Oil palm expansion into rain forest greatly reduces ant biodiversity in canopy,epiphytes and leaf-litter

Oil palm cultivation is expanding rapidly into many of the world's most biodiverse tropical regions. One of the most functionally important and ecologically dominant animal groups in these environments is the ants. Here, we quantify the overall impacts of clear-felling lowland dipterocarp rainforest and conversion into oil palm plantation on ant diversity. At study sites in Sabah, Malaysia we collected ants from three microhabitats: 1 – the canopy, 2 – bird's nest ferns (Asplenium nidus complex, a common epiphyte in forest and oil palm), and 3 – leaf litter. We also measured temperature, humidity and light at collection sites to assess their impacts on ant community composition. Total ant species richness decreased from 309 to 110 (?64%) between forest and oil palm plantation. However, this impact was not the same across all microhabitats, with bird's nest ferns maintaining almost the same number of ant species in oil palm compared to forest (forest-oil palm, ferns: 36–35 (3% loss), canopy: 120–58 (52% loss), leaf litter: 216–56 (74% loss)). Relative abundance distributions remained the same for fern-dwelling ants, but became less even for oil palm ants in both the canopy and the leaf litter. These differences may be due in part to the ability of bird's nest ferns to provide a stable microclimate in hot, dry plantations. We also found that non-native ant species were more abundant in oil palm than in forest, and few forest ant species survived in plantations in any of the microhabitats. Only 59 of the 309 forest species persisted in oil palm plantations, corresponding to an 81% loss of forest species resulting from habitat conversion. Although oil palm supports many more ant species than has been previously reported, converting forest into plantation still leads to a dramatic reduction in species richness. The maintenance of forested areas is therefore vital for the conservation of ant biodiversity.     

The influence of nest availability on the abundance and diversity of twig-dwelling ants in a Papua New Guinea forest

Tropical ant communities are frequently diverse, but highly patchy in nature. The availability of suitable nest sites may be a regulating force in structuring litter ant communities. Our aim was to examine ant resource utilization in naturally occurring twigs, and to modify the availability of these resources in order to quantify the influence of nest availability on ant communities in a Papua New Guinean forest. First, we compared ant communities that assemble in artificial twigs (drilled, wooden dowels), naturally occurring twigs, and the leaf litter. A total of 55 ant species were captured: 33 from the leaf litter, 29 from naturally occurring twigs, and only 12 from artificial nests. Significantly different communities formed in each of the three nest types. Second, we examined how the density of natural or artificial nest material influenced the ant abundance and species richness. Plots had between 5 and 96 potential nest sites. An average of only 11.2% of these twigs was colonized. Both species richness and the total abundance of adult ants were significantly positively correlated with increasing naturally occurring twig density. Conversely, increasing the availability of artificial nests from 5 to 20 per plot had no significant effect on the proportion of artificial nests colonized, species richness, or the colony size. We observed that ant species richness and abundance increased with natural twig density, at least for naturally occurring communities. But why so many twigs remain vacant and available for ant colonization remains unknown. Other biotic and abiotic factors likely influence the use of nesting habitat in these ant communities.     

