Rarefaction Method Research Articles

Trophic state (TSISD) and mixing type significantly influence pelagic zooplankton biodiversity in temperate lakes (NW Poland).

BackgroundLake depth and the consequent mixing regime and thermal structure have profound effects on ecosystem functioning, because depth strongly affects the availability of nutrients, light, and oxygen. All these conditions influence patterns of zooplankton diversity. Zooplankton are a key component of the aquatic environment and are essential to maintaining natural processes in freshwater ecosystems. However, zooplankton biodiversity can be different regard to depth, mixing type and trophic state. Therefore, the aim of this study was to examine how depth and mixing regime affect zooplankton diversity in lakes. We also investigated the vertical distribution of diversity across a trophic gradient of lakes.MethodsA total of 329 zooplankton samples from 79 temperate lakes (36 polymictic and 43 dimictic) were collected. The biodiversity of zooplankton was calculated using species richness (SR) and the Shannon index (SI). An index based on Secchi disc visibility was used to determine the trophic state index (TSISD) of lakes. The one-way ANOVA with Duncan’s post hoc test were used to determine differences in zooplankton biodiversity between mictic lake types and thermal layers. To find the best predictors for zooplankton biodiversity a multiple stepwise regression was used. The rarefaction method was used to evaluate the impact of mixing types, thermal layers, and the TSISDon zooplankton biodiversity indices. A Sørensen similarity analysis and nonmetric multidimensional scaling (NMDS) were performed to describe the similarity patterns in species composition among lakes.ResultsWe identified a total of 151 taxa from 36 polymictic and 43 dimictic lakes. Lake depth and the TSISD were significantly correlated with the biodiversity of lake zooplankton. The results of ANOVA and Duncan tests show that mictic type and thermal zones had a significant effect on zooplankton biodiversity. The rarefaction curve showed significant differences in zooplankton biodiversity, which was greater in lakes with lower trophic state. Ordination by NMDS showed clustering of different mictic types, thermal layers, and composition changes throughout the TSISDprofile. Moreover, we determined that polymictic lakes are more heterogeneous than dimictic lakes in regard to zooplankton similarities.DiscussionBoth mictic lake types were characterized by varying levels of zooplankton biodiversity, which is shaped by the communities’ response to lake depth, thermal layers and TSISD values. The zooplankton SR and SI (during daylight hours) depends greatly on the mixing type. Lake type also indicates the importance of the metalimnion in shaping zooplankton biodiversity in dimictic lakes. In addition, data from NW Polish lakes indicated that the increase of the TSISD leads to taxonomic shifts and has a negative effect on the diversity of all groups of zooplankton.

On species richness and rarefaction: size- and coverage-based techniques quantify different characteristics of richness change in biodiversity

Changes in biodiversity today shape the future patterns of biodiversity. This fact underlines the importance of understanding changes in biodiversity through time and space. The number of species, known as species richness, has long been studied as a key indicator that quantifies the state of biodiversity, and standardisation techniques, called rarefaction, have also been used to undertake a fair comparison of the richness observed at different times or locations. The present study asks whether utilising different rarefaction techniques attains comparable results when investigating changes in species richness. The study framework presents the statistical nature of two commonly adopted rarefaction techniques: size-based and coverage-based rarefaction. The key finding is that the rarefied richness results calculated by these two different rarefaction methods reflect different aspects of biodiversity change, the shift in community size and/or composition. This fact illuminates that richness analyses based on different rarefaction techniques can reach different conclusions that may be contradictory. The study also investigates the mechanism creating such divergence. As such, special care is required when evaluating biodiversity change using species richness as an indicator.

Measuring geomorphological diversity on coastal environments: A new approach to geodiversity

