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Spillover of terrestrial arthropod species and beta diversity in perennial crops relative to spatial scale of land‐use intensity
Author(s) -
van Schalkwyk Julia,
Pryke James S.,
Samways Michael J.,
Gaigher René
Publication year - 2020
Publication title -
journal of applied ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.503
H-Index - 181
eISSN - 1365-2664
pISSN - 0021-8901
DOI - 10.1111/1365-2664.13638
Subject(s) - species richness , crop diversity , ecology , habitat , geography , agroforestry , biodiversity , biology
Arthropod diversity in agricultural areas is influenced by land‐use intensity (LUI) at both local and landscape scales. In agricultural systems, non‐crop habitats are important for promoting in‐field arthropod diversity, although in perennial orchard systems, boundary contrast (i.e. structural differences between crop and non‐crop habitats) may impede spillover of arthropods from non‐crop areas. We focus on ground‐dwelling arthropods sampled within orchards in the Kogelberg Biosphere Reserve, South Africa, that do not show a strong association with this habitat type (i.e. ‘non‐cultural’ species), and assess the influence of local (in‐field scale; FLUI) and landscape scale LUI (LLUI), boundary contrast, cover‐crop management, and population effects on species richness, assemblage variation within orchards, and the dissimilarity between assemblages in crop and non‐crop habitats (i.e. ‘cross‐edge dissimilarity’). Higher LLUI (lower amounts of non‐crop habitat) was associated with higher in‐field species richness but also higher cross‐edge dissimilarity (i.e. these habitats were more distinct in certain landscapes). FLUI was important for non‐cultural species, especially non‐cultural predators and detritivores, for which higher levels of fertilization reduced in‐field species richness. Reduced contrast enhanced in‐field species richness, but there was limited evidence that this enhanced spillover from non‐crop habitats. Synthesis and applications . In production systems with high border contrast and highly productive crop habitats, higher landscape scale land‐use intensity can enhance in‐field diversity. By supporting a subset of the assemblage able to thrive in both crop and non‐crop habitats, this is contributing to community divergence. To promote farmland diversity, we advocate the reduction of agrochemical inputs, production diversification at the landscapes scale, and the incorporation of a network of non‐crop corridors and stepping‐stone habitats to maintain connectivity and resilience across the landscape.