云南橡胶林和天然次生林枯落物层蚂蚁物种多样性、群落结构差异及指示种

橡胶树Hevea brasiliensis是云南省重要的经济林木, 但对其生态服务功能尚存在争议。本研究以天然次生林为对照, 使用Winkler法对橡胶林枯落物层蚂蚁进行初步研究, 探讨橡胶林枯落物层蚂蚁的生态状况。于2012年10月和2013年4月采用Winkler袋法调查了云南省绿春县大黑山乡橡胶林和牛孔乡天然次生林枯落物层蚂蚁群落的物种多样性、 群落结构差异及指示种。结果表明： 橡胶林枯落物层蚂蚁多度（转换后）、 物种丰富度S和ACE值显著低于无干扰的天然次生林（P<0.05）; 蚂蚁多度（转换后）显著低于有干扰的天然次生林（P<0.05）, 而物种丰富度S和ACE值差异不显著。橡胶林枯落物层蚂蚁群落结构与两种天然次生林都不相似（F=3.93, df=12, P<0.01）。橡胶林中流浪种大头蚁属Pheidole的蚂蚁种类与天然次生林相比, 物种丰富度增加了100%。天然次生林枯落物层中蚂蚁指示种有3种, 分别为刘氏隆头蚁Strumigenys lewisi、 黄足厚结猛蚁Pachycondyla luteipes和女娲角腹蚁Recurvidris nuwa, 而橡胶林枯落物层中指示种仅为菱结大头蚁Pheidole nodus。枯落物层蚂蚁物种多样性与枯落物厚度呈显著正相关, 而枯落物盖度仅与蚂蚁多度（转换后）有相关性。结果说明, 橡胶林经过长期的经营管理, 生态环境趋于稳定, 对枯落物层蚂蚁群落具有一定的保护作用, 但与天然次生林相比, 蚂蚁多度（转换后）及群落结构仍显示出明显的不同。     

Influences on the structure of suburban ant (Hymenoptera: Formicidae) communities and the abundance of Tapinoma sessile

Urbanization can alter the organization of ant communities and affect populations of urban pest ants. In this study, we sampled ant communities in urban and suburban yards to understand the habitat factors that shape these communities and influence the abundance of a common pest species, Tapinoma sessile (Say). We used pitfall traps to sample ant communities and a combination of pitfall traps and baiting to collect T. sessile at 24 sites in Knoxville, TN. In total, we collected 46 ant species. Ant species richness ranged from seven to 24 species per yard. Ant species richness tended to be lowest near houses, whereas T. sessile abundance was highest near houses. The best predictors of ant species richness in yards were canopy cover and presence of leaf litter: ant species richness peaked at mid-levels of canopy cover and was negatively correlated with the presence of leaf litter. Tapinoma sessile abundance increased with presence of logs, boards, or landscaping timbers and leaf litter in yards. Our results indicate that ant communities and the abundance of particular pest species in these urban and suburban landscapes are shaped by many of the same factors that structure ant communities in less anthropogenically disturbed environments.     

Can ants be used as indicators of environmental impacts caused by arsenic?

We evaluated ants as bioindicators of environmental impacts caused by arsenic residuals in the soil. We tested the hypotheses that the presence of arsenic in the soil affects: (1) estimates of resources and habitat condition for arboreal and epigaeic ants; (2) species richness of arboreal and epigaeic ants and (3) arboreal and epigaeic ant species composition. Ants were sampled at an inactivated raticide factory in Nova Lima, Minas Gerais, Brasil, which used arsenic as one of its main byproducts. The following environmental variables were measured: bioavailable arsenic concentration in the soil, the number and density of tree species, plant cover and leaf litter depth. The species richness of arboreal ants decreased with increased bioavailable arsenic concentration whilst epigaeic ants increased with arsenic. Arboreal ants were positively related to the number of tree species, which in turn were negatively affected by arsenic. We verified which ants are good bioindicators of arsenic. Independent verification of the influence of arsenic on background environmental variables was fundamental in defining responses of ant communities, as well as in identifying the most effective pathways for the recovery of biological communities in degraded areas.     

Evaluating community effects of a Keystone Ant,Azteca sericeasur,on Inga micheliana leaf litter decomposition in a shaded coffee agro-ecosystem

