Ant Diversity Studies 2017
The number of contemporary publications that focus on ant communities and ant biodiversity shows that these topics continue to be strong areas of interest. This page lists 2017 publications that focus on these topics.
- Albuquerque, E. Z., E. Diehl, and R. R. Silva. 2017. Structure of ground-dwelling ant communities in burned and unburned areas in Brazilian subtropical grasslands. Entomological Science. 20:427-436. doi:10.1111/ens.12270
Abstract Fire is frequently used in the management of pastures in southern Brazil, but its effects on ground-dwelling ant communities in Brazilian subtropical grasslands is still poorly understood. Here, we compared ant species richness and composition between periodically burned and unburned areas in native grasslands of the Atlantic Forest biome. In total, we found 35 epigeic ant species in burned and unburned areas. There was slightly higher species richness in burned than in unburned areas, independent of the sampling period (season). There was a significant difference in richness over the sampling period (season effect). Species composition varied significantly between the areas, in which nine species (26%) occurred only in burned areas, eight (23%) occurred only in unburned areas, and 18 (51%) occurred in both. Four species showed a significant preference for burned sites (Camponotus crassus, Linepithema humile and two undetermined species of Pheidole and Solenopsis). Although this study did not separate fire effects on ground-dwelling ant communities (due to sampling design), it provides new information regarding subtropical native grasslands that can be used as a baseline for future studies.
- Dassou, A. G., P. Tixier, S. Depigny, and D. Carval. 2017. Vegetation structure of plantain-based agrosystems determines numerical dominance in community of ground-dwelling ants. Peerj. 5. doi:10.7717/peerj.3917
Abstract In tropics, ants can represent an important part of animal biomass and are known to be involved in ecosystem services, such as pest regulation. Understanding the mechanisms underlying the structuring of local ant communities is therefore important in agroecology. In the humid tropics of Africa, plantains are cropped in association with many other annual and perennial crops. Such agrosystems differ greatly in vegetation diversity and structure and are well-suited for studying how habitat-related factors affect the ant community. We analysed abundance data for the six numerically dominant ant taxa in 500 subplots located in 20 diversified, plantain-based fields. We found that the density of crops with foliage at intermediate and high canopy strata determined the numerical dominance of species. We found no relationship between the numerical dominance of each ant taxon with the crop diversity. Our results indicate that the manipulation of the densities of crops with leaves in the intermediate and high strata may help maintain the coexistence of ant species by providing different habitat patches. Further research in such agrosystems should be performed to assess if the effect of vegetation structure on ant abundance could result in efficient pest regulation.
- Donoso, D. A. 2017. Tropical ant communities are in long-term equilibrium. Ecological Indicators. 83:515-523. doi:10.1016/j.ecolind.2017.03.022
Abstract Communities change with time. Studying long-term change in community structure permits deeper understanding of community dynamics, and allows us to forecast community responses to perturbations at local (e.g. fire, secondary succession) and global (e.g. desertification, global warming) spatial scales. Monitoring efforts exploring the temporal dynamics of indicator taxa are therefore a critical part of conservation agendas. Here, the temporal dynamics of the Otongachi leaf litter ant community, occurring in a cloud forest in coastal Ecuador, were explored. By sampling this community six times over eleven years, I assessed how the ant fauna caught by Winkler traps (more diverse and cryptic fauna) and caught by pitfall traps (larger, more mobile fauna) changed over time. The Otongachi leaf litter ant community was dynamic. Although species richness in the community remained constant, temporal turnover of species was high: on average, 51% of the ant species in Winkler traps, and 56% of those in pitfall traps, were replaced with other ant species from one year to the other. Shifts in the rank abundance of species in the community were also large across the eleven years and, on average, shifts in the rank abundance of species collected by Winkler traps doubled those occurring in pitfall traps from one census to the other. In spite of these trends, the Otongachi ant fauna showed no (Winkler) or weak (pitfall) evidence of directional change (towards a new community). Thus, this tropical ant community can be divided in two community compartments. The Winkler compartment composed by a more diverse and cryptic ant fauna appears to be resilient and stable in time. The pitfall compartment composed by larger and more mobile ants may be prone to respond to disturbance. This study suggests that 1) species appearing/disappearing from a site may be rather the rule, difficult to separate from responses to ecological stress. 2) Conclusions made in short-term studies, or studies comparing two (e.g. before and after) snapshots of a community, should thus be revisited. Finally, 3) the ant fauna caught by pitfall traps (a rather simple and cheap survey method) is the most likely community compartment to indicate ecological perturbation. This study adds to the growing evidence that using ants as ecological indicators should incorporate long-term temporal dynamics.
