In an attempt to conserve and monitor biodiversity, field studies are often undertaken involving the use of biodiversity indicators. Selection of appropriate species is an integral component of the research design of such ecological programs. There are strong arguments for selecting invertebrates as a reliable biodiversity indicator but broad invertebrate assemblages are rarely used as biodiversity indicators in environmental monitoring or inventorying programs. The selection of a narrow invertebrate species grouping is often preferred but there is little research-based evidence to justify such selection in biodiversity studies. To validate such an approach, a biodiversity study was undertaken in several linear green strip areas within urban streetscapes. These strips had a width range of 2.5 to 5 m. The sites were pitfall trapped and selection of the best invertebrate taxa group as a biodiversity indicator was investigated in summer and spring sampling regimes. In both the summer and spring surveys, the number of species (S) in the double-order of Coleoptera and Hymenoptera consistently correlated best to the total number of species of the invertebrates captured in the studied sites (R2= 0.81 in the summer survey and R2= 0.94 in the spring survey). The correlation was even stronger between the Shannon diversity index (H’) of Coleoptera and Hymenoptera and the Shannon diversity index of the total invertebrates of the sites (R2= 0.96 in the summer survey and R2= 0.83 in the spring survey). These findings suggest that for the sites investigated, Coleoptera and Hymenoptera together may be considered as surrogates for invertebrate diversity measures in these small-scale urban landscapes. The outcomes of this study reinforce that conducting pilot studies can help to validate the selected biodiversity indicator while rationalising time and effort in biodiversity monitoring. Further studies are needed to test whether the results are specific to the studied region or whether they can be used generally in biodiversity studies in such urban landscapes.

Keywords