The importance and use of taxon sampling curves for comparative biodiversity research with forest arthropod assemblages

Abstract

For over three decades, the importance of taxon sampling curves for comparative biodiversity studies has been repeatedly stated. However, many entomologists (both within Canada and worldwide) continue to publish studies without standardizing their data to take sampling effort into account. We present a case study to illustrate the importance of such standardization, using the collection of spiders (Araneae) by pitfall traps as model data. Data were analyzed using rarefaction to represent one example of a taxon sampling curve, and by a variety of traditional diversity indices to describe alpha diversity. Raw species richness and single-index diversity measures (Shannon–Wiener, Simpson's, and Fisher's α) provided contradictory results. Rarefied species richness standardized to the number of individuals collected enabled more accurate comparisons of diversity and revealed when sampling was insufficient. Focusing on arthropods occurring in forested ecosystems, we also examined the use of taxon sampling curves in current literature by reviewing 133 published articles from 14 journals. Only 26% of the published articles in our review used a taxon sampling curve, and raw species richness and the Shannon–Wiener index of diversity were the most commonly used estimates. There is clearly a need to modify how alpha diversity is measured and compared for arthropod biodiversity studies. We recommend the abandonment of both raw species richness and single-index measures of diversity, and reiterate the need to use rarefaction or a related technique that allows for meaningful comparisons of species richness while taking into account sampling effort.

Influence of boreal forest succession and dead wood qualities on saproxylic beetles

“…To remove the possible influence of uneven catch rates, rarefaction was used to compare species richness ( Gotelli & Colwell, 2001;Buddle et al , 2005 ), and Chao2, an incidencebased estimator of species richness ( Chao, 1987 ), was used to estimate the species richness of the entire community. These calculations were performed for the entire data set (before standardization for sampling time) for each cover type independently, using EstimateS software ( Colwell, 2000 ).…”

Descrição da estrutura de uma Floresta Ombrófila Mista, RS, Brasil, utilizando estimadores não-paramétricos de riqueza e rarefação de amostras

“…A comparação da riqueza de espécies entre comunidades diferentes ou entre amostragens diferentes depende do uso de curvas de amostragem, pois a comparação direta do número observado de espécies ignora as diferenças entre esforços amostrais, entre as distribuições de abundância entre as espécies, assim como diferenças na densidade de indivíduos entre áreas, levando quase sempre a conclusões espúrias (Gotelli & Colwell 2001;Buddle et al 2005). Entretanto, apesar da importância da utilização de curvas de acumulação de espécies para padronização dos dados de estudos envolvendo a diversidade biológica ter sido enfatizada nas últimas três décadas (Simberloff 1972), os estudos de descrição de comunidades vegetais terrestres no Brasil continuam a ser publicados sem essa padronização de dados, tornando o grande volume de informações existente de difícil comparação.…”

Dung beetle communities: a neotropical-north temperate comparison

“…The species richness differences were established by use of taxon sampling curves (Buddle et al 2005). These results are reinforced by our use of standardized methodology to collect dung beetles at all sites.…”

“…Dung beetles are decomposers and primarily consume animal dung, although carrion, rotting fruit and other decaying material may also be eaten (Gill 1991). First, we hypothesize that tropical forests will exhibit higher dung beetle species richness (alphadiversity) than temperate forests, as shown by rarefaction (Buddle et al 2005). Second, we expect greater community similarity, measured as rank-abundance distributions, rank-volume distributions and beta-diversity within tropical forests and within temperate forests than between temperate and tropical forests.…”