Our research examined the effect of Azteca sericeasur, a keystone arboreal ant, on the decomposition of leaf litter of the shade tree, Inga micheliana, in coffee agro-ecosystems. This interaction is important in understanding spatial heterogeneity in decomposition. We hypothesized that A. sericeasur could affect leaf litter decomposition by excluding other ants, which could release decomposers, like collembolans, from predation pressure. Determining the relative strengths of these interactions can illuminate the importance of A. sericeasur in decomposition and nutrient cycling processes. We assessed the ant and arthropod communities surrounding 10 pairs of trees, where each pair included one shade tree with an established A. sericeasur nest. Tuna baits were used in conjunction with pitfall traps to assess the ant and arthropod community, and litterbags with I. micheliana leaf litter were used to assess rates of decomposition. The species richness of ants did not change in proximity to A. sericeasur nests, though the ant communities were distinct. Abundance of Collembola and community composition of other invertebrates did not change in the presence of A. sericeasur nests, and there were no differences in leaf litter decomposition rates. This contradicts past studies that suggest A. sericeasur reduces ant species richness in its territory. We suggest that other ants may avoid A. sericeasur by moving within and beneath the leaf litter. Our results indicate that there is no net effect of A. sericeasur on leaf litter decomposition.     

Effects of habitat complexity on ant assemblages

We investigated responses of ant communities to habitat complexity, with the aim of assessing complexity as a useful surrogate for ant species diversity. We used pitfall traps to sample ants at twenty-eight sites, fourteen each of low and high habitat complexity, spread over ca 12 km in Sydney sandstone ridge-top woodland in Australia. Ant species richness was higher in low complexity areas, and negatively associated with ground herb cover, tree canopy cover, soil moisture and leaf litter. Ant community composition was affected by habitat complexity, with morphospecies from the genera Monomorium, Rhytidoponera and Meranoplus being the most significant contributors to compositional differences. Functional group responses to anthropogenic disturbance may be facilitated by local changes in habitat complexity. Habitat complexity, measured as a function of differences in multiple strata in forests, may be of great worth as a surrogate for the diversity of a range of arthropod groups including ants.     

Ant diversity as a direct and indirect driver of pselaphine rove beetle (Coleoptera: Staphylinidae) functional diversity in tropical rainforests,Sabah, Malaysian Borneo

Pselaphinae is a species‐rich beetle subfamily found globally, with many exhibiting myrmecophily—a symbiotic association with ants. Pselaphine–ant associations vary from facultative to obligate, but direct behavioral observations still remain scarce. Pselaphines are speciose and ecologically abundant within tropical leaf litter invertebrate communities where ants dominate, implying a potentially important ecological role that may be affected by habitat disturbances that impact ants. In this study, we measured and analyzed putative functional traits of leaf litter pselaphines associated with myrmecophily through morphometric analysis. We calculated “myrmecophile functional diversity” of pselaphines at different sites and examined this measure's relationship with ant abundance, in both old growth and logged rainforest sites in Sabah, Borneo. We show that myrmecophile functional diversity of pselaphine beetles increases as ant abundance increases. Old growth rainforest sites support a high abundance of ants, which is associated with a high abundance of probable myrmecophilous pselaphines. These results suggest a potential link between adult morphological characters and the functional role these beetles play in rainforest litter as ecological interaction partners with ants.     

Ants on the Move: Resource Limitation of a Litter‐nesting Ant Community in Costa Rica1

The leaf litter of tropical wet forests is replete with itinerant ant nests. Nest movement may help ants evade the constraints of stress and disturbance and increase access to resources. I studied how nest relocation and environmental factors may explain the density, size, and growth of leaf litter ant nests. I decoupled the relationships among litter depth, food abundance, and nest availability in a 4‐mo manipulation of food and leaf litter in a community of litter‐nesting ants in a lowland wet forest in Costa Rica. Over 4 mo, 290 1 m² treatment and control plots were sampled without replacement. Nest densities doubled in response to food supplementation, but did not decrease in response to litter removal or stress (from litter trampling). The supplementation of food increased the utilization of less favored nesting materials. In response to food supplementation and litter trampling, arboreal ants established nests in the litter, and growth rates of the most common ants (Pheidole spp.) increased. Colony growth was independent of colony size and growth rates of the most abundant ants. In general, I conclude that litter‐nesting ant density is driven primarily by food limitation, that nest relocation behavior significantly affects access to resource and the demographic structure of this community, and that nest fission may be a method to break the growth–reproduction trade‐off.     

