Abstract:
Restoring riparian buffers is a common means of reducing the degradation of freshwater resources in New Zealand. However, restoration efforts usually focus on the vegetation community, and rely on passive dispersal for invertebrate species to colonise. In landscapes with extensive development, remnant riparian forest may be thousands of meters from restoration sites. Apple orchards are known to support a range of native invertebrate species, and are often located near freshwater systems. For this thesis, I studied the impact of apple orchard proximity on invertebrate communities in areas of riparian restoration in the Hawke’s Bay, New Zealand. Invertebrate community sampling in riparian buffers adjacent to and isolated from apple orchards was carried out using pitfall traps, sticky traps, and branch beating. Coleoptera were identified to as close to species level as possible, and all other invertebrates assigned to orders. Dispersal of an apple orchard-dwelling spider Anoteropsis hilaris into the adjacent riparian restoration area was explored using mark-release-recapture and laboratory choice tests. Significant differences in the abundance of invertebrate orders were found between orchard and riparian environments, and only Hymenoptera and Thysanoptera abundances were significantly different between restoration sites adjacent to and isolated from apple orchards. The riparian restoration environment had a significantly higher number of predator, fungivore, and total number of beetle species than the orchard. However, almost all of the beetle species collected from the orchard sites were also collected from the restoration environment. A. hilaris was mobile enough to be capable of dispersing between orchard and adjacent riparian environments, although no movements across the habitat boundary were observed. Laboratory-based testing revealed that A. hilaris may avoid saturated soil moisture levels. Only limited evidence for an impact of apple orchard proximity on invertebrate communities in areas of riparian restoration was found. Implications for future riparian restoration efforts are discussed.