- Drose, W., L. R. Podgaiski, A. Cavalleri, R. M. Feitosa, and M. S. Mendonca. 2017. Ground-Dwelling and Vegetation Ant Fauna in Southern Brazilian Grasslands. Sociobiology. 64:381-392. doi:10.13102/sociobiology.v64i4.1795
Abstract Non-forest ecosystems, as natural grasslands from Southern Brazil, are still neglected in conservation policies. Measuring their biodiversity is one of the main steps to generate management strategies for these habitats. This study aims to (i) describe grassland ant richness and composition in Rio Grande do Sul state, and (ii) compare ant communities sampled on the ground and in grassland vegetation, adding to our knowledge of habitat use patterns and vegetation associated species. Six sites were sampled, three belonging to the Pampa biome and three in highland region from the Atlantic Forest biome. Ant fauna was collected once per year in summer during four years in each site with pitfalls traps and sweeping nets. Overall, 29,812 ant individuals were sampled belonging to eight subfamilies, 30 genera and 106 species. The grasslands of Pampa accumulated 91 species and 45 exclusive species, while highland grasslands summed up 61 species and only 15 exclusive species. Species composition differs between biomes as well as between sampling methods. Ant communities sampled from vegetation represented a clear subset of the fauna sampled with pitfall traps, and indication analysis showed only two species associated with this stratum: Myrmelachista gallicola and Pseudomyrmex nr. flavidulus. This study highlights the importance of Southern Brazilian grasslands and the need for specific conservation strategies for the natural grasslands from each biome.
- Goncalves, F., V. Zina, C. Carlos, L. Crespo, I. Oliveira, and L. Torres. 2017. Ants (Hymenoptera: Formicidae) and Spiders (Araneae) Co-occurring in the Ground of Vineyards from Douro Demarcated Region. Sociobiology. 64:404-416. doi:10.13102/sociobiology.v64i4.1934
Abstract This study, held in vineyards from Douro Demarcated Region, aimed to: a) identify the communities and main functional groups of spiders and ants; b) check patterns of co-occurrence between the two communities; and c) evaluate the impact of ground cover and non-crop habitats adjacent to vineyards, on the two communities. Samplings were done using pitfall trapping. Twenty species of ants and 44 species of spiders were identified. The most abundant were: Aphaenogaster gibbosa, Aphaenogaster iberica, Cataglyphis hispanica, Cataglyphis iberica, Messor barbarus and Tapinoma nigerrimum which totaled 71.21% of ants; and Alopecosa albofasciata (Brullé 1832), Callilepis concolor Simon 1914, Eratigena feminea Simon 1870, Zodarion alacre (Simon 1870) and Zodarion styliferum (Simon 1870) which accounted for 38% of spiders. Three Iberian endemic ants and nine Iberian endemic spiders were also identified. Abundance of both ant-mimicking and ant-eating spiders were positively correlated with abundance of Formicinae, while only abundance of ant-eating spiders showed positive correlation with abundance of Myrmicinae ants. All genera/ species of antassociated spider were associated with one or more genera/specie of ants. Both spiders and ants have not benefited from the adjacent non-crop habitat. Sheet web weaver spiders were found to be positively correlated with the percentage of ground cover. These results show that a) vineyard agroecosystem support a rich assemblage of ants and spiders evincing that wine production and species conservation is possible and b) non-random co-occurrence between ants and ant-associated spiders exist in the field.