Geodiversity can be defined as the spatial variability of geo-elements. Its emergence as a research field is relatively recent, with a wide range of approaches and methods of evaluation and quantification already in use. The work described in this paper was carried out from a novel perspective. Firstly, the emphasis is specifically centred on geomorphological diversity. Secondly, mathematical ecology calculations are applied which tackle the problem on the basis of a larger number of diversity parameters. In addition, whereas most authors have focussed on mountainous and/or continental areas, for the first time a study of this type is applied to coastal landscapes. The analysis covers the full 459 km of volcanic coastline of the islands of Gran Canaria and La Palma (Canary Islands). These two oceanic islands were chosen for purposes of diversity comparison given their differing stages of geomorphic development. In accordance with an ad hoc geomorphological taxonomy, as developed in this study, 14 geomorphic groups and 42 subgroups were identified and quantified according to their presence [1] or absence [0] along the coastline. A cartographic-analytical method (coastline data-storing or CDS), based on the computation of binary information in the cartographic vector of the coastline, enabled calculation of the occurrence probability of these groups and subgroups. Both at local level (analyses of coastal morphoassemblages) and general level, three components of geomorphological diversity (richness, evenness and dissimilarity) were estimated, through indices of richness (R), Shannon's entropy (H′) and Rao's quadratic entropy (Q). The data reveal that geomorphological coastal diversity is between 11.1% and 48.2% higher in Gran Canaria than in La Palma. The method was subjected to a fractal stress test through iterative mapping procedures to assess the effect of scale on the behaviour of the relative frequencies and indices. The variability that was obtained allowed the extraction of corrected values in the indices for La Palma (H′c = 1.88 ± 0.008 and Qc = 0.183 ± 0.004) and Gran Canaria (H′c = 2.11 ± 0.019 and Qc = 0.232 ± 0.003). A moving-window test was also applied as a rarefaction method to confirm the contrast in diversity in coasts of different size. The results enabled to advance hypotheses about the relation between coastal geomorphic diversity and geological age of islands.

Effect of sample size and resolution on palaeomalacological interpretation: a case study from Holocene calcareous‐fen deposits

ABSTRACTThis study investigates the effects of sample volume, resolution and accumulation time on the interpretation of a mollusc record from terrestrial deposits. We tested (i) if, and to what extent, small sample sizes impoverish the reconstructed mollusc species richness, and (ii) whether fine‐resolution sampling is worth the effort. We analysed three mollusc sequences, covering continuously the entire Holocene, which were collected in a tufa‐forming spring fen and differed in sample size and resolution. More than 36 000 specimens of 76 species were processed. Using a rarefaction method, we observed that different sample volumes had a significant effect on the recorded species richness in this type of environment, and 100‐cm3 samples seemed to be sufficient for a reliable reconstruction in tufa deposits. Although the thickness of the sampled layers had no influence on the palaeoecological interpretation, we observed a shift in the mollusc diversity peak once different resolutions were applied. Furthermore, the layers of finer resolution allowed detailed radiocarbon dating and better understanding of trends in species dynamics. We also observed significant confounding relationships among the number of species, number of specimens and accumulation time that can be disentangled if a precise depth–age model is available.

Tempo and mode in the replacement of trilobite evolutionary faunas from the Cordillera Oriental basin (Northwestern Argentina)

Major ecological transitions among evolutionary faunas are matters of continual debate. Our study analyses the timing and mode of replacement of Ibex I and II Trilobite Evolutionary Faunas (TEF) in Lower Ordovician successions of northwestern Argentina, with special emphasis on olenids and asaphids as key groups of the Ibex I and Ibex II faunas, respectively. We explore richness by using the sample rarefaction method, and occupancy based on a presence–absence dataset. The late Tremadocian 2 (Tr2) represents an inflexion point in richness and occupancy trajectories of asaphids and olenids. While olenids diminish their generic richness through time, asaphids became the richest family since the Tr3 predating the global trend recognized for the expansion of the Ibex II Fauna. Asaphids gained diversity at the expense of other trilobites as well, their rise in diversity lags behind the increase in occupancy suggesting a displacement scenario as the probable mode of replacement between the Ibex I and II TEFs. Apparently, the processes of replacement variate among regions across the globe, configuring a complex global mosaic of regional patterns.

Estimation of river ecosystem biodiversity based on the Chao estimator

The research was focused on identification of plant diversity assessment approach which would be suitable for flowing waters. Moreover, the study attempted to estimate the extent of the survey (sampling effort) needed for detection of full plant diversity in river ecosystems. The analysed data were collected in a botanical survey carried out on the lowland sandy bottom Wel river, which is a very common river type in Europe. The Chao method of estimation of total species richness of macrophytes and Hill numbers were used to estimate the diversity based on very common plants (inverse Simpson index) as well as frequent species (Shannon index) and also including rare species (species richness). The analysis showed that using standard macrophyte survey approach for rivers, it is relatively easy to record abundant plants, but it is not possible to detect all species, because many aquatic macrophytes occur with low frequency and abundance requiring enormous sampling effort to detect all of them. It exceeds capabilities of most scientific projects. To improve the accuracy of diversity estimation, the rarefaction and extrapolation method was recommended. This method can reduce the bias in diversity estimates based on limited observational data, and thus limit inaccurate conclusions and subsequent wrong decisions in the conservation frameworks related to freshwater protection.

