Small grassland fragments and connectivity support high arthropod functional diversity in highly modified landscapes

• Published in: Insect conservation and diversity 2023-09, Vol.16 (5), p.701-711
• Main Authors: Korányi, Dávid, Gallé, Róbert, Torma, Attila, Gallé‐Szpisjak, Nikolett, Batáry, Péter
• Format: Article
• Language: English
• Subjects: arable land; Arthropods; community weighted mean; Connectivity; Ecosystems; Entropy; fragmentation; Grasslands; Habitat preferences; Hemiptera; Humidity; Land use; Landscape; pine plantation; Preferences; RaoQ; spiders; steppe; Steppes; Taxonomy; traits; true bugs; Web building
• ISSN: 1752-458X; 1752-4598
• DOI: 10.1111/icad.12668

Grassland ecosystems undergo dramatic habitat loss and fragmentation worldwide due to agricultural expansion and intensification. Among different taxonomic groups, grassland arthropods are particularly sensitive to this process and, therefore, are exposed to considerable risk. Although many studies focus on land use impacts on arthropod diversity, these mostly consider taxonomic diversity and neglect trait‐mediated functional responses. However, studying functional diversity often provides more accurate insights into ecosystem processes. Here, we assessed the effect of fragment size and connectivity on the functional composition (community‐weighted mean trait values) and diversity (Rao's quadratic entropy) of two diverse and abundant arthropod groups: spiders and true bugs. We assigned functional traits for more than 300 species collected from 30 sandy steppe (forest‐steppes) and 30 loess steppe fragments (kurgans) in the southern part of the Hungarian Great Plain. Functional responses to fragmentation were observed for spiders in forest‐steppes and for true bugs in kurgans. We found higher functional diversity in better‐connected fragments for spiders and in small fragments for both groups. We collected small, humidity‐preferring and web‐building spiders in small fragments, and there were more ballooning spiders with moist habitat preferences in well‐connected fragments. Furthermore, increasing grassland connectivity resulted in a significantly higher proportion of polyphagous and humidity‐preferring individuals in the true bug communities. Our results highlight the importance of small grassland fragments in maintaining high arthropod functional diversity. Even small fragments in a well‐connected grassland network can promote ecosystem functioning and associated services within human‐dominated landscapes. We assessed the effect of fragmentation on the functional composition and diversity of spider and true bug communities collected from sandy steppe and loess steppe fragments in Hungary. Our results show that small and well‐connected grassland fragments supported high arthropod functional diversity. In addition, fragment size and connectivity shaped some functional traits of arthropods. Our findings suggest that connected grassland networks incorporating small fragments are needed within human‐dominated landscapes to promote functionally diverse arthropod communities.