- Groc, S., J. H. C. Delabie, F. Fernandez, F. Petitclerc, B. Corbara, M. Leponce, R. Cereghino, and A. Dejean. 2017. Litter-dwelling ants as bioindicators to gauge the sustainability of small arboreal monocultures embedded in the Amazonian rainforest. Ecological Indicators. 82:43-49. doi:10.1016/j.ecolind.2017.06.026
Abstract One of the greatest threats to biodiversity and the sustainable functioning of ecosystems is the clearing of forests for agriculture. Because litter-dwelling ants are very good bioindicators of man-made disturbance, we used them to compare monospecific plantations of acacia trees, cocoa trees, rubber trees and pine trees with the surrounding Neotropical rainforest (in contrast to previous studies on forest fragments embedded in industrial monocultures). Although the global level of species turnover was weak, species richness decreased along a gradient from the forest (including a treefall gap) to the tree plantations among which the highest number of species was noted for the cocoa trees, which are known to be a good compromise between agriculture and conservation. Species composition was significantly different between natural habitats and the plantations that, in turn, were different from each other. Compared to the forest, alterations in the ant communities were (1) highest for the acacia and rubber trees, (2) intermediate for the cocoa trees, and, (3) surprisingly, far lower for the pine trees, likely due to very abundant litter. Functional traits only separated the rubber tree plantation from the other habitats due to the higher presence of exotic and leaf-cutting ants. This study shows that small monospecific stands are likely sustainable when embedded in the rainforest and that environmentally-friendly strategies can be planned accordingly.
- Gutiérrez et al. 2017. Ants’ higher taxa as surrogates of species richness in a chronosequence of fallows, old-grown forests and agroforestry systems in the Eastern Amazon, Brazil. Revista de Biología Tropical/International Journal of Tropical Biology and Conservation. 65(1):279-291.
Abstract Deforestation in Amazon forests is one of the main causes for biodiversity loss worldwide. Ants are key into the ecosystem because act like engineers; hence, the loss of ants’ biodiversity may be a guide to measure the loss of essential functions into the ecosystems. The aim of this study was to evaluate soil ant’s richness and to estimate whether higher taxa levels (Subfamily and Genus) can be used as surrogates of species richness in different vegetation types (fallows, old-growth forests and agroforestry systems) in Eastern Amazon. The samples were taken in 65 areas in the Maranhão and Pará States in the period 2011-2014. The sampling scheme followed the procedure of Tropical Soil Biology and Fertility (TSBF). Initially, the vegetation types were characterized according to their age and estimated species richness. Linear and exponential functions were applied to evaluate if higher taxa can be used as surrogates and correlated with the Pearson coefficient. In total, 180 species distributed in 60 genera were identified. The results showed that ant species richness was higher in intermediate fallows (88) and old secondary forest (76), and was lower in agroforestry systems (38) and mature riparian forest (35). The genus level was the best surrogate to estimate the ant’s species richness across the different vegetation types, and explained 72-97 % (P < 0.001) of the total species variability. The results confirmed that the genus level is an excellent surrogate to estimate the ant’s species richness in the region and that both fallows and agroforestry systems may contribute in the conservation of Eastern Amazon ant community.
- Hanisch, P. E., P. D. Lavinia, A. V. Suarez, D. A. Lijtmaer, M. Leponce, C. I. Paris, and P. L. Tubaro. 2017. Mind the gap! Integrating taxonomic approaches to assess ant diversity at the southern extreme of the Atlantic Forest. Ecology and Evolution. 7:10451-10466. doi:10.1002/ece3.3549
Abstract Understanding patterns of species diversity relies on accurate taxonomy which can only be achieved by long-term natural history research and the use of complementary information to establish species boundaries among cryptic taxa. We used DNA barcoding to characterize the ant diversity of Iguazú National Park (INP), a protected area of the Upper Paraná Atlantic Forest ecoregion, located at the southernmost extent of this forest. We assessed ant diversity using both cytochrome c oxidase subunit 1 (COI) sequences and traditional morphological approaches, and compared the results of these two methods. We successfully obtained COI sequences for 312 specimens belonging to 124 species, providing a DNA barcode reference library for nearly 50% of the currently known ant fauna of INP. Our results support a clear barcode gap for all but two species, with a mean intraspecific divergence of 0.72%, and an average congeneric distance of 17.25%. Congruently, the library assembled here was useful for the discrimination of the ants of INP and allowed us to link unidentified males and queens to their worker castes. To detect overlooked diversity, we classified the DNA barcodes into Molecular Operational Taxonomic Units (MOTUs) using three different clustering algorithms, and compared their number and composition to that of reference species identified based on morphology. The MOTU count was always higher than that of reference species regardless of the method, suggesting that the diversity of ants at INP could be between 6% and 10% higher than currently recognized. Lastly, our survey contributed with 78 new barcode clusters to the global DNA barcode reference library, and added 36 new records of ant species for the INP, being 23 of them new citations for Argentina.