Comparación de dos métodos para analizar la proporción de riqueza de especies entre comunidades: un ejemplo con murciélagos de selvas y hábitats modificados

The most frequently used measure of biodiversity is species richness, and it is especially important to detect how many times is richer one community regarding another one, i.e., the species richness ratio or relative difference in the number of species between communities. To assess this richness ratio, it is necessary to standardize samples. In this work we use 2 standardizing methods to assess the richness ratio: traditional rarefaction based on the number of individuals, and rarefaction based on the degree of sample completeness (sample coverage). We used both methods to analyze bat richness ratio between tropical forests and modified habitats in the Neotropics. We used information from 53 study cases reported in 34 published papers. With traditional rarefaction, 35 studies showed higher species richness in the forest, while rarefaction based on sample coverage led to 38 studies with higher richness in the forest than in the modified habitat. Richness ratios were higher with the new rarefaction method than with the traditional rarefaction. This means that traditional rarefaction gives a richness difference between forest and modified habitats lower than the real difference. To avoid this reduction in richness ratios, and its possible consequences in conservation biology, it would be better to use sample coverage based rarefaction. These results can be widely applicable, beyond the study group and the region.

Myrtaceae na Bacia do Rio Caveiras: Características Ecológicas e Usos Não Madeireiros

RESUMO Objetivou-se descrever o padrão florístico-estrutural, as características ecológicas e os potenciais das Myrtaceae na bacia hidrográfica do Rio Caveiras. As comunidades de Myrtaceae estudadas localizam-se no Planalto Sul Catarinense, Lages, São José do Cerrito e Urupema. Foram instaladas quatro blocos por município, totalizando 30 mil m2 de área amostral, nos quais todos os espécimes de Myrtaceae com diâmetro à altura do peito (DAP) ≥ 5 cm foram amostrados. A estrutura da comunidade de Myrtaceae foi avaliada pelos descritores fitossociológicos e a suficiência amostral foi verificada utilizando-se o método de rarefação. As abordagens ecológicas e indicações de uso não madeireiro basearam-se em bibliografia especializada e base de dados científicos. Foram amostrados 1.480 exemplares de Myrtaceae pertencentes a 21 espécies e 11 gêneros. As espécies mais abundantes foram Myrceugenia euosma, Siphoneugena reitzii e Myrcia palustris, as quais representaram mais de 50% da estrutura da comunidade. Quanto à classificação ecológica, destacou-se o grupo das secundárias iniciais (57%). As espécies amostradas são indicadas para restauração de áreas alteradas, usos ornamentais (100%) e fitoterápicos (60%). Apesar da representatividade e potencialidades das Myrtaceae, ainda são necessárias pesquisas para embasar a conservação via plano de manejo.

Estimates of the magnitudes of major marine mass extinctions in earth history

Procedures introduced here make it possible, first, to show that background (piecemeal) extinction is recorded throughout geologic stages and substages (not all extinction has occurred suddenly at the ends of such intervals); second, to separate out background extinction from mass extinction for a major crisis in earth history; and third, to correct for clustering of extinctions when using the rarefaction method to estimate the percentage of species lost in a mass extinction. Also presented here is a method for estimating the magnitude of the Signor-Lipps effect, which is the incorrect assignment of extinctions that occurred during a crisis to an interval preceding the crisis because of the incompleteness of the fossil record. Estimates for the magnitudes of mass extinctions presented here are in most cases lower than those previously published. They indicate that only ∼81% of marine species died out in the great terminal Permian crisis, whereas levels of 90-96% have frequently been quoted in the literature. Calculations of the latter numbers were incorrectly based on combined data for the Middle and Late Permian mass extinctions. About 90 orders and more than 220 families of marine animals survived the terminal Permian crisis, and they embodied an enormous amount of morphological, physiological, and ecological diversity. Life did not nearly disappear at the end of the Permian, as has often been claimed.

