Efficiency in inventories of ants in a forest reservein Central Amazonia

Abstract

-The objective of this work was to evaluate an inventory method effi ciency for ants. We used subsamples collected in 24 transects of 100 m, distributed in 6 plots of 600 ha each in primary forest, as part of a long-term project. Ten litter subsamples were extracted per transect using Winkler extractors. Ants were identifi ed to genus level, and Crematogaster, Gnamptogenys and Pachycondyla genera to species/morphospecies level. To evaluate the consequences of reduced sampling on the retention of ecological information, we estimated the lowest number of subsamples needed to detect the effects of environmental variables. Multidimensional scaling (MDS) was used to generate dissimilarity matrices, and Mantel correlations between each reduced-sampling effort and maximum effort were used as an index of how much information was maintained and could still be used in multivariate analyses. Lower p-values was observed on the effect of soil pH in the community of genera, and on the effect of the litter volume for the community of Crematogaster. The trend was still detectable in the analysis based on reduced-sampling. The number of subsamples can be reduced, and the cost-effi ciency of the protocol can be improved with little loss of information.Index terms: Formicidae, environmental impact assessment, soil biodiversity, Winkler extractors, tropical forest, sampling protocols. Efi ciência em inventários de formigas em uma reserva fl orestal na Amazônia CentralResumo -O objetivo deste trabalho foi avaliar a efi ciência da metodologia de inventário de formigas. Foram usadas subamostras coletadas em 24 transectos de 100 m, distribuídos em 6 parcelas de 600 ha, em fl oresta primária, como parte de um projeto de longa duração. Dez subamostras foram extraídas por transecto com extratores de Winkler. As formigas foram identifi cadas quanto ao gênero. Crematogaster, Gnamptogenys e Pachycondyla foram identifi cados quanto a espécies ou morfoespécies. Para avaliar as consequências de redução da amostragem na retenção da informação ecológica, foi estimado o menor número de subamostras necessário para detectar os efeitos das variáveis ambientais. A ordenação em escala multidimencionais (MDS) foi usada para gerar matrizes de dissimilaridade, e as correlações de Mantel, entre cada esforço reduzido de amostragem e o esforço máximo, foram usadas como índice da informação retida que ainda poderia ser usada em análises multivariadas. Foram detectados baixos valores de probabilidade para os efeitos do pH do solo na comunidade de gêneros e do efeito do volume de serapilheira na comunidade de Crematogaster. O mesmo padrão foi detectado em análises baseadas em amostragem reduzida. O número de subamostras pode ser reduzido e o custo-benefício do protocolo otimizado, com pouca perda de informação.Termos para indexação: Formicidae, avaliação do impacto ambiental, biodiversidade do solo, extratores de Winkler, fl oresta tropical, protocolos de coleta.

Synthesis of the first 10 years of long-term ecological research in Amazonian Forest ecosystem – implications for conservation and management

“…For example, not sorting the less frequent species did not severely affect the observed pattern of similarity among sample plots, indicating that more abundant species can be used as substitutes for less abundant species in biomonitoring studies. In addition, the sampling effort reduction did not affect the capacity to detect the effect of soil pH for the community of ant genera (Souza et al, 2009).…”

“…For studies designed to detect environmental changes, it is better to evaluate changes in the presence of more common species (Moraes et al, 2011) or even use reduced-sampling techniques (Souza et al, 2009). For example, not sorting the less frequent species did not severely affect the observed pattern of similarity among sample plots, indicating that more abundant species can be used as substitutes for less abundant species in biomonitoring studies.…”

A comparison between time of exposure, number of pitfall traps and the sampling cost to capture ground-dwelling poneromorph ants (Hymenoptera: Formicidae)

“…Traditionally, pitfall traps remain in the field for 48 hours in studies with ground-dwelling ants (Pik et al, 1999;Bestelmeyer et al, 2000;Vasconcelos et al, 2003;Oliveira et al, 2009;Souza et al, 2009;Baccaro et al, 2012Baccaro et al, , 2013Souza et al, 2012). Nevertheless, it is argued that the permanence of the traps for longer periods could capture more diversity (Bestelmeyer et al, 2000).…”

“…The major constraint to the expansion of existing ant surveys in tropical forests is the labor-intensive laboratory effort in sorting and identifying these invertebrates (Lawton et al, 1998;Purvis & Hector, 2000;Souza et al, 2009Souza et al, , 2012. The biggest challenge to investigate a more efficient use of resources is to ensure that sufficient ecological gradients are captured in relation to changing environmental variables .…”

Characterising the phytophagous arthropod fauna of a single host plant species: assessing survey completeness at continental and local scales

“…Our analysis suggests that less than half of the total species richness in the surveyed areas (838 species) has been recorded. However, complete sampling may not be essential for characterising community composition (de Souza et al 2009;Santos et al 2008), and may not be a realistic expectation in biodiversity surveys (Chao et al 2009). It is typical for speciesrich arthropod faunas to not approach the asymptote of the species accumulation curve even with intensive sampling (Gotelli and Colwell 2001;Soberón and Llorente 1993).…”