- Lutinski, J. A., C. J. Lutinski, C. Guarda, M. A. Busato, and F. R. M. Garcia. 2017. Richness and structure of ant assemblies (Hymenoptera: Formicidae) in Atlantic forest in southern Brazil. Anais Da Academia Brasileira De Ciencias. 89:2719-2729. doi:10.1590/0001-3765201720160892
Abstract Ant diversity is influenced by the structural complexity of the environment. Ants are thus an ecologically important group due to their potential to serve as indicators of environmental quality. The objective of this study was to evaluate ant diversity in areas with different land use histories and thus, within different stages of regeneration in the Permanent Preservation Area of the Foz do Chapecó Hydroelectric Plant reservoir. Ant assemblies among sample sites were compared using rarefaction analysis, and estimated richness, frequency of occurrence, and relative abundance were calculated. Associations between species and sample sites were evaluated using Principal Component Analysis (PCA). We identified 55 species in total from 24 genera, distributed among seven subfamilies. Eight species had positive associations with sample sites. Estimates indicated that ant richness may be up to 21.4% greater than that observed. This study presents an inventory of species capable of colonizing environments undergoing natural regeneration processes, and aids our understanding of ecological recovery dynamics in protected areas near hydroelectric plant reservoirs southern Brazil.
- MacGown, J. A., S. Y. Wang, J. G. Hill, and R. J. Whitehouse. 2017. A List of Ants (Hymenoptera: Formicidae) collected during the 2017 William H. Cross Expedition to the Ouachita Mountains of Arkansas with New State Records. Transactions of the American Entomological Society. 143:735-740.
Abstract The William H. Cross Expedition is an endowed collecting trip conducted annually by the Mississippi Entomological Museum. This year’s expedition was held from 19 to 24 June 2017 at the Ouachita Mountains Biological Station (OMBS) in Polk County, Arkansas. We focused our collecting efforts on the mountainous Ouachita Mountains Biological Station, but we also collected at various sites within the Ouachita National Forest, at Queen Wilhelmina State Park, Big Fork Creek Natural Area, and Stone Road Glade Natural Area. During a five-day period, we collected 63 ant species, including five not previously reported for Arkansas: Brachyponera chinensis (Emery), Hypoponera inexorata (Wheeler), Strumigenys creightoni Smith, Syscia augustae Wheeler, and Temnothorax longispinosus (Roger).
- Marques, T., M. M. Espirito-Santo, F. S. Neves, and J. H. Schoereder. 2017. Ant Assemblage Structure in a Secondary Tropical Dry Forest: The Role of Ecological Succession and Seasonality. Sociobiology. 64:261-275. doi:10.13102/sociobiology.v64i3.1276
Abstract This study identified the main biological mechanisms governing the diversity of ants on different ecological time scales. Ants were sampled in 15 plots distributed in early, intermediate and late stages of succession (five plots per stage) at the Parque Estadual da Mata Seca, Brazil. At each sample point, unbaited pitfall traps were installed in hypogaeic, epigaeic and arboreal strata. We collected 95 ant species from 26 genera and nine subfamilies. Our results indicated that there was an increase in species richness in advanced stages of succession. We also observed that ant assemblages were different among successional stages. For the arboreal and epigaeic strata, species richness did not change with succession progression, but species composition of these two strata differed among successional stages. Unlike to arboreal and epigaeic ants, hypogaiec ant species richness was higher in the intermediate and late stages of succession and the composition of hypogaeic ants differed among successional stages. Similarity between ant species foraging in arboreal and epigaeic strata decreases with succession progression and β-diversity was higher in advanced successional stages. Additionally, species richness was higher in the dry season, whereas the composition of ant assemblages did not change between seasons. A considerable fraction of the ant assemblage was found only in advanced stages of succession, demonstrating the importance of secondary habitats in maintaining biodiversity in dry forests.