Checklist and analysis of completeness of the reef fish fauna of the Revillagigedo Archipelago, Mexico

This paper presents an updated checklist of cartilaginous and bony fishes from the Revillagigedo Archipelago reefs and nearby areas (Tropical Eastern Pacific). To compile this list, we gathered data from field surveys between 1994 and 2015, from an exhaustive literature review, and by consulting museum collections and databases. With these records we estimated the completeness of the local fish inventory using four non-parametric rarefaction methods. We report a total of 389 species in 102 families; 235 of these are reef fish that occur in the Eastern but also in the Central Pacific, and 13 species were identified as endemic to the archipelago. A non-parametric statistical model predicts that the expected number of reef fish present at Revillagigedo should be 244.3 ± 3.2 species, which is 9 species more than the observed richness, and this difference was statistically significant (p = 0.02). That predictive model estimates that about 96% of the total richness of reef fish from the archipelago is known. Comparisons of the completeness of the inventory at Revillagigedo to that reported for the fish fauna of the Eastern Pacific and worldwide, showed that the quality of the sampling effort is remarkably high, in spite of the geographic isolation of the archipelago.

Diversity of Tiphiidae (Insecta: Hymenoptera) in the fragmented Brazilian semi-deciduous Atlantic Forest

The Atlantic Forest is one of the most important areas of biodiversity in the world, but it has been largely replaced with agropastoral areas and at the present only 12.5 % of the original cover remains. Despite the ecological importance of insects, few studies have been used in conservation approaches for the Atlantic Forest, mainly due to a great taxonomic impediment. A group quite ecologically important but deeply neglected includes parasitoid wasps that control a great number of invertebrates, like tiphiid wasps that are parasitoids of underground coleopteran larvae. The present study aimed to estimate Tiphiidae species richness and diversity in 15 patches of a highly fragmented Atlantic Forest region, using factors that drive the diversity pool from a metacommunity, such as immigration and speciation probabilities. The parameters were estimated using the Neutral Biodiversity Theory, which is based on the total ecological equivalence of species at the same trophic level. Diversity values were molded to the area size, the immigration probabilities, and/or the speciation probability. Eight genera and 460 individuals of Thynninae, Myzininae and Tiphiinae were collected. Variation in species richness, estimated by both rarefaction and first-order jackknife methods, was explained by patch size and by immigration and speciation probabilities. These variables also explained the variation in Shannon diversity and species evenness. Variations in species richness and diversity of Tiphiidae are strongly associated with neutral processes, but they are also influenced by forest fragmentation and intensive agricultural activities.

Incorporating spatial autocorrelation in rarefaction methods: Implications for ecologists and conservation biologists

Recently, methods for constructing Spatially Explicit Rarefaction (SER) curves have been introduced in the scientific literature to describe the relation between the recorded species richness and sampling effort and taking into account for the spatial autocorrelation in the data. Despite these methodological advances, the use of SERs has not become routine and ecologists continue to use rarefaction methods that are not spatially explicit. Using two study cases from Italian vegetation surveys, we demonstrate that classic rarefaction methods that do not account for spatial structure can produce inaccurate results. Furthermore, our goal in this paper is to demonstrate how SERs can overcome the problem of spatial autocorrelation in the analysis of plant or animal communities. Our analyses demonstrate that using a spatially-explicit method for constructing rarefaction curves can substantially alter estimates of relative species richness. For both analyzed data sets, we found that the rank ordering of standardized species richness estimates was reversed between the two methods. We strongly advise the use of Spatially Explicit Rarefaction methods when analyzing biodiversity: the inclusion of spatial autocorrelation into rarefaction analyses can substantially alter conclusions and change the way we might prioritize or manage nature reserves.

Effects of Spartina alterniflora Invasion on the Abundance and Community of Meiofauna in a Subtropical Wetland

To assess the effects of S. alterniflora establishment on benthic meiofauna, we compared the abundance and community of meiofauna between non-vegetated sandflats, native species (Phragmites australis and Bolboschoenus planiculmis) and S. alterniflora in the Kaomei wetland located on the central western coast of Taiwan in spring and summer. The sediment characteristics differed among vegetation types. The abundance of meiofauna was significantly greater in the dense vegetation of S. alterniflora (2.86 × 106 ind. m−2) than in the adjacent vegetation of B. planiculmis and P. australis (0.36 × 106 ind. m−2 and 0.49 × 106 ind. m−2, respectively) and non-vegetated sandflats (0.0045 × 106 ind. m−2). In both seasons, nematodes were the most dominant group, comprising > 90 % of the total abundance in the meiofaunal community, whereas foraminifera and copepods were the second and third most dominant taxa, respectively. Using rarefaction methods, the highest diversity of meiofaunal taxa occurred in the non-vegetated sandflats, whereas the lowest diversity was found in the dense vegetation of S. alterniflora. Our results suggest that the invasion of S. alterniflora leads to an abrupt increase in the total abundance and a decrease in the diversity of the benthic meiofaunal community in subtropical wetlands.