Disentangling the Diversity of Arboreal Ant Communities in Tropical Forest Trees

Tropical canopies are known for their high abundance and diversity of ants. However, the factors which enable coexistence of so many species in trees, and in particular, the role of foragers in determining local diversity, are not well understood. We censused nesting and foraging arboreal ant communities in two 0.32 ha plots of primary and secondary lowland rainforest in New Guinea and explored their species diversity and composition. Null models were used to test if the records of species foraging (but not nesting) in a tree were dependent on the spatial distribution of nests in surrounding trees. In total, 102 ant species from 389 trees occurred in the primary plot compared with only 50 species from 295 trees in the secondary forest plot. However, there was only a small difference in mean ant richness per tree between primary and secondary forest (3.8 and 3.3 sp. respectively) and considerably lower richness per tree was found only when nests were considered (1.5 sp. in both forests). About half of foraging individuals collected in a tree belonged to species which were not nesting in that tree. Null models showed that the ants foraging but not nesting in a tree are more likely to nest in nearby trees than would be expected at random. The effects of both forest stage and tree size traits were similar regardless of whether only foragers, only nests, or both datasets combined were considered. However, relative abundance distributions of species differed between foraging and nesting communities. The primary forest plot was dominated by native ant species, whereas invasive species were common in secondary forest. This study demonstrates the high contribution of foragers to arboreal ant diversity, indicating an important role of connectivity between trees, and also highlights the importance of primary vegetation for the conservation of native ant communities.     

A comparison of pitfall traps with bait traps for studying leaf litter ant communities.

A comparison of pitfall traps with bait traps for sampling leaf litter ants was studied in oak-dominated mixed forests during 1995-1997. A total of 31,732 ants were collected from pitfall traps and 54,694 ants were collected from bait traps. They belonged to four subfamilies, 17 genera, and 32 species. Bait traps caught 29 species, whereas pitfall traps caught 31 species. Bait traps attracted one species not found in pitfall traps, but missed three of the species collected with pitfall traps. Collections from the two sampling methods showed differences in species richness, relative abundance, diversity, and species accumulation curves. Pitfall traps caught significantly more ant species per plot than did bait traps. The ant species diversity obtained from pitfall traps was higher than that from bait traps. Bait traps took a much longer time to complete an estimate of species richness than did pitfall traps. Little information was added to pitfall trapping results by the bait trapping method. The results suggested that the pitfall trapping method is superior to the bait trapping method for leaf litter ant studies. Species accumulation curves showed that sampling of 2,192+/-532 ants from six plots by pitfall traps provided a good estimation of ant species richness under the conditions of this study.     

The truncated bell: an enigmatic but pervasive elevational diversity pattern in Middle American ants

Studies on elevation gradients in Panama and Costa Rica have shown that leaf‐litter ants exhibit a mid‐elevation peak in diversity. This diversity pattern has been observed in other groups and regions, but uncertainty remains as to just how pervasive it is and what might explain it. Here we examine the robustness of the mid‐elevation peak in ant diversity across the entire Middle American corridor, from Veracruz, Mexico, to Costa Rica. We sampled 56 sites distributed throughout Middle America. All were in closed‐canopy evergreen wet forest, spanning 11° latitude, from near sea level to 2600 m elevation. Ants were extracted from 100 litter samples from each site and identified to genus or species. Model selection was performed on richness and diversity variables to test if ant diversity best fits a linear model or one allowing for a mid‐elevation peak. Linear models were also used to examine the relationships among diversity measures and temperature, precipitation, and seasonality. Species richness measures and diversity indices that incorporate relative abundance show a similar relationship to elevation throughout the region: a truncated bell curve with a mode near 400 m. A cubic relationship is statistically favored over quadratic or linear. Temperature is a significant correlate with diversity, but does not predict a bell‐curve. Precipitation and precipitation seasonality fail to explain much of the variability, and no combination of environmental variables predicts a bell curve. Potential causes of the truncated bell curve include lowland biotic attrition, mid‐point attractors, and ecotonal transitions from lowland to montane communities. Analysis of 17 subclades within ants mostly showed the same truncated curve but six clades were anomalous. Distinctive behavioral or historical features potentially explain their patterns.     

