Effect of habitat complexity attributes on species richness

Habitat destruction is a leading cause of biodiversity loss worldwide. Destruction involving structural simplification tends to be a large contributing factor to this loss as many studies have reported a positive relationship between habitat complexity and taxonomic richness. However, the aspects of complexity that are most important for this relationship are still unclear. We tested whether several attributes of complexity contribute significantly to the effects of habitat complexity on macroinvertebrate richness. We sampled macroinvertebrates associated with several species of macrophytes covering a wide complexity gradient in freshwater coastal wetlands. Macrophyte complexity was quantified by measuring vertical and horizontal interstitial distances. Multiple regression was used to assess the relative importance of complexity attributes including the overall complexity as a space size/frequency index, space-size heterogeneity as the variation in space sizes, as well as the more commonly used macrophyte biomass, number of stems and the number of macrophyte species. Our results indicate that space-size heterogeneity is a more important contributor to taxonomic richness than overall complexity and the other complexity attributes examined. The results of this study have implications for the use of this concept in habitat restoration by the enhancement of habitat structures.