Methods Applied for Measurement and Visualization of Changes in Biodiversity

Abstract The article presents the possible methods for determining biological or statistically significant differences between taxocenoses compared with respect to biodiversity. To obtain a complete description of biological differences between the compared hypothetical communities, the following indices were calculated: S (taxon richness), H (the Shannon index), Hmax (the maximum value of the Shannon index for the richness of taxa represented by the same number of individuals), Vd (a percentage value of covering the structural capacity of community, “evenness deficiency”), E (the MacArthur index - a taxon number (S) in a community for which the observed value of H equals Hmax ), and Ps (a taxon richness shortage in percents). Moreover, a graphic profile method (Дд, Tj, and Lj profiles) was used for comparing the diversity of the communities. To obtain information about statistically significant differences in biodiversity between the analysed communities, rarefaction curves were applied. The curves are based on the null models and the Monte Carlo method. The rarefaction method resulted in determination of the statistical significance of the differences between taxon richness and Shannon's index values for the compared communities. The Vd and Ps indices and the profile method allowed concluding about the significance of the biological differences between taxocenoses, even when their values of Shannon's H indices were numerically similar.

Bioindication assessment of activated sludge Adaptation in a Lab-Scale Experiment

Abstract The adaptation of activated sludge from the Hajdow sewage treatment plant in a laboratory SBR was studied. The structure of the ciliate assembly was considered as a criterion. 32 ciliate species were found during the experiment. The composition and changes in the ciliate community structure during the process of activated sludge adaptation was examined. In the process of adaptation, reduction was observed in the number of ciliate species together with an increase in assembly total abundance. The decrease in the Shannon diversity index and equitability index in the adaptation process was observed. In the process of adaptation, two states of ciliate assembly were marked out - unstable transient period and stable period. During the transient period, reduction of ammonium utilization efficiency down to 50% and its subsequent increase up to 80% in the stable period were observed. In the transient period, the Simpson dominance index remained low but increased in the stable period. At a temperature of 10°C, the transient period lasted from six to nine days. After the stabilization process, the diversity of the ciliate assemblage remained at a lower level. Rarefaction methods showed that the number of potential ecological niches of ciliate amounted to 30 in the adaptation period, whereas there were only 15-20 ecological niches in adapted sludge.

The influence of taxonomic revisions on species distribution assessment: the case of threeAspleniumspecies on Tuscan ultramafic soils

Herbarium data can be useful to deduce geographical information (e.g. distribution, rarity) about plant species. The rarefaction method can be used to compare the distribution of two or more species based on collections containing different numbers of specimens. Herbarium collections are however continually subject to taxonomic revisions, which cause variation in the number of specimens attributed to each species and, as a consequence, in knowledge of the species distribution. This paper investigated the effects of taxonomic revisions on species distribution, using the rarefaction technique. Herbarium data for three Asplenium species of ultramafic soils of Tuscany before and after recent taxonomic revision were analysed with the use of individual-based rarefaction curves. Rarefaction curves for the data set prepared before and after taxonomic revision appear different. The starting data set showed a great number of specimens determined as Asplenium cuneifolium. The rarefaction curves of each of the three ...

Rarefaction, richness estimation and extrapolation methods in the evaluation of unseen plant diversity in aquatic ecosystems

Defining the adequate sampling effort necessary in tropical ecosystems is a sensitive subject. It is virtually impossible to sample every single species in an ecosystem. Thus, sampling must be a compromise between the desired completeness of the dataset and the amount of time and work that is feasible for researchers to do during fieldwork. Here, we used rarefaction procedures and richness estimators to evaluate sampling issues in a coastal lagoon in Ceará state, Brazil. We used 70 plots (1m2 each) to perform a phytosociological study in the lagoon and complemented the data with opportunistic floristic observations. We then applied statistical methods to the phytosociological survey to estimate how much of the local plant diversity had been sampled. Extrapolating our sampling accumulation curve to a sampling effort three times larger than the actual sampling done (210 plots), we were able to estimate the cumulative richness expected. After this, we used a different approach and calculated how many plots would be necessary to record a certain proportion of the total plant community. We recorded 49 species using phytosociological plots and 65 species in the floristic compilation. Richness estimators calculated the local alfa diversity to be between 68 and 85 species. We show that sampling 80% of the total local richness would require 100 plots, which is a reasonable sampling effort, but to sample 99% of the species, an extremely large amount of sampling would be needed (580 plots). This is not practical during fieldwork. We show here how rarefaction and extrapolation can be used as a framework to gauge the amount of field effort needed in aquatic ecosystems.