Litter Biomass and Nutrient Determinants of Ant Density, Nest Size, and Growth in a Costa Rican Tropical Wet Forest

The nutritional demands of animals vary by taxon. Across landscapes, communities of animals experience variability in the stoichiometry of carbon and nutrients within their resource base. Thus, we expect stoichiometry to contribute to the spatial variance in the demographic parameters of animal communities. Here, we measure how the composition of a litter-nesting tropical rainforest ant community is influenced by spatial variation in environmental stoichiometry relative to litter biomass, a known predictor of ant density. We found the density of ants and their nests were strongly related to litter biomass and carbon: phosphorus stoichiometry. The spatial variation in soil nutrients, which determines leaf litter stoichiometry, was an excellent predictor of nest size in the two most common genera of ants. We found a negative relationship between species' growth rate and local soil stocks of phosphorus. Overall, the density of litter-dwelling ants varied greatly across this tropical forest landscape and environmental stoichiometry can account for limits on ant density independent of the biomass of the leaf litter resource base.     

千岛湖陆桥岛屿地表蚂蚁群落物种多样性空间格局及其影响因素

为了探讨千岛湖岛屿景观参数对地表蚂蚁群落物种α和β多样性空间格局的影响, 作者分别于2017和2018年的5-8月, 采用陷阱法、凋落物分拣法和手捡法调查了千岛湖33个岛屿上的地表蚂蚁群落, 并依据食性将其划分为捕食性蚂蚁和杂食性蚂蚁。利用回归模型分析了全部蚂蚁、捕食性蚂蚁和杂食性蚂蚁群落α和β多样性与岛屿景观参数的关系。结果表明, 岛屿面积对全部蚂蚁、捕食性蚂蚁和杂食性蚂蚁的物种丰富度均有显著的正向影响, 而隔离度则无显著作用。蚂蚁群落的β多样性由空间周转组分主导。岛屿面积差对全部蚂蚁、捕食性蚂蚁和杂食性蚂蚁群落β多样性的嵌套组分有正向影响, 隔离度差只对杂食性蚂蚁的总体β多样性有正向影响。因此, 岛屿面积是影响千岛湖地表蚂蚁群落物种丰富度的主要因素, 并且岛屿面积通过嵌套组分来影响蚂蚁群落的β多样性, 表现出选择性灭绝过程。此外, 不同食性蚂蚁可能因为扩散能力的差异对岛屿景观参数产生不同的响应。     

Ant Diversity and Abundance along an Elevational Gradient in the Philippines1

Ant communities were surveyed along an elevational gradient in the Philippines extending from lowland dipterocarp forest (250 m elevation) to mossy forest (1750 m). Standardized pitfall trapping in arboreal and terrestrial microhabitats at seven sites yielded 51 species. Collecting by hand at five of the sites yielded 48 species. The two methods produced substantially different assemblages, with only 22 species (29%) taken in common. Only a fraction of the total ant community appeared to be sampled at most of the sites. Measures of species richness and relative abundance peaked at mid-elevations and declined sharply with increasing elevation. Ants were extremely rare above 1500 m elevation. Arboreal ants were trapped much less frequently than terrestrial ants at all sites. Ant species that were abundant had broader elevational distributions than those that were less common, but most species were rare and occurred at only one or two sites. The elevational patterns for ants are largely the inverse of those documented for Philippine small mammals which reach their greatest diversity and abundance at high elevations where ants are rare. This suggests that the two groups may interact competitively. Some of the patterns observed or inferred from this study may apply to tropical ant communities in general, and are presented as series of testable hypotheses as a guide and stimulus for future research.     

