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Many wetland systems are being lost or degraded by human activities such as plantation forestry. Therefore, efforts to restore these wetland systems are important for biodiversity recovery. We assess the recovery of arthropod assemblages that occupy hydromorphic grassland topsoil and leaf litter after the removal of exotic pine trees. We sampled arthropods in three biotopes (natural untransformed hydromorphic grasslands, restored hydromorphic grasslands, and commercial pine plantations) replicated across a large‐scale timber‐grassland mosaic in the KwaZulu‐Natal Midlands, South Africa. In the restored sites, overall species richness, as well as species richness of spiders, ants, and orthopterans, was significantly higher than in plantations, and was as high as in natural, untransformed sites. Additionally, overall assemblage structure along with spider, beetle, ant, and orthopteran assemblages showed no significant differences between restored and natural grasslands. Therefore, pine tree removal enables recovery of these arthropod taxa to levels similar to those in natural hydromorphic grassland. Recovery was rapid, with the assemblages in some restored sites resembling those in untransformed sites after only 6 years, indicating a high level of resilience and recovery in these systems. Contrary to expectations, time since pine removal had a negative effect on arthropod recovery. This was due to the strongly negative effect of alien invasive American bramble (Rubus cuneifolius), which was most common in older restored sites, causing deviation from their restoration trajectory. The potential for arthropod recovery in these hydromorphic grasslands is high, but successful restoration is dependent on ongoing appropriate grassland management, especially removal of bramble. [ABSTRACT FROM AUTHOR]

• Equally high alpha-and beta-diversity in plantations compared to natural vegetation. • Beta-diversity driven by species replacement rather than nestedness. • Plantations did not contribute to biotic homogenization. • Arthropod assemblage composition differed between plantations and natural areas. • Conservation corridors maintain regional soil biodiversity. Landscape transformation for agriculture threatens global biodiversity through simplification of ecosystems. We determine whether large-scale timber plantations contribute to biotic homogenization of soil biodiversity relative to remnant natural vegetation. We examined ant and springtail alpha- and beta-diversity, and assemblage composition, among biotopes in two different climatic and soil regions in a subtropical area of South Africa. Surprisingly, we observed equally high levels of alpha- and beta-diversity in plantations (Eucalyptus and Pinus) as in natural biotopes (indigenous forest and grassland) for both taxa in both regions, except in the inland sites where ant species richness was highest in grassland. Furthermore, beta-diversity in all biotopes was mainly due to species replacement rather than nestedness. The high diversity in plantations is likely due to high environmental variation among plantation sites, likely providing diverse niche opportunities across plantations. A possible mechanism for the large proportion of shared species between natural areas and plantations is colonization of arthropods from natural areas into plantations and/or source populations surviving harvesting and tree planting and then their populations growing during long periods of tree maturation. Plantations and natural areas supported complementary assemblages, which builds on the idea that remnant natural vegetation in production landscapes is essential for conserving not only unique aboveground biodiversity, but also unique belowground biodiversity. Furthermore, timber plantations do not homogenize soil arthropod taxonomic diversity as expected. This contrasts with global trends on biodiversity response to land-use change and emphasizes that conservation principles for soil biodiversity may differ from those aimed at aboveground biodiversity. [ABSTRACT FROM AUTHOR]

Humanity relies on soil fauna for important ecosystem services, as such our soils need sustainable management to ensure long-term biotic viability. However, environmental factors influencing the distribution and diversity of soil fauna are poorly understood, which limits effective conservation management. To address this issue, we assessed the influence of variables at different spatial scales (site, soil, and landscape) in different biotopes (natural forest patches and grasslands) in two contrasting geographical regions (inland Midlands and coastal Zululand, South Africa) on ant and springtail diversity in large-scale conservation corridors among commercial plantations. Midlands sites, with complex topography and nutrient-rich and deep soils, had higher soil arthropod diversity than sandy, shallow Zululand soils. Indigenous forest and grassland supported complementary arthropod assemblages. The responses of arthropod diversity and assemblage composition to local environmental variables varied greatly among biotopes, taxa, and regions, but responses were more pronounced in the Midlands than in Zululand, and arthropods were more responsive to site- and soil-related variables than to landscape variables. Lower soil biodiversity in Zululand compared to the Midlands emphasizes that management efforts to limit further homogenization from inappropriate management is particularly important in this sandy region. Lack of common drivers of soil arthropod diversity suggests that conservation strategies need to be tailored to different locations. Nonetheless, the conservation of both indigenous forest and grassland, together with promotion of small-scale spatial heterogeneity, will maximally benefit the widest range of soil-inhabiting organisms. • Environmental drivers of soil fauna distributions are poorly understood. • Soil arthropod response is taxon, biotope and region specific. • Small-scale variables are more influential than landscape-scale variables. • Remnant natural areas contribute to regional soil biodiversity. [ABSTRACT FROM AUTHOR]