Sampling Patterns and Edge Effects in a Biodiversity Study of Urban Linear Streetscapes

In biodiversity monitoring programs, the selection of an unbiased sampling pattern has remained a significant challenge. This has been highlighted in systematic samplings where repeated habitat patterns may constantly occur or where over- or under-sampling of specific habitat areas may bias sampling efforts. A pilot study was designed to determine the best sampling pattern for a later full biodiversity study between bioretention swales, as a linear type of stormwater management linear system, and equivalent conventional green spaces in urban streetscapes in the Australian city of Melbourne. The sites were pitfall trapped and two spatial sampling patterns were compared to examine edge effects and the effects of regularly repeated habitat areas on invertebrate diversity in these landscapes. The number of species, Margalef's species richness (d) and the Shannon diversity index (H') showed non-significant differences between the two sampling patterns in any of the two landscape types of bioretention swales and conventional green spaces and in combining the landscape types. These results implied that it was experimentally valid to select any of the sampling patterns. The outcomes of this study may inform future sampling design in linear small- scale streetscapes and may support the use of pilot studies of different sampling patterns prior to finalising a sampling design.