Effects of management intensity on ant diversity in cocoa plantation (Oume,centre west Côte d’Ivoire)

Anthropogenic habitat modifications, including conversion of forest to agricultural production cause losses of native species. In this study we examined the losses suffered by ant communities in relation to the intensity of management in cocoa plantations established in former tropical forest. An extensive sampling protocol consisting of pitfall trapping, leaf litter sampling, soil sampling and hand sampling was used to characterize ant species richness and composition in the native forest and compare it with three cocoa farms differing in their management intensity. Species richness was negatively correlated with management intensity and differed greatly between management practices and the forest. Two subfamilies (Myrmicinae and Amblyoponinae) showed a significant negative correlation with agricultural intensification probably because their species are constrained to living in forest like habitat. The species composition differed greatly between management practices and the forest. Intensively and moderately managed cocoa plantations were most dissimilar to the forest. In contrast, forest ants were well represented in the least intensively managed plantation. Overall, the findings of this study show that only slightly managed cocoa plantations sustain an ant diversity that comes close to that of the forest. This also holds true for cocoa plantations on former agricultural, and thus previously heavily used, land. The findings may help in the conservation of biodiversity as management practices most likely to sustain forest like ant communities have been identified.     

Spatial structure of litter-dwelling ant distribution in a subtropical dry forest

Understanding the spatial patterns of species distribution is essential to characterize the structure of communities, to optimize species inventories and to evaluate the impact of biotic and abiotic variables. Here we describe the spatial structure of the distribution of leaf litter ant species, and of biotic factors that could explain it, in a subtropical semi-deciduous forest of the Argentinian Chaco, characterized by a dense understorey of shrubs and terrestrial bromeliads. Environmental variables (leaf litter quantity and ground bromeliad density) were measured and ants were collected in 1 m² quadrats distributed along two 200 m transects at intervals of 1.25 m. Overall 87 species were collected. Sixteen positive associations and a single negative association were observed between the 11 most frequent species taken pair-wise. Our results suggest that the spatial distribution of leaf litter ants was determined at two different scales. At a small scale (period below 10 m) a periodic spatial structure, likely due to intraspecific competition, produced a succession of peaks of abundance separated by gaps. At a larger scale (period around 50 m), periodically distributed environmental factors induced aggregates of colonies of species responding positively to these factors. A high quantity of leaf litter and, to a lesser extent, a high density of ground bromeliads promoted a high density and a high species richness of ants. Numerically dominant ants being generally positively associated, interspecific competition was apparently weak. All ant species whose abundance was correlated with an environmental factor were not completely spatially structured by it. This suggests that some other factors, such as intraspecific competition, may have counter-effects. Received 14 March 2005; revised 26 April 2005; accepted 10 May 2005.     

Contribution of cocoa plantations to the conservation of native ants (Insecta: Hymenoptera: Formicidae) with a special emphasis on the Atlantic Forest fauna of southern Bahia,Brazil

