Despite its negative impacts on the environment and biodiversity, tree plantations can contribute to biodiversity conservation in fragmented landscapes, as they harbor many native species. In this ...study, we investigated the impact of Eucalyptus plantations on the taxonomic and functional diversity of ant communities, comparing ant communities sampled in managed and unmanaged (abandoned for 28 years) Eucalyptus plantations, and native Atlantic rain forests. Eucalyptus plantations, both managed and unmanaged, reduced the functional diversity and increased the similarity between ant communities leading to functional homogenization. While communities in managed plantations had the lowest values of both taxonomic and functional ant diversities, ant communities from unmanaged plantations had similar values of species richness, functional redundancy and Rao's Q compared to ant communities from forest patches (although functional richness was lower). In addition, communities in unmanaged Eucalyptus plantations were taxonomically and functionally more similar to communities located in managed plantations, indicating that Eucalyptus plantations have a severe long-term impact on ant communities. These results indicate that natural regeneration may mitigate the impact of Eucalyptus management, particularly regarding the functional structure of the community (α diversity), although it does not attenuate the effects of long term homogenization in community composition (β diversity).
General principles that shape community structure can be described based on a functional trait approach grounded on predictive models; increased attention has been paid to factors accounting for the ...functional diversity of species assemblages and its association with species richness along environmental gradients. We analyze here the interaction between leaf-litter ant species richness, the local communities' morphological structure and fundamental niche within the context of a northeast-southeast latitudinal gradient in one of the world's most species-rich ecosystems, the Atlantic Forest, representing 2,700 km of tropical rainforest along almost 20° of latitude in eastern Brazil. Our results are consistent with an ecosystem-wide pattern in communities' structure, with relatively high species turnover but functionally analogous leaf-litter ant communities' organization. Our results suggest directional shifts in the morphological space along the environmental gradient from overdispersed to aggregated (from North to South), suggesting that primary productivity and environmental heterogeneity (altitude, temperature and precipitation in the case) determine the distribution of traits and regulate the assembly rules, shaping local leaf-litter ant communities. Contrary to the expected and most common pattern along latitudinal gradients, the Atlantic Forest leaf litter ant communities show an inverse pattern in richness, that is, richer communities in higher than in lower latitudes. The morphological specialization of communities showed more morphologically distinct communities at low latitudes and species redundancy at high latitudes. We claim that an inverse latitudinal gradient in primary productivity and environmental heterogeneity across the Atlantic forest may affect morphological diversity and species richness, enhancing species coexistence mechanisms, and producing thus the observed patterns. We suggest that a functional framework based on flexible enough traits should be pursued to allow comparisons at local, regional and global levels.
Tropical ecosystems are often biodiversity hotspots, and invertebrates represent the main underrepresented component of diversity in large‐scale analyses. This problem is partly related to the ...scarcity of data widely available to conduct these studies and the lack of systematic organization of knowledge about invertebrates' distributions in biodiversity hotspots. Here, we introduce and analyze a comprehensive data compilation of Amazonian ant diversity. Using records from 1817 to 2020 from both published and unpublished sources, we describe the diversity and distribution of ant species in the Brazilian Amazon Basin. Further, using high‐definition images and data from taxonomic publications, we build a comprehensive database of morphological traits for the ant species that occur in the region. In total, we recorded 1067 nominal species in the Brazilian Amazon Basin, with sampling locations strongly biased by access routes, urban centers, research institutions and major infrastructure projects. Large areas where ant sampling is non‐existent represent about 52% of the basin and are concentrated mainly in the northern, southeastern and western Brazilian Amazon. We found that distance to roads is the main driver of ant sampling in the Amazon. Contrary to our expectations, morphological traits had lower predictive power in predicting sampling bias than purely geographic variables. However, when geographic predictors were controlled, habitat stratum and traits contribute to explain the remaining variance. More species were recorded in better‐sampled areas, but species richness estimation models suggest that areas in southern Amazonian edge forests are associated with especially high species richness. Our results represent the first trait‐based, large‐scale study for insects in Amazonian forests and a starting point for macroecological studies focusing on insect diversity in the Amazon Basin.