Comparison between the shrimp species richness (Caridea and Dendrobranchiata, Decapoda, Crustacea) of the south and north mid Atlantic ridge

The Mid Atlantic Ridge (MAR) is a seamount chain extending for 60.000 km, divided into south and north regions by the Equatorial Fracture which cuts across it. This latter has a maximum depth of 7,760 m and an average width of 19 km. In this study we include data from the two cruises of the international project MAR-ECO, undertaken, respectively, one on the north and the other on the south MAR. Our main objective is to compare the species richness and species composition of pelagic and benthic decapod shrimps of these two areas to observe the patterns of their latitudinal distribution along the MAR. Using rarefaction methods, we obtained interesting results: the pelagic samples curve of the northern MAR is almost an asymptote, so we concluded that we are close to the true number of pelagic shrimp species for this region. The pelagic samples curve of the southern MAR had the greatest slope, so our conclusion is that we are still far from the true number of species for this region. A comparison of species richness at 12 samples (the smallest number of samples shared by both the surveys) revealed that the pelagic species richness was greater than the demersal, and that the northern MAR contained a larger number of species than the southern.

Quantitative stratigraphy of the Wufeng and Lungmachi black shales and graptolite evolution during and after the Late Ordovician mass extinction

Graptolite-bearing black shales are widely distributed on the Yangtze Platform in South China. Based on 19 sections systematically studied recently, we conducted a quantitative stratigraphic analysis of the graptolite biodiversity change during and after the Late Ordovician mass extinction. The combination of graphic correlation and rarefaction methods make it possible to evaluate the effect of sampling intensity on biodiversity estimates. Graptolite diversity reached its peak in the Dicellograptus complexus Chron, and then a gradual decline to the P. pacificus Chron. It was followed by a two-step mass extinction, the first and major phase occurred in the Metabolograptus extraordinarius Chron, and the second and minor phase in the latest M. persculptus Chron. The second phase of the extinction was mostly represented by the elimination of the Diplograptina survivors from the major extinction event, but did not show significant decline in standardized diversity curve. Thereafter, a moderate increase in richness appeared in the early and mid Parakidograptus acuminatus Chron, which was followd by a considerable decrease of graptolite richness in the late P. acuminatus Chron and early C. vesiculosus Chron. The present study also indicates slow and uneven sedimentation rates in the studied sections from mid-Katian to early Rhuddanian, including a relatively slower sedimentation rate during the Hirnantian Epoch. The latter, and the hiatus at the Honghuayuan and Guanwu sections, probably reflect the effects of the Hirnantian glaciation and regional tectonic movements.

Gradients of Bat Diversity in Atlantic Forest of South America: Environmental Seasonality, Sampling Effort and Spatial Autocorrelation

AbstractTemperature seasonality has been proposed to be an important determinant of bat community structure in Atlantic Forest of South America and elsewhere. I characterized spatial and environmental patterns of species richness of phyllostomid bats in Atlantic Forest of South America and examined the degree to which temperature seasonality relative to other important environmental gradients was related to patterns of diversity across 60 heterogeneously sampled assemblages. I compared efficacy of different methods of accounting for inventory completeness (rarefaction, species estimation, minimum number of individuals and raw data) in characterizing gradients of bat diversity. I also compared levels of spatial autocorrelation generated by these methods and the degree to which such autocorrelation influenced results of regression analyses. Temperature seasonality was consistently the most important predictor of species richness across all methods of accounting for inventory completeness as well as between spatial and non‐spatial regression methods. Spatial autocorrelation of both species richness and regression residuals was lowest for species richness estimators and highest for data rarefied to the highest sample sizes. Strong and characteristic environmental gradients typifying Atlantic Forest of South America translate into coincident gradients of richness of bat assemblages. Although data were characterized by heterogeneous sampling efforts, relationships of species richness with seasonality of temperature were strong and easily detectable. Methods of accounting for inventory completeness improve assessment with species richness estimators performing better than rarefaction methods.