Evaluating leaf litter beetle data sampled by Winkler extraction from Atlantic forest sites in southern Brazil

Abstract

Evaluating leaf litter beetle data sampled by Winkler extraction from Atlantic forest sites in southern Brazil. To evaluate the reliability of data obtained by Winkler extraction in Atlantic forest sites in southern Brazil, we studied litter beetle assemblages in secondary forests (5 to 55 years after abandonment) and old-growth forests at two seasonally different points in time. For all regeneration stages, species density and abundance were lower in April compared to August; but, assemblage composition of the corresponding forest stages was similar in both months. We suggest that sampling of small litter inhabiting beetles at different points in time using the Winkler technique reveals identical ecological patterns, which are more likely to be influenced by sample incompleteness than by differences in their assemblage composition. A strong relationship between litter quantity and beetle occurrences indicates the importance of this variable for the temporal species density pattern. Additionally, the sampled beetle material was compared with beetle data obtained with pitfall traps in one old-growth forest. Over 60% of the focal species captured with pitfall traps were also sampled by Winkler extraction in different forest stages. Few beetles with a body size too large to be sampled by Winkler extraction were only sampled with pitfall traps. This indicates that the local litter beetle fauna is dominated by small species. Hence, being aware of the exclusion of large beetles and beetle species occurring during the wet season, the Winkler method reveals a reliable picture of the local leaf litter beetle community.<br>Avaliação dos besouros da liteira amostrados por extração Winkler na Floresta Atlântica do Sul do Brasil. Para avaliar a confiabilidade dos dados obtidos pela extração Winkler em coletas na Floresta Atlântica do Sul do Brasil, nós estudamos as assembléias de besouros da liteira em florestas secundárias (5 a 55 anos após abandono) e no estágio avançado em dois pontos no tempo sazonalmente diferentes. Para todos os estágios de renegeração, a densidade e abundância das espécies foram menores em abril comparado a agosto; porém, a composição das assembléias dos estágios florestais correspondentes foi similar em ambos os meses. Nós sugerimos que amostragens de pequenos besouros habitantes de liteira em diferentes pontos no tempo usando o método Winkler revelam padrões ecológicos idênticos. Um forte relacionamento entre a quantidade da liteira e a ocorrência de besouros indica a importância dessa variável no padrão temporal de densidade das espécies. Adicionalmente, o material amostrado foi comparado com dados de besouros obtidos utilizando armadilhas do tipo pitfall em um estágio avançado de regeneração. Cerca de 60% das espécies de interesse capturadas em pitfall foram também amostradas pela extração Winkler. Poucos besouros com tamanho corporal grande para ser amostrado pela extração Winkler foram capturados com a armadilha pitfall. Isso indica que a fauna local de besouros da liteira é dominada por espécies...

The conservation value of secondary forests in the southern Brazilian Mata Atlântica from a spider perspective

“…The identified genera can serve as indicator taxa for the evaluation of priority areas for forest conservation. For future evaluations they should be combined with the outcomes of other arthropod studies (Bihn et al 2008b;Hopp et al 2011;Ottermanns et al 2011), and ecological traits should also be included to establish a reliable multi-taxon approach for the implementation of conservation strategies (Kotze & Samways 1999;Uehara-Prado et al 2009).…”

“…The Brazilian-German cooperative project SOLOBIOMA (Hofer et al 2007(Hofer et al , 2011 studied the biogeochemistry and, in a multi-taxon approach, the diversity of earthworms , enchytraeids (Schmelz et al 2009, 201 1 ), ants (Bihn et al 2008a,b), beetles (Hopp et al 2010(Hopp et al , 2011Ottermanns et al 2011) and spiders in order to evaluate the conservation value of secondary forests in the Mata Atlantica. The overall aim of this project was to check the possibility of classifying secondary forest stages by their soil fauna and comparing that with the "traditional" classification by age and vegetation.…”

Can immature stages be ignored in studies of forest leaf litter arthropod diversity? A test using Oxford Nanopore DNA barcoding

“…Immature stages are understudied and unknown for most species, genera and many families of arthropods (Pfingstl & Schatz, 2021). Consequently, immature stages are usually discarded, and the diversity is evaluated based on adults only (Chung et al, 2000; Didham et al, 1998; Hopp et al, 2011; Olson, 1994). The effect of the exclusion of immature stages is unclear.…”

Diversity of Beetles (Coleoptera) in an Inter-Andean Dry Tropical Forest in Ecuador

“…In the future, we recommend sampling other strata (e.g., canopy, ground, underground), and using a variety of active and passive collection methods. Considering the heterogeneous landscape at BPJ, a combination of Winkler extractors to sample leaf litter fauna and pitfall traps for ground-foraging species is recommended (Carneiro et al 2016;Hopp et al 2011;Krell et al 2005). Given the abundance of epiphytes, using canopy-sampling methodologies could enhance the discovery of beetles specialized in this stratum (Savini et al 2015;Staines and Zamorano 2012;Wardhaugh et al 2013;Weiss et al 2019).…”