We present a new approach to determine the number and composition of guilds, using the hyperdiverse leaf-litter ant fauna as a model, based on appropriate morphological variables and species ...co-occurrence null models to describe the complex asemblages of interacting species community structure at the 1-m 2 scale. We obtained 18 linear morphometric measures from 949 workers of 171 leaf-litter ant species (18 762 measurements) surveyed in four Atlantic Forest localities to test whether the assemblages are morphologically structured; the morphological characters were selected to indicate diet and foraging habits. Principal components analysis was used to characterize the morphospace and to describe the guild structure (number of species and composition). The guild proportionality assembly rule (significant tendency toward constant proportion of species in guilds) was assessed at the 1-m 2 scale. Our analysis indicates that the division of leaf-litter ants into guilds is based mainly on microhabitat distribution in the leaf-litter, body size and shape, eye size, and phylogeny. The same guild scheme applied to four more sites shows that diferent Atlantic confirmed for most guilds, suggesting that there are guild-specific limitations on species coexistence within assemblages; on the other hand, in a few cases the variance in guild proportion was greater than expected under the null assumptions. Other studies on ant functional group classification are partially supported by our quantitative morphological analysis. Our results, however, imply that there are more compartments than indicated in previous models, particularly among cryptic species (confined to soil and litter) and tropical climate specialists. We argue that a general null model for the analysis of species association based on morphology can reveal objectively defined groups and may thus contribute to a robust theory to explain community structure in general and have important consequences on studies of litter ant community ecology in particular.
In this study, we investigated the termites of the Brazilian Atlantic Forest, one of the most threatened biodiversity hotspots in the world, in regularly spaced sites from 7° S to 27° S latitude. To ...our knowledge, this is the only report of a latitudinal survey of termites at species level performed with a standardized sampling protocol. We evaluate termite diversity and abundance, and describe patterns of species composition based on feeding groups along the latitudinal gradient. We also describe the relative contribution of environmental variables to explain diversity patterns. Termite assemblages were investigated by standardized surveys at 15 Atlantic Forest sites, on six transects divided into five sections of 10 m², with 30 sections per site (or 300 m²/site), which were investigated by one trained person for one hour. Observed species richness and abundance were negatively correlated with latitude. The influence of latitude was explained mainly by variables related to temperature, precipitation and ambient energy (potential evapotranspiration). Our results also suggest that temperature exerts a greater constraint on Atlantic Forest termites than productivity, because ambient productivity increases with latitude in this forest but termite diversity decreases. Termite species richness in the Atlantic Forest showed a different pattern than those described for other organisms, increasing in diversity where the coastal‐forest strip narrows. Overall, our results indicate comparatively high termite species richness at northeastern sites and a significant impoverishment of termite assemblages in the southeastern and southern regions of the Atlantic Forest.
AIMS: Climatic change is expected to rearrange species assemblages and ultimately affect organism‐mediated ecosystem processes. We focus on identifying patterns and relationships between common ant ...species (representing 99% of total ant records) richness and functional diversity; modelling how these patterns may change at local and regional scales in future climatic conditions; and interpreting how these changes might influence ant‐mediated ecosystem processes. LOCATION: Forested ecosystems of eastern North America. METHODS: We used a previously published dataset to evaluate functional diversity at 67 sites in the eastern U.S. and quantified 14 taxonomic, morphometric and natural history traits for 70 common ant species in the region. We used functional diversity metrics, functional groups and species distribution modelling methods to address our aims. We used stacked species distribution models and stacked functional group models to predict species assemblages and functional richness at the 67 sites and at a regional scale for current and future climatic conditions. RESULTS: Species richness and functional diversity are positively correlated throughout the region. Under future climate scenarios, species richness and functional group richness were predicted to decrease in southern ecoregions and increase in northern ecoregions. This may be due to increased thermal stress for species in the southern extent of their ranges and increased habitat suitability in the northern ecoregions. Decomposers, arthropod community regulators and seed dispersers are forecast to be the most threatened ant functional groups. MAIN CONCLUSIONS: Climate change will likely lead to major changes in ant species richness and functional group richness in the forests of the north‐eastern United States, and this may substantially alter ant‐mediated ecosystem processes and services.