- Rosumek, F. B. 2017. Natural History of Ants: What We (do not) Know about Trophic and Temporal Niches of Neotropical Species. 64:244-255. doi: 10.13102/sociobiology.v64i3.1623
Abstract Our understanding of the natural history of Neotropical ants is limited, due to lack of descriptive efforts and widespread use of morphospecies in literature. Use of trophic resources and period of activity are two central niche aspects little explored for most species. This work aimed to broadly review the literature and provide empirical field data on these aspects for 23 species. The fieldwork was carried out in the Atlantic forest of southern Brazil. Trophic and temporal niches were assessed with pitfall traps and seven kinds of bait representing natural resources. Crushed insects were the preferred resource, whereas bird feces and living prey were less exploited. Most species broadly used the resources, but pronounced quantitative differences were found. Odontomachus chelifer (Latreille, 1802) and Pachycondyla striata Smith, 1858 were relatively well studied and field data matched previous accounts. They were the only species that consistently used large prey, and avoided oligosaccharides. Wasmannia auropunctata (Roger, 1863) differed remarkably from previous studies, using feces as its sole trophic resource. The six Pheidole species had no previous records and presented quantitative differences in resource use. Most species had no strong preference for period of activity. Camponotus zenon Forel, 1912 was nocturnal and Crematogaster nigropilosa Mayr, 1870, Linepithema iniquum (Mayr, 1870) and Linepithema pulex Wild, 2007 were diurnal. Complementary methods, context-dependence and descriptive studies have a central role in the understanding of ant natural history. Community assessments can contribute significantly to this knowledge if researchers also pay attention to the individual species involved.
- Schmidt, F. A., C. R. Ribas, T. G. Sobrinho, R. Ubaidillah, J. H. Schoereder, Y. Clough, and T. Tscharntke. 2017. Similar alpha and beta diversity changes in tropical ant communities, comparing savannas and rainforests in Brazil and Indonesia. Oecologia. 185:487-498. doi:10.1007/s00442-017-3960-y
Abstract Local biodiversity can be expected to be similar worldwide if environmental conditions are similar. Here, we hypothesize that tropical ant communities with different types of regional species pools but at similar habitat types in Brazil and Indonesia show similar diversity patterns at multiple spatial scales, when comparing (1) the relative contribution of alpha and beta diversity to gamma diversity; (2) the number of distinct communities (community differentiation); and (3) the drivers of β-diversity (species replacement or species loss/gain) at each spatial scale. In both countries, rainforests and savannas (biome scale) were represented by three landscapes (landscape scale), each with four transects (site scale) and each transect with 10 pitfall traps (local scale). At the local scale, α-diversity was higher and β-diversity lower than expected from null models. Hence, we observed a high coexistence of species across biomes. The replacement of species seemed the most important factor for β-diversity among sites and among landscapes across biomes. Species sorting, landscape-moderated species distribution and neutral drift are potential mechanisms for the high β-diversity among sites within landscapes. At the biome scale, different evolutionary histories produced great differences in ant community composition, so the replacement of species is, at this scale, the most important driver of beta diversity. According to these key findings, we conclude that distinct regional ant species pools from similar tropical habitat types are similarly constrained across several spatial scales, regardless of the continent considered.
- Segat, J. C., R. L. F. Vasconcellos, D. P. Silva, D. Baretta, and E. Cardoso. 2017. Ants as indicators of soil quality in an on-going recovery of riparian forests. Forest Ecology and Management. 404:338-343. doi:10.1016/j.foreco.2017.07.038
Abstract The increasing devastation of the Brazilian Atlantic Forest stresses the need to recover areas within this biome, and studies using potential indicator organisms to assess the forest recovery process are important to determine the intensity of human interference during this process. We aimed to evaluate the richness and abundance of ant genera in forests at different stages of recovery, and to identify soil attributes that contribute to differentiate these areas. Four areas with different periods of recovery were studied: one native undisturbed site (NT), and three sites with five (R05), 10 (R10), and 20 (R20) years without human perturbance. In each site, we defined a 10 × 10 m sampling grid with 30 random points (15 Pitfall +15 Monoliths) and collected the ants at a depth of 0–20 cm. We also analyzed physical, chemical, and biological properties at each site to correlate them with the ant genera. These variables were used in canonical discriminant analysis (CDA) and canonical correlation analysis (CCA). Leaf litter quality, higher ant genera diversity and abundance correlated with both NT and R20, more than with the other areas evaluated. The ant genera abundance was appropriated for separating the different vegetation recovery stages. The CDA analysis indicated that Atta (0.418) correlated with R05, and Brachymyrmex (0.136) with NT, being genera that contributed to area differentiation, and these genera may serve as indicators to qualify the stages of the recovery gradient. The ant genera correlated with the areas R05 and R10 also are correlated closely with environments defined by little vegetation complexity and with urban areas, while those predominating in NT and R20 are common to areas with more structured floristic composition. These results highlight the strong relationship between ants and some of the physical, chemical, and biological soil properties of the different areas.