By maintaining a forest-like structure, shaded cocoa plantations contribute to the conservation of ants that usually live in the soil, leaf litter or canopy of tropical forests. Here we synthesize the available information on the diversity and community structure of ants in shaded cocoa plantations in the Atlantic forest region of Brazil, compare ant assemblages in cocoa agroforests with forests and other forms of agriculture, and discuss how these shaded plantations contribute to the conservation of the ants in the Atlantic Forest region. We also discuss ants of economical importance and of special interest, including Camponotus, Dolichoderus, Gnamptogenys, Pachycondyla, Pseudomyrmex and other litter dwelling genera. We discuss the situation of the tramp ant Wasmannia auropunctata in the Bahian cocoa-producing region where it is considered as native, and that of the two cryptobiotic genera Thaumatomyrmex and Typhlomyrmex, as well as that of proven and possible endangered army ant and Ponerini species. A total of 192 ant species from four strata were found in extensive sampling of a cocoa plantation with a relatively simple shade canopy (comprised primarily of Erythrina). Species richness in the cocoa plantations corresponded roughly to that of low diversity native forests, and species composition of cocoa plantations was most similar to native habitats (forest and mangroves) while ant composition in other agricultural habitats was most similar to that of urban areas. Although occurrences of Wasmannia auropunctata were similar in cocoa plantations and forests, abundance of Thaumatomyrmex and Typhlomyrmex, generally thought to be rare ants, was relatively high in cocoa plantations. These results, from cocoa plantations with relatively simple shade, demonstrate the importance of cocoa for ant conservation in the Atlantic forest region of Brazil. It is likely that cocoa plantations with a greater number of vegetation strata and higher tree species richness (such as traditional cabruca plantations) provide even more important habitat for ants generally and for ant species of conservation concern.     

Ant mosaics occur in SE Asian oil palm plantation but not rain forest and are influenced by the presence of nest‐sites and non‐native species

Interaction networks within biotic communities can be dramatically altered by anthropogenic habitat modification. Ants, an important ecological group, often interact competitively to form mosaic‐like patterns in disturbed plantation habitats, in which dominant species form mutually exclusive territories. However, the existence of these ant mosaics in pristine forests is contentious. Here we assess the relative strengths of ant competitive interactions in oil palm plantation and primary rain forest in Sabah, Malaysia, using null models of species co‐occurrence. We use two metrics: the C‐score, which measures mean degree of overall co‐occurrence, and a novel metric, the C_var‐score, which measures the variance in degree of co‐occurrence. We also investigate the role of nest sites by collecting ants from canopy and leaf litter microhabitats, and from epiphytic ferns, an important nest site for canopy ants. Furthermore, we assess whether non‐native species, which were widespread in oil palm plantation (61 occurrences vs five in rain forest) are important in driving the formation of ant mosaics. We found no evidence for ant mosaics in any primary forest microhabitat. In oil palm plantation, segregation between species was pronounced in epiphytes, weak in the rest of the canopy and absent in leaf litter communities. Intriguingly, exclusion of non‐native ant species from analyses increased the degree of negative species co‐occurrence in all three microhabitats, with species segregation in the oil palm canopy becoming statistically significant. Our results suggest that invasion of plantation habitats by non‐native species does not drive increased species segregation in ant communities. Rather, high degrees of species segregation might relate to changes in the importance of canopy nest sites, with colonies competing more strongly for these in plantations. In primary forests, weaker nest‐site limitation and the highly complex, more vertically stratified, non‐uniform canopy could lead to random co‐occurrence between ant species at the scales studied here.     

Comparison of leaf litter ant communities in woodlands, lowland forests and montane forests of north-eastern Tanzania

Ants were extracted in Winkler bags from sifted leaf litter sampled in arange of forest and woodland types in and around Mkomazi Game Reserve innorth-eastern Tanzania, including the Eastern Arc Mountains of South Pare andWest Usambara. A total of 87 ant species were recorded, of which 32.2% were onlyrecorded from montane forests (1400–1850 m altitude), 6.9%only from lowland forest (540–810 m), 19.5% only fromwoodland (300–1080 m), and 16.1% in all three forest types.Of the 28 species recorded only from montane forests, 12 species were only foundin the Mkomazi forests, four only in the Pares and seven species only in theUsambaras. Sites of similar altitude grouped together in a cluster analysis, andspecies richness decreased with an increase in altitude. The lowland forest andclosed woodland sites did not form distinct communities. To ensure preservationof ant species, forests from a full range of altitudes need to be conserved.This study confirms the status of the West Usambara forests as having a highlyendemic biota, and the critical need to adequately conserve the remainingvestiges of montane forest within Mkomazi Game Reserve.