Efficiency of sampling methods for accurate estimation of species richness of corticolous microlichens in the Atlantic rainforest of northeastern Brazil

Abstract

Three diVerent sampling methods were compared with regard to accurate estimation of species richness of crustose and microfoliose lichens in Atlantic rainforest remnants of northeastern Brazil. Quantitative transect sampling yielded three times as many species as non-quantitative opportunistic sampling, even if the number of sampled phorophyte trees was higher on average for the latter method. Repetitive non-quantitative opportunistic sampling of a single site resulted in twice the number of species than one-time sampling, but only two thirds of the number recovered by means of quantitative transect sampling, even of the number of sampled phorophyte trees was highest for this method. The analysis showed that opportunistic sampling fails to detect rare, inconspicuous, sterile, and/ or cryptic species, usually neglected or overlooked even by the experienced collector upon visual inspection in the Weld. On the other hand, quantitative sampling forces even the inexperienced collector to sample lichen thalli or pieces of bark which only after detailed morphological, anatomical, and chemical study in the laboratory reveal themselves as distinct species. Accordingly, of the 456 lichen species collected and identiWed across the 22 studied localities, no less than 76 were unique to the quantitatively sampled transect, and the lichen species sampled with this method had a signiWcantly higher proportion of rare, 1 C inconspicuous, sterile, and/or cryptic species. It is also apparent that it is not the higher number of specimens collected via quantitative sampling that results in a higher number of species, but the method of selection of the specimens, which is subjective and biased towards abundant, conspicuous, fertile and/or distinctive species in opportunistic sampling, but objective and unbiased in quantitative sampling.

When family matters: an analysis of Thelotremataceae (Lichenized Ascomycota: Ostropales) as bioindicators of ecological continuity in tropical forests

“…(h) A standardized sampling protocol is required. Based on our experiences in Costa Rica (Lücking et al , 2007, as well as in southern and northeastern Brazil (Marcelli 1992;Cáceres et al 2007c), Venezuela (Komposch and Hafellner 2000) and on published sampling protocols , including those using lichens as bioindicators of atmospheric pollution (Kirschbaum and Wirth 1997;Nimis et al 2002;Bartholmess et al 2004), we propose a preliminary protocol to be tested by further studies (Box 1).…”

Phorophyte specificity and environmental parameters versus stochasticity as determinants for species composition of corticolous crustose lichen communities in the Atlantic rain forest of northeastern Brazil

“…About 50% of these taxa (76 species) were found exclusively within the transect, not being present at other collecting sites or outside the transect at the study site. Most of these were inconspicuous or cryptic taxa, which were not visualized on the field or were at first mistaken for common species (Cáceres et al 2007b). As a whole, 205 species were found at the study site RPPN Fazenda São Pedro, only 21% of which (44 species) were shared between the transect and the area outside the transect.…”

Epiphytic microlichens as indicators of phytosociological differentiation between Caatinga and Brejos de Altitude

“…The different results found here may be due to the disparity in sampling technique, since opportunistic sampling had been used in the previous work. Cáceres et al (2008b) showed that the sampling method is critical for estimating species richness of lichens within a given area, indicating that the transects (quantitative method) used in the present study is most efficient for microlichen inventories. On the other hand, since the same technique was used for both regions, this might not actually explain the differences.…”