Higher taxa can be effective surrogates for species-level data in detecting changes in invertebrate assemblage structure due to disturbance: a case study using a broad range of orders

Cost-effective assessment tools are needed to manage the impacts of natural and human disturbances on communities. Higher taxa are widely used as surrogates for species-level identification in invertebrates; however, few studies have compared their effectiveness with species-level data for terrestrial invertebrates or assessed the mechanistic basis for their performance, and none of these studies have used a broad range of orders. Here, a terrestrial invertebrate dataset comprising 21 orders, 197 families and 751 species was used to investigate whether order- and family-level identifications were effective surrogates for species-level identification in representing patterns in assemblage structure and detecting the effects of fire. Factors potentially influencing the performance of surrogates among invertebrate orders were also investigated. Family-level identification of invertebrates in moorland sites with a wide range of fire history was found to be an effective surrogate for species-level identification. Order-level identification was also an effective surrogate, but the level of discrimination among sites was typically lower than for species- or family-level identification. Higher taxonomic surrogates performed well for invertebrate orders comprising a few species that were abundant and with a small mean and variance in the number of species per higher taxon. Use of higher taxa as surrogates for species-level identification can be a cost-effective approach to monitoring impacts of disturbance, but outcomes are influenced by taxonomic diversity and community structure.