Effects of interactive scale-dependent variables on beetle diversity patterns in a semi-arid agricultural landscape

• Published in: Landscape ecology Vol. 22; no. 5; pp. 687 - 703
• Main Authors: Yaacobi, Gal, Ziv, Yaron, Rosenzweig, Michael L
• Format: Journal Article
• Language: English
• Published: Dordrecht Dordrecht : Kluwer Academic Publishers 01.05.2007; Springer; Springer Nature B.V
• Subjects: Agricultural land; Animal, plant and microbial ecology; Applied ecology; Arid environments; Biodiversity; Biological and medical sciences; Carabidae; Community structure; Fragmentation; Fundamental and applied biological sciences. Psychology; General aspects; GIS; Habitat variability; Insecta; Invertebrates; Landscape heterogeneity; Patch size; Path analysis; Plant diversity; Plant species; Predators; Remote sensing; Species diversity; Tenebrionidae; Variables; Path analysis; Variable; Coleoptera; Insecta; Scale effect; Rural landscape; Carabidae; Landscape heterogeneity; Tenebrionidae; Remote sensing; Fragmentation; GIS; Species diversity; Heterogeneity; Habitat variability; Geographic information system; Semi arid zone; Arthropoda; Habitat; Patch size; Invertebrata
• ISSN: 0921-2973; 1572-9761
• DOI: 10.1007/s10980-006-9061-7

Understanding species-diversity patterns in heterogeneous landscapes invites comprehensive research on how scale-dependent processes interact across scales. We used two common beetle families (Tenebrionidae, detrivores; Carabidae, predators) to conduct such a study in the heterogeneous semi-arid landscape of the Southern Judean Lowland (SJL) of Israel, currently undergoing intensive fragmentation. Beetles were censused in 25 different-sized patches (500-40,000 m²). We used Fisher's α and non-parametric extrapolators to estimate species diversity from 11,125 individuals belonging to 56 species. Patch characteristics (plant species diversity and cover, soil cover and degree of stoniness) were measured by field transects. Spatial variables (patch size, shape, physiognomy and connectivity) and landscape characteristics were analyzed by GIS and remote-sensing applications. Both patch-scale and landscape-scale variables affected beetle species diversity. Path-analysis models showed that landscape-scale variables had the strongest effect on carabid diversity in all patches. The tenebrionids responded differently: both patch-scale and landscape-scale variables affected species diversity in small patches, while mainly patch-scale variables affected species diversity in large patches. Most of the paths affected species diversity both directly and indirectly, combining the effects of both patch-scale and landscape-scale variables. These results match the biology of the two beetle families: Tenebrionidae, the less mobile and more site-attached family, responded to the environment in a fine-grained manner, while the highly dispersed Carabidae responded to the environment in a coarse-grained manner. We suggest that understanding abiotic and biotic variable interactions across scales has important consequences for our knowledge of community structure and species diversity patterns at large spatial scales.