sampled using pitfall traps and active searches. Natural forests surrounded by grassland had higher species richness than those surrounded by pines. Greater arthropod abundance was in grassland edges than other stations. Pairwise comparisons revealed significant differences in assemblages between all vegetation types. This implies that forest biodiversity in these patches is altered by the main vegetation type in the matrix or in close proximity. Qualitative differences in assemblages between natural forest‐grassland boundaries were greater than differences between natural forest‐pine boundaries, indicating greater sharing of species between pines and natural forests. Our findings emphasise the value of natural forest‐grassland edges for conserving arthropod diversity as they add to the local species pool. Overall, we show that when maintaining small isolated natural forest patches, the role of the surrounding vegetation must be considered as it has a major influence on the local patch fauna.

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