There is often a vertical stratification of the vegetation in tropical forests, where each forest stratum has a unique set of environmental conditions, including marked differences in habitat ...heterogeneity, physical complexity, and microclimate. Additionally, many tropical forests are highly seasonal, and we need to consider the temporal variation in environmental conditions when assessing the functional aspects of their organisms. Here, we tested the hypothesis that vertical stratification and seasonality shape tropical ants’ functional ecology and that there are differences in the functional trait diversity and composition between arboreal and ground-dwelling ant communities. We collected ants in the arboreal and ground strata in the rainy and dry seasons in six different areas, measuring seven morphological traits to characterize their functional ecology and diversity. Irrespective of the season, we found a distinct functional composition between arboreal and ground-dwelling ants and a higher functional richness on the ground. However, ground ants were more functionally redundant than arboreal ants. The differences in functional richness and redundancy between ant inhabiting strata and season could also be observed in the community-weighted mean traits: arboreal and ground ant traits can be distinguished in Weber’s length, mandible length, eye length, and eye position on the head capsule. The differences in these functional traits are mainly related to the ants’ feeding habits and the complexity of their foraging substrates. Overall, by providing the first systematic comparison of continuous traits between arboreal and ground-dwelling ants, our study opens new investigation paths, indicating important axes of functional diversification of tropical ants.
Species loss in tropical regions is forecast to occur under environmental change scenarios of low precipitation. One of the main questions is how drought will affect invertebrates, a key group for ...ecosystem functioning. We use 1 year of data from a long-term rainwater exclusion experiment in primary Amazonian rainforest to test whether induced water stress and covarying changes in soil moisture, soil respiration, and tree species richness, diversity, size, and total biomass affected species richness and composition (relative abundance) of ground-dwelling ants. Data on ant abundance and environmental variables were collected at two sites (control and experimental) in the Eastern Amazon. Since 2002, drought has been induced in the experimental plot by excluding 50% of normal rainfall. Ant species richness in the experiment plot was reduced and some generalist species responded positively. Ant species richness also increased in the experimental plot with increasing diversity of the plant species of the leaf litter. The relative abundance of ants differed between plots. The experimental plot was characterized by a higher frequency of generalist and other species that appeared to be favored by the reduction in rainfall. Between-plot comparisons suggested loss and changes in ant species composition in tropical forests were affected by increasing dryness. These changes could ultimately lead to cascading effects on ecosystem processes and the services they mediate.
We evaluated the effects of changes in habitat structure resulting from conventional logging (CL) and reduced-impact logging (RIL) on the ecomorphological structure of stream fish assemblages in the ...eastern Brazilian Amazon, investigating (1) which habitat characteristics are influenced by different logging methods, (2) the differences in the ecomorphological structure of fish assemblages between two logging methods and undisturbed forest (UF), and (3) the relationships between ecomorphological traits of fish assemblages and habitat variables. We measured 13 habitat variables and characterized 11 ecomorphological traits of 55 fish species collected in 34 sampling sites (stream stretches) located in CL, RIL, and UF. In logged areas, the streams present a fine sediment increase and reduced vegetation cover, while in the UF a greater amount of natural shelter and more cover vegetation were observed. These environmental changes selected ecomorphological traits of stream fish assemblages, recording a greater relative width of the mouth in UF, higher ventral flattening index in RIL, or greater relative head length, and higher caudal peduncle compression index in CL. In this sense, we recommend that logging practices, including RIL, should be reviewed as a means of adopting better strategies to minimize human disturbances in streams.
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