- Silva, E. F., J. E. Cora, A. Y. Harada, and I. B. M. Sampaio. 2017. Association of the Occurrence of Ant Species (Hymenoptera: Formicidae) with Soil Attributes, Vegetation, and Climate in the Brazilian Savanna Northeastern Region. Sociobiology. 64:442-450. doi:10.13102/sociobiology.v64i4.1209
Abstract Ants occur in all tropical forest strata by nesting, foraging, and interacting with plants and other residents from these habitats. Most ants build their nests in the soil. Selecting the proper soil for nesting depends on soil attributes and other factors. The question is: Which of these attributes can affect more strongly the decision for nest installation? This study aims to discover if the occurrence of some species of ants from Cerrado, in the Northeastern State of Maranhão, depends on attributes of soils and climatic factors. We found 48 species of ants, of which ten had the highest importance value. These are correlated with soil properties, litter biomass, basal area, humidity, and temperature by using the principal component analysis (PCA). The soil properties, vegetation (basal area and dry mass of litter), temperature, and humidity had an impact on the occurrence of the ten studied species of ants. Camponotus comatulus (Mackay, 2010), Ectatomma muticum (Mayr, 1870), Solenopsis substituta (Santschi, 1925), [[Pseudomyrmex termitarius]] (Smith, 1855) and Pheidole casta (Wheeler 1908) were associated with sites of arbustive vegetation, poorly and acidic chemical and physical limited (dense, high micro-pores volume) soils. Pseudomyrmex boopis (Roger, 1863), Dinoponera gigantea (Perty, 1833), Ochetomyrmex neopolitus (Fernández, 2003) are found in fertile soils, covered by arboreal forest, while Crematogaster cf acuta, Solenopsis bruesi (Creighton, 1930) was mainly found in saturated soil, and covered with palm trees. The species of ants recorded in this study are strongly associated with soil properties, as well as vegetation parameters, air temperature, and relative humidity at soil level.
- Silva, L. F., R. M. Souza, R. R. C. Solar, and F. D. Neves. 2017. Ant diversity in Brazilian tropical dry forests across multiple vegetation domains. Environmental Research Letters. 12. doi:10.1088/1748-9326/aa5f2a
Abstract Understanding the environmental drivers of biodiversity persistence and community organization in natural ecosystems is of great importance for planning the conservation of those ecosystems. This comprehension is even more important in severely threatened ecosystems. In this context, we analyzed ant communities in tropical dry forests (TDFs) in Brazil. These forests are embedded within other biomes, such as Cerrado and Caatinga. In this study, we asked whether (i) ant species richness and composition changes between TDFs within different vegetation domains; (ii) whether ant species richness and b-diversity increase north-to-south, possibly related to changes in tree richness and tree density; and (iii) species replacement contributes relatively more to b-diversity than does nestedness. We found that species composition is unique to each TDF within different biomes, and that species richness and b-diversity differ among the vegetation domains, being smaller in the Caatinga. We also found that replacement contributes most to b-diversity, although this contribution is lower in Caatinga than in Cerrado. We show that regional context is the main driver of species diversity, which is likely to be driven by both historical and ecological mechanisms. By analyzing large spatial scale variation in TDF environmental characteristics, we were able to evaluate how ant diversity changes along an environmental gradient. The high levels of species replacement and unique species composition of each region indicates that, to fully conserve TDFs, we need to have various conservation areas distributed across the entire range of vegetation domains in which these forests can be found. Thus, we demonstrate that a landscape-wise planning is urgent and necessary in order to preserve tropical dry forests.
- Tiede, Y., J. Schlautmann, D. A. Donoso, C. I. B. Wallis, J. Bendix, R. Brandl, and N. Farwig. 2017. Ants as indicators of environmental change and ecosystem processes. Ecological Indicators. 83:527-537. doi:10.1016/j.ecolind.2017.01.029
Abstract Environmental stressors and changes in land use have led to rapid and dramatic species losses. As such, we need effective monitoring programs that alert us not only to biodiversity losses, but also to functional changes in species assemblages and associated ecosystem processes. Ants are important components of terrestrial food webs and a key group in food web interactions and numerous ecosystem processes. Their sensitive and rapid response to environmental changes suggests that they are a suitable indicator group for the monitoring of abiotic, biotic, and functional changes. We tested the suitability of the incidence (i.e. the sum of all species occurrences at 30 baits), species richness, and functional richness of ants as indicators of ecological responses to environmental change, forest degradation, and of the ecosystem process predation on herbivorous arthropods. We sampled data along an elevational gradient (1000–3000 m a.s.l.) and across seasons (wetter and drier period) in a montane rainforest in southern Ecuador. The incidence of ants declined with increasing elevation but did not change with forest degradation. Ant incidence was higher during the drier season. Species richness was highly correlated with incidence and showed comparable results. Functional richness also declined with increasing elevation and did not change with forest degradation. However, a null-model comparison revealed that the functional richness pattern did not differ from a pattern expected for ant assemblages with randomly distributed sets of traits across species. Predation on artificial caterpillars decreased along the elevational gradient; the pattern was not driven by elevation itself, but by ant incidence (or interchangeable by ant richness), which positively affected predation. In spite of lower ant incidence (or ant richness), predation was higher during the wetter season and did not change with forest degradation and ant functional richness. We used path analysis to disentangle the causal relationships of the environmental factors temperature (with elevation as a proxy), season, and habitat degradation with the incidence and functional richness of ants, and their consequences for predation. Our results would suggest that the forecasted global warming might support more active and species-rich ant assemblages, which in turn would mediate increased predation on herbivorous arthropods. However, this prediction should be made with reservation, as it assumes that the dispersal of ants keeps pace with the climatic changes as well as a one-dimensional relationship between ants and predation within a food-web that comprises species interactions of much higher complexity. Our results also suggested that degraded forests in our study area might provide suitable habitat for epigaeic, ground-dwelling ant assemblages that do not differ in incidence, species richness, functional richness, composition, or predation on arthropods from assemblages of primary forests. Most importantly, our results suggest that the occurrence and activity of ants are important drivers of ecosystem processes and that changes in theincidence and richness of ants can be used as effective indicators of responses to temperature changesand of predation within mega-diverse forest ecosystems.
- Wallis, C. I. B., G. Brehm, D. A. Donoso, K. Fiedler, J. Homeier, D. Paulsch, D. Sussenbach, Y. Tiede, R. Brandl, N. Farwig, and J. Bendix. 2017. Remote sensing improves prediction of tropical montane species diversity but performance differs among taxa. Ecological Indicators. 83:538-549. doi:10.1016/j.ecolind.2017.01.022
Abstract Texture information from passive remote sensing images provides surrogates for habitat structure, which is relevant for modeling biodiversity across space and time and for developing effective ecological indicators. However, the applicability of this information might differ among taxa and diversity measures. We compared the ability of indicators developed from texture analysis of remotely sensed images to predict species richness and species turnover of six taxa (trees, pyraloid moths, geometrid moths, arctiinae moths,ants, and birds) in a megadiverse Andean mountain rainforest ecosystem. Partial least-squares regression models were fitted using 12 predictors that characterize the habitat and included three topographical metrics derived from a high-resolution digital elevation model and nine texture metrics derived from very high-resolution multi-spectral orthophotos. We calculated image textures derived from mean, correlation, and entropy statistics within a relatively broad moving window (102 m × 102 m) of the near infrared band and two vegetation indices. The model performances of species richness were taxon dependent, with the lowest predictive power for arctiinae moths (4%) and the highest for ants (78%).Topographical metrics sufficiently modeled species richness of pyraloid moths and ants, while models for species richness of trees, geometrid moths, and birds benefited from texture metrics. When more complexity was added to the model such as additional texture statistics calculated from a smaller moving window (18 m × 18 m), the predictive power for trees and birds increased significantly from 12% to22% and 13% to 27%, respectively. Gradients of species turnover, assessed by non-metric two-dimensional scaling (NMDS) of Bray-Curtis dissimilarities, allowed the construction of models with far higher predictability than species richness across all taxonomic groups, with predictability for the first response variable of species turnover ranging from 64% (birds) to 98% (trees) of the explained change in species composition, and predictability for the second response variable of species turnover ranging from 33%(trees) to 74% (pyraloid moths). The two NMDS axes effectively separated compositional change along the elevational gradient, explained by a combination of elevation and texture metrics, from more subtle, local changes in habitat structure surrogated by varying combinations of texture metrics. The application of indicators arising from texture analysis of remote sensing images differed among taxa and diversity measures. However, these habitat indicators improved predictions of species diversity measures of most taxa, and therefore, we highly recommend their